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Please enter any significant events related to the AuScope VLBI project, including observations, configuration changes, hardware upgrades etc.
29 Jan 2013: Randall installed replacement CoMo B sent by Gino
30 Jan 2013: (Jim & Jamie)
Ran calibration procedure using the profile dbbc_config_file_102_calibration.txt and found nulls as follows:
old values 100 75 80 100
new values 103 86 102 97
edited all _102_ config files on dbbcyg to these new values
Then a calibration run to peak up on pcal tones. Yg DBBC optimisation, Jan 2013
Dear Gino, At Yarragadee today Randall swapped the replacement CoMo B you sent with the old one and I ran some tests. The conclusion is that it has made no difference and our phase cal amplitudes are about a factor of 3 lower in CoMo B than CoMo A. Here’s what we did: 1. Ran the usual calibration procedure with a 764 MHz tone and filter 1 in all CoMos, chose the first null as the phase. 2. DBBC config for a R1/R4: CoMO A : X-band with filter 1 CoMo B: X-band with filter 4 CoMo C: S-band, filter 2 CoMo D : S-band, filter 2 3. Measured phase cal tone strength as a function of target power level. The peak strength (in Whitneys) for each CoMo was: CoMo max ph cal at this CoMo power level: A ~50 35000 B ~15 25000 C ~60 40000 D ~70 35000 Note that the maximum power level CoMo B could produce was ~35000. All the others can go past 50000 4. I then ran the above tests again but with the following changes: CoMo A: X-band with filter 4 (and corresponding high BBC frequencies) CoMo B: X-band with filter 1 (and corresponding low BBC frequencies) The results were: CoMo A was well behaved with a maximum phase can signal of ~40 Whitneys at a power level of 25000 CoMo B was poorly behaved with maximum phase cal levels of ~15 Whitneys So we get low phase cal levels through CoMo B regardless of whether we use filter 1 or 4. 5. We also swapped the X-band IF inputs to CoMo’s A and B to see if the input signals were at fault, but there was no change. 6. Randall then changed the the SMA IF cable running from CoMo B to the core (?) board with a spare and checked all the SMA connections for tightness. Some of the S-band cables were a little loose but everything else was good. However, there was no improvement in performance through CoMo B. So, given that the old and new CoMo B units have similar behaviour, my guess is that the CoMo hardware might be OK. It looks like the "IF out" cable of CoMo B is also OK. Given that the high end of X-band looks good through CoMo A, I don’t think the cause is our input signal strength or band shape. One further check we could do would be to swap CoMo A and CoMo B. If the problems are then seen in the new "CoMo A”, then that unit (and the old one!) is faulty. I don’t think this is likely, but we can try. However, I guess the fault is further downstream. Can you suggest some other tests we can try? Please feel free to log in via Hamachi and try things out. I’ll leave the 764 MHz tone on, which is on input 3. The DBBC is currently set up for a calibration run. If you want a R1/4 config, the file is dbbc_config_file_102_rapid.txt and IF settings are: dbbcifa=1,agc,1 dbbcifb=4,agc,4 dbbcifc=2,agc,2 dbbcifd=2,agc,2
31 Jan 2013:
Randall replaced CoMo B IF cable and checked connections again. Nothing moved. Re-did phase calibration and new phases are:
103 86 80 105
Edited all cal files with these new values.
Re-ran phase cal amplitude peaking. Looks like S-band lower could be optimised a little by going to a target of 35000. All others seem OK
Hb and Ke DBBCs have had upgrades to v102 of the firmware and corresponding software. Yg is still at v100 for now as routing through CoMos A and B are swapped.
Note that with the new software, the config file formats are different. Also there is a bug at the moment: when the client software is started, it expects the new file format. However, the load command still expects the old format!
IF target levels for Hb and Ke now default to those determined by optimisation of PCAL signals. The old (higher) target levels are still required for SEFD, pointing and (possibly) Tsys measurements, hence a “point” config file.
New config files are as follows. They have been edited for the appropriate target IF levels and phase (calibration) settings:
dbbc_config_file_102.txt New format, loaded at start dbbc_config_file_102_APSG_CRF.txt APSG/CRF config dbbc_config_file_102_T2_OHIG.txt T2/OHIG config dbbc_config_file_102_aust.txt AUSTRAL experiment config dbbc_config_file_102_point.txt For pointing. Higher IF target levels for more resolution dbbc_config_file_102_rapid.txt For R1/R4
The appropriate file should be loaded at the start of each experiment.
7/9/2012 - The S-Band LNA that was labelled & colour cable tagged previously as RCP was discovered by Jamie to be LCP during fringe checks (with the diplexer in circuit). The LNA cables have now been swapped and LNAs relabelled. The LCP power cable has been left unplugged for now.
A borrowed s-band diplexer has been installed (06-09-12) in between the SRCP LNA and the RF Box SRCP In.
It filters out the s-band uplink RFI from USN's AUWA01 13m antenna.
See the Delta Microwave webpage for details of the S5933 diplexer:
The pointing for Yarragadee has been updated following a pointing run. Tests after uploading it show good pointing (errors < 0.02 degrees). The new model parameters are
P1 = -0.0443 P2 = 0.0239 P3 = 0.0322 P4 = 0.0055 P5 = 0.0008 P7 = 0.0343 P8 = -0.0155 P9 = 0.0040