RAD FOM-8H High Speed Fiber Optic Modem    

FOM-8H Miniature Sync/Async Fiber Optic Modem

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RAD FOM-8H High Speed Fiber Optic Modem

  • The FOM-8H, High Speed, Fiber Optic Modem is used in local data distribution for connecting full duplex synchronous or asynchronous terminals or controllers to high-speed computers over fiber optic cable. FOM-8H operates at data rates of 56 or 64 kbps, and at distances up to 20 km (13 miles), over single mode fiber.
  • FOM-8H performs diagnostic loops in compliance with ITU V.54 standard. Two V.54 loops are available: local analog loop (V.54, loop 3) and remote digital loop (V.54, loop 2). These are activated by an external switch or by toggling the DTE interface signals, Circuit 141 (pin 18) and Circuit 140 (pin 21).

Note: In X.21 and RS-530 interfaces, the loops are only activated by the external switch.

  • Transmit timing can be provided by three alternative sources:
    • Internal oscillator
    • Loopback clock derived from the receive signal
    • External clock derived from the terminal.

Note: FOM-8H/X21 has no external clock.

  • The carrier can be strapped for either continuous operation or for switched operation. When in switched operation, the carrier is controlled by the RTS signal, enabling transfer of a control signal end-to-end.
  • FOM-8H incorporates all the advantages of a fiber optic modem:
    • Lower attenuation than with copper wire;
    • EMI/RFI immunity for cost effective savings on expensive and heavy shielding and on complex error checking routines;
    • High data security: risk of eavesdropping is minimized as fibers radiate negligible power; cost of data encryption is reduced;
    • Safety and electrical isolation: no spark hazard and no ground-loop noise.
  • Four models are available:
    FOM-8H/V24 with V.24/RS-232 interface;
    FOM-8H/V35 with V.35 interface;
    FOM-8H/X21 with X.21 interface, and
    FOM-8H/530 with RS-530 interface.
    All models have an integral 25-pin D-type connector for the DTE interface. For the V.35 connector, a 45 cm (17.8") cable is supplied, with a 25-pin male connector on one side and a 34-pin, V.35 male or female connector on the other side. For the X.21 connector, a 45 cm (17.8") cable is supplied, with a 25-pin male connector on one side and a 15-pin, X.21 male or female connector on the other side.
  • Three fiber optic interface options are available: SMA, ST or FC.
  • Power is supplied from an external wall-mounted power supply, 9V / 300 mA
    (Center - positive; sleeve - negative).


  • Synchronous or asynchronous
  • Data rates: 56 or 64 kbps, selectable
  • V.54 diagnostics, including local and remote loops
  • Transmission range up to 20 km (13 miles) over single mode fiber, and up to 4 km (2.5 miles) over multimode fiber
  • V.24/RS-232, V.35, X.21 of RS-530 interface
  • Controlled or continuous carrier
  • Internal, external or receive clock
  • LED indicators
  • Miniature, lightweight, easy to install

Miniature High Speed Fiber Optic Modem

* Specify DTE connector:
V24 for V.24 interface, female
V35/F for V.35 interface, female
V35/M for V.35 interface, male
X21/F for X.21 interface, female
X21/M for X.21 interface, male
530 for RS.530 interface, female
+ Specify fiber optic connector:
SMA for SMA connector
ST for ST connector
FC for FC connector
ST13 for 1300 nm single mode with ST
FC13 for 1300 nm single mode with FC

Wall-mounted 9 VDC / 230 VAC power supply






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