Data Sheet

FOM-20Fiber Optic Modem

Provides a secureand long-range datalink of up to 140 km(87 miles)• Selectable data rates from 19.2 to 256 kbps
• Multimode or single mode operation• Extended transmission range of up to 140 km (87 miles) with 1550 nm laser diodeoption• V.54 diagnostic loopbacks and built-in V.52 BERT
• Single modem card version for RAD’s ASM-MN-214 modem rack

The FOM-20 fiber optic modem provides asecure, long-range data link between
computers, routers, multiplexers, andother data communication devices. Itoperates at 16 selectable synchronous or
asynchronous data rates from 19.2 kbps
to 256 kbps.
The built-in Ethernet bridge enables
cost-effective LAN-to-LAN connectivity
without the need for an external bridge.

FOM-20 converts electrical signals fromDTE equipment into optical signals using
an infrared light emitting diode (LED) orlaser diode.
The following DTE interfaces are available:•

V.24/RS-232

•

V.35

•

X.21

•

RS-530•V.36 (RS-449)•

Built-in Ethernet bridge•

G.703 codirectional (64 kbps).

The Access CompanyFOM-20
Fiber Optic Modem

FOM-20 operates with several grades andsizes of fiber optic cable, and can beordered with the following interfaces:•850 nm LED/VCSEL for multimodefibers•

1300 nm laser for single-mode fibers•

1550 nm laser for single-mode fibers.

FOM-20 provides immunity againstelectrical interference, such as EMI, RFI,
spikes, and differential ground loops.
Sparking and lightning protection isprovided and a secure link is maintained inhazardous or hostile environments.
Three clocking modes provide maximum
flexibility: internal clock, receive loopback
clock, and external DTE clock.

V.54 diagnostics include local analog anddigital loopbacks, and remote digitalloopback. The loopback commands arecontrolled either by a manual switch, orthrough DTE interface signals. For testing
end-to-end connectivity, BER tests
generate an internal pseudo-random test
pattern (511 bits) according to theITU V.52 standard. The ERR LED flashes
whenever a bit error is detected.

Specifications

FOM-20 is available as a standalone unit
(1U, 1.75 inches high) or as a card for
installation in RAD’s ASM-MN-214 rack.

Interfaces and Connectors
V.24/RS-232, 25-pin D-type, female
V.35, 34-pin D-type, female
RS-530, 25-pin D-type, female
X.21, 15-pin D-type, female
V.36/RS449, 37-pin D-type, male(via cable adaptor)
Built-in (10/100BaseT) Ethernet bridge,
RJ-45
G.703 codirectional (64 kbps),
terminal block or RJ-45

An optional mounting kit (RM-9) isavailable for mounting one or two
standalone units side-by-side in a 19-inchrack.

A phase locked loop (PLL) circuit recovers
jitter-free data and clocking from theincoming optical signal.

ELECTRICAL
Transmission Rates
Asynchronous:
19.2, 28.8, 38.4, 57.6,115.2 kbps
Synchronous:
19.2, 32, 48, 56, 64, 72, 112,128, 144, 192, 256 kbps

Note: For G.703 codirectional interfaces,end-to-end byte synchronization is not maintained.

Table 1. FOM-20 Fiber Optic Interface Characteristics
Wavelength

Fiber Type

[nm]

[μm]

850

62.5/125
multimode

1310
1550

Transmitter
Type

Typical Output
PowerReceiver
Sensitivity

Typical Max. Range

[dBm]

[dBm]

[km]

[mi]

LED/VCSEL-18-48

7.7

4.8

9/125
single mode

Laser

-12-50

70

43.7

9/125
single mode

Laser-12-50

14087

Figure 1. Point-to-Point Application

Data SheetOPTICAL

GENERAL

Operating Wavelength
850 nm multimode fiber, LED/VCSEL
1300 nm single mode fiber, laser diode1550 nm single mode fiber, laser diode

Diagnostics
Local digital loopback (DIG), activated by afront-panel switch
Local analog loopback (ANA), activated bya front-panel switch or by DTE
interface signals (excluding X.21 andG.703 interfaces)
Remote loopback (REM), activated by afront-panel switch or by DTE interface
signals (V.35 or RS-530 andV.24/RS-232)

Transmission Line
Dual fiber optic cableInterface Characteristics
See Table 1
Optical connectors
ST, SC, or FC

Timing Elements
Receive clock: derived from the receivesignal
Transmit clock: derived from threepossible sources:• Internal oscillator (INT)• External from the DTE (EXT)• Recovered from the receive signal,looped back as a transmit clock (RCV).

