Smart Seis Version c

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SmartSeisExploration

Seismograph26325-01 Rev. C

Operation ManualCopyright 8March 2000

GEOMETRICS, INC.2190 Fortune Drive, San Jose, CA 95131 USAPhone 408-954-0522, Fax: 408-954-0902

E-mail: [email protected]


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SmartSeis Seismograph Owners Registration

Copy this page, fill in the information, and mail it to Geometrics when you receive this

instrument and again whenever the operator of this instrument changes so that we can provide

updates to the system software and this manual.

Users Name ______________________________ Telephone __________________________

Company ________________________________ Fax ________________________________

Address _________________________________ E-mail _____________________________

__________________________________ Date Received _______________________

__________________________________ Serial Number _______________________

First Registration New User

Country _________________________________ Change of Address


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SmartSeis Operating Manual Page i-1 Introduction

Introduction

The SmartSeisis unlike any earlier seismograph. It is easy to use and it gives you answers in

the field; features made possible by an internal computer programmed to help you solve your

problems in looking beneath the surface.

New users will be pleased to find a tutorial which may be viewed when the seismograph is

turned on. A menu bar makes it easy to set up the instrument to take and display your data. The

menus include an option for "standard settings" which will be adequate for any initial refraction

survey. Use these first to avoid grappling with unfamiliar concepts or choices like "sample rate"

and "display gain". After you gain more experience, you can re-visit these concepts and

comfortably adapt the instrument as your surveys become more complex.

Surprisingly, you will find that the SmartSeiscombines simplicity of use with remarkable

improvements in capability. The SmartSeis, with its 16-bit precision and 100-dB dynamic

range, is a high-performance exploration seismograph, applicable to reflection, refraction,

borehole and other specialized seismic surveys.

To expand on these capabilities, the system stores its data on either floppy disk or hard disk. The

recording media are DOS compatible, and may be read on any DOS-compatible computer

equipped with the same storage device. The computer built in is equivalent to an IBM AT

computer with 80386sx microprocessor. If you purchased the computer port option, it may also

be accessed with an external keyboard.

Depending on your level of experience, you may wish to proceed directly to Chapter 2 for an

abbreviated set of instructions (designed for experienced users), or start with Chapter 1 (which

provides an expanded tutorial). Appendix A contains a detailed explanation of the menus; while

the remaining appendices provide supplementary and reference information.

The SmartSeisSeismograph is a software controlled device which will receive periodic

enhancements. Thus, it is likely that the menus and operating instructions in this manual may

differ in minor respects from those on your instrument. As a general rule, operating menus will

be self-explanatory and this will not cause any inconvenience or confusion. There may be a

"README" file on the system disk containing updated information.

It is absolutely essential that we maintain a record of SmartSeisusers so that we can provide

you with periodic updates of this manual and the system operating software. Copy the user's

registration form and send it to us when you take possession of the instrument and whenever a

new user takes responsibility for the SmartSeisSeismograph. Please include comments on theinstrument and suggestions for improvements in this manual.


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SmartSeis Operating Manual Page 1-1 Complete Operating Instructions

Chapter 1. Complete Operating Instructions

This chapter is written for less experienced, or new users of exploration seismographs, but not

with the intent of teaching fundamental geophysics. However, the system has a tutorial which

includes basic principles. This tutorial is available when the system is turned on, offered as amenu selection. There are instructions included to print the tutorial for convenience.

Besides the tutorial, the operator should read the application literature sent with the instrument,

as well as standard textbooks on geophysics1.

This manual will focus on the hardware, its use, and a few things not found in textbooks. You

should also read Appendix A which explains operation of the menus, and Appendix B which

provides details on the actual hardware: seismograph, geophones, cables, etc.

If you consider yourself an experienced user of modern exploration seismographs, you may wish

to go directly to Chapter 2, which contains a condensed set of operating instructions.

For first time use, keep things simple. In fact, practice first in a comfortable office to gain

thorough familiarity with the menus and equipment. Then, the first survey should be done close

to home, with a sledgehammer source, and short geophone spread (say 10 ft or 5 meters between

geophones). This section will be written with this setup assumed, and the operator can

extrapolate this experience to more complex surveys and those using explosive sources.

Preparation

Before going to the field, see that paper is loaded in the printer. Open the case, then the front

panel (press the two latches on either side) and look at the paper supply. If necessary, load paper,using the instructions inside the front panel lid.

You will need a supply of 1.4-Mbyte, 3.5-inch floppy disks (these are the type labeled HD or

high density, not DD or double density) You can format these disks on a DOS-compatible

desktop computer or with the SmartSeis, or you can buy disks already formatted. Formatting

prepares the disks for recording data. The SmartSeiswill format disks in the field, but it's not a

good way to expend field time and battery power. Instructions for formatting disks on the

SmartSeiswill be found in Appendix A in the FILE-FORMAT section.

Setup

Unpack the system and gather your accessories. You will need a 12-volt battery if one was not

purchased with the system. Since the SmartSeisS12 only draws about 22amps (or 32amps

1For example, Exploration Geophysics of the Shallow Subsurface, by H. Robert Burger, 1992, published by Prentice Hall, ISBN

0-13-296773-1.


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for the SmartSeisS24), a medium capacity (say 20 to 30 amp-hour) battery should be

sufficient for a day in the field.

The SmartSeiswill normally be operated vertically; it is rain resistant in this position, and the

display is readily viewable. Do not leave the instrument exposed in a heavy rain. Place theSmartSeisup on a reasonably flat surface and remove the cover.

Spread the geophone cable in a line. Plant (by pressing the spike into the ground) a geophone by

each connector (called a takeout) on the cable. The geophone connectors will have a method to

encourage proper polarity (such as wide and narrow color-coded clips) connections. Connect the

geophones to their connectors, and the geophone cable to the seismograph. If you are using a

24-channel SmartSeisR24, you will locate the seismograph in the center of the line and use

two geophone cables and 24 geophones.

Connect the 12-volt battery with the red clip to positive and black clip to the negative lead. If the

connections are reversed, it will not damage the instrument, but it will not function.

Operation

Turn on the switch near the power connector. One of the light-emitting-diodes on the front panel

should light, indicating the battery voltage. Note and remember which LED lights for a fully

charged battery. As the battery charge is expended, the voltage will decrease and different LED's

will light. The transition will be particularly fast in the last few minutes of operation. The voltage

indicator will provide advance warning of battery discharge, as well as an aid in troubleshooting

power problems

Wait several seconds while the system powers up, conducts its internal tests and loads theseismic software. After the power up cycle, the screen should display a message or a set of

seismic traces.If the screen is blank or faint, adjust the display contrast with the two arrow keys

just above the battery level indicator.The display may be completely blank until the contrast is

adjusted. There is a backlight for the screen, which may be turned on or off, depending on which

gives the best display in the ambient lighting conditions. The backlight on-off control is in the

Display menu discussed below.

The screen will display a menu with the option of reading the tutorial, proceeding with

instrument setup, or using the prior setup.

To read the tutorial, just press the ENTER key when the "Tutorial Setup" is selected. You may

print a paper copy of the tutorial using the directions provided in the tutorial.

COMPLETE SETUP will take you directly to the menu used to select the operating parameters

TUTORIAL SETUP COMPLETE SETUP USE LAST SETTINGS


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of the seismograph. Several of the menus have a QUICK SETUP option at the top of the list.

These choices will be adequate for most refraction surveys, and are a good place to start.

Once you have used the system, you will use the USE LAST SETTINGS option. That means that

the controls are set as they were when the instrument was last used, as though your seismograph

had mechanical switches. It is not necessary to actually select this menu item, just pressing the

CLR key will turn off this menu and use the last settings.

Geometry

The term geometry is used to describe the locations of the geophones and the seismic energy

source. Since seismic data processing requires knowing the locations of these items, their

coordinates can be recorded with the data. The line geometry is also used by the ANALYZEfunctions, which you will see later can give you answers right in the field.

