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Debugging Antennas

Here is a guide to finding faulty antennas and working out the root cause of the issue. This guide will help you identify the problem and provide solutions to fix it.

Finding faulty antennas​

Your first port of call is to check the telescope web app, specifically the gains and phases section. The calibration process will set the gain of a faulty antenna to zero. If you see a gain of zero for an antenna, it is likely faulty. Work through the following steps to check the specific antenna.

Test 1: Check the radio data​

Put the telescope into Diagnose Mode. Remember to wait a few minutes, as it takes a little while for the interface to download the raw data and calculate all the spectra.

TART Spectra
The Diagnose display showing spectra from each antenna.

Then check the spectrum for the antenna you suspect is faulty. If the signal is zero then the problem is likely (but not necessarily) to be the radio rather than the antenna. If the spectrum looks normal, then the problem is likely to be the antenna.

Test 2: Check the visibilities​

Select a baseline that includes the antenna you suspect is faulty. If the antenna is faulty, and the radio is receiving zeros. The visibilities should be zero for the faulty antenna. If the antenna is not connecting to the radio then the visibilities should be low amplitude (lower than other visibilities).

  • Low Amplitude. Check for antenna connection issues
  • Normal Amplitude. Antenna is probablly functioning well. Possible problem: Antenna Location is incorrect.

Test 3: Swapping Antennas​

Swap the SMA connections between the suspect antenna and another convenient antenna. Check that the visibilitiy amplitude returns to normal. If it does not, then the problem is between the SMA on the box and the internal radio. Solution: Try swapping radio modules, and double check the internal connection between the SMA and the radio. This is called a pigtail.

Unlikely but Possible Causes​

Check the antenna location​

If the antenna is functioning well, but the location is incorrect, the antenna will receive signals from the sky, but the imaging and calibration will find that the visibilities make no sense. This is solved by checking the antenna position calibration.