Op25 with Raspberry pi 4

[azduststorm]

Hello everyone,
I recently was able to get op25 working on the pi 4, with my local police department. I am wondering, if I am able to use one-dongle, to scan both police department and fire department. The frequencies are pretty close to each other. Here are the frequencies, I am trying to get 155.820 and 155.700.

 

[awasser1]

I believe this should be under "software defined radio" but I think admin needs to move it. All my op25 systems are trunked. I haven never tried any single channels. but it depends on the dongle being used. most the cheapy ones do about 4 mhz. so i would say yes because this is well in that range. Are you using Boatbod's Version? He usually catches these and should answer. I would go ahead and try it. My best guess would be it would work. Let us know.

Alec
N1AJW

 

[azduststorm]

I believe this should be under "software defined radio" but I think admin needs to move it. All my op25 systems are trunked. I haven never tried any single channels. but it depends on the dongle being used. most the cheapy ones do about 4 mhz. so i would say yes because this is well in that range. Are you using Boatbod's Version? He usually catches these and should answer. I would go ahead and try it. My best guess would be it would work. Let us know.

Alec
N1AJW

Okay thank you. Sorry about the post, being in the wrong spot not sure how to move it. I have the rtl sdr dongle. I am using matts version. I will let you guys know how it goes thank you for your time and helping me.

 

[Watton925]

A lot of p25 sites are linked these are not?

 

[azduststorm]

A lot of p25 sites are linked these are not?

no they are not linked. I am still trying to figure out how to write the frequencies out to get both of the channels playing on one rtl.

 

[Watton925]

As long as they have different NAC you can add them to trunk file.

 

[azduststorm]

As long as they have different NAC you can add them to trunk file.

Not sure how to do that, because when I open the box with the ./rx.py code it opens this box, the frequency use to go back to default. Now it stays on the 155.8200 frequency and does not have a nac. It still plays my local police department, loud and clear all day with zero hiccups. This program gave me a whole lot of issues, just getting my local pd up and running. This is my fist pi project. When I first got it running, I hit the f key and put in 155.8200 when I heard them start talking, on a different rtl hooked to the computer. I hit enter and op25 started working on the Raspberry. Then I followed a video, on how to get op25 to auto start on that particular frequency. That's how I am listening to them now. yes, both police and fire in my town have different nacs

 

[boatbod]

As long as they have different NAC you can add them to trunk file.

I think the OP is saying he is trying to listen to P25 Conventional (non trunked) traffic in which case the NAC is undefined and trunk.tsv wouldn't be used anyway. The correct solution would be to set up a cfg.json file (using the example below) with two channel entries and then use multi_rx.py (rather than rx.py) to tune both channels from a single RTL dongle.

{
    "channels": [
        {
            "name": "Voice_chA", 
            "frequency": 155820000,
            "device": "sdr0",
            "trunking_sysname": "",
            "meta_stream_name": "",
            "demod_type": "fsk4", 
            "destination": "udp://127.0.0.1:23456",
            "excess_bw": 0.2,
            "filter_type": "rc",
            "if_rate": 24000,
            "plot": "",
            "symbol_rate": 4800,
            "enable_analog": "off",
            "blacklist": "",
            "whitelist": ""
        },
        {
            "name": "Voice_chB",
            "frequency": 155700000,
            "device": "sdr0",
            "trunking_sysname": "",
            "meta_stream_name": "",
            "demod_type": "fsk4",
            "destination": "udp://127.0.0.1:23466",
            "excess_bw": 0.2,
            "filter_type": "rc",
            "if_rate": 24000,
            "plot": "",
            "symbol_rate": 4800,
            "enable_analog": "off",
            "blacklist": "",
            "whitelist": ""
        }
    ], 

