Station Channel Spacing Test

Purpose

This Test is intended to verify the centre of each channel is an integer number of the channel spacing 781.25 KHz. The test operates on 8 to 384 numbers of channels. Test Genrators are configured to output a synthesized sinusoid at 50 MHz by default or a different start channel if specified. The test has 2 modes: without DAQ (recommended for bandwidth > 48 channels) and with DAQ.

Without DAQ

The beamformer is started for the specififed bandwidth, up to the full badwidth. A Test tone is generated in the centre of a channel, then a buffer filled with packets. A packet with the logic ID matching the expected channel is found and the power calculated. All other channels are checked to have power less than a certain fraction of the active channel. If not all other channels are seen in the buffer, the buffer is refilled several times or until all channels have been seen. This is repeated for all channels.

With DAQ

Due to limitations in how quickly the DAQ keeps up with larger bandwidths, the total bandwidth to test is split up into groups of up to 48 channels. The DAQ is started and a tone generated in the first channel. Every time the timestamp of received data increments by 0.33 seconds, the test frequency steps by 0.78125MHz. The data is checked that integrated sample power is only in the expected received channel. This is repeated for the number of channel groups.

NOTE: This test operates on a single TPM if in DAQ mode. This is to reduce processing in the DAQ callback (More actions while the DAQ is running leads to earlier saturation or crashes).

Methodology (without DAQ, default)

  1. Connect to the station. Read the initial state of some registers.

  2. Check start and total channels are in acceptable range and calculate groups and group size.

  3. Verify the Network interfaces and prepare frequencies for the various channels.

  4. Disable any Test Generator outputs and ADCs in the station.

  5. Start the Beamformer for the specified number of channels.

  6. Set the test frequency tone to the centre of the first channel.

  7. Fill a buffer with received packets and check that only packets with the active channel have power.

  8. Repeat steps 6 & 7 for all specified channels.

  9. Reset the initial conditions. Disable the Test Generators and reset any modified registers.

Methodology (with DAQ)

  1. Connect to the station. Read the initial state of some registers.

  2. Check start and total channels are in acceptable range and calculate groups and group size.

  3. Verify the Network interfaces and prepare frequencies for the various channels.

  4. Disable any Test Generator outputs and ADCs in the station.

  5. Start the Beamformer and DAQ for the group of channels.

  6. After a set time period, increment the Test generator frequency through the centre channel frequencies of this group before stopping the DAQ

  7. Save the group data for later processing. Repeat steps 5 - 7 for all groups

  8. For all the channels in all groups, verify there is integrated power in the expected channel only.

  9. Reset the initial conditions. Disable the Test Generators and reset any modified registers.

Typical issues

Some typical issues and how they present are shown in the following table:

Segmentation Fault: Occasionally the DAQ causes a segmentation fault, causing the test to abort.