Update on the New Developments & Analysis from Hawaii

Larry Ruckman & Gary VarnerInstrumentation Development Laboratory (ID-Lab)

University of Hawaii at ManoaJanuary 31, 2008

Agilent Pulse Measurement• Two separate BLAB1

ASIC with a common sampling strobe

• RF split the Agilent pulse with additional cable delay in the 2nd channel

• Tune the AC coupling capacitor to create a fairly Gaussian looking signal

CH1

CH2

Agilent Pulse Fitting• Apply Gaussian fit to both

functions• Measure the time

difference between the two fit means => actually a factor sqrt(2) better

• High timing resolution for a fixed amplitude over a small timing window

Gaussian Fit

6.4 psRMS

Pulse Fitting Disadvantages• Spend a lot of time

developing an amplitude varying fit function

• Requires software• Sluggish online

processing duty cycle• Offline processing

requires a very large data storage

• Offline processing requires a lot of CPU time

Cross-Correlation Theorem

 

   

                  

CH1

Peak = 15

CH2

Peak = 45

F[CH1*(v)CH2(v)]

Peak = 30

Agilent Pulse Cross-Correlation Method

• Also, high resolution• Same timing jitter as

the fitting method• Hitting a timing

resolution limit from time base drifting

• Waveform splining was used to remove quantization effects for this plot

6.4 psRMS

Why use the Cross-Correlation Method?• Universal method to find the

time between the peaks of any two functions

• Cross-Correlation can be done with firmware=> “an online solution”

• Currently working on a developing firmware to determine the required FPGA resources and readout speed for this method

Cross-Correlation with Firmware

• FFT, INV_FFT, FIR Filter, and Complex Multiplier are free IP cores from Xilinx

Waveform DATA

FIR Filter (optional)

FFT Memory Stored Fourier test

function

Complex Multiplier

INV_FFTCorrelation Waveform

DATA

Peak Measurement

Charge Measurement

Time Measurement

Online “Spline”

• Artificially extend INV_FFT input array

• Set Re & Im part of array > Nyquist frequency to zero

• Possible to implement in firmware

1024 array @ 100 ps steps

8192 array @ 12.5 ps steps

System Block Diagram

• Up to 7x64 channels per cPCI card• Up to 4 cPCI cards per CAMAC card

MCP

BLAB2

BLAB2

BLAB2

BLAB2

MCP

MAIN cPCI

CARD

x7 cPCI

Crate

(Linux)x1

CAMAC

CARDCAMAC

Backplane

fDIRC Fiber Optic cPCI

• 8x 1.25Gbit Fiber Optic channels

• 8x 16Mbit SRAM• Initiator Transfer

through PCI bus• Store all waveforms

with a cPCI crate using Sci-Linux

• Linux PCI driver is currently under development

fDIRC Fiber Optic CAMAC

• 4x 1.25Gbit Fiber Optic channels• USB 2.0 optional computer interface• Enough IOs for all CAMAC pins

Action Items

• BLAB2 ASIC development• Online cross-correlation firmware development• Fiber optic firmware development• Linux cPCI driver development• Setup CAMAC data transfer protocol