The system may have already asked you for the distance between geophones as part of the

power-up sequence. You also need to set the shot location. Press the MENU key. A menu bar

will appear on the screen with several choices in different categories.

One of the menu selections (DO_SURVEY) will be highlighted in reverse video, and a

secondary menu will be displayed below it. One of the secondary items (INSPECT ARRIVALS)

will be shown in reverse video. This secondary menu will be used routinely during actual

surveys, and thus it always appears first for your convenience. However, before starting to

survey, you need to set up the system.

When you first use your seismograph, position the cursor over the OTHER position. Set the

clock and calendar for your time zone, and set the units to meters or feet. Do this by positioning

the cursor over the item in the list, or press the matching number key. Follow the directions on

the screen to change the settings. If in doubt, refer the OTHER section in Appendix A.

Now set the line geometry. Position the cursor over GEOMETRY. Start with the QUICK

SETUP by pressing ENTER with the reverse video cursor over that position, or by pressing the

number 0. That will set the geometry to the default settings, including setting the mode to

refraction.

Next, set the phone interval (if needed), and go to the phone and shot locations menu. This menu

requires actual linear coordinates for the shotpoint and geophones, but it is easy to set by

exception. Point the cursor at the shot coordinate and enter the correct value (or use the default).

If you don't have a coordinate, then assign an arbitrary shot coordinate which will at least be

valid for all the shot points related to this particular geophone spread, and preferably for the

GEOMETRY ACQUISITION FILE DISPLAY DO_SURVEY ANSWERS OTHER


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entire survey line. Similarly, set the shot offset or any geophone location. If the distances

between the geophones are not equal, set these as appropriate. Follow the directions in the menu

or refer to Appendix A for further assistance. SHOT INTERVAL is only used for reflection

surveys, you may ignore this function temporarily.

Acquire Data

In seismic data acquisition, electrical signals from the geophones are amplified, digitized, and

stored in the seismograph's memory. The variables which affect the process are selected in the

ACQUISITION Menu. Wrong choices of acquisition parameters can be corrected by clearing the

memory and repeating the shot.

If you are using a hammer source, and summing multiple impacts, most of these settings should

not be changed between blows. Thus, the seismograph will not allow you to change those

parameters when data is in the memory. The memory must first be erased.

Use the arrow keys to point the cursor at the ERASE command and press ENTER. This will

erase any data in memory (it may already be erased). Next, use the arrow keys to move the

reverse video cursor to the ACQUISITION position, displaying the menu used to set the

acquisition parameters. Position the cursor over the QUICK ACQ SETUP command and press

ENTER. This will set the acquisition parameters to a commonly used set of default values.

Except for variations in the sample rate and record length, these are the basic settings for routine

refraction surveys, and they should be adequate for most surveys. Later on, as you gain more

experience, you might choose different settings for unusual surveys.

Engage the noise monitor by selecting NOISE DISPLAY in the DO_SURVEY menu. In the

NOISE DISPLAY mode, signals from the geophones are used to wiggle the traces on the screen.Use the up and down arrow keys to adjust the noise monitor sensitivity, until small excursions

are visible on the traces. These trace excursions represent the background vibrations sensed by

each geophone. The screen will display a set of moving traces, writing the noise record on the

screen. Stomp the ground and you should see a noise burst on the traces representing the

geophones closest to you. If there are two people present, one can walk the line while the other

observes the footsteps on the screen. This noise display is a useful diagnostic tool. You can

confirm that your cable and geophones are working properly, identify noise problems, and

usually schedule your shot during quiet periods.

Let the seismic noise settle a little, and look at the relative amplitudes of each trace on the noise

monitor display. If the geophones are all connected and properly planted, and if the cables aregood, all traces should look about the same. Unusually small or large excursions on any trace are

indicative of some problem that should be investigated. Disconnect a geophone to see the effect

of a problem.


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The level of background noise can be measured with the scale factor displayed on the screen just

above traces 1 and 2, and noted in the observer's log as a quantitative measure of background

noise.

Your next step is to generate the seismic wave and record it on the instrument. Use a metal plate(called a striker plate) as the impact point for the hammer. Place it on the ground near the end of

the string of geophones, separated by the distance set in the GEOMETRY menu (or, position the

plate and set the shot offset to the distance from the striker plate to the near geophone). Attach

the hammer switch to the hammer, taping it to the top edge of the handle near the head with

stretchy electrical tape. Tape the wire to the handle near the hammer switch, and again near the

end of the handle. Connect the hammer switch to the start connector on the seismograph. Since

working with the hammer will probably trigger the seismograph, clear the memory (in the DO

SURVEY menu) again.

The hammer blow should be timed for quiet periods (when background seismic vibrations

decrease) as monitored by the noise display. (The SmartSeiscan be triggered only when thedisplay is in "noise display" or "trace display"; you can prevent accidental triggers by selecting

any screen with a menu displayed). Advise anyone in the area to stand still and not talk while

recording data. Hit the striker plate to create a seismic impulse and trigger the seismograph.

The word SAMPLING on the top line will temporarily be displayed in reverse video, indicating

that the system was triggered. The digitized record is stored in the seismograph memory, and the

computer is processing the data display.

Data Display

After a few seconds, the noise monitor record will disappear and a seismic record will appear onthe screen (the data may not look right yet, perhaps there will be only straight lines, or wildly

overlapping traces). The Display Menu is used to control how the data looks on the screen. The

display functions may be changed at any time, since they do not affect the original data stored in

memory, only the way it looks on the screen (and the paper plot).

Press the MENU key and move the cursor to the DISPLAY menu. Select QUICK DISPLAY

SETUP and press ENTER. This will set the display parameters to a set of popular default values.

Press CLEAR to remove the menu from the screen and expose the traces. You should see a

seismic record on the screen. The record can be scrolled up or down on the screen by pressing

the up and down arrow keys. You can time specific events on the record by using any of the

three timing lines on the display.

Press the MENU key and the reverse video cursor will be positioned on the INSPECT

ARRIVALS command. Press ENTER. The seismograph will automatically adjust the traces,

pick the first arrivals (putting a marker on each trace) and position the traces so that the first

breaks are on the screen.


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There should be a collection of traces with excursions representing the vibrations at each

geophone. The trace for the geophone nearest the impact point should have clear, early arrivals.

First arrivals on traces from geophones further away should occur later and later in time.

Since the instrument is set to the refraction mode, you will be offered the option of manuallyediting the first break picks and saving these numbers on the active disk drive. Remember that

you should have the values in the geometry menu properly entered as part of this stored

information. It may be necessary to go to the DISPLAY menu and adjust the individual trace

sizes to make the picks easier to see and edit.

At this point, you may wish to

experiment a little with the

display functions to change the

look of the record and to gain

familiarity with the system. The

trace size adjustments control theexcursions of the individual

traces on the screen. If necessary,

use the TRACE SIZE ADJUST:

INDIVIDUAL function to adjust

the appearance of the display (see

Appendix A in you need

directions). TIME SCALE will

stretch the waveforms on the

screen, so that the first arrivals

are easier to pick, or compress

them so that more of the record isvisible on the screen.

Examination of the entire record

should also show surface waves

and perhaps signals from the

sound of the hammer striking the

plate (see Figure 1 for an

example). Use the up and down

arrow keys to scroll the display

on the screen if necessary.

Print

Make a paper copy by using the

PRINT command in the DO

SURVEY menu. To stretch or

Figure 1, Example seismic record, shown in wiggle-trace format and

compressed time scale.


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compress the printed record, use the PRINT TIME SCALE command in the DISPLAY menu

before printing. The NORMAL, EXPAND and COMPRESS functions change the time scale of

the record on the printer. These change the character of the seismic record, and the best choice

will depend on a particular data set and the type of information displayed. Expanding or

compressing the record can compensate for less than optimum choice of sample rate or recordlength. Experiment with these functions to see how they affect the character of the display. On

the SmartSeis, the print and display scales are independent, providing flexibility in use.

