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VSB Car Loop Amplifier

VSB V-LIM Vehicle Loop Amplifier for the VSB System and Simultaneous operation of standard Inductive Wireless Earphones



The V-LIM Vehicle Loop Amplifier for the VSB System and Simultaneous operation of standard Inductive Wireless Earphones which will allow for non-VSB earphone users to work in the same vehicle. This amplifier will also help with system migration and any uncertainty that may arise where forces are using different systems or are drafted in for support.

The VSB Wireless Transmitter uses a novel, specialised audio signal modulation method which has been specifically developed to provide optimum performance in conjunction with the advanced digital signal processing implemented in the VSB Digital Wireless Receiver.  The patent-pending method used in the VSB transmitter/receiver combination delivers drastically reduced levels of audible interference and noise when used in areas of high AC magnetic field strength, such as in motor vehicles, on trains, and in sites with significant levels of electronic and electrical technology.  As a result, the system achieves outstanding speech quality across the whole spectrum of covert applications where standard inductive devices are inoperable.

The modulation scheme uses only carrier frequencies within the audio band, is highly tolerant to frequency drift, transmit coil response and mismatch of operational frequencies between transmitter and receiver. The receiver is programmed to decode only audio signals modulated onto the carrier frequency thus making it immune from inductively-coupled noise sources.   The system provides consistent performance over temperature and battery discharge level, while permitting compact construction.  No matching or pairing between transmitter and receiver is required.  The transmitter is entirely based on robust low-frequency electronics and is categorically not a radio frequency device.

Installation of the system is simple using the supplied cables harness and it will operated from 4 - 24 volts DC. " levels controls aduct the VSB and Standard Inductive levels.



Power supply

12VDC nominal (4.7* - 17VDC)

Active state power demand

40 Watts max (drive level & ambient temperature dependent)

Standby current


Power switching

Automatic: radio output bias detect min 2VDC

Standby to active time

50 milliseconds max

Input level

±0.1 to ±6Vpp differential, ±1Vpp nominal with AGC

Input impedance

47 Ohms (3 Watts max)

Output level

0.43A RMS/28V RMS max (differential)

Output design load impedance

21 Ohms in series with 500 microHenries (standard 10 turn flat cable roof loop)

Operating temperature range

-30 to 55°C, to 70°C with reduced output

Non-operating temperature range

-40 to 85°C

Climatic performance

100% RH at 40°C

Protection features

Input and output transients, over temperature, over current, load short circuit

Electrical interface

Single 15 way male D Sub connector

Electrical certifications


Environmental certifications

EN 300 019-2-*

*Lower input voltage limit determined by power cable volt drop and required output drive level)





Contact Us

Sensorcom Ltd.

London, BR3 4LZ, 

United Kingdom

Tel: +44 (0) 208 639 4440

Fax: +44 (0) 208 639 4442

E-Mail: info@sensorcom.com 


The MEL Group

Laurence Walter House

Addison Road, Chilton Ind. Est,

Sudbury, Suffolk

CO10 2YW, UK


BSI registered

Holds Certificate No: FM 561435 and operates a Quality Management System which complies with the requirements of ISO 9001:2008 for the following scope:

The design, manufacture, repair and supply of audio communication devices, assisted listening devices and a range of associated products and accessories.


The “end of life disposal” of electrical products  in an environmentally friendly way, is the responsibility of the Purchaser.