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Thread: Anybody get P25 trunking to work?

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    Default Anybody get P25 trunking to work?

    We are trying to get P25 trunking to work with the Johnson radios. We have a valid system key and trunking controller feeding 900 Quantars. Can't seem to get the radios to affiliate or even see the control channel. I plan on disabling FPP on one of my XTS2500's to confirm the backend is working, but we know it's working in UHF, so we assume it's working at 900.

    Any suggestions would be appreciated.


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    New Clue:

    We set the base channel for the system at 927.1875 and say the offset is -25Mhz. Those entries go in fine, but when we go an enter the control channel it appears in Red. It accepts the value, but clearly doesn't like it.

    Today we took an XTS2500 on 900Mhz and set it up the same way. It presented the same quirk - the control channel receive value was highlighted in red. The invalid flag was set on the tab, but went to View -> Invalid fields, it did not show it as invalid. When we sent the codeplug to the radio, it accepted it - but displayed Fail 001 on the XTS. We assume that it is reporting the VCO out of lock because the invalid receive frequency was not programmed into the radio. There was an option for "Infinite search of control channel" and when that was set, the radio did not display Fail001 - but it also didn't affiliate or find the control channel.

    We have all this working on a UHF Quantar in the same rack, so we believe the configs are good. It just seems that there may be an additional OOB mod required for trunking.

    Any ideas?

    Thanks.

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    Sounds like you've got your Channel ID ranges set improperly or your frequencies aren't valid.

    The frequency in red usually means that the frequency entered does not fall on a valid frequency for the Channel ID range.

    You've got 927.1875Mhz entered as your base. You'll have to calculate out where your valid frequencies are depending on your step.
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    They may have a hard coded -39 MHz offset in them since that is the standard split for the commercial band.

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    I would think that if you program up the system with a non-standard offset in the repeaters and the same non-standard offset in the subscriber gear, it should work.

    However, the fact that the control channel receive is red tells me that they're not even getting as far as the input.
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    Yesterday was spent only with the Motorola radio. We did try the standard 39Mhz offset, which still did not work if the receive frequency was 927. If however, we set the receive frequency to 935 or above, then it would accept either 39 or 25Mhz offset without showing anything in red.

    We did a quick hex parse through PatPort.exe for 935.0125 and found 7 occurrences, but changing them to 925.0125 rendered more problems than solutions.

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    What's your channel ID range show for Base and Spacing and what control channel frequencies are you trying to enter?

    Have you verified what you've entered matches what you've got in the system controller?

    Not sure why you're going through the CPS trying to hex edit? Is this a commercial system?
    Cyrus

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    The base channel is set for 927.1875, -25 offset and 6.25 spacing. In the control channel tab, we enter 927.1875 for receive and it auto fills the transmit with 902.1875. The problem is that the receive frequency is highlighted in red - it clearly doesn't like the value. The only way to clear the red, is to enter a frequency above 935 - which is why we are thinking its an OOB issue.

    What's interesting is that both the Motorola software and the Johnson software show the 927 freq as invalid. Yet the 927 values are accepted on the base/offset screen.

    As I mentioned, this is all working fine on UHF, just won't work on 900. Others seem to have tried to get the Johnson radios to work on 900 systems with no success - the radios just don't see the control channels.

    Has anybody gotten one to work on a commercial 900 repeater at 935+?

    Thanks for all the suggestions.

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    Yes I have used XTS on a 900 meg typeII system with no troubles.

    The commercial range for 900 is 935-941. you will have to hex the band limits to take 925 and up. once you get the radio to take the freq you can then test on conventional to confirm proper rx and tx VCO lock. One you know the rx/tx are working and locked you can then look at things like the deviation and waveforms sent in trunking mode at the 927 freqs.

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    Thanks, the XTS2500 has the typical OOB limit mod done and does work successfully on a conventional P25 repeater on the same frequency. I'm wondering if there could be one last OOB limit that needs to be changed for trunking? or just the lowest control channel limit?

    Any ideas would be appreciated. We know that the repeater is transmitting the control channel and it looks correct on the service monitor, but the radios just don't seem to know it's there. The Johnson is just oblivious and the XTS shows Fail001 like the VCO is out of lock. Yet we can turn the channel knob to the next channel which is conventional on the same frequency and don't get a Fail message - it works.

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    to confirm when you program in the trunking control channel its in red but if you load the freq as a conventional it works fine. if so the trunking band limitrs may be in the firmware.

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    Exactly, in a conventional personality the radio will work fine at 927.1875/902.1875. If you enter those values in the trunking control channel, the RX 927.1875 will appear in red (Johnson or Motorola). It seems the band limits must be in the programming software because that is what is saying the value is not acceptable. We are assuming that the CPS is not writing anything in that field to the radio since the value is out of range. Without a value being written, it would make sense that the radio would say Fail001 - VCO out of lock (there's no freq to lock on).

    We were really hoping to have this all working for Dayton. UHF an 900 (plus other sites like Columbus) all P25 trunked together. Pick a talkgroup - come out on one or multiple frequencies or repeaters. It all works very slick at the moment - we just want to add 900 since the Johnson radios came about so inexpensively.

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    Quote Originally Posted by khw View Post
    Exactly, in a conventional personality the radio will work fine at 927.1875/902.1875. If you enter those values in the trunking control channel, the RX 927.1875 will appear in red (Johnson or Motorola). It seems the band limits must be in the programming software because that is what is saying the value is not acceptable. We are assuming that the CPS is not writing anything in that field to the radio since the value is out of range. Without a value being written, it would make sense that the radio would say Fail001 - VCO out of lock (there's no freq to lock on).

    We were really hoping to have this all working for Dayton. UHF an 900 (plus other sites like Columbus) all P25 trunked together. Pick a talkgroup - come out on one or multiple frequencies or repeaters. It all works very slick at the moment - we just want to add 900 since the Johnson radios came about so inexpensively.
    Would it be possible to get the codeplug from you to look deeper into it?

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    One thing to consider, these radios were designed to only ever talk on a Multinet and conventional system for a specific customer. I would wager there is not a p25 or smartzone trunking band plan in the radio for 900mhz at all. Why take the time to code something in the firmware for something that would never be used in legit operation? If the customer ever needed it, you could add it in and send the customer new firmware along with the option files to enable the feature. There are versions of x series firmware that were only designed for one customer to meet a need they had and were not for general release.

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    If you check the Astro 25 Portable CPS under "System", then under "Advanced" you'll see the "Trunking Repeater Offset" is set to 39 MHz.