Notice the trace size multipliers above each trace. The numbers are different, with smaller

numbers for those traces near the impact point. Traces away from the impact point will have

larger trace size numbers. The trace size number is related to the amplification applied to the

original data to display the traces. Thus, a small signal (like that from the more distant

geophones) will require more amplification to make the excursions a usable size.

The numbers are in decibels, or dB, and they change in steps of 3 dB from 0 to 99. Each 3 dB

step is an increase of 1.414 times the previous value; 6 dB is 2 times. Thus, the trace sizeincrements in a logarithmic manner, providing a very wide range of adjustment. Reducing the

trace size decreases the excursions by .707 for 3 dB and 2for 6 dB. As a normal rule, you

need not concern yourself with these numbers, but they are diagnostic of certain problems. For

example, if a trace is "dead" (shows no excursions) and the trace size value is small, that means

that the trace size is turned down too small. If the number is large (say 99 dB), that means the

signal is very small, perhaps from a bad geophone or other cause.

As a learning exercise, you can compare the relative strength of the vibrations on each trace. Use

the TRACE SIZE control on INDIVIDUAL and adjust each number to the same value. Then, use

ADJUST ALL to increase or decrease all the traces simultaneously until the display is scaled to

the best value. The near traces will have very large excursions and the far traces will be straightlines. In this mode, it is easy to judge the attenuation of the seismic signal with distance from the

impact point. Make a copy if desired, then use the AUTO ADJUST and INDIVIDUAL trace size

options to return the traces to a normalized display.

Signal Enhancement

The distant traces may be noisy. A noisy seismic trace is caused when extraneous vibrations are

mixed with the signal, sometimes making it difficult to identify the first arrivals. These

vibrations come from wind, vehicles, airplanes, and people. Because the signal on the geophones

furthest from the seismic source are quite small, seismic noise is normally more of a problem on

the far traces.

When working with explosive sources, this is not generally a problem. If the signals are too

weak, you just use more dynamite the next time. That is not the case with a sledgehammer (and

other mechanical sources), you can only hit the ground with a certain amount of energy. To

extend the depth penetration attainable with a sledgehammer, the SmartSeiscan add signals


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from multiple hammer blows. This process is usually called "signal enhancement" or "summing"

or "stacking". The record is saved in the memory, and each time the ground is hit, the new data is

added to the old sum, and the signal grows. Ambient noise is random, and it does not increase as

much, so the "signal-to-noise" ratio improves as you strike the ground repeatedly. In practice, the

noise increases as the square root of the number of blows, while the signal increases linearly.Thus, the improvement is proportional to the square root of the number of impacts.

Try summing. Hit the striker plate again with the hammer. The record should grow larger as two

records are now stacked into the memory. Further impacts should cause the traces to continue to

grow. Traces that were noisy will still be noisy, but a larger seismic signal will be superimposed

on the record. Using the trace size adjustments will shrink the traces back near their original size,

and there should be much less noise now. First arrivals should be more distinct and easier to

pick, especially on those traces distant from the energy source.

Although the SmartSeisis designed to stack thousands of hammer blows without problems,

there is a practical limit to the improvement available from signal enhancement, usually around10 to 20 blows.

Freeze

FREEZE is used to lock in the data on individual channels. This stops the selected channels from

stacking or erasing. Freeze is often useful when working in noisy conditions where many

hammer impacts are needed to produce a usable record. Commonly, some traces will have good

first breaks and others will be noisy (random chance dictates that some channels will be bad).

Use freeze to save the good traces, then focus on the noisy weak channels individually or in

small groups.

Freeze is also used in specialized surveys, like "Optimum Window" reflections (where you

collect data on only one channel at a time) and borehole shear wave studies (where you might

activate two channels while hitting one end of a plank, then two others while you hit the other

end, then two others while you hit the top).

To try this function, return to the DO SURVEY menu, select FREEZE, them SOME. Use the

arrow keys to freeze some of the channels (see Appendix A for detailed instructions). The

channel numbers on the frozen traces will be displayed in reverse video. Clear the memory.

Notice that the frozen channels remained on the screen. Hit the ground a few times and observe

that the frozen channels do not change while the normal channels will change, growing with

each impact.

Unfreeze all the channels by selecting FREEZE in the DO_SURVEY menu, then "NONE" in the

sub-menu. Clear the memory with the ERASE function.

Other display modes


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The traces can be displayed on the screen several different types. The basic mode is wiggly lines,

each representing the motion of the ground at a geophone. This is the classic form of a

seismogram, and is called "wiggle trace" (or wriggle trace) as shown in Figure 1. Wiggle trace is

a good mode for getting an overview of the record, but less useful than the other modes for mostpurposes.

Once seismographs made the transition from analog to digital instruments, data was processed

on computers. Interpreters found that if you shaded the positive trace excursions black, it was

easier to see reflections in the record. The SmartSeisoffers this option, called "variable area"

or VAR AREA in the display menu. An example is shown in Figure 2. Variable area is generally

better for reflection surveys.

Notice however, that the variable

area shading turns much of the

record solid black, obscuringportions of the individual traces.

This suggests another option,

which has been called "shaded". In

shaded, the positive excursions are

shaded grey instead of black, and

you can see individual traces even

when they pass through the shaded

portion. Choose variable area or

shaded for reflection surveys,

depending on which works best for

an individual recording.

In refraction surveys, the first

arrival of the wave at the geophone

is the major event. In either

variable area or wiggle trace,

adjacent traces can swing over and

obscure the first arrivals. To solve

this problem, there is another mode

called "clipped". In this mode, the

traces are stopped just before they

get halfway to the next trace, and aflat top replaces the normal swing.

No trace can interfere with viewing

another, so this mode is preferred

for picking first arrivals for

refraction surveys. The traces look

Figure 2, Seiamic record display in Variable Area format.

Figure 3. Record with data displayed in "clipped wiggle".The trace

display gain has been increased to sharpen the first arrivals for better

" ickin ".


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strange, and you lose the character

of the later arrivals, but you don't

care, the information you want to

see is clearly visible, as in Figure

3. "Clipped" is available incombination with wiggle trace,

variable area or shading.

Although "Clipped" is a better

form for picking refraction records,

its tendency to obscure the

character of the wave makes it

difficult to use. To really see the

seismic picture, you need the

whole waveform, with background

noise, first arrivals, sound waves,and surface waves displayed.

Seeing the whole picture allows

you to predict the location of the

desired first arrivals almost

exactly, and you should work with

normal wiggle trace first, adjusting

the trace size for the best image.

Then, you can switch to the

clipped format to eliminate overlap

between traces. It will be very

helpful to have the data stored onfloppy disk, even though you may

have a pickable paper record in the

field.

Experiment with these options. Hit the ground with the hammer to produce a new record on the

screen. Change the display by switching the TYPE to each of the other combinations. Observe

the effect on the trace display. Print a copy if desired.

AGC


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Until now, the display was in fixed gain, which means that the trace size scale factor on a

particular trace is constant throughout the length of the record (though the scale factor on

individual traces may be different). Notice that each trace contains a quiet early portion, a large

signal as the vibrations pass the geophone, and then a quiet portion near the end. For manyapplications (particularly reflection surveys) you might wish to use a different gain at different

times in the record. The automatic gain control (AGC) performs this function, increasing or

decreasing the trace size to keep the excursions at some reasonable value throughout the record.

