rdev sineWave test 04feb13
test was done with the rdev spectrometer using a sinewave on
- Rdev setup :
- 140 MHz clock. Use bandwidth 10,20,35 MHz
- 10 MHz bandwidth:
- dec_f=3, upshift output (shift_fir)=5
- txSamples=5500, dataDelay=6250, data samples=20000
- i/o rate: 10.2 Mbytes/sec
- 20 MHz bandwidth:
- dec_f=2, upshift output (shift_fir)=5
- txSamples=11000, dataDelay=12500, datasamples=40000
- i/o rate 20Mbytes/sec 35.7 Mbytes/sec
- 35 MHz bandwidth:
- dec_f=1, upshift output (shift_fir)=5
- txSamples=19250, dataDelay=21000 datasamples=70000
- all bands gave 550 usecs tx samples, 2 milliseconds data
- data ranges would have been:
- Start Height: 93.75 km
- last Height: 393.75 Km
- Rdev setup for sine wave.
- 140MHz clock at @-2bm.
- 10 millisecond ipp. rf pulse fed into rdev from sps.
- sine wave= 30MHz+ 1160 hz, amp=0dbm -> splitter than
tx,and height samplers
- This should have been + 11160 hz.. 1160 does not give very
many cycles in tx window.
- took 3 files about 10-15 seconds each.
- files: sasdr_final.20130204.b0a.00000, 00100,00300 (10,20,35
- Used upshift =5 for all bandwidths.
- running 10 milliseond ipp
- test run on pdevs0.
- scripts in ~thall
- pnet --conf=/home.local/thall/pnet.conf.fir10M
--fpga=/pcmn/sasdr_dds.gz --extclk --dump=10
- pnet --conf=/home.local/thall/pnet.conf.fir20M
--fpga=/pcmn/sasdr_dds.gz --extclk --dump=6
- pnet --conf=/home.local/thall/pnet.conf.fir35M
--fpga=/pcmn/sasdr_dds.gz --extclk --dump=50
The Sine wave test:
The plots show the results of the sine wave test.
- Page 1:plot spectra, check sine wave frequency.
- top spectra 1 ipp tx sample
- 2nd spectra 1 ipp height samples
- 3rd blowup tx spectra about sine wave
- bottom: blow height spectra about sine wave.
- Page 2: measure phase offsets:
- top: sine wave Height[smp0] - tx[smp0] for each ipp. The red
line shows the expected difference.
- 2nd:check phase difference for tx[smp0] 1 ipp to the
next. Check that it remains constant
- Bottom:check phase difference for height[smp0] 1 ipp to the
next. Check that it remains constant.
- Page 3: plot voltages start of 1st ipp (plotted real
portion of sine wave).
- The black line is the sampled data.
- The red line is a sine wave fit to the tx samples and the
plotted for the tx and height samples.
- Top: first 1200 useconds. The green,blue lines show where
the txWindow stopped and the height window started.
- 2nd:start of tx samples. Shows that the sine wave fit
follows the tx sample data.
- 3rd:end of tx samples. Shows that fit still works at end of
tx sample data
- bottom; start of height samples.You see the jump in data and
Computing the correct input power levels:
- 10 MHz bandwidth
- Sine wave peak voltage:5000 counts
- Height-tx phase difference: -11.5 usecs
- page 4 shows data - sinewave fit.
- 20 MHz bandwidth
- Sine wave peak voltage:2500 counts.
- Height-tx phase difference: -11 usecs
- 35 MHz bandwidth
- Sine wave peak voltage:1500 counts
- Height-tx phase difference: -10.7 usecs
- spectra spurs height spectra down at least 80db
- spectral width around sine wave probably narrow data window.
The input digitizers power levels:
- maximum input is .786 Volts peak to Peak. This is .28 volts
- .28 Volts rms i is log10(.28^2/2) + 30 = 2 dbm. So the
max power would probably be a little higher than this.
- If the input sine wave was -4dbm ( 0dbm, split then 1db loss
in the cable). this is 6db below the peak value.
- If the peak counts was 32767 then we should have had:
32767/sqrt(4.)=16384 counts. We had less than this:
- 10 MHz 5000 Vcounts-> Voltage 6.5 times low, 43 time low
- 20 MHz 2500 Vcounts-> voltage 13.2 times low, 172 times
low in power
- 35 MHz 1500 Vcounts-> voltage 21.8 times low, 477 times
low in power.
- Used upshift value of 5 (2^5) for output. New upshift values
for given bandwidths:
- 10 MHz: 5 + alog2(43)= 5 + 5.4 = 10
- 20 MHz: 5 + alog2(172)= 5 + 7 = 12
- 35 MHz 5 + alog2(477)= 5 + 8.9=14
- The frequency of the sine wave is correct.
- Within 1 ipp, tx to data window sampling is stable for the
duration of the test (10-15 secs).
- The tx to height phase is off by about 11 usecs.
- It changes a little depending on the bandwidth.
- the tx and height starting phase is stable for all ipps.
- new output fir upshift bits should be:
- 10MHz - 10
- 20 MHz - 12
- 35 MHz - 14