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RAD FOM-9 Sync/Async High Speed Fiber Optic Modem    

FOM-9 Miniature Sync/Async Fiber Optic Modem

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RAD FOM-9 Sync/Async High Speed Fiber Optic Modem

  • The FOM-9, sync/async Short Range Modem, is used for local data distribution, connecting full or half duplex, sync or async terminals to computers over Single Mode or Multimode fiber optic cable. FOM-9 operates at data rates of 32 to 128 kbps in sync mode or 9.6 to 115.2 kbps in async mode. FOM-9 operates at distances up to 16 km (10 miles) depending on the type of fiber optic cable.
  • There are five available FOM-9 models:
    • FOM-9/V.24/UP, unpowered,with V.24 interface*
    • FOM-9/V.24, with V.24 interface
    • FOM-9/V.35, with V.35 interface
    • FOM-9/X.21, with X.21 interface
    • FOM-9/530, with RS-530 interface

    Each model has a 25-pin D-type connector for the DTE interface. The V.35 interface is supplied with a 45 cm (17.7") cable, with a 25-pin female connector on one side and a 34-pin male or female connector on the other side. The X.21 interface is supplied with a 45 cm (17.7") cable with a 25-pin male connector on one side, and a 15-pin X.21 female connector on the other side.

    *FOM-9/V.24/UP is an unpowered ultra-miniature version of FOM-9.

  • FOM-9 performs diagnostic loops in compliance with ITU V.54 standard. Two V.54 loops are available: analog loop (V.54 Loop 3) and remote digital loop (V.54 Loop 2). These loops are activated either by a dip-switch or by the DTE interface Circuit 141 (Pin 18) and Circuit 140 (Pin 21). (Loopbacks in FOM-9/X.21 can only be activated via dipswitch.) A proprietary local-digital loop is available and can be activated only by the product's switches. This loop connects the local RD to the TD. A TEST LED lights when any of the diagnostic loops is ON.
  • FOM-9 includes a built-in V.52 standard BER tester for testing link integrity. The internal BER tester is activated by a switch on the top of the product. The BER tester checks the receive data and turns on an ERROR LED when an error is detected.
  • Asynchronous transmission is provided by internal conversion from async to sync, in compliance with ITU V.22 bis standard. Different async formats are switch selectable.
  • In synchronous mode, transmit timing can be provided by one of three user-selectable sources:
    • Internal oscillator
    • External clock
    • Loopback clock derived from the receive signal.
  • The modem's carrier can be strapped for either continuous operation or for switched operation. In switched operation, the carrier is controlled by the RTS signal and enables transfer of a control signal end-to-end.
  • FOM-9 incorporates all the advantages of a fiber optic system:
    • Lower attenuation than with copper wires; attenuation is not related to frequency;
    • EMI/RFI immunity which saves the cost of expensive and heavy shielding and 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 problems.
  • FOM-9 includes six LEDs for indicating signal status: RTS, TD, RD, CD, TST & ERR.
  • FOM-9/V.24/UP's innovative circuitry design allows operation without power supply, by using ultra-low power from the standard RS-232/V.24/UP data and control signals. For proper operation, both data and control signals must be connected, i.e. TD, RD, RTS and DTR.If the DTE cannot provide enough power for normal operation of the unit, use FOM-9/V.24.
  • FOM-9/V.35, FOM-9/X.21, FOM-9/V.24 and FOM-9/530 include an external power jack for normal operation of the unit. An additional external 9 VDC 300 mA wall mounted adapter should be ordered separately and used to power the unit.


  • Synchronous or asynchronous
  • Single Mode and Multimode supported
  • Data rates up to 128 kbps sync and 115.2 kbps async
  • V.54 diagnostics, including local and remote loopbacks
  • Built-in BERT in compliance with V.52
  • Full or half duplex
  • Controlled or continuous carrier
  • Internal, external or receive clock
  • Transmission range up to 16 km (10 miles) over Single Mode fiber
  • LED indicators
  • V.24, V.35, X.21 or RS-530 interface options
  • External, wall mounted power supply for all models except FOM-9/V.24/UP

Synchronous/Asynchronous Short Range Fiber Optic Modem

Synchronous/Asynchronous Short Range Fiber Optic Modem, Unpowered

* Specify DTE interface:
V24/UP for unpowered V.24 interface, female connector
V24 for V.24 interface, female connector
V35 for V.35 interface, female connector
X21 for X.21 interface, female connector
530 for RS-530 interface, female connector
+ Specify optical interface:
85ST for 850 nm Multimode ST connector
85SC for 850 nm Multimode SC connector
85FC for 850 nm Multimode FC-PC connector
13ST for 1300 nm Single Mode ST connector
13SC for 1300 nm Single Mode SC connector
13FC for 1300 nm Single Mode FC-PC connector





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