The particular type of AGC used in the SmartSeisis called "digital AGC". The average signal

in a section of the trace, called a "window", is used to adjust the trace size (larger or smaller) for

the data sample in the middle of the window time period. Then, the window is advanced slightly

and the adjustment repeated for the next data sample. Digital AGC is able to look ahead in time,

see a large signal coming, turn the trace size down

in advance, and properly display large first

arrivals. Look at the record in Figure 4. The veryearly portion of the record looks noisy on the far

traces. This is normal, since the AGC increases

the trace size until something shows, even if it's

only background noise. Then, as the window

advances to include the first arrivals, the gain is

decreased in anticipation. The process continues

throughout the record.

The length of the window (in data samples) can

be selected by the operator to fit the data set. For

very shallow reflection surveys, with highfrequency signals, the time should be relatively

short. For deep reflections, or if you choose to use

AGC on refraction surveys, use longer time

windows. As a general rule, adopting a standard

number of samples (say 250) will work for most

cases, correcting automatically when the sample

interval is changed.

Turn the AGC on, setting the window length to 250. Adjust the trace size (you always will need

to adjust the trace size when switching between AGC and Fixed Gain). The appearance of the

wave will be quite different than in the previous experiment. Identification of events in therecord now depends on the character of the wave and comparisons to adjacent traces (rather than

on amplitude).

Clear the memory and stack a few impacts with AGC on. Notice that much less adjustment is

required of the trace size with AGC operating. Turn off the AGC and readjust the trace sizes.

Sample of AGC data display

Figure Unavailable

Figure 4, Data display with AGC.


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Remember that AGC, like the rest of the DISPLAY menu items, has no affect on the original

data stored in memory, only on how it looks when displayed and plotted.

AGC is an advanced function, normally only used for reflection surveys, and new users should

used fixed gain trace display.

Once familiar with basic data acquisition and display, the operator should experiment with some

enhancements, described in the following section.

Use of the filters

Filters are like the tone control on a music system. Different frequencies (such as bass and treble

sounds) can be boosted or attenuated to affect the sound. Likewise, the filters in the SmartSeis

can attenuate low or high frequencies in the seismic record.

The seismic record will contain many different signals: refractions, reflections, surface waves,vibrations from traffic or wind, and other interference. Most of these are considered "noise" and

are undesirable. Some noise signals are different in frequency than the desired signals, and filters

may be used to improve the visibility of the desired signals. In particular, noise from a source

some distance away tends to be lower in frequency than seismic data (because the earth carries

the low frequency signals for long distances).

Some signals may be considered noise, even though they are not random. The prime example is

surface waves, which will grow with every hammer blow, but which can obscure useful

reflection arrivals. Surface waves are always lower in frequency than shallow reflections, and

you can use a lowcut filter to reduce them, letting the reflections appear.

Noise from wind may be either high frequencies (from wind blowing on the geophones) or low

frequencies (from wind blowing on trees or buildings, which then push on the ground). Different

types of filters can be used to reduce either type of noise.

The SmartSeisoffers two sets of filters: acquisition and display. The acquisition filters are

improved "real-time" digital filters which operate on the incoming data to the system just like

traditional analog filters. When data is acquired with acquisition filters, their effect becomes part

of the record stored in memory. The display filters on the other hand, are temporary. They

operate on the data after it is stored in memory, and the type and corner frequencies can be

changed to examine the effect of different filters on the stored data. When the display filters are

used, the filtered data is displayed on the screen and a paper copy can be plotted, but the originaldata is held in memory. If the record is saved on a disk, the original raw data is saved, not the

filtered result. This allows the user to select a different set of filters later when the data is

processed or read back into the SmartSeisfor analysis. It is generally better to use less filtering

when acquiring data, and more when displaying data, to preserve the option for later changes

during analysis.


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Lowcut filters are used to remove low-frequency signals (like surface waves, and noise from

distant traffic). Notch filters are used to reject interference from power lines. Highcut filters

attenuate higher frequencies, such as wind noise or nearby machinery. Each filter has an

effective frequency, called the corner frequency, which can be selected in the menu. Lowcutfilters attenuate frequencies below the corner, and highcut filters attenuate frequencies above the

corner frequency. Notch filters attenuate frequencies near their frequency, passing those above or

below.

To experiment with the display filters, return to the DISPLAY menu and select LOWCUT 50

HZ. Optimize the trace display and print a copy. Repeat the experiment with other, higher

frequency, lowcut filter settings. Compare the records from each filter (including the one made

earlier with no filter) to see the

effect of the lowcut filter. If there

is noise from a low frequency

source, it should get progressivelysmaller as higher frequency filters

are used. The first arrivals should

grow more distinct, and then later

fade away again as you pass into

the frequency range where they are

also filtered out.

There may be a range of filter

settings where reflections are

visible on the record. The low

frequency surface waves shoulddisappear when higher frequency

lowcut filters are used.

Figure 5 shows a record displayed

with a double lowcut filter. Using

the same filter twice doubles the

attenuation slope from 24

dB/octave to 48 dB/octave. This is

the same survey line used for the

previous examples; note that some

of the low-frequency surfacewaves have been removed and

some possible reflection events are

visible in the data at around 100

milliseconds.

Figure 5, Data plotted with double lowcut filter.


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Try the same experiment with the notch filters. These will be less dramatic in their effect on the

record and changes may not be visible at all unless there is some power line noise present.

Remember that ideally they will not change the character of the seismic record (although there is

always some change in the signal from removing 50 or 60 Hz information). Since 3-phase power

lines also radiate at three times the fundamental frequency, 150 and 180 Hz notch filters are alsoprovided.

Repeating the experiment with the highcut filters should show some reduction in high

frequencies, particularly at 250 Hz. This may be evidenced by rounding of first breaks or other

effects.

You will need to choose between acquisition and display filters. Acquisition filters have the

disadvantage of permanence, but the advantage of eliminating so-called edge effects at the

beginning and end of the record. In general, when a notch filter is required, it is better to select

one in the acquisition menu.

Using Preview for Discretionary Stack

Preview lets the operator inspect each new record before stacking it into memory. Commonly,

noise is transient; cars pass by, gusts of wind blow, so some individual records are better than

others. When operating at greater distances between the energy source and the far geophones, or

when working in areas with troublesome noise bursts, you can use preview to control which

records are stacked.

Turn the filters to OUT. Select PREVIEW in the STACK MODE Menu. Clear the memory and

hit the ground with the hammer. After a few moments, the screen will display a seismic record,

with a message in the corner of the screen advising the operator that this is preview data. Therecord may be accepted for stacking into memory (by pressing ENTER), or rejected (by pressing

CLEAR). Press ENTER to stack the data.

Try a few more times, selecting in each case. Try an intentionally noisy shot by moving your

body or having someone walk down the geophone spread as you hit the ground. The most

significant advantage of PREVIEW occurs when working in marginal conditions with say 10 or

20 hammer blows per shotpoint. After hitting the ground 19 times, the whole record can be lost if

a car goes by during the 20th stack. With PREVIEW, this problem can be eliminated.

Note that a similar function, UNSTACK, is available in the DO SURVEY menu. UNSTACK

will subtract the most recent record from memory.

Return STACK MODE to Autostack.


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Using Delay

Normally, the seismograph begins recording data instantly when the source triggers. The delay

function is provided to postpone the start of the record by a selected time. This is applicable to

surveys where there is a substantial distance between the shotpoint and the nearest geophone,and where there is no usable information in the early part of the record. One example might be

velocity logging of deep boreholes.

The delay can also be used to increase the effective record length by shooting sequential records

with and without a delay and then merging the files.

To test the delay, take a sample record as was done earlier. Print a copy. Then, enter a delay

equivalent to some point prior to a recognizable portion of the record. Repeat the shot with the

delay and compare the two records. Notice that the record made with the delay has not recorded

the early portion of the record, but has appended some additional time to the record. The timing

line times (and annotated time lines on the plotted record) are automatically adjusted for thedelay values, so times picked on the record are referenced to shot time.

