Reports 1-1 of 1 Clear search Modify search
AdV-DAQ (Data Acquisition and Global Control)
letendre, masserot - 16:28 Thursday 22 March 2018 (40872) Print this report
LNFS demodulation troubles

Triggered by the noise on the RFC demodulated channels we have look on the LNFS demodulated channels.

The plots contains,  starting from the top

  • blue: 2018-01-23-08h39UTC(Ok), purple: 2018-03-22-09h43UTC(troubles), brown: 2018-03-22-14h43UTC (after the recovering)
  • the first line:  the fft of the channels sampled at 400MHz (raw input of the demodulation board)
    • Atomic_Clock: 10MHz
    • LNFS_OUT1: 6MHz modulation signal
    • LNFS_OUT2: 8MHz modulation signal
    • LNFS_OUT3: 56MHz modulation signal
  • the second line : the time display of the acquired channel @400Mhz
  • the third line: the extracted phase built based on the output channels of the demodualtion mezzanine

This morning, the noise level of the channels was 100 times higher than in Janunary 23th (see the purple FFT spectrums and the time displays ).

After severals configuration trials, we succeeded to recover the correct noise level .

We take this opportunity to reduce the VGA value of the 8MHz (LNFS_OUT2) from 0x12 t0 0x9 to avoid some saturations of the 400MHz Adc.

To check that all the others demodulations mezzanines are working correctly, we enable all the sample packets and they were corrects

Images attached to this report
Search Help
×

Warning

×