A common programming mistake: Radio doesn't always transmit

In my experience, the most common mistake technicians make when programming MOTOTRBO radios is not setting the Transmit Admit Criteria correctly in the channel.

Screenshot from the CPS showing the admit criteria in a digital channel.

The Admit Criteria selection Channel Free only allows the radio to transmit when when there is no signal whatsoever on the channel - this is quite a common configuration. However, there are some differences:
  • Unlike analogue, if there is a signal present on the MOTOTRBO radios' receive frequency, the user will not notice it. In analogue radios, one could press the monitor button and hear whatever it was that was making the busy light flash.
  • This signal could also be interference.
  • The concept of squelch is different in MOTOTRBO radios. 
  • -124dBm [or 0,141┬ÁV] (see above) represents a very weak signal.
The correct choice in this case, would be to increase the RSSI Threshold to a high - more realistic - value. Alternatively, try changing Admit Criteria to Color Code Free or Always.

22 comments:

  1. i try to use color code free but channel busy tone come in most of time,while no one use channel,i use trbonet server for gps.

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    Replies
    1. You may be busying up the channel with GPS traffic. Are you sending GPS over the selected channel or are you using a revert channel?

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    2. Also, how many users on the channel and what is the GPS update rate? Are you using ARS?

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    3. hi sir wayne, i also experienced the busy channel even no one is using the channel. my set.up:

      admit criteria: color code free
      in call criteria: follow admit criteria

      gps and call are in one channel, no revert channel for the gps.

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    4. How many radios are on the channel? How many of these radios have GPS enabled? What is the average GPS update rate per radio? On a scale of 1 to 10, how busy is the channel in terms of voice calls? When you say "one channel" are you saying same frequency and slot? In other words, GPS is not sent on slot 2?

      Do you have SmartPTT Monitoring (http://bit.ly/1ujXNfM); TRBONET Watch (http://bit.ly/1KXjBrZ); GW3 TRBO (http://bit.ly/1ujXYHQ) or a similar system monitoring application?

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    5. there were 36 radios on 1 slot. 34 radios have GPS enabled. GPS of every radio will update every 30 seconds. ill rate 2 because all radios are not yet functional. yes, GPS and call are in same slot no revert channel.

      i dont have trbonet watch, only dispatch console.

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    6. sir, just want to ask if it is better to check the ENCHANCED CHANNEL ACCESS on portable radio?

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    7. The GPS update rate you are using is way too high! With 36 radios and a 60/hour GPS update rate, you will have 25-30% blocking. If you reduce the cadence, the number of busies will reduce.
      If you had TRBONET Watch (or one of the applications I mentioned above), you would be able to see this.

      Enhanced Channel Access will only prevent voice call collisions. The call blocking is due to the excessive number of GPS updates.

      You need to consider using a revert channel and possibly Enhanced GPS - and maybe CSBK data if your dispatch application supports it.

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  2. hi do you have a solution for Voice distortion ?

    ReplyDelete
    Replies
    1. It depends on what you term "distortion"? I assume you mean slurred or broken up speech? If so, this is generally caused by poor signal conditions or by interference (desense; intermodulation; jamming). If these can be excluded then there are a few tweaks that can be made in terms of usage and configuration.

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    2. It only came to me now: a lack of IP bandwdth could also cause distortion...

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  3. Hi Wayne, I get 'channel busy' or 'called party not available' in the LCD of the control station. It is Linked capacity plus network, two sites, one DR3000 at each site and 160 Mobiles. As of our CPS, no mobiles can make a private call or group call and only the controller can make the calls. Actually, we tested the system with 2 mobiles in the lab and everything was okay. Even with 160 mobiles, first 2 or 3 days were okay, but after that system clogged up and Repeaters and controller station are continuously transmitting something (blinking green led). Will it be caused by the above two parameters you mentioned? or anything else you can think of?

    Thanks

    ReplyDelete
    Replies
    1. Are you using GPS? Is GPS or ARS enabled in the radios?

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  4. GPS is not enabled. But ARS is enabled. We use the ARS for SmartPTT Enterprise server.

    ReplyDelete
    Replies
    1. If you have SmartPTT you should be able to see what is making your system busy.

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    2. You could also just have interference on the channel.

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  5. hi wayne, i have 2 dr3000 on two different sites which am trying to link up as area wide voice, they are both operating on two different frequency groups ie 6 x channels on each site. please give some heads up on how to link them up using point to point radio link.

    ReplyDelete
    Replies
    1. Hi, have a look at my videos on that https://m.youtube.com/playlist?list=PLajLE2N1ugvAZmpCewiML2I9yxgUJ46Da

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  6. Hi Mr. Holmes,
    firsly, congrats for your useful blog!
    Some years ago I used programing the analog motorola Radios, GP340,380,388... etc.
    Now, we have adquired 12 radios DP2600, and now, I am learning a lot about the amazing digital world.
    I am looking for admit criteria when I add a new digital/analog channel in CPS, but I am not able to find it. Is this option available with capacity plus feature?
    If you want , I can send a screenshot of my CPS.
    thanks in advance!
    Jordi

    ReplyDelete
    Replies
    1. Hi. Make sure Expert View is chosen (tick next to Expert under the View menu). Also there is no Channel Free option for Capacity Plus - only Colour Code Free - and this would only apply to the Personality, not the channels in the channel pool.

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    2. Thanks!
      I am not still familiarized with CPS...

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