Delay can also be set to a negative number, which means that the record will display some data

prior to the actual trigger. This is helpful when using an energy source which is difficult to time

precisely, such as a weight drop, or an air gun. One of the seismic channels can be connected to

the trigger signal or to a motion sensor near the source to record the signal. Routinely using a

little negative delay will help the automatic first break picking program do a better job.

Set the delay back to -10

Using negative stack polarity

The SmartSeisnormally adds a new record into memory. It will also subtract. This polarity

reversal is provided for the enhancement of shear waves, a special type of survey.

Shear wave surveys are conducted by using a directional source which impacts perpendicular to

the axis of the survey line (horizontal geophones are generally used). For confirmation, the

direction of impact of the source is reversed, which creates shear waves of the opposite polarity.

The SmartSeisstack polarity can be reversed at the same time, so that the shear waves will

enhance and P-waves tend to cancel, providing an optional method of conducting shear wave

surveys in difficult conditions.

Since the principles involved are not important in learning to operate the SmartSeis, an actual

shear wave survey should be deferred until a need exists. To test the process, try stacking a

hammer blow in the normal mode, then invert the polarity and stack again. The seismic

waveforms should tend to cancel, leaving just noise on the record.


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Negative stack polarity may also be used to invert, or reverse the polarity of the record. If you

prefer your first breaks to move up instead of down, or vice versa.

Reducing the number of acquisition channels

The number of channels in use may be reduced when not needed. In borehole surveys, it is

common to use only three geophones (or even one). Reducing the number of channels limits the

amount of memory required, so that more records may be stored on a single disk.

To change the number of channels, use the ACTIVE CHANNELS menu. A list of channels will

appear; use the arrow keys to select and de-activate the unused channels, referring to Appendix

A if necessary.

Storing data

If you used a seismograph before, chances are that your result was a paper plot which you tookhome, picked the arrivals, analyzed, and interpreted. If that is the case, you know that records

which looked fine in the field suddenly develop poor first arrivals. Perhaps even the location was

uncertain. The SmartSeiswill save the digital records on a disk. Once saved, it can be read

back into memory, or read and displayed on a personal computer. This can be extremely useful,

even for ordinary refraction surveys, since the records plotted in the field are never optimum and

often difficult to pick. Plotting the records again in the office, picking them from the screen or an

optimized paper plot, is a great improvement. Automatic refraction analysis on the computer is

an even greater benefit. Of course, digital recording and processing is required for reflection

surveys.

As with other operating procedures, this is simple with the SmartSeis, although experienceoperating DOS compatible computers is helpful in understanding drive selection and directories.

Insert a disk in the 3.5-inch drive behind the side cover. Be sure that the disk is not write

protected, by sliding the tab to cover the hole. Engage the Menu; position the Cursor over FILE.

Check the CHANGE DRIVE status. If necessary, set to Drive A:.

Return the acquisition parameters to the initial settings used earlier and acquire a record. Look at

the record on the screen (and print a copy if desired). Position the cursor over the DO SURVEY

menu and select SAVE. Press ENTER.

If the disk is not formatted, a "disk error" message will appear. Move the cursor to the FORMATcommand in the FILE menu and press ENTER to format the disk. Follow the commands on the

screen and wait several seconds for the "format complete" message. Then, try saving the file.


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When the file is saved, a file saved message will appear on the screen. The message in the top

right corner of the screen will change from "UNSAVED STACKED DATA" to "SAVED AS

FILE xxx".

Clear the memory, and observe the blank traces characteristic of a cleared memory. Move thecursor back to the FILE menu and select READ. A list of available files will appear on the

screen (there may be only one file at this point, but eventually there will be several files on the

disk). Position the cursor over the file number just saved and press ENTER. The disk drive will

hum again, retrieve the data, and it will display on the screen. Compare it with the previous

record. Remember that you can still use the options in the Display menu to change the way the

data looks or even filter the records to enhance the specific events of interest.

You also have the option of storing the data on the internal hard disk (Drive D:) instead of the

floppy. The hard disk is quite a bit faster, and is more convenient in the field. Use of directories

and the other disk operations are discussed in Appendix A.

At this point, you should know how to acquire data, save it on disk, and read the data back. You

should also be quite familiar with the use of the system menus at this point.

Remember to set your floppy data disks to "write protect" when full. Slide the write protect tab

to the open position, leaving the hole open. If you try to save data on a disk which is "write

protected", the screen will display some sort of disk error message.

The hard disk may also be used to store data. In general, it will be faster, more convenient, and

immune to dust. You will need to copy the files to floppies later. The hard disk is drive D:,

which can be selected in the FILE menu.

Answers

The Answers menus is used to analyze the seismic data. Programs are provided to provide a

fairly complete seismic refraction solution, including a geologic interpretation with layer depths

and velocities.

A proper seismic refraction interpretation should have at least two records, one with the source at

each end of the line. Better detail and deeper information can be obtained by also locating the

source well off either end of the line and in the center. For each shot, the INSPECT ARRIVALS

function will pick the first breaks and save the data on disk.Be sure that the line geometry is

properly entered for each shotpoint.To help you remember, the SmartSeiswill prompt you forgeometry data at appropriate intervals.

Once the first breaks are saved, the Answers menu has functions to draw the time-distance

graphs and plot the interpreted section on the plotter. The complete procedure is described in

Appendix A. in the section describing the ANSWERS menu.


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There are additional functions to analyze reflection data and linear velocities, also described in

Appendix A. While these programs will not provide final seismic sections, they should assist the

user greatly in knowing he has good quality data before leaving the field.

Conclusion

By now, you should appreciate that the SmartSeisis an extremely powerful and easy to use

seismograph. Only a portion of the features have been exercised, and you should continue

familiarization by reading the appendices and conducting further field experiments. Try different

choices in the Acquisition and other menus to see the effect. As a general rule, the SmartSeis

is very forgiving, and will gather the highest quality data possible with a minimum of effort in

the field. If you have conducted surveys before, you will quickly learn to appreciate the

advantage of not having to set the gain controls for every refraction shot. Of course, the

SmartSeisis capable of shallow reflection surveys. You are encouraged to explore these

possibilities further. Geometrics can offer advice, short courses, and application notes to assistyou.


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SmartSeis Operating Manual Page 2-1 Condensed Operating Instructions

Chapter 2. Condensed operating instructions

This section of the manual is provided for users who are experienced in the use of seismic

equipment. Every effort has been made to make the operation of the SmartSeissimple and

self-explanatory, and you may be able operate the system by just reading this introductorymaterial.

You should acquaint yourself with the rest of the manual at your convenience.

System Setup

Unpack the system and gather your accessories. You will need a 12-volt battery if you did not

receive one with the system. Since the SmartSeisS12 only draws about 22amps (or about 32

amps for the SmartSeisS24), a medium capacity (say 20 to 30 amp-hour) battery should be

sufficient for a day in the field. Connect the battery pack, with the red clip to positive and black

clip to the negative lead. If the connections are reversed, it will not damage the instrument, but itwill not work. Connect the geophone cables, geophones, and energy source.

Switch on the instrument with the switch near the power connector. One of the

light-emitting-diodes on the battery level indicator should light. Wait several seconds while the

system powers up, conducts its internal tests and loads its software. After the power up cycle,

the screen should display a message or a set of seismic traces. If the screen is blank or faint,

adjust the display contrast with the two arrow keys just above the battery level indicator.

The liquid crystal display and keypad are used to operate the system. The seismic record is

displayed on the screen, with operating menus overlaid when used to control the instrument.

The display consists of four message lines above a set of vertical seismic traces. The first two

lines list the acquisition parameters and other status messages. The next two list the channel

numbers and the trace size scale factor in decibels. There are also three horizontal cursor lines

across the screen, annotated with times in milliseconds. The information lines should be

self-explanatory. Further information may be found in Appendix A or Chapter 1, Detailed

Operating Instructions.

