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Voice Alert

The Voice Alert concept makes use of the fact that the radio in your mobile/portable setup is always going to be monitoring the national APRS frequency. Voice Alert gives all mobile APRS users an instant calling channel to other mobile APRS users, regardless of the voice frequency each station is monitoring. Its also like a radar detector for other mobile APRS operators in simplex range on the open road.

It is ESSENTIAL that this is only implemented by mobiles and portables ONLY, otherwise it defeats the purpose of this application.

The concept is simple - Instead of turning the speaker volume down on your noisy 145.175 channel, simply set CTCSS encode/decode to  91.5Hz. This does 2 things.

  1. It keeps your speaker quiet, however anyone who understands voice alert knows they can contact you by voice by simply calling on 145.175 with a 91.5Hz tone.

  2. Your APRS position transmission will be sent with the 91.5Hz sub-tone, and serve as a radar ping to other Voice Alert stations in range.

Effectively, you will never hear anything on your 145.175 Voice Alert unless another APRS Voice Alert station is in simplex range. This will make sure you will have an opportunity for a voice call and then to QSY to other channel for a QSO.

On the road you may pass another ham, but you never know it. With Voice Alert, you now will be aware of each other's presence AND you will have a KNOWN contact frequency.


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