[aaron, rana]

• Drive RF amplifier with -6 dBm from Marconi (amp is +16 dB), and observe RF level at the 1% RF couple out just before the delay line box
• Sweep the Marconi carrier frequency from 75 to 230 MHz at 1 MHz / 50 ms. Observed a somewhat assymetrical sine wave, indicating there's some switching or other issue giving us amplitude-to-phase coupling at the mixer (see Rana technical docs above)
• Removed the Marconi drive and power off RF amp, then open up the delay line box to add a 4 dB attenuator on the RF path.
• The output of the delay line box is now a more or less symmetrical sine wave across our sweep
  • Turned off the sweep, and tuned the carrier frequency to record a 382 mV pkpk output of the discriminator between about 75 MHz (higher voltage) and 145 MHz (lower voltage). THe null is around 108 MHz
• Disconnected the Marconi from the system, and instead plugged in the Rio laser E x Rio laser W beat note from the 1611. Tuned the laser current to null the discriminator output, and recorded the beat frequency with the Moku phasemeter. The lasers have been on for a while and are no longer drifting, so apparently it's staying within the phasemeter bandwidth.
  • After measuring Rio E x Rio W, swapped in the Teraxion laser and measured Rio E x Teraxion. The Teraxion laser exhibited some low frequency drift (several MHz / min), which seemed to improve over time
  • Then, measured Rio W x Teraxion
  • Lastly, I sent a sine wave from the Marconi (amplitude chosen such that the signal going into the moku remained -35 dBm) into the phasemeter to measure its noise floor.

Data logged:

We uploaded the data from moku to dropbox, and pulled it to spirou via the web interface. Should give the workstations dropbox.

Later, I realized we could probably have done better by sending the output of the 1611 directly to the moku. Instead, we were amplifying +16 dB then using an RF coupler to pick off 1% for the moku.

Figures:

1. ASD for the three beat notes, using 10 minutes at 488 Hz sampling for each. Each curve is the ASD from Welch's method with bias-adjusted median averaging, 50% overlap and a Hanning window. The shaded regions are the 15.8-84.1% percentiles. Welch's method is applied 'decade-by-decade', so within each frequency decade the window size is adjusted to maximize the number of averages (as in labutils/moku/modifiedPSD.py). The ASD of the Marconi sine wave is also shown for a rough noise floor reference.
2. The ASD for the Teraxion laser using a three corner hat with the PSD from attachment 1.
3. The remaining figures are the time series plots, for reference.