Menu Operation

The SmartSeisoperation is through an interactive set of menus and sub-menus. These are

engaged by pressing the MENU key, and making choices with the arrow keys, ENTER, andCLR. In general, use the arrow keys to move around in the menus, the ENTER key to make a

selection, and the CLR (clear) key to exit from menus or escape without making changes. Avoid

the tendency to exit some menus (like FREEZE) with the CLR key instead of ENTER. In that

case, the selected choices are not entered.


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When MENU is pressed, a set of menus appears on the screen:

One of the main menu choices (DO_SURVEY) will be selected, shown in reverse video, and a

secondary menu displayed below on the screen. Use the left and right arrows to move between

menu choices, and the secondary menu will change depending on which item of the main menu

is selected. Use the up and down arrows to select items on the secondary menus. Work your

way through the list and examine each set of menus. You can also select a menu item by

pressing the key for the number next to the item in the menu. This is faster than pointing with

the reverse video cursor, and for repetitive operations in routine surveys, you will soon

memorize the numbers corresponding to the function.

The secondary menus may either be action items (e.g. PRINT, NOISE DISPLAY) or they may

be names for third level (tertiary) menus (e.g. FILTER, TRACE SIZE). In either case, the actionor the tertiary menu is selected with the ENTER key. If you press ENTER while PRINT is

selected, the seismograph will print a copy of the seismic record. Try selecting PRINT and

printing a copy of the record. Load paper if necessary, using the instructions inside the panel.

Experiment with the menus and explore the function of each. Since this chapter is for

experienced users, and since the menus of the SmartSeisare generally self-explanatory,

obvious features will not be discussed here. Refer to Appendix A for detailed information about

any menu item that is not clear. Some are unique to the SmartSeisand will require

investigation.

After you are familiar with the menus and their structure, you should be able to operate thesystem.

There are some subtleties, listed below:

1. When the seismic record is displayed, and there are no menus on the screen, the up anddown arrow keys will scroll the data on the display. The three annotated time lines on

the display can be used to time events.

2. The SmartSeiswill only trigger when the screen is in trace display or noise displaymodes. When a menu is on the screen, the trigger is disabled. This feature can be used

to prevent false triggers.

3. While in the noise display, the noise monitor sensitivity is set with the up and downarrow keys. The same gain is used on all channels. The sensitivity will be displayed on

the screen (top left, line 4), so that the operator can log ambient noise in millivolts. If



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you know the sensitivity of the geophones, you can convert noise level in volts into

seismic motion levels.

The noise monitor is also the geophone test. If any geophone (or cable) is open, shorted,

or has a stuck coil, its trace on the noise channel should be noticeably smaller than theother channels.Some problems may be indicated by excessive signal, perhaps an open or

leaky conductor near a power line for instance. In general, this geophone test will be

much more diagnostic than a simple continuity/leakage test.

4. There are two sets of signal filters available. The filters in the ACQUISITION menuoperate on the incoming data, just like analog filters. Once data is acquired with these

filters, the process is permanent, and filtered data is stored in memory (and will be saved

on disk).

The filters in the DISPLAY menu are post-acquisition filters which only affect the data

shown on the display and printed on the plotter. The original raw data is held in memoryand saved on disk. As a general rule, it is better to acquire your data with a wider

bandwidth, then filter it later. This gives you more information content and flexibility in

processing.

The SmartSeishas digital anti-alias filters (except at the 32 microsecond sample

rate). The corner frequency is selected when the sample interval is set, and the phase

response is selected when the survey mode is set (see Appendix A). So, anti-alias filter

operation is automatic.

5. SAMPLE INTERVAL and RECORD LENGTH are interdependent parameters on the

SmartSeis. To allow use of less than the maximum memory, there is a menu option toselect just a portion of the available memory. Set the sample interval first, then record

length. Changing the sample rate will affect the record duration but not the number of

samples in a record.

6. Many acquisition parameters cannot be changed with data in memory. Clear the memoryfirst before changing those parameters that affect how data is acquired (e.g. sample rate,

filters, record length, etc.). Parameters which may be changed include freeze, stack

mode, and stack polarity.

When a record is read from disk, the acquisition parameters displayed on the top of the

LCD screen will reflect those read from the header, not the instrument settings.However, the parameters listed in the secondary menus will continue to reflect the

current instrument settings. This is particularly significant in the GEOMETRY menu

which contains the line geometry. To find the line geometry parameters which were

stored on a disk file, it is necessary to print a copy of the record and read the values listed

in the print header.


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7. When saving a file, the system will assign a default file name, one digit higher than thelast file saved. If a new name is selected, that will become the new base name.

The SmartSeis

will also allow the use of Directories as with any DOS computer. Youmay assign directories to the project, the day, and even the line if desired. Once a

directory is selected (using the Directory menu options), the files will be saved in that

directory. Since a directory is established on each individual disk, their use on the

3.5-inch floppies should be avoided. Swapping disks may lead to directory errors.

A directory can have a maximum of 100 files (shots). If an attempt is made to store more

than 100 files in a directory, the system will automatically create a new directory one

number higher.

8. Under the GEOMETRY menu are entries for line geometry and other file header

information. It is good field practice to make these entries, and they are required for anumber of operations, including all the ANSWER programs and for saving or printing

files in the refraction mode. See Appendix A. for an explanation of these parameters.

9. The OTHER menu includes a choice of units, meters or feet, used in the ANSWER

programs, plus a clock and calendar. Set these parameters to your local standard.

10. The ANSWERS menu contains several geophysical analysis programs used for qualitycontrol in the field. Experiment with these if you wish. A complete list and detailed

instructions are in Appendix A. Note before you start that most of the programs require

that accurate information be entered for line geometry in the GEOMETRY menu.

Acquire data

Go to the GEOMETRY MENU and set those parameters to reflect the survey line.

Clear the memory in the DO SURVEY menu. Select the ACQUISITION menu and set the

acquisition parameters for the line: sample rate, record length, filter settings, etc.

Engage the NOISE DISPLAY (found in the DO SURVEY menu). Raise or lower the sensitivity

by pressing the up or down arrow keys. The screen should display the noise envelope on each of

the active channels, continuously updating. Check to see that all the traces are functional, thus

testing the geophones and cables. The background noise level will vary with the situation.Stomp on the ground and watch the noise display vary.

Operate the energy source to trigger the seismograph. The noise monitor display will disappear,

and be replaced by the seismic record.


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Examine the record

Select the DISPLAY menu and adjust the display parameters for the desired record display.

Trace Size includes an automatic selection, usually a good place to start to get some usable data

on the screen. Other choices include variable area/wiggle trace modes, digital filter functions,AGC, time scale, trace size, and channels displayed. Since you can observe the effect of each

change, little explanation is required.

You may need to readjust the trace size whenever changing between AGC and fixed gain

displays. AGC has the effect of keeping trace amplitude relatively the same for the entire record,

whereas fixed gain gives a more familiar display with large first arrivals and smaller later

waveforms. Try an AGC window length of 200 samples as a first choice.

Print a copy (in the DO_SURVEY menu). Change the printer scale if the physical length of the

record is too long or too short (see PRINT TIME SCALE in the DISPLAY menu).

If the record is noisy, and it is difficult to recognize the significant arrivals, you may wish to

repeat the energy source and stack additional shots. Note that stacking in the AGC mode does

not increase trace size as in a conventional seismograph, but the data should become more noise

free.

Save the data

The SAVE file command, which commands the system to save the seismic record onto the

default disk drive, is located in the DO_SURVEY menu. The remaining disk drive commands

are located in the FILE menu.

You can save files on either Drive A: (the 32-inch floppy) or Drive D: (the internal hard disk).

To use a floppy, check to see that the default drive is A:, insert a formatted disk into the disk

drive, and press SAVE. If the disk is unformatted, the system will prompt you, then use the

FORMAT command to format the disk. To use the hard disk, select Drive D: and make a

sub-directory if desired.

