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DBBC-HB

• Replaced CPU unit and Xilinx programmer 29/9/10. Now able to communicate with FPGAs and apparently configure them. Currently exits with “Register_Card error=-13”. All cards are securely inserted into the backplane. Replugging does not seen to affect the result - possible backplane fault?

DBBC-AUSCOPE2

• Timing issues - clock-1024.exe was not starting correctly when DBBC Control was run and this lead to serious timing errors from the PPS, where a drift of ~0.5 microsec/sec was seen in the PPSMon-GPS difference. Fixed temporarily by restarting clock-1024.exe from C:\DBBC\bin. The problem has not recurred in such a rapid formbut the PPSmon-GPS output is often drastically incorrect. We have measured an offset of 100-200 microseconds where the maser PPS-GPS is 12 microseconds. pps_sync does not correct this. The problem can sometimes be resolved by power cycling the electronics and reconfiguring. At the best, a slow trend is seen in the PPSMon-GPS, of a few microseconds in tens of minutes. This is still too high for use in geodesy.

• Missing channels - Some channels (9,13) appear to be permanently stuck with the recorded data consisting entirely of -1 (1-bit recording). The problem is not fixed by power cycling the electronics. Other channels intermittently appear distorted and full of weak, spurious tones (1-8).

• LEDs on front panel show that they occasionally go into a fault state without apparent cause. No PPS is seen in the FPGA module and the device requires a power cycle of the electronics to function. The only LED lit up on the fault modules is the 10th from the bottom (10 kHz retuning enable?)
• dbbcifc always reads slightly low (52000-54000). We have switched CoMos without make any difference and amplifying the signal does not affect this.
• This DBBC is currently powered on with 10 MHz & 1 PPS applied but no input IFs.
• CoMos do not seem to have good isolation on the input selector switch. Inputs without any attached IFs can still read as having significant total power.

DBBC-AUSCOPE3

• Currently in use for IVS testing observations. Performance seems ok except that channels 3 and 4 intermittently drop out, with recorded data consisting solely of -1 (1-bit recording). There are no indications of this error state in the LEDs of the front panel.
• dbbcifd power always reads slightly low (52000-54000). We have switched CoMos without make any difference and amplifying the signal does not affect this.
• This machine is currently in use (4th October-6th October). Do not make any changes to the configuration until after this IVS run!