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Jasons short CFDP tool usage guide

This is a quick guide to using the CFDP transcoder tool I wrote. Once you successfully comile

the tool! run it and you see the following screen"

This tool has two main functions" rocessing raw data! and rocessing CFDP data. If you ha#e

raw data you ha#e catured at your ground station! then you need to erform the raw

rocessing ste first. This guide assumes you will $e comleting $oth stes.

%ee the sequence num$er length at & $ytes if you are working with 'andsat ( data. The

Otional )ace Packet rocessing )*O+'D $e ena$led, This sace acket rocessing otion

is only rele#ant for the CFDP rocessing functions $ut I always ena$le it as soon as I run the

tool. The ma-imum #er$osity otion uts a 'OT more information into the log files which is

useful when trou$leshooting $ut the resulting files are huge. The scan only and reort otion

hasnt $een used in a long time so may not function correctly.

/efore I e-lain the two rocessing stes! let me oint out one thing. This tool was de#eloed

as an engineering and I0T tool during sacecraft hardware de#eloment. The sace to ground

ICD had $een written $efore the s1c was $uilt! so I used this tool in art as a 2#erification tool3 to

look for comliance to #arious requirements in this ICD. For this reason! logfiles can contain a

lot of messages which in#oke a requirement ID from the ICD. 4ou can search for that

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requirement ID to find the rele#ant section for more conte-t regarding the error message. This

tool has not $een made 5667 consistent with the as8$uilt #ersion of the o$ser#atory so there

can $e error messages which are not really an error $ut reflect the fact that I ha#ent udated

the tool to match the final8final #ersion of the ICD.

Processing raw data

First click the /8format reader $utton. /8format is a really old term used at one oint in the

'andsat ( de#eloment rocess. I#e ne#er gotten around to renaming the $utton! so en9oy

your o$scure iece of 'andsat history. 4ou will $e resented with a normal :indows file oen

dialog"

The default e-tension I filter for is .rec. If you ha#e data with any other e-tension change the

data tye ulldown to ;ll in the $ottom right corner. 4ou can see in this e-amle that my

directory has one file! which was roduced $y an ;#tec PTP. )elect the file and click Oen. ;

status window oens! which looks like this during rocessing"

The < ossi$le #irtual channels are shown at the left. This is a =realtime status dislay showing

the current state where the tool is in your inut file. In the e-amle a$o#e! the tool currently is

seeing a mi- of >C ? and >C5@ ackets. The 2scale3 of this grah from left to right can $e

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considered to $e data #olume in $ytes. It is always normaliAed regardless of the siAe of your

inut file to these dimensions. The counters on the right show how many C;D+ ackets were

found in total! in each >CID. O#er time! you get a history of which >Cs are encountered. Bach

>C is actually colored on a grayscale from 6 to 5667 of the data stream for that chunk. :hen

there are two or more >CIDs resent! then tyically one will $e lighter gray instead of white.

4ou will tyically only ha#e realtime data! so only >C6 and >C?. I ha#e ne#er o$tained goodtest data to test my 2oise3 channel rocessing 1 dislay. The oise channel should dislay

content when you ha#e a section of the inut file with no detecta$le ;). :hen the entire file

has $een rocessed! you will see the whole ma"

In my e-amle! the right8most section of my data file is tyical for what you should see for

realtime8only data. There are more O'I Packets than TIE) ackets so the >C6 strie is $righter

than the >C? strie. 4our directory will now contain more data files"

The cadureaderlog file has a useful and imortant set of records and summaries for the

rocessing. For each #irtual channel! you will see two files. The .#c66 file contains the entiretyof the D;T; FIB'D of each C;D+ found in >C66. The ;) and the C;D+ headers are not

included in these data files. To assist the CFDP tool in dealing with messy data! there is a

second file G.#c66F*PH. F*P stands for First *eader Pointer this file is a $inary dum of an

integer array of the offsets from the start of the .#c66 file! of the acket starting locations from

the F*P #alues in the C;D+ headers. Please refer to the 'andsat ( sace to ground ICD for

related information.

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CFDP processing

This ste only works on outut files created from the 2/8format reader3 ste a$o#e. Press the

Decode $utton on the main interface and you get another file selection dialog"

:e will rocess the O'I data channel! so I will ick the file ending in .#c66. Once you select

Oen! you will see the following interface which is again a realtime status dislay"

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The em$edded filename is shown on the left. The middle grah uses a fi-ed scale of 5 /

which is the largest ossi$le 'andsat ( file siAe. The )ource should $e the instrument! in thiscase O'I. There is some code here which e-tracts one s1c timestam from the ancillary data

record! and the current8most timestam rocessed is udated on the right side until the file is

comleted. There can $e more data files in your inut file than this window will dislay. It

should scroll so that the most recent files are dislayed and the oldest files scroll out of the

window. 4ou will not $e a$le to scroll $ack to re#iew the earlier files. ;ll of this information is

catured in the CFDP rocessing log file anyway! so no need to worry a$out that.

If files fail to rocess! then the tool will dislay the file status in red instead of green. Its #ery

imortant to note that the Checksum code does not work correctly. I ha#e ne#er had the time to

correct my code! so if you manage to work out the $ug! I would lo#e to get the correction from

you. /ecause of this! I cannot #alidate the checksum. I instead rely on actual #s stated filesiAe! gas in the acket sequence num$ers! and other information I can use to infer a

transmission failure. y results will not match those of a real PTP $ecause of this checksum

ro$lem. For our samle inut! this is the final status window"

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4our directory now contains a lot more files"

I aend a 2.out3 file e-tension onto each file found! so instead of 5&.666 it is 5&.666.out.

There is also a cfdreaderlog added for the >C inut file in question. 4ou can roceed to

rocess each of the remaining >C channel files to comlete your rocessing of this inter#al.

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;s with the raw format reader! the logfile for the CFDP tool has a lot of interesting information.

If you are ha#ing ro$lems caturing or reading data you may Gor may notH find these messages

useful. ;s with the raw reader! a retty su$stantial familarity with the o#erall K8$and downlink

format and interface is required to make sense of the messages.