Tel: 0118 933 2533

Fax: 0118 933 1224

email: sales@teelectronics.co.uk


THE JACKDAW

THE DEVIL'S HIGHWAY

MORTIMER WEST END

READING, BERKS RG7 2AD

 

COMMUNICATIONS

 

 

16 CHANNEL 4 USER TELEPHONE SYSTEM

for PLESSEY AIRPORTS, 1992.

 

4 wire/2wire system with voice band single tone, conventional ring voltage or E and M signalling selectable on a line by line basis. The system allows conferencing on up to 4 phones, up to 4 simultaneous calls and up to 16 calls held. There is provision for recording any call. It was installed in West Africa for inter-airport communications.

 

 

PAIR GAIN TELEPHONE SYSTEM

for TELETECH Pty (Australia), 1993

 

Allows two additional voice/data channels on each physical line so overcoming difficulties of limited infrastructure in the local loop.

 

 

30 CHANNEL 4 WIRE 2 WAY TELEPHONE LINE SWITCHER

for PLESSEY AIRPORTS, 1992

To select alternative land line or microwave link for 30 channels under manual or dual tone signalling control. Used for inter-airport communication in Africa.

 

ACOUSTIC COUPLER

for K&N Electronics, 1980

 

The GPO did not allow direct connection to telephone lines, so data had to be coupled in and out acoustically from the handset.

The data rate in full duplex was 300 bps.

 

The data I/O was RS232 or current loop.

 

The Coupler was mains or battery powered and had an option for rechargeable batteries.

 

Seen used on a BBC science programme!

 

 

 

TELEPHONE BASEBAND FILTER

for PLDT (Phillipines Long Distance Telephone Company); 1991.

We produced 5000 of these passive low pass filters which were used by PLDT to separate POTS (Plain Old Telephone System) signals from higher frequency data.

 

 

TE1062 RS232 to TELEX

CONVERTER

for BLT, Denmark, 1980.

 

In 1980 text documents were mostly transmitted by Telex; Fax was still exotic.

 

Telex used a separate network communicating at 110 baud with a 5bit (Baudot) code. Special shift characters overcame the 32 combination limit and determined the meaning of succeeding data.

The 0s and 1s were represented by large negative and positive voltages on the nominally 600ohm lines.

 

 

last updated 26th August 2001

Copyright 2001,  All rights reserved.