    "devices": [
        {
            "args": "rtl=0",
            "frequency": 155000000,
            "gains": "LNA:39",
            "gain_mode": false,
            "name": "sdr0",
            "offset": 0,
            "ppm": 0.0,
            "rate": 1000000,
            "usable_bw_pct": 0.85,
            "tunable": false
        }
    ],
    "trunking": {
        "module": "",
        "chans": [
        ]
    },
    "metadata": {
        "module": "",
        "streams": [
        ]
    },
    "audio": {
        "module": "sockaudio.py",
        "instances": [
            {
                "instance_name": "audio0",
                "device_name": "pulse",
                "udp_port": 23456,
                "audio_gain": 1.0,
                "number_channels": 1
            },
            {
                "instance_name": "audio1",
                "device_name": "pulse",
                "udp_port": 23466,
                "audio_gain": 1.0,
                "number_channels": 1
            }
        ]
    },
    "terminal": {
        "module": "terminal.py",
        "terminal_type": "curses",
        "curses_plot_interval": 0.1,
        "http_plot_interval": 1.0,
        "http_plot_directory": "../www/images",
        "tuning_step_large": 1200,
        "tuning_step_small": 100
    }
}

 

[azduststorm]

As long as they have different NAC you can add them to trunk file.

I think the OP is saying he is trying to listen to P25 Conventional (non trunked) traffic in which case the NAC is undefined and trunk.tsv wouldn't be used anyway. The correct solution would be to set up a cfg.json file (using the example below) with two channel entries and then use multi_rx.py (rather than rx.py) to tune both channels from a single RTL dongle.

{
    "channels": [
        {
            "name": "Voice_chA",
            "frequency": 155820000,
            "device": "sdr0",
            "trunking_sysname": "",
            "meta_stream_name": "",
            "demod_type": "fsk4",
            "destination": "udp://127.0.0.1:23456",
            "excess_bw": 0.2,
            "filter_type": "rc",
            "if_rate": 24000,
            "plot": "",
            "symbol_rate": 4800,
            "enable_analog": "off",
            "blacklist": "",
            "whitelist": ""
        },
        {
            "name": "Voice_chB",
            "frequency": 155700000,
            "device": "sdr0",
            "trunking_sysname": "",
            "meta_stream_name": "",
            "demod_type": "fsk4",
            "destination": "udp://127.0.0.1:23466",
            "excess_bw": 0.2,
            "filter_type": "rc",
            "if_rate": 24000,
            "plot": "",
            "symbol_rate": 4800,
            "enable_analog": "off",
            "blacklist": "",
            "whitelist": ""
        }
    ],

    "devices": [
        {
            "args": "rtl=0",
            "frequency": 155000000,
            "gains": "LNA:39",
            "gain_mode": false,
            "name": "sdr0",
            "offset": 0,
            "ppm": 0.0,
            "rate": 1000000,
            "usable_bw_pct": 0.85,
            "tunable": false
        }
    ],
    "trunking": {
        "module": "",
        "chans": [
        ]
    },
    "metadata": {
        "module": "",
        "streams": [
        ]
    },
    "audio": {
        "module": "sockaudio.py",
        "instances": [
            {
                "instance_name": "audio0",
                "device_name": "pulse",
                "udp_port": 23456,
                "audio_gain": 1.0,
                "number_channels": 1
            },
            {
                "instance_name": "audio1",
                "device_name": "pulse",
                "udp_port": 23466,
                "audio_gain": 1.0,
                "number_channels": 1
            }
        ]
    },
    "terminal": {
        "module": "terminal.py",
        "terminal_type": "curses",
        "curses_plot_interval": 0.1,
        "http_plot_interval": 1.0,
        "http_plot_directory": "../www/images",
        "tuning_step_large": 1200,
        "tuning_step_small": 100
    }
}

 

[azduststorm]

I honestly do not understand a word you are saying. I'm really new at raspberry pi. I am surprised I got this far. How do I get to a cfg.json file ?

 

[azduststorm]

Do I copy and paste what you made me up above into one of these files?