The shot and geophone group locations (set in the GEOMETRY menu) will be saved with the

data file. Read that section of Appendix A for an explanation of these variables.

When saving a file, the system will suggest a number for the file name, listed in the

DO_SURVEY menu. Press ENTER to use the suggested name or, (if you want to change) selecta new name-number in the FILE menu. The data will be saved under that selected file name.

The next time you save a file, the system will suggest a name one number higher. Since a file

name can have 8 digits, you can easily incorporate additional information as part of the name

(such as the survey line, or date, or project). Then, it becomes easy to sort the records with

standard DOS commands.


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The seismic record will be saved with the extension .DAT, indicating a data file. Related files

(such as first breaks) will be saved with the same name but a different extension.

It is unlikely that the system will save the data incorrectly, without providing an error message.

However, you can check by first clearing the memory, then reading the same file from disk usingthe READ option in the FILE menu. It is not necessary to clear the data from memory first, but

it may be reassuring.

Once the operating parameters are set, the commands used to acquire data are all located in the

DO_SURVEY menu, which is also the active menu selected by the MENU key. This grouping

in sequence of routine commands will expedite actual surveys.

If the SURVEY MODE is set to REFRACTION, the INSPECT ARRIVALS command will

automatically position the traces on the screen so that the first arrivals show. Then, the system

will pick the first breaks automatically. You have an option to adjust the picks manually, then

save the picks as a file. As the process is repeated for the same spread with different shot points,additional picks are saved for the other shots. The ANSWERS menu will read this data and

draw a Time-Distance Plot, and then, after the layers are assigned, plot a geologic cross section.

This concludes the experienced user operation section. It is assumed that the reader will exercise

the system and learn the subtleties of the menu through experimentation. There is a significant

amount of material not discussed in this section which is felt to be obvious to an experienced

user, but no doubt some subjects were not covered in adequate depth. For additional

information, read Chapter 2, Appendix A, and Appendix B.


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SmartSeis Operating Manual Page A-1 Appendix A, Menus

Appendix A. Interactive Menus

This section describes the display, keyboard, and interactive menu. The menu section is

organized in a glossary style so that individual sections may be used alone to explain menu items

in detail.

The Display

A backlit, high-contrast, liquid-crystal display is used to display the seismic data. It is VGA

compatible, composed of a matrix of dots 640 pixels wide and 480 pixels high. The top rows of

pixels are reserved for message lines showing the acquisition parameters, system status, the

channel numbers, and trace amplitudes.

The remaining area is reserved for displaying the seismic data. Depending on the time scale in

use, portions of the record may not fit on the screen at any one time. The up and down arrow

keys may be used to scroll the data on the screen.

There are also three timing lines on the screen. These are labeled to show the relative amount of

time displayed, and to allow picking the arrival times of specific events.

The first two lines of the Header contain the following information. (xx.xx will be some

numerical value depending on the parameters selected.):

SAMPLING x.xx ms LENGTH xxxx ms DELAY xxxx ms [data message]

Acquisition Filters Display Filters AGC [length] STACK [type] STACK xxx

1 2 3 4 5 6 7 8 9 10 11 12

| | | | | | | | | | | |

00.0 | | | | | | | | | | | |

| | | | | | | | | | | |

| | | | | | | | | | | |

| | | | | | | | | | | || | | | | | | | | | | |

100.0 | | | | | | | | | | | |

| | | | | | | | | | | |

| | | | | | | | | | | |

| | | | | | | | | | | |

| | | | | | | | | | | |

| | | | | | | | | | | |

200.0 | | | | | | | | | | | |

| | | | | | | | | | | |

| | | | | | | | | | | |


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SAMPLING x.xx is the data acquisition sampling interval (in microseconds). The word

"sampling" will be displayed in reverse video when the system is triggered, and return to normal

after the new data is displayed.

LENGTH xxxx is the record length (in milliseconds). The SmartSeis

allows the use of all orpart of the available memory, so the record duration will depend on the combination of sample

rate and memory length in use.

DELAY xxxx is the delay in the start of the record (in milliseconds) after the trigger signal, or if

negative, the amount of data prior to the trigger signal.

[data message] is a message describing the status or type of data displayed on the screen, for

example:

MEMORY CLEAR indicates the memory has been cleared.

UNSAVED STACKED DATA is seismic data stacked into the memory (but not saved

on disk).

SAVED AS XXXX.DAT indicates the stacked data has been saved on disk (in file

XXXX.DAT).

READ FROM XXXX.DAT indicates data read from disk (from file XXXX.DAT).

UNSAVED PREVIEW DATA indicates the data on the screen is new seismic data to be

rejected or accepted by the operator.

ACQUISITION FILTERS are the type and frequency settings of the filters used during

data acquisition.

DISPLAY FILTERS are the type and frequency settings of the filters used to display the

data.

AGC [length] will be the status of the Automatic Gain Control function in the trace

display. [length] will indicate the AGC window length in samples.

STACK MODE indicates the type of stacking, either AUTO (automatic) or PREVIEW

(which allows the operator to examine a new data set before stacking it to memory) orREPLACE (which will automatically replace the data with a new record).

STACK xxx is the total number of times data was stacked into memory since last cleared.


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The remaining two lines in the display header show the channel numbers and the relative trace

size. Frozen (protected) channels are shown in reverse video. Relative trace sizes are labeled in

decibels. Relative trace amplitudes are accurately displayed, so that absolute amplitude

comparisons can be made when the traces are displayed in fixed gain (as opposed to AGC, or

automatic gain control).

The Keyboard

The keyboard has 22 keys, including numbers 0 through 9, MENU, ENTER, CLR (clear), "-"

(hyphen or minus), "." (decimal point), 4 arrow keys, a key with the propeller logo, and a pair of

keys for controlling the display contrast.

When the data is displayed on the screen (without the menu), the up and down arrow keys will

scroll the data on the screen. This allows viewing the entire record when the time scale is

expanded beyond the screen, and will position specific portions of the record on the cursor lines

(for timing event arrivals).

The MENU key is used to select the operating menu.

The Arrow keys are used to position the cursor among menu options on the screen. The

left arrow key "


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used for CLR. With an alphanumeric keyboard, files may be named with letters as well as

numbers.

The F10 key is used to exit the seismic program to DOS. See Appendix D for information on

using the computer, operating in DOS, and re-loading the seismic program.


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The Menus

When the MENU key is pressed, the display will show a list of menus.

One of the selections will be highlighted in reverse video. Below this line, overlaying the data

display, will be a box containing secondary menu selections. The selections will correspond to

the highlighted main menu item. There may be a single selection shown, or a long list. Some

selections are execution statements, meaning that an action will be performed if ENTER is

pressed while the selected item is highlighted. Other selections will cause another menu to be

displayed, or a request for a number to be entered, or suggestions for further action. In operation,

the menu system is quite easy to use.

The secondary menu items are numbered. You can also select an item by pressing thecorresponding number key instead of moving the cursor. Pressing the number key to select a

menu item will be much faster when conducting actual surveys, especially after the operator has

learned the numbers.

GEOMETRY menus are used to record the locations of the geophones and the energy source.

ACQUISITION menus control the data gathering parameters (such as sample interval, record

length, filters).

FILE menus control the saving and reading of data files onto disk.

DISPLAY menus control the way the data is displayed on the screen and plotted.

DO_SURVEY contains the functions normally used to acquire, display, and analyze data in a

production mode.

ANSWERS menus are used to run the field quality control software programs to analyze the

data.

OTHER menus are used for general operating and test functions.

Experiment with the system. The complete menu structure is listed on the following pages. Manysecondary menus have a status indication which identifies the current setting.

The current settings in the following examples are representative. The actual menus will display

many other alternatives.



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GEOMETRY

Geometry is a collection of menus used to annotate the seismic data with the locations of the

geophones and seismic source. The SEG-2 standard for seismic DOS files provides space in the

header for 3-dimensional coordinates (X, Y, and Z) for the energy source and each geophone

group.

