DSP board takes the noise out of radiocomms

Edited by the Engineeringtalk editorial team Feb 12, 2002

A novel DSP board will allow clear verbal radio communication where there is high ambient noise, without the use of a full fleet of headsets, complicated programming or soldering.

Icom (UK) has a novel DSP board that will allow clear verbal radio communication where there is high ambient noise, without the use of a full fleet of headsets, complicated programming or soldering.

The DSP board uses patented neural network technology digital signal processing and allows recognition of and differentiation between voice patterns and mechanical noise from a transmitting Icom PMR transceiver, leaving only speech.

The DSP board, developed for Icom by Adur Communications and Cortologic, simply slots into a wide range of Icom commercial transceivers.

The DSP board is ideal for a variety of environments including construction sites, motorsport, airports or anywhere there is loud noise.

For example, on construction sites, loud noises are generated from various pieces of machinery such as site generators and pneumatic drills.

The worker in this environment, using an Icom radio, transmits audio which has all the construction noises superimposed on it.

On each of the receiving radios, this extra noise is completely removed.

The receiving radio recognises the voice signal and removes all the background noise.

The worker is still transmitting all the noise but the receiving units are filtering out all the mechanical noise.

Motor racing is another application for this product.

At any track there are high levels of noise generated.

No matter how a microphone is mounted in a driver's headset, the noise is transmitted and there's no way of stopping that.

Wind noises, gearbox noise, engine noise and tyre noise are all transmitted with the same signal.

With the Icom radio, the receiver presses the assigned noise-cancelling button and the noise is removed.

The DSP board operates on most Icom commercial radios that have an internal accessory socket.

This new device uses an innovative process of noise reduction in a voice signal.

Designed around a self-adjusting neural network, voice signals and surrounding noise, such as engines, drills etc are distinguished by means of their spectral and temporal behaviour and separated from the required audio.

The system is fully adaptive and adjusts itself continuously to changing environmental conditions.

This makes training or configuration unnecessary; the system does not require knowledge of noise conditions or speaker characteristics.

Only signals, varying in the order of 1Hz, pass through the system; because this modulation range is typical of human speech.

Other sounds, with higher or lower modulation frequencies can be suppressed.

Using this technology, interference is eliminated from the voice signal, with adjustable noise suppression up to 20dB, which automatically adjusts to the characteristics of the voice signal and noise within 1s.

This new module is installed in the "option" socket and the programming software is set up to "enable OPT 1" on one of the assignable buttons such as P0 to P3 on the mobiles or if used with a hand portable there are also the buttons above and below the PTT.

Noise level is set at 6; this is adjustable by links on the module.

Ian Lockyer, Marketing Executive at Icom (UK) said, "This new DSP board will ultimately reduce stress levels for users and improve productivity, profitability for companies operating in high noise environments.

The processed sound is so good that it is very difficult to notice that it has been processed".