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3GHz Analog DFB Modular Links

This versatile, high performance, low cost modular fiber optic link is the ultimate in wideband analog signal transmission.   The transmitter is battery powered and shielded against high level EMI.   The new 2-input version FOL3000-H transmitter has one 50 Ohm input and one 1M Ohm input.   Although both inputs are active when the transmitter is powered on, only one input can be used at a time, the other being capped with a non-shorting SMA metal dustcap.   The link can provide an active integrator function for use with derivative type sensors or probes, by connecting our in-line Passive Integrator to the transmitter's 1M Ohm input.

The transmitter module incorporates the latest low threshold DFB coaxial laser diodes, combined with a novel low voltage laser driver/amplifier design, achieving an overall level of link performance that is unmatched in the industry.   The laser bias is stabilized against temperature and long term drift using compensated integral optical feedback.   The receiver module incorporates automatic gain control (AGC) to compensate for variations in the optical path loss  -  i.e. different lengths of fiber optic cable (from a few meters to several kilometers), plus any additional losses introduced at the optical connectors due to the ingress of dirt or moisture over time.

NEW Technology

Now incorporating MEMS variable optical attenuator technology into the latest receiver amplifier design, achieving superb automatic gain control (AGC), with virtually zero change in system gain or SNR throughout the entire AGC dynamic range.   The MEMS VOA device is controlled via an adaptive feedback control circuit to ensure ultra stable performance over frequency, temperature and time.


Summary Specification

3dB bandwidth:        50 Ohm input:    80Hz - 3GHz  (minimum),  60Hz - 3.3GHz  (typical)

                                               1M Ohm input:    80Hz - 2GHz  (typical)  when driven from a 50 Ohm source impedance

System gain:     0dB for each input

Full scale receiver output:     0dBm (632mVp-p) for <0.2dB gain compression;  4dBm (1Vp-p) at 1dB gain compression

Receiver output noise:     Typically below 136dBm/Hz for system gains up to +30dB

Fiber optic cable:     Simplex ruggedized single mode (optional radiation hard cable can also be supplied) in standard lengths from 50 meters up to 3000 meters (lengths up to 5000 meters can be specified)

Fiber optic connectors:     Simplex SC/APC type, with EMI shielded SC type panel adapters 

EMI shielded transmitter dimensions:     H  1.6 in (41 mm), W  2.5 in (64 mm), D  3.9 in (99 mm), excluding connectors


Internal battery pack:     Rechargeable Lithium-Polymer, 7.4V/2.2Ah (battery charger supplied)

Receiver dimensions:     H  0.75 in (19 mm), W  3.1 in (78 mm), D 3.6 in (92 mm), excluding connectors

The link can also be configured as an ultra high speed digital data link using our differential Pulse Conditioner module.


Opcom Research Limited
Stag Farm Barn, School Road, Bedingham NR35 2DB, United Kingdom
Tel.  +44 (0)1508 482255

Fax. +44 (0)870 8386531