Digital Voice Conversion Method Re-visted for LSM Reception

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Jan 16, 2002
Orlando, FL & Ocean City, NJ
Hi All,

Years ago I designed the Digital Voice Conversion Method (before digital scanners) see Wiki:

Digital Voice Conversion Method - The RadioReference Wiki

This method uses the 10.7 IF output of a communications receiver such as ICOM R7000 mixed with an RF signal source to produce a frequency that a commercial digital radio can receive in conventional digital carrier squelch mode. So basically when you tune the ICOM communications receiver, the digital commercial radio would demodulate and voice the digital signal. This works receiving conventional and trunked voice channels.

The radio I used back then to monitor the digital voice was an Astro Saber programmed using C4FM modulation digital carrier squelch conventionally receive-only.

Since there is also an option for CQPSK modulation for conventional receive-only programming, this should enable correct and clear reception of LSM trunked voice channels on Astro 25 systems using Phase I talk groups. It would not work on Phase 2 because of TDMA.

So my idea would be to use this method on a scanner with the 10.7 IF tapped. Let the scanner track the system and the commercial radio decode the audio.

Unfortunately I can't test this because my Astro Saber only has 512 Meg vocoder and is not CQPSK enabled.

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