1. IF processor and Spectrometer
Laboratory Test Setup
CIT IF processor
8 channel prototype
Digital FFT spectrometer

2. Supercam IF processing consists of basic analog filtering, down-conversion, amplification, and total power measurement.

3. Half of Supercam Spectrometer in narrow band mode (16 IF's, 500 MHz each, 2048 channels)
IF bandpasses
Injected tones

4. Half of Supercam Spectrometer, in wide-band mode (8 IF's, 1 GHz each, 1024 channels)
225, 250 MHz
bandpasses
Injected tones

5. Spectrometer & IF processor combination is stable
Caltech IF processor, spectroscopic variation
10% deviation from radiometer noise at ~200 sec
30% deviation from radiometer noise at 450 sec
traditional Allan time is 650 sec

6. Supercam spectrometer data system
and integration
Accumulate spectra to RAID disk array, with synchronization and header information from the TCS.
Background thread on data computer performs baseline subtraction and regridding, returns single OTF spectrum every N dumps and a preprocessed integrated intensity map ~hourly.
By computing TRMS continuously, data computer can determine if a scan needs to be re-observed.

7. Data rates, formats, storage, and archival
Data cadence 2-5 Hz, typical scan rate 10-15”/s
Raw data rate: 32 x 2048 x 32 bpp = 2 MB/s x Hz over ethernet
Raw data will rotate off the disk to make way for new data. It will be lost in 1 week without intervention (assuming 2 TB storage array).
Native format will be FITS. Optionally, user can flag that the final products be also converted to GILDAS and/or Miriad native formats.
Archival: FITS headers will be written to MySQL database w/ a web frontend, so observers can search for scans and retrieve processed data. Notional search criteria: date, RA/DEC, frequency, object name.

8. Initial processing Quicklook Facilities
By subscans: Optionally thunk raw data to 16 bpp upon writing to disk. Subtract reference scan from on-source data but store separately so that process can be undone.
By rows: window and baseline-subtract entire row. Compute Trms, s, and compare to expectation from Tsys and tint. Flag observer/operator if data quality conditions not met, try adjacent reference scans, and requeue observation.
By map: Perform offline regridding into Nyquist-sampled data set and extract moment maps.
Quicklook Facilities
Running average plot: show “64 spectra in a window” from average of last ~10 seconds
End of row update, plot of data products at “end of map”.
Integration with existing OTF plot at the SMT: send single beam's worth of of data to SMT TCS.