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Monitoring Phase Cal tones

Recording one scan with Phase Cal ON for 19 minutes using Followed by another scan of just a couple of minutes with Phase Cal off for comparison. Inifile configured as:

# Do a test to record Phase Cal ON at different Frequencies
dBBC3Address =
dBBC3Port = 4000
Station = Hb
LOfreq = [3500, 3000, 4500]
NumberOfChannels = [8, 8, 8, 8, 8, 8]
CutOffFreqA = [3200.0,3600.0,4000.0,4400.0,4800.0,5200.0,5600.0,6000.0]
CutOffFreqB = [3200.0,3600.0,4000.0,4400.0,4800.0,5200.0,5600.0,6000.0]
CutOffFreqC = [6400.0,6800.0,7200.0,7600.0,8000.0,8400.0,8800.0,9200.0]
CutOffFreqD = [6400.0,6800.0,7200.0,7600.0,8000.0,8400.0,8800.0,9200.0]
CutOffFreqE = [9600.0,10000.0,10400.0,10800.0,11200.0,11600.0,12000.0,12400.0]
CutOffFreqF = [9600.0,10000.0,10400.0,10800.0,11200.0,11600.0,12000.0,12400.0]

Data processing

First need to change PythonPath every-time you open a new terminal, otherwise is using DifX defaults one:

export PYTHONPATH=/usr/lib/python3.4
cd /home/observer/PcalTests

I recommend using the program call screen in order to have the processing in the background. A short description on how to use screen is below:

observer@flexbuffhb DiFX-2.5.2 ~> screen YourName - You can recognise the screen later
observer@flexbuffhb DiFX-2.5.2 ~> screen -raAD

There are several suitable screens on:

  14835.pts-4.flexbuffhb	(28/05/19 17:39:31)	(Detached)
  18325.pts-4.flexbuffhb	(14/05/19 13:53:38)	(Detached)
Type "screen [-d] -r [pid.]" to resume one of them.
observer@flexbuffhb DiFX-2.5.2 ~> screen -raAD 18325 - Check if that is the screen you were using last!!

Commands to use inside a screen:

ctrl+a c - creates
ctrl+a p - previous
ctrl+a n - next
ctrl+a d - leaves the current screen

You should find most of the necessary files inside of the folder

The processing takes 3 steps:
1- Running the software spectrometer to see the spectrum of the signal recorded (swspec)
2- Making a first estimate of the pcal measurements (calculatePcalCpp)
3- Running the tracking software (sctracker).

1. Take the inifile.ini that is in the directory and prepare it for the scan you want to process. There are basically 2 settings you can modify:
Channel from 1 to 8. I did the recording with 8 channels

IF from A to F. We recorded the data from the 6 boards in the dbbc3. So for a total of 6×8 channels = 48.

UseFile1Channel = 1
BaseFilename1 = p190522_Hb_VDIF_If000A_%fftpoints%pt_%integrtime%s_ch%channel%
# Change then channel value from 1 to 8, one per channel
# Change IF000A to A/B/C/D/E/F to cover all boards

We run the program by executing this program. If we process the 8 channels per each of the 6 files (6 IFs), You should end up with 48 spectra data files.

swspectrometer inifile.ini /mnt/vbsPcal/pcal_on_2205_Hb_No0001_46227

2. Check the quality of the spectrum. I have written several Python scripts to provide a quick validation of the recorded data.

-bw sets the bandwidth
-f0 sets the minimum frequency to search for the peak
-f1 sets the maximum frequency to search for the peak
-p plots the output - don't put anything if you don't need

python3 p190522_Hb_VDIF_If000A_320000pt_5s_ch1_swspec.bin -bw 32e6 -f0 4e6 -f1 6e6 -p
python3 p190522_Hb_VDIF_If000A_320000pt_5s_ch1_swspec.bin -bw 32e6 -f0 4.9e6 -f1 5.1e6

The calculatePcalCpp will provide a set of polynomials that will be used for the tracking software to study the Phase Cal tone. Example:

  1. rw-r–r– 1 observer observer 75 May 23 12:07 p190522_Hb_VDIF_If000A_320000pt_5s_ch1.poly2.txt
  2. rw-r–r– 1 observer observer 50 May 23 12:07 p190522_Hb_VDIF_If000A_320000pt_5s_ch1.X1cfs.txt
  3. rw-r–r– 1 observer observer 34558 May 24 13:23 Fdets.cal2019.05.22.Hb.ifA.ch1.r0i.txt

3. Configure and run sctracker

Edit inifileHb and modify the following fields
# Input file . InputSource = /mnt/vbsPcal/pcal_on_2205_Hb_No0001_46227
# Here you select channel 1 to 8 UseChannel = 1
# Select Cpp text file . PhasePolyCpmFile = p190522_Hb_VDIF_If000A_320000pt_5s_ch1.poly2.txt
# Select Cpp text file . PhasePolyCppFile = p190522_Hb_VDIF_If000A_320000pt_5s_ch1.poly2.txt
# Output file name . . BaseFilename = p190519_Hb_VDIF_If000A_%fftpoints%pt_%integrtime%s_ch%channel%

Run the sctracker as:

sctracker inifileHb

Once sctracker has finished, which can take several hours, it produces several output files. The most important one is

Once it has finished please remove the scscec.bin because it is very large and we better save some storage space.
rm p190519_Hb_VDIF_If000A_3200000pt_5s_ch1_scspec.bin

Next step will be to run tone file into the PLL script.


1. Process all 6 scans (3 IFs x 2 pols) and extract the spectra for each channel. We will have 48 spectra at the end.
2. Calculate the Polynomials for one of the phase cal at the beginning of the band, the tone at f=5 MHz.
3. Run sctracker (48 times) for each spectra.

4. To decide if we want to repeat with another cal tone at the end of the frequency band, f=25 MHz (?)

/home/www/auscope/opswiki/data/pages/hardware/phasecal.txt · Last modified: 2019/11/26 00:29 by Guifre