FOM-20 fiber optic modem from RAD
The FOM-20 fiber optic modem provides a secure, long-range data link between computers, routers, multiplexers, and other data
communication devices. The RAD FOM-20 operates at 16 selectable synchronous or asynchronous data rates from 19.2 kbps to 256
kbps. The built-in Ethernet bridge option enables cost-effective LAN-to-LAN connectivity without the need for an external bridge.
FOM-20 converts electrical signals from DTE equipment into optical signals using an infrared light emitting diode (LED) or
The following DTE interfaces are available on the FOM-20:
Built-in Ethernet bridge
G.703 codirectional (64 kbps).
FOM-20 operates with several grades and sizes of fiber optic cable, and can be ordered with the following interfaces:
850 nm LED/VCSEL for multimode fibers
1300 nm laser for single-mode fibers
1550 nm laser for single-mode fibers.
FOM-20 provides immunity against electrical interference, such as EMI, RFI, spikes, and differential ground loops. Sparking
and lightning protection is provided and a secure link is maintained in hazardous or hostile environments. Three clocking
modes provide maximum flexibility: internal clock, receive loopback clock, and external DTE clock. A phase locked loop
(PLL) circuit recovers jitter-free data and clocking from the incoming optical signal.
V.54 diagnostics are used for local analog and digital loopbacks, and remote digital loopback. The loopback commands are
controlled either by a manual switch, or through DTE interface signals. For testing end-to-end connectivity, BER tests
generate an internal pseudo-random test pattern (511 bits) according to the ITU V.52 standard. The ERR LED flashes whenever a
bit error is detected.
FOM-20 is available as a standalone unit (1U, 1.75 inches high) or as a card for installation in RADís
An optional mounting kit (RM-9) is available for mounting one or two standalone units side-by-side in a 19-inch rack.
RAD FOM-20 fiber optic modem data sheet (pdf)