Results 1 to 7 of 7

Thread: Tech tip - channel select in TRBO repeaters

  1. #1
    Join Date
    May 31, 2012
    Posts
    229
    Thanks
    41
    Thanked 61 Times in 31 Posts

    Default Tech tip - channel select in TRBO repeaters

    I just wanted to share a tech tip that I've found very useful, especially in terms of testing XPR/MTR TRBO repeaters. Since most of us still only have analog service monitors, trying to do a 'quick' test in the field on a digital programmed XPR/MTR can be a pain. Many of you have probably resorted to re-programming in analog mode temporarily for testing, then back to digital afterwards.

    By using the channel select feature, it's possible to have a secondary analog 'test' channel in the repeater, that can be accessed by a simple jumper on the repeater accessory/MRTI connector.

    In the XPR for example, program in a second analog channel with the same frequencies as the digital channel, with a desired PL (I tend to use 156.7 as a standard). Set pin #19 for "channel select 1" (even though you want it to switch to 'channel 2', use 'channel select 1'...the repeater treats the first channel as 'zero'). Place a jumper between pin 19 and any ground pin (12, 16, 18) in an accessory plug. When you plug this connector into the repeater, it will re-boot and default to the analog channel. Do your testing, and remove the jumper. The repeater will once again re-boot and now default back to the digital channel.

    We now set up all our deployed repeaters this way during initial set up and testing, and leave it for future field testing.

    This can also have other uses. As an example, I recently set up a customer system whereby they had multiple repeaters mounted in transportable cases for rapid temporary deployment. They would primarily use a single repeater during an incident, and had TRBOnet connected to base stations for GPS tracking, using Enhanced GPS. They wanted the option of linking multiple repeaters in an IPSC configuration using wireless canopy links, if needed for greater coverage. Problem being, with Enhanced GPS, for single site repeaters you set the timing (periodic window reservation) in each repeater. For an IPSC system, only a single repeater is set to provide timing for the entire system, the rest of the repeaters have the timing set to 'none'. If you do not do this, GPS updates will only go out over the repeater the radio is sending on, they do not go across the entire system. So, we set up a secondary digital channel that was programmed identically to the primary channel, except it had the timing set to 'none'. When the customer wants to link repeaters, they simply plug the accessory jumper into the desired repeaters, leaving a single repeater without a jumper to be the timing master for the IPSC system. Works great!

    Hopefully this helps out some of you.

    Ice


  2. #2
    Join Date
    Jun 10, 2012
    Location
    The Old Dominion
    Posts
    189
    Thanks
    146
    Thanked 52 Times in 36 Posts
    Country: United States

    Default

    Very cool, thanks! I'll have to add one to my laptop bag.

  3. #3
    Join Date
    Feb 13, 2012
    Posts
    169
    Thanks
    107
    Thanked 14 Times in 9 Posts

    Default

    Like it - I see many uses for this (channel change, high/low power, etc).

  4. #4
    brizey No Longer Registered

    Default

    Great tech tip, The repeater may take up to 40 seconds to change just to add my two cents in there.

  5. #5
    Join Date
    May 31, 2012
    Posts
    229
    Thanks
    41
    Thanked 61 Times in 31 Posts

    Default

    Quote Originally Posted by brizey View Post
    Great tech tip, The repeater may take up to 40 seconds to change just to add my two cents in there.
    I can't say I've seen it take that long...right around 10 seconds for me, with XPR's at least. Do you mean MTR's?

  6. #6
    Join Date
    Jun 10, 2012
    Location
    The Old Dominion
    Posts
    189
    Thanks
    146
    Thanked 52 Times in 36 Posts
    Country: United States

    Default

    Either way, it's still a lot faster than plugging in a cable, waiting for the PC to recognize it, programming, etc.

  7. #7
    Join Date
    Mar 22, 2013
    Location
    Mazama WA
    Posts
    37
    Thanks
    114
    Thanked 45 Times in 10 Posts
    Country: United States

    Default

    Great tip! I program my repeaters with 6 or 7 modes by default...normal in position 1, then a mode with IPCS TS1, then TS2, then both, then none. Toss in the analog mode with PL encode/decode for testing. Also a couple of secret squirrel modes like a different Color Code and a Rx freq wobbled up or down by 20 Khz or so the standard Rx won't work but the admin can still get through the bottles or combiner system. Easy access via Channel Select or RDAC if on an IPSC network.

    For channel select, a dip switch mounted to the 26 pin body will enable access to all 16 modes possible rather nicely.
    -- Mike, NO7RF, Mazama WA