New back-end for dual-channel 21cm spectrometer

We’ve upgraded the back-end of the 21cm spectrometer, including both DSP software and the matching SDR hardware.

The SDR receivers are now synchronized to a GPS-derived 10MHz reference clock, which provides an uncertainty in doppler measurements of approximately 30cm/sec.

The FFT resolution has been improved, by covering only the +/- 200km/sec of doppler velocity that is “visible” within the galaxy. This provides a resolution in the FFT of approximately 0.26km/sec or approximately 0.1% of the peak velocity that we are able to observe within the galaxy.

Further DSP work will allow us to double the resolution (half the doppler velocity) in the
coming weeks. Stay tuned for updates.