Results 1 to 6 of 6

Thread: Encode p25 PC?

  1. #1
    RFfreq No Longer Registered

    Lightbulb Encode p25 PC?

    I have a P25 Portable radio and there is a HAM Repeater that I Barely make it in on portable.

    I am wondering if there is software that I can Encode Voice into p25 and Feed it into the Flat Audio Input on my Maxtrac.

    As well as Decoding (Not as Important) as i can hear the repeater on my portable.


    I am Interested in doing this. ( too cheap to buy a Base p25 radio) as of the moment


  2. #2
    Astro Spectra's Avatar
    Astro Spectra is offline T S - Moderator
    CS Forums $upporter
    Join Date
    Nov 22, 2012
    Posts
    910
    Thanks
    353
    Thanked 620 Times in 308 Posts
    Country: Great Britain

    Default

    Whilst it is not technically impossible to do what you propose, it will be beyond what most people can achieve.

    It would be a whole lot easier to simply use an external ready-made amp or indeed hook up to the amp in your Maxtrack with some appropriate T/R relays and a bit of surgery.

  3. #3
    Join Date
    Apr 09, 2012
    Location
    Australia
    Posts
    930
    Thanks
    286
    Thanked 670 Times in 250 Posts
    Country: Australia

    Default

    ASTRO Spectra is (as usual) spot on - an amplifier will be far far easier. What you have proposed has been done before in the experimental OP25 project, and it requires real engineering skills to pull it off. Heres a demo using a USRP1, transmitting about 100 milliwatts or so...



    Max, KA1RBI also did the same thing using sound card output into a 70cm radio, however the radios lack of linearity prevented it from working properly - and thats just one of many challenges you will face. Any amp that can handle FM will do P25 Phase 1. I use a TPL PA6 to amplify the output of my XTS5000 up to 60 watts when required and it works very well.

    Cheers
    Matt

  4. #4
    RFfreq No Longer Registered

    Default

    Quote Originally Posted by MattSR View Post
    What you have proposed has been done before in the experimental OP25 project, and it requires real engineering skills to pull it off. Heres a demo using a USRP1, transmitting about 100 milliwatts or so...

    Max, KA1RBI also did the same thing using sound card output into a 70cm radio, however the radios lack of linearity prevented it from working properly - and thats just one of many challenges you will face. Any amp that can handle FM will do P25 Phase 1. I use a TPL PA6 to amplify the output of my XTS5000 up to 60 watts when required and it works very well.

    Cheers
    Matt
    Yea, I have done a bit of research and would Like to Give it a Try. If it doesnt work out. Maybe it will work ok for Simplex. Or somthing like that. Only thing i have to loose is Time and i will learn somthing from it.

    I do have the ability to hook up the Flat Audio Inputs and outputs to the Computer and the COS/PTT controls... I Have a 440MHz Mactrac Repeater I built myself interfaced with EchoStation and Echolink. I believe thats what you ment by "Engenering Skills". I am not experenced in or have worked alot With P25, But I believe I can Do this. Similar to The video.

    I have seen the video and another one like it were someone transmitted P25 to the Maxtrac, Recorded the Data and then Transmitted it back to the P25 Radio. and it worked.
    What I am looking for now is Software to Encode the audio to Data where i can put in the Flat Audio in and Transmit to the Repeater input Freq. or Run simplex (for testing and getting it ready to work on the repeater).

    It looks like it will work... But I could not find any software. (If not, I can always go and buy an SMA to BNC and hook up a base antenna to my Portable) XTS3000
    But I would like to mess around a bit with the Maxtrac and P25

  5. #5
    Join Date
    Feb 14, 2012
    Posts
    194
    Thanks
    23
    Thanked 59 Times in 19 Posts

    Default

    You might be better of just getting a mobile p25 radio with more power to get into to the repeater.

    Quote Originally Posted by RFfreq View Post
    I have seen the video and another one like it were someone transmitted P25 to the Maxtrac, Recorded the Data and then Transmitted it back to the P25 Radio. and it worked.
    The video where you saw recording and playing back is more likely a recording of the baseband audio from the radio, being played back. There is no capabilities to encode audio into digital there.

    Quote Originally Posted by RFfreq View Post
    What I am looking for now is Software to Encode the audio to Data where i can put in the Flat Audio in and Transmit to the Repeater input Freq. or Run simplex (for testing and getting it ready to work on the repeater).
    The IMBE voice codec is patented technology that you must buy a hardware dongle/chip to encode or decode. Your ONLY chances of doing this in software, as mentioned above is OP25. It has the ability to encode and decode P25 in software. It will take some more "ENGINEERING SKILLS" then just plugging in flat audio and COR/PTT to get it working. Compiling from source the gnuradio framework and op25 will be required. If your not familiar with linux or the command line this is not be the right project for you.
    Last edited by radio313; Jan 28, 2013 at 01:20 PM.

  6. #6
    RFfreq No Longer Registered

    Default

    Ah. Ok. Im basically am better off buying an amplifier... I have seen Hardware for encoding p25 on analog radios, maybe someday ill try that. But, Im happy with whatever works
    Thanks for all the helpful Information everyone-