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Spectrum Monitor

Low cost portable spectrum monitor, providing a quick and reliable reading of ambient RF-Signal Levels in internationally assigned radio communications bands. Deployment may be covert or overt.


Developed by Crownhill Associates Limited this low cost solution provides reliable detection of RF sources. A spectrum analyser remains the instrument of choice for detecting and identifying RF activity. However Spectrum Analysers are expensive bulky and not always readily available. This solution provides RF detection in specific frequency bands using state of the art technology in a small and flexible form factor. Presented as a dedicated product or an OEM module for use in thrid party solutions.

Output from the monitor can be used to trigger local alarms, remote alarms via ethernet or covert personal alerting via vibration.

Spectrum Monitor is a proven design aaimed at bespoke applications tailored to end user requirments.



Based upon a highly selective front end tailored to the band or bands of choice, the Spectrum Monitor utilises multisatge logarithmic amplifiers to accurately convert radio frequency signals power to an equivalent DC voltage. Full advantage is taken of multi layer chip band pass filters, to provide high attenuation of unwanted signals. The outstanding dynamic range and precision over temperature make the design particularly suitable for harsh environments and situations where false alarms are extreemly undesirable.


Potential uses

The sspectrum monitor is incredibly versatile. Potentially examples of deployment include:



General Specifications

Typical Band coverage

GSM 850 Band:

Standard or primary GSM 900 Band, P‑GSM:

Extended GSM 900 Band, E‑GSM (includes Standard GSM 900 band):

Railways GSM 900 Band, R‑GSM (includes Standard and Extended GSM 900 Band);

DCS 1 800 Band:

PCS 1 900 Band:



Typical application

The spectrum monitor design is very versatile, applications are wide and varied, however typically With GSM phones getting ever smaller, they are increasingly being used in areas where they may compromise security. GSM and wide band or hopping technologies are becoming the preferred medium for bugs and video surveillance devices.

The Spectrum Monitor design can be used to detect detect activity in these areas, alerting the operator by visual means or viberation, providing covert indication of illicit activity.

For example an LED display can indicate signal strength to assist in location of the source.

Users might include

Suggested Features

Variable Sensitivity and detection with graphical or visual indication. The received signal strength of detected signals indicated by the number of LEDs illuminated on the bargraph display. The higher the signal strength, the more LEDs are illuminated.

An audio output to allow modulation signatures to be samples and compared to known sources.

A band switch to allow monitoring of specific bands.



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