The information in the Geometry menu is optional, and surveys may be conducted without

reference to this menu. However,its use is highly recommended as this information is essential

when using the ANSWERS functions which depend on line geometry. Some interpretation

packages also use this information for automated processing.

This information will be attached to the data when the file is saved to disk. If a file is read from

memory, the menu values on the LCD display will continue to indicate the current instrument

settings, not the data read from disk. However, the information read from the disk file can be

printed on the paper records. Proper use of these capabilities will label each file with the shot

geometry and source location.

The QUICK GEOMETRY SETUP option will set default values for the location coordinates.


0 QUICK GEOMETRY SETUP1 SURVEY MODE ........REFRACTION

2 LINE NUMBER..............00-00

3 PHONE INTERVAL...........10.00

4 SET PHONE & SHOT LOCATIONS

5 SHOT INTERVAL...............10


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SURVEY MODE

Survey mode will affect how the coordinates are adjusted after a file is saved. When Survey

Mode is selected, a menu box appears:

Position the reverse video cursor over the desired

mode and press ENTER.

REFLECTION MODE

In a CDP reflection survey, it is common to physically move the shot point and the geophones by

the same distance each shot. If the system is set to reflection mode, the coordinates in the line

geometry are incremented (or decremented) by the SHOT INTERVAL value each time a file is

saved.

The anti-alias filter is set to a "linear phase" response in the reflection mode.

REFRACTION MODE

In a refraction survey, the geophone spread stays in one position for several shots with the shot

in different locations. When the SmartSeisis set to refraction mode, line geometry is updated

manually my setting a new SHOT LOCATION each time.

The anti-alias filter is set to a "zero phase" response in the refraction mode.

OTHER MODE

In the other mode, line geometry behaves like the refraction mode, but the anti-alias filter is set

to linear phase as in reflection mode.

Differences in the behavior of the two types of anti-alias filters will not be important to the

average user.


0 QUICK GEOMETRY SETUP

1 SURVEY MODE ........REFRACTION

2 LINE NUMBER..............00-00



5 SHOT INTERVAL...............10

REFLECTION REFRACTION OTHER


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LINE NUMBER

Used to store an arbitrary line number in the header. Optional. When selected, a message

appears:

ENTER LINE NO: 0000

Key in the desired number and press ENTER. Punctuation marks may be used, e.g. 12-76.

Note that a line number can also be included as part of the file name or as a directory. The later

choices will be very useful when handling files on the computer during processing, as standard

DOS routines (such as copy 123*.DAT) are simple and convenient ways to copy and move

selected files around.




2 LINE NUMBER..............00-00



5 SHOT INTERVAL...............10


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PHONE INTERVAL

Phone Interval is the distance between geophones or groups of geophones in meters or feet.

When selected, a message appears:

ENTER PHONE SPACING 10

Key in the distance between geophones and press ENTER.




2 LINE NUMBER..............00-00



5 SHOT INTERVAL...............10


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SET PHONE & SHOT LOCATIONS

When SET PHONE & SHOT LOCATIONS is selected, a menu box appears:

This is a map of the geophones and shot point locations, with coordinates listed. One of the

numbers will be in reverse video. The arrow keys will move the reverse video cursor around the

map. If the cursor is moved past the limits of the shot map, the display will scroll to show more

of the line. To change any of the numbers, just position the cursor over it, key in a new number,

and press enter or any arrow key except


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When in the INTERVAL row, the key will flip the geophone spread over so that channel 12 is

on the left and channel 1 on the right side of the box. However, reverse spreads may confuse the

SIPQC refraction analysis program.

Experiment with this menu to gain familiarity. You will notice that the distance intervalsbetween geophones are filled in with the number you entered earlier. If any of the geophone

separations are different, use the arrow keys to position the cursor over that number and enter the

correct value.

Next, assign coordinates to one of the geophones. You should know the absolute location of at

least one of the geophones, or if not, assign a location. Position the cursor over the position of

the known geophone and enter the value. Notice that as geophone intervals or positions are

changed, the other numbers in the map will adjust automatically, giving you a visual picture of

the line geometry. If the position numbers increment in the wrong direction for your spread,

press the "-" key to flip the line over, then adjust the coordinates again.

Now, position the cursor over the shot point location and enter the correct value for the shot

point coordinate. This should complete your setup. The top lines in the window will provide a

visual representation of the line and shotpoint. Look at this map and see if it corresponds to the

actual placement of the geophones (v) and shotpoint (*).


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SHOT INTERVAL

Shot Interval is the physical distance between subsequent shot points. It is normally only

applicable to reflection surveys. When selected, a message box appears:

Key in the distance between sequential shot points and press ENTER. When a record is saved on

disk, the coordinates of the geophones and shotpoint are also saved in the file header. Then, if the

survey mode is set to REFLECTION, when the next record is saved, all the coordinates will be

incremented by the shot interval value. In this manner, the system will automatically update the

line geometry coordinates in a CDP type reflection survey.

In practice, the sequence will be interrupted eventually. In that case, just enter the correct values

for the line geometry before saving the file. If the geometry changes (different group interval for

example), just update the information. To prevent the coordinates from incrementing each file,

enter zero for the shot interval or set the system to the refraction mode.




2 LINE NUMBER..............00-00



5 SHOT INTERVAL...............10

ENTER SHOT INTERVAL 10


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ACQUISITION

This set of menus contains the acquisition parameters, those variables which affect how the data

is collected.

If newly acquired data is in the memory, the system will not allow you to change most of these

parameters until you erase the data from memory, because stacking records with different

acquisition parameters is normally invalid. For example, there is no logic in changing the sample

rate between stacks. Attempting to change these parameters without clearing memory will result

in an error message.

Acquisition parameters are permanent in their effect on the data (unlike display parameters). You

cannot change the sample interval, record length, or filters once the data is in memory or savedon disk. Fortunately, the wide dynamic range of the system and automatic gain controls makes

the SmartSeissystem flexible in handling variations in the survey.

The QUICK ACQ SETUP option will immediately set most of the acquisition parameters to a set

of default values appropriate to a refraction survey. These are chosen to be a good initial guess

for most such surveys. If you are a first time user, or unsure of the proper settings, then use

QUICK ACQ SETUP.


0 QUICK ACQ SETUP

1 SAMPLE INTERVAL.........500 us

2 RECORD LENGTH..........1024 ms

3 DELAY......................-10

4 FILTER 1.........LO CUT 100 HZ

5 FILTER 2...........NOTCH 60 HZ

6 STACK MODE.............PREVIEW

7 STACK POLARITY........POSITIVE

8 ACTIVE CHANNELS


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SAMPLE INTERVAL

A seismic signal is continuous. When the seismograph measures this signal, the value is digitized

at intervals and the resultant numbers are stored in a digital memory. The SAMPLE INTERVAL

control is used to select this interval between data samples. When selected, the menu displays a

list of the available sample rates in microseconds.

There is a limit to the number of samples which can be stored in the memory (and a limit to the

useful number of samples). The sample interval is selected to match the scale and type of the

survey. The fastest sample rates will be used for short surveys in hard materials (such as rock

and concrete). The slow sample rates are used for long refraction surveys and reflection surveys

where events of interest arrive late in time.

To set the sample interval, just position the cursor over the desired value and press ENTER.

When in doubt, use the sample interval chosen by the QUICK SETUP menu.


0 QUICK ACQ SETUP

1 SAMPLE INTERVAL.........500 us

2 RECORD LENGTH..........1024 ms

3 DELAY......................-10

4 FILTER 1.........LO CUT 100 HZ

5 FILTER 2...........NOTCH 60 HZ

6 STACK MODE.............PREVIEW

7 STACK POLARITY........POSITIVE

8 ACTIVE CHANNELS

31.25 62.5 125 250 500


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Smart Seis Version c