Table 2. Fiber Optic Modem Comparison ChartFeature

Data rates

FOM-E1/T1

E1/T1

FOMi-E1/T1

E1/T1

FOM-2019.2–256

FOM-4056–2048

FOMi-40

56–2048[kbps]DTE Interfaces G.703

G.703

Serial,Serial,Serial,

Ethernet

Ethernet

Ethernet,

FOM-E3FOMi-E3

FOM-E3/ETH

FOM-T3FOMi-T3

FOM-T3/ETH

E3

E3

E3

T3

T3

T3

G.703

G.703, HSSI

10/100BaseTVLAN Bridge

E1/T1
Laser diode33333333–3––3–3–

optionSNMPmanagement

Figure 2. Extension of G.703 Codirectional Network

Data Sheet
FOM-20Fiber Optic Modem

Power Supply
115 or 230 VAC (±10%), 47–63 Hz, 5 VA
–48 VDC (±20%), 24 VDC

Ordering

DTE interface:
V24
V.24/RS-232
V35
V.35
530
RS-530X21
X.21
V36
V.36/RS-449
703/% G.703 codirectional (64 kbps)UTP
10/100BaseT built-in
Ethernet bridge%

G.703 interface connector(standalone only):
TB
Terminal block
RJ
RJ-45

FOM-20/~/#/^Standalone unit
FOM-20R/#/^
Card version for ASM-MN-214 modem rackLegend~#Power supply:
115
115 VAC230
230 VAC
48
48 VDC2424 VDC
Optical interface:
SC85 850 nm multimode, SC
ST85 850 nm multimode, ST
FC85 850 nm multimode, FC
SC13L 1310 nm laser diode, SC
ST13L 1310 nm laser diode, ST
FC13L 1310 nm laser diode, FC
SC15L 1550 nm laser diode, SC
ST15L 1550 nm laser diode, ST
FC15L 1550 nm laser diode, FC

SUPPLIED ACCESSORIESAC power cord (for standalone units, withAC power supply)
DC connection kit (for standalone units,with DC power supply)
OPTIONAL ACCESSORIES
RM-9Hardware kit for mounting one or two
FOM-20 units in a 19-inch rack

Power Consumption
AC: 5 VA
DC: 4.3W

CIA/&
Connector interface adapter for FOM-40R(card version only) in an ASM-MN-214 rack

Physical
FOM-20 Standalone:
Height: 4.4 cm (1.7 in)
Width: 19.3 cm 7.6 in)Depth: 24.0 cm (9.6 in)
Weight: 1.5 kg (3.3 lb)

Legend&FOM-20R Card:
Fits the ASM-MN-214
modem rack
Weight: 0.27 kg (0.6 lb)
Environment
Temperature: 0°–50°C (32°–122°F)
Humidity:
Up to 90%, non-condensing

International Headquarters
24 Raoul Wallenberg Street
Tel Aviv 69719, Israel
Tel. 972-3-6458181
Fax 972-3-6498250, 6474436
E-mail market@rad.com

www.rad.com^

Adapter:
V35/1 one 25-pin rack DTE
connector to one V.35 34-pin
connector
X21/1 one 25-pin rack DTE
connector to one X.2115-pin connector
ETHone 25-pin rack DTE
connector to one RJ-45connector

North America Headquarters
900 Corporate Drive
Mahwah, NJ 07430, USA
Tel. 201-5291100
Toll free 1-800-4447234
Fax 201-5295777
E-mail market@radusa.com

Order this publication by Catalog No. 801293

The Access Company

312-100-10/10 Specifications are subject to change without prior notice. © 1989–2010 RAD Data Communications Ltd. The RAD name, logo, logotype, and the terms EtherAccess, TDMoIP and TDMoIP Driven, and theproduct names Optimux and IPmux, are registered trademarks of RAD Data Communications Ltd. All other trademarks are the property of their respective holders.

IndicatorsPWR (green):
On: Unit is powered on
RTS (yellow):
On: DTE activated Request To Send
TD (yellow):
On: Transmitting steady SPACE
Flashing: Transmitting data
RD (yellow):
On: Receiving steady SPACE
Flashing: Receiving data
DCD (yellow):
On: Valid receive signal present
ERR (yellow):
On: Alarm initiatedFlashing: Error detected during BER
tests
TEST (red):
On: Loopback mode and/or
BERT activated