Hughes 3814115-100 Galaxy Range Tone Processor 28.44 MHz Rackmount Satcom

Hughes 3814115-100 Galaxy Range Tone Processor 28.44 MHz Rackmount Satcom

The Hughes 3814115-100 is a Range Tone Processor designed for the Galaxy satellite ground system, built by Hughes Aircraft Company's Satellite Ground Equipment Division. It generates and processes range tones used in satellite ranging operations — measuring the round-trip signal delay between a ground station and a transponder to determine satellite position or distance. The unit supports both computer-controlled and manual operation, with selectable internal or external oscillator reference.

Specifications & What's Included

• Manufacturer: Hughes Aircraft Company — Satellite Ground Equipment Division
• Part Number: 3814115-100
• System: Galaxy, Rev A
• Unit Type: Range Tone Processor
• Reference Frequency: 28.44 MHz
• Form Factor: Rackmount (approximate 3U chassis with rack ears)
• Operating Mode: Computer / Manual (front-panel toggle)
• Input Mode: Normal / Test (front-panel toggle)
• Oscillator Source: Internal / External (front-panel toggle)
• Measure Control: Start / Stop (front-panel toggle)
• Phase Count: Front-panel numerical phase count display
• Tone Frequencies (front-panel buttons): 277.7, 507.2, 434, 54.25 Hz
• EXT OSC IN: BNC connector on front panel for external oscillator input
• Rear Computer Interface: J2 — 25-pin D-sub connector
• Rear Signal Connectors: J3 Receiver, J4 Analog Ø Out, J5 T&C, J6 Transponder (Range Tones Out) — all BNC
• Rear Status Connector: J7 — multi-pin circular connector
• Rear Computer I/O: J8 Computer In, J9 Computer Out — BNC
• Rear Test Points: J10 Analog Ø Out, J11 Range Tone Out, J12 RCVR Input, J13 OSC Freq — BNC
• AC Power: IEC inlet (rear), with S1 On/Off rocker switch; E1 Chassis GND, E2 Signal GND
• Internal Power Supply: Acopian model PB15-50 AC to DC Power Module (Easton, PA)
• Country of Manufacture: United States
• Serial Number: 004 (internal reference)

Applications

Range tone processors are used in satellite ground station systems to perform ranging — the process of transmitting modulated tones through a satellite transponder and measuring the phase shift of the return signal to calculate range (distance) to the satellite. The Hughes Galaxy system was a commercial geostationary satellite program operated from the 1980s onward, and the ground equipment supporting it required precise, dedicated hardware for tone generation, phase measurement, and telemetry, tracking, and command (TT&C) functions. This unit supports both manual bench operation and computer-driven automated ranging sequences, making it suitable for ground station ranging racks or test setups. Equipment of this type was standard at commercial satellite control centers and teleport facilities during the Galaxy satellite program era. Today, units like this are of interest to satellite ground system integrators, legacy system maintainers, aerospace research labs, and collectors of Hughes Aircraft ground equipment.