Phase Monitor Troubleshooting

Is the system is working correctly? See Checking the instrument status.

Are data being acquired?

To find out: tail -f ~phasemon/data/1sec.new

Yes

No:

• Errors from phasemon program?
• Look at end of message.log
• phasemon program not running?
• ps -ax | grep phasemon
• Serial port on the workstation OK?
• cat filename > /dev/cua/a
• Communication cabling and RS232/RS485 conversion box OK?
• Check continuity from pit box to correlator room
• Check grey metal box under floor in correlator room
• A/D unit in correlator box OK?
• Is the green light on? It should flash for every acquisition request.
• Are the correct ASCII characters going down the line?
• Is the baud rate etc. configured correctly (see ADAM User's Manual)
• Power supply in the correlator box OK?
• +14 V available for A/D?
• AC power supply to the pit box OK?
• Still plugged in at Lab 2?

Does the problem affect all 4 channels?

Use pmn_status, pmn_volts, pmn_volts_vs_t

No

Yes:

• Glitches?
• Errors from phasemon?
• Intermittent communication problems?
• Interference from lightning strikes?
• Intermittent AC power dips?
• Demodulation board OK?
• Low amplitudes?
• Rainstorm?
• Satellite having trouble?
• Demodulation board OK?
• High noise?
• Interference from Intermittent narrowband spectral features?

Does the problem affect only one interferometer (1 pair of channels)?

Use pmn_status, pmn_volts, pmn_volts_vs_t

No

Yes:

• Glitches?
• Bad connection?
• Low amplitude?
• Measure signal level
• Amplifier gone bad?
• Power to LNB and in-line amp?
• Reflector badly aligned?
• Poor connection?

Does the problem affect only one channel?

Use pmn_status, pmn_volts, pmn_volts_vs_t

No

Yes:

• Bad Gilbert Cell Multiplier?
• Bad chip on demodulation board?

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