The following consists of technical specifications and may or may not be easily distilled by the reader. The information is included mainly to illustrate the capabilities of the Spectrometer.
The Spectrometer, in its present state, can analyze up to eight 800 MHz or up to sixteen 50 MHz baseband outputs from the GBT. Thirty-two 50 MHz baseband outputs were originally planned, but the number was halved due to costs. A total of 262,144 correlator lag channels is provided. A similar instrument with half the lags was built for the Tucson 12-meter telescope and is in use as its primary spectrometer.
The Spectrometer supports many modes of operation. An observer can select the number of active telescope baseband outputs in binary steps from 1 to 32 and allot the 262,144 available lags to analyze the outputs selected. Full Stokes parameters can be computed by cross correlation. Bandwidths in factors of 4 from 12.5 MHz to 800 MHz are available. Combinations of high and low speed baseband outputs are possible.
The Spectrometer can support pulsar observations. In experiments where a pulsar of known period is observed, the spectrometer will maintain separate integration results for 256 lags in up to 4096 time bins across the pulsar period. Time resolutions as fine as 1.5 msec are possible as well as other combinations of lags and time bins. In search observations where no pulsar period is known, unprocessed integration results are available every 1.3 msec.
The "chip" used in the spectrometer was designed by the NASA Engineering Research Center for VLSI Systems Design at the University of New Mexico. The spectrometer uses 256 in its design.
RAM memory is included in the spectrometer's design to deliver 1.3 msec bursts of contiguous 2-bit samples, originally taken at the 1.6 GHz sample rate, to an array of 16 banks of correlator chips being clocked at 100 MHz. Each chip can thus analyze one sixteenth of a high-speed sampler's output.