The Navy's special receivers monitor the entire possible range of doppler shifted frequencies, about 28 Khz. My receiver permits only a narrow observing window of 2 Khz at any given time. Combined with the interferometer's limited beamwidth, this system is far from capable of keeping track of all orbiting satellites, or even detecting all newly launched ones. (The steered yagi array however, is capable of observing most all satellites, but only with advance notice where to look.) With patience, the interferometer does permit the occasional capture of satellites crossing the fence within the desired spatial and doppler windows. Commercial software is used with the A/D converter card to capture and store the recordings to disk. The calibration standard also drives the interferometer switching. It alternates between the three antennas, dwelling for 20 ms. on each one in turn. The RF output of the calibration standard is a combline spectrum with lines every 1 Khz. It also provides a time "tick" which is recorded on the second A/D channel. With careful calibration to the WWV time ticks over a period of a few days, the calibration standard provides time within a few milliseconds and better than +/- 2 Hz frequency accuracy at 217 Mhz.