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The GPR40 range of interference measuring radio receivers were developed by a British company, Chase Electronics, based (when I joined them at least) in a two storey industrial building, St. Leonards House, close to Mortlake railway station in East Sheen, South London.

The GPR40 was a highly specialised device, each of which was hand built, with a list price of around £10,000 in 1986.

At some point the rights to the devices was sold to a German company, Willtek Communications GmbH.

Copyright Information

No copyright infringement is intended here. As far as I am aware all the material copyright remains with the original authors (largely Willtek Communications GmbH, but also RSi of Staines, Middx.). I am providing copies in the hope that they are useful but will comply with any requests by the legitimate copyright holders.

Model Numbers

I am aware of the following models, please use the contact page if you can add any more information to the list!


Presumably this existed as at least a prototype but it was before my time

GPR40.2 / Willtek 8100

This is the version that I worked on. At some point the rights appear to have been sold to Willtek GmbH of Ismaning, Germany.

Flyers and Manuals

Promotional material and basic user manuals can be found on this page.

Circuit Diagrams

Schematic diagrams of the electrical circuits can be found on a separate page.

Assembly Diagrams

A partial set of assembly diagrams showing the main physical sections of the reciever can be found here.

Remote Operation

It is possible to control all the functions of the GPR 40 over an RS232 serial interface. Full details of this can be found here (this was my major contribution to the GPR reciever development).

Calibration Process

I was given a complete set of programs to calibrate the receiver but this relies on some equipment (both expensive and old) which I don’t have access to. There may be useful information that can be gleaned from reading the program code however. For what it is worth all the information can be found here.

Associated Software – Promotional Materials

Software was written to take advantage of the GPR remote comms features, largely involving mapping cellular signal strength. Flyers for these products can be found here.

Associated Software – User’s Manuals

And the full software user manuals are on this page.