What Causes the ‘Static’ Sound on Two way radios

With very little information on the internet about walkie talkie over’s, it is very rare when we get a chance to re post, with permission, an article from this industry.

Essentially, radio static during a call is a sign that the signal strength is degrading (or that there is no signal coming through at all). When signal strength degrades sufficiently, the static sound emerges.

When there is no message coming through, it’s a slightly different story. A Walkie Talkie has what’s known as a ‘squelch’ control circuit that keeps tabs on the signal strength. The squelch circuit will mute the speaker as soon as it realizes that there is no signal coming through to the device. This is, essentially, the same function as your TV has when it cuts off an unavailable channel after a preset time. However, in the moments before your walkie-talkie ‘squelches’ the sound, you will hear static, or ‘white noise’ as its also called.

‘Squelching’ is a pretty vital part of any/all broadcasting equipment. The method used in your walkie-talkie is called a ‘carrier squelch’ and is more than likely to be manually adjustable.

From Wikipedia (as of 17th of May 2013):

“A carrier squelch or noise squelch is the most simple variant of all. It operates strictly on the signal strength, such as when a television mutes the audio or blanks the video on “empty” channels, or when a walkie talkie mutes the audio when no signal is present. In some designs, the squelch threshold is preset. For example, television squelch settings are usually preset. Receivers in base stations at remote mountain top sites are usually not adjustable remotely from the control point.
In devices such as two-way radios (also known as radiotelephones), the squelch can be adjusted with a knob, others have push buttons or a sequence of button presses. This setting adjusts the threshold at which signals will open (un-mute) the audio channel. Backing off the control will turn on the audio, and the operator will hear white noise (also called “static” or squelch noise) if there is no signal present”.

So what is ‘white noise?’ According to Joe Shambro, writing for About.com’s guide to home recording,

“White noise is a static sound that has equal energy on every frequency. Think about this for a second: every frequency from 20Hz to 20kHz is equally represented at the same velocity; this type of frequency scale is called a “linear” scale. This gives the noise a uniform, static sound that the human ear detects as somewhat harsh and heavy-handed toward the high frequencies. However, white noise represents a very unnatural way of presenting frequency data in terms of how our ears work.”

If you’re experiencing signal degradation on your walkie talkie, there may be several causes for this. ‘Wireless Woman’ a blogger with an excellent site about two-way radios, has this to say:

“Signal loss can happen in any number of places in the system. Antennas may not properly direct the signal toward the horizon. Cables to repeaters may need replacement. Connectors can be corroded. Finally, the quality of the system may not be adequate. The old adage “you get what you pay for” certainly applies to two-way radios, and their quality does vary. Receiver specifications, engineering, tuning, the antenna, and even design generally improve as the price increases. This really happened: Two public safety officers were at a scene. One was using a radio that cost more that twice as much as the other. Guess which one could hear and which one couldn’t?”

So there you go.

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