FMT CMD/RNG Select Unit 12-Port BNC Video Switcher RF Modulation Satcom Rack

FMT CMD/RNG Select Unit 12-Port BNC Video Switcher RF Modulation Satcom Rack

The FMT CMD/RNG Select Unit is a rackmount signal routing switcher used in satellite ground system installations to direct command and ranging (CMD/RNG) signals — including RTP, T&C ranging, transponder ranging, and LM tones — to downstream FM modulators. The front panel provides discrete selector switches for each signal path, and the rear panel exposes 12 BNC ports (J2–J13) plus a 25-pin D-Sub connector (J14) for signal I/O. Internally, the unit uses a bank of 24VDC R30D relays to switch signal paths under front-panel control.

Specifications & What's Included

• Unit: FMT CMD/RNG Select Unit
• Internal part number: 2586-BA, Rev 1
• Form factor: Rackmount (approximately 2U), with integral rack ears
• Power input: 120 VAC, 1A, 47–440Hz (IEC inlet, J1)
• Power entry module: Corcom 6VM1S F7361A — 6A, 120V, 47–440Hz (UL/CSA listed)
• Internal switching relays: R30D-E1Z4-24V (24VDC coil, 2A/120VAC contact rating)
• Rear panel connectors: 12 × BNC (labeled J2–J13), 1 × D-Sub 25-pin (J14)
• Front panel inputs (RTP IN section): T&C RNG, XPNDR RNG
• Front panel functions: RTP / LM TONES selector, RNG / CMD selector, SCG / CG selector
• Output routing: signals directed TO FM MODULATORS (labeled on front panel)
• Chassis ground lug: E1 on rear panel
• Unit only — no cables or accessories included

Applications

The FMT CMD/RNG Select Unit is designed for use in satellite ground station command and ranging systems, where it serves as a signal routing switch between uplink signal sources (RTP feeds, tone generators, ranging chains) and FM modulators. In a typical ground station architecture, the command and ranging chain processes telemetry and command (T&C) signals and transponder ranging tones, which must be flexibly routed to one or more FM modulators depending on which satellite or transponder is being accessed. A switcher like this unit allows ground station operators to select between ranging and command signal inputs and direct them to the correct modulator path without manual repatching of coaxial cables. The use of BNC connectors throughout and the relay-based switching approach are characteristic of satcom ground equipment built from the 1980s through the early 2000s. This type of unit is found in fixed and transportable earth stations supporting geostationary satellite operations, including range safety, telemetry, and uplink control facilities.