Using digital voice with a PC/Phone and regular UHF radio

Joined
Oct 10, 2018
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#1
I'm a pretty inexperienced station operator. I've spent a little bit of time on local 144 and 440 repeaters, but stepped away from the hobby for a while and thinking about getting back in.

The digital modes are interesting to me, especially digital voice. What I'm wondering about is whether it is possible to use a PC or smartphone to "drive" a regular mobile or HT radio having the phone do the digital mode and then using the radio to TX and RX. As I understand it APRS can work this way, with a TNC connecting the radio and the PC or phone. Can I do DMR, D-Star, Fusion, or other digital voice modes this way? If not, why? Is there something about the mode that isn't just "encoding a signal, send"?

Thanks for helping me understand what's going on here.
 

DaveNF2G

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#2
Your phone would need software capable of generating the amateur digital protocols. I'm not aware of any in existence at this time. It is much easier to obtain a transceiver that operates with the mode you desire.
 

wa8pyr

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#3
<snip>As I understand it APRS can work this way, with a TNC connecting the radio and the PC or phone. Can I do DMR, D-Star, Fusion, or other digital voice modes this way? If not, why? Is there something about the mode that isn't just "encoding a signal, send"?

Thanks for helping me understand what's going on here.
Your phone would need software capable of generating the amateur digital protocols. I'm not aware of any in existence at this time. It is much easier to obtain a transceiver that operates with the mode you desire.
To add to what Dave noted, there are certain parameters in the transmitted signal (which vary depending on the mode) that define certain important parts of the signal; simply generating a digital audio signal and porting it to your transceiver would leave out those parameters.

Modes like APRS (and "sound-card modes" like PSK-31) which can use a computer to generate the digital signal are data modes as opposed to voice modes, and operate within the audio passband of a transceiver; they're specifically designed to be generated by a computer and injected into a transceiver microphone port.

While I think I've seen an HF digital voice mode which is kind of like that (generated by a computer or external box and injected into the microphone port), I'm not aware of any like that for VHF/UHF, although I suppose it could work in theory.

Also as Dave noted, there are plenty of inexpensive digital transceivers out there; I'd start with DMR as it's rapidly becoming the most prevalent amateur VHF/UHF digital mode.
 
Joined
Aug 15, 2008
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#4
Your phone would need software capable of generating the amateur digital protocols. I'm not aware of any in existence at this time. It is much easier to obtain a transceiver that operates with the mode you desire.
There are actually a couple of options... MMDVM and OP25. In the case of OP25, there is no need for any external hardware, such as modems or Arduino boards or USB dongles, etc. Everything that's needed to do P25, DMR (Base Station), YSF ("C4FM") and D-star are included in the OP25 software. For these modes both TX and RX are supported.

Both MMDVM and OP25 are free and open source released under the GNU General Public License (GPL).

One of the methods supported by OP25 is a direct connection from a PC sound card output to the direct modulator input of an FM transmitter. Unfortunately this doesn't work well with just any FM voice transmitter, since the modulation must be both linear and time-invariant. Radios that have been vetted for "Satellite" and "Packet" usage are ideal for this. For example I've used an ICOM 820H and an Icom 275H (1980s radio) successfully (in YSF C4FM) to check into a local net that meets weekly. For these Icom radios it's necessary to set a switch setting inside the radio for "9,600 packet" operation...

73

Max
 
Joined
Oct 10, 2018
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#5
Following up.

So while doing some more research, I discovered there are a few HT models that came out in the last couple of years that do DMR but also analog FM on UHF and VHF. So, I'm going to get one of those. Likely something like the AnyTone AT-D868UV.
 
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