D+M Systems and Test

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FOVC Instruments

The FOVC is a secure fibre optic communications system specifically designed for use in taxing test environments including high EMC and Lightning scenarios.

Aircraft have to be able to operate in very demanding environments, including very close proximity to high power RADAR and other transmitters. In order to ensure that the sophisticated electronics on board will work properly part of the design process demands that such aircraft and vehicles are “illuminated” by such RADAR systems at distances of just a view tens of feet. The essential communications required during such tests means that the use of copper conductors between the control centre and the aircraft or vehicle under test is simply not possible.

This problem has been solved with the FOVC a fibre optic communication system. The system is contained in two fully screened units, each equipment allows the use of up to four standard military headsets giving perfect clarity of communication in this very demanding area of testing thereby allowing DMST to play an important role in military vehicle development.

This compact system provides a secure voice communications net with fibre optic modem transmission; the system is fully multiplexed for up to eight users. Two interchangeable units are used as a secure medium distance communications system connected together via fibre optic cable. Built into the system is an aircraft interface that allows communications with most modern aircraft voice communication systems.

The system incorporates tone transmission via a dedicated internal modem. The design offers mains and battery operation. A 100-metre reel of multimode fibre optic cable is provided as standard. External connections can be made via the side panel when the unit is fully closed down

The FOVC has been used on various aircraft including the Merlin (Mk3), Apache, Sea King, Tornado, Phantom and Harrier.

Full Specifications

Operating ModesVoice transmission, Tone transmission
Voice frequency range300Hz to 3.4KHz
Tone Bandwidth300Hz to 3.4KHz
EMC/RFIE Fields susceptibility from 100MHz to 18GHz Field Strength 200V/m Compiles with DEF STAN 59-41 Part 3 DRS02
No. of communication channels1 voice channel, 1 data (tone) channel
Max no. of operators on net8 plus aircraft
Headset TypeThales headset with dynamic boom microphone and headphones (optional)
Remote operationNi-MH battery pack enables operation for 8 hours on single charge
VOX operationOptional
Onset <0.5s termination >2s
Fibre Optic cable62.5/125 multimode
Modem4-wire analogue duplex operation
Headset Connections4 x NATO Socket
Mic/Tel Input Impedance150Ω nominal
Headphone Impedance300Ω nominal
Fibre Optic ConnectionsLEMO waterproof FGG4K series
Headphone output amplitudeVbatt minus 0.25V P-P (Vbatt = battery voltage)
Headset Volume ControlFront Panel Controllable, zero to full volume
Volume for each headset to be independently controllable
Aircraft Intercom OutputPre-set 0-50mV P-P output impedance 300Ω
Aircraft Intercom Input0-3.5V P-P, 150Ω
Background Noise level-40dB
NATO Number5895-99-4765714

Front Panel

Mains InputIEC Connector
Mains Fuse1.0 Amp Anti Surge
Headphone connectors4 x NATO Socket to accept headset plug
Headphones Volume ControlVolume control independently ajustable for each channel
Tone Input/OutputBNC connector I/P, BNC Connector O/P
Audio OutputXLR Connector

Side Panel

Fibre Optic ConnectorLEMO Waterproof connector EGG4K style for duplex data comms
Aircraft Interface ConnectorLEMO 5 way waterproof connector EGG2K style for two way voice communication
SwitchFully sealed SPST switch, battery on/off


Mains Operating Voltage230Vac ±10%, 47-63Hz Single Phase
Current Consumption1A max.
Operating temperature range-100 C to +400 C
Storage temperature range-200 C to +700 C
50 C to 250 C for minimal battery discharge
InterchangeabilityUnits are identical and fully interchangeable
Environmental Protection (Ingress)Case with lid closed IP65 Case Lid Open IP40
Operational capabilitySystem operational in all weather conditions with lid closed
Dimensions (excluding carrying handle and feet)327 x 411 x 297 (lid fitted) 227 x 411 x 297 (lid removed)
PortabilityMan Portable
Weight10Kg approx.
Charging of battery packCharging with unit on or off
Charging rateFast Charge rate 2A
Trickle charge rate 400mA approx. Temp. range for charging 00 C to 400C
CablesFibre Optic Inter Unit Cable (100m std.)
Wound on cable drum
Mains Supply Cable (one 2m cable each unit)
Aircraft Auxiliary Output Cable (one 3m cable in each unit)