Tracking Science

Tracking Science

Back to Station Equipment

There were six tracking antennas at the Carnarvon Tracking Station.

The Acquisition Aid (Acq Aid) broad-beam antennas acted as the ‘ears’ for the station providing angle pointing data to the Station’s acquisition bus so that other MSFN tracking systems with narrower beam widths lock on to the spacecraft more quickly using it’s the angles provided. Similarly the RARR VHF antenna acted as an acquisition aid to the RARR S-band antenna.

Next were the two pulse radars, the FPQ-6 and the VERLORT (VERy LOng Range Tracking) radar The Q6,’state of the art' precision C-band radar with a maximum range of 59,000Km, was one of only two in the MSFN network. Computer feedback and control, and frequency stability featured prominently as factors in the precision of its tracking. The VERLORT S-band radar, originally designed in WWII, was a veteran of the Mercury missions; it was transported from Muchea as a backup for the Q6.

STADAN’s two RARR systems were examples of the continuous wave (CW) ranging process. Both used ranging tones; upgraded to digital coding for the S-band system in later years. A feature of CW systems is calculating spacecraft velocity from the frequency shift between the uplink and downlink signals; commonly known as the Doppler effect - the ‘eeeee-aaaaah’ engine sound you would hear as a racing car comes towards you standing at the side of the track, and as it goes past you and off into the distance - a change from a high tone to a lower one. Sub-carriers also provided telemetry and command facilities.

The sixth system, the Unified S-Band, added later for the Apollo missions, was also a CW system. It had several sub-carriers to provide range measurement, telemetry data, biomedical data, command, and television and voice communications on its single carrier frequency.

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