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Thread: Single Frequency Repeater Offerings

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    Default Single Frequency Repeater Offerings

    What is the current status on single frequency DMR repeater capability?

    We know the Hytera PD982 offers the ability, but it doesn't appear they have yet extended it to the mobile form factor, adding the flexibility of using external power. Has anyone set one up as a longer-term solution?

    I found a thread from 2016 mentioning Simoco had a setting in the programming software, but there was no confirmation of if it had been used.

    The quick searching I've done doesn't reveal any of the other manufacturers advertising the capability.


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    I'd also like to hear about this too. I had posted over in the tetra forum about the DMO operation which is essentially what you are talking about just with tetra. DMR would be much better for us here in the US.
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    TRBO offered this starting last year some time. It is an eid for the repeater. It receives on one slot and transmits on the other. It requires Tx rx antenna separation of like 40ft horizontal in uhf, unsure of other bands. FB

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    I just got back from IWCE and was blown away at the array of DMR products they have at Hytera.

    The have a "Pack" portable repeater, and a Pole" pole mountable repeater, not sure the exact nomenclature, will have to find the catalog sheets.

    In any event these operate on a single frequency TDMA basis and can form a self healing mesh network. You can put a couple or many in any sort of arrangement and repeat a timeslot in DMO mode through all of them. It appears that repeating one timeslot occupies 4 time slots in the repeater and the subscribers can pick from one of among four repeated timeslots to receive.

    I looked at the catalog sheet and found that though they claim DMR tier 2 compliance, they pass 4 time slots for purpose of linking and broadcasting from several repeaters. Further the spec says 25 KHz . Not sure if DMR tier 2 specs 4 time slots in 25 KHz, but this would pose some regulatory problems in the US at 470 MHz and below. Maybe a waiver is doable. Because this show was in Florida and there are South American participants, this may have been the target market.

    The concept is pretty fantastic and would solve a problem that was posed in an SBIR years ago to provide coverage in tunnels caves and mines for rescue operations.

    I never asked specifically if they have a mobile that will operate as a DMO repeater, but that would certainly be a common requirement for many situations.



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    Quote Originally Posted by Fatboy View Post
    TRBO offered this starting last year some time. It is an eid for the repeater. It receives on one slot and transmits on the other. It requires Tx rx antenna separation of like 40ft horizontal in uhf, unsure of other bands. FB
    I heard that as well. It seems odd that separate antennas would be required for TDMA duplex.

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    Quote Originally Posted by RFI-EMI-GUY View Post
    I heard that as well. It seems odd that separate antennas would be required for TDMA duplex.

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    Time slot desense. The two slots in the repeater operate on the same frequency, but the receiver has to detect in between the transmit pulses from the other slot. Physical separation is the only defense.
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    Quote Originally Posted by com501 View Post
    Time slot desense. The two slots in the repeater operate on the same frequency, but the receiver has to detect in between the transmit pulses from the other slot. Physical separation is the only defense.
    Yet somehow DMO works with a portable.

    Time division duplex is used in other services with only a PIN antenna switch. I can see having an AGC saturation problem, but, that can be defeated with logic.

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    You used 'logic' in a discussion about Motorola.
    Retarded Mongoloid on PCP...

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    Quote Originally Posted by com501 View Post
    You used 'logic' in a discussion about Motorola.
    Oops!

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    Quote Originally Posted by RFI-EMI-GUY View Post
    In any event these operate on a single frequency TDMA basis and can form a self healing mesh network. You can put a couple or many in any sort of arrangement and repeat a timeslot in DMO mode through all of them. It appears that repeating one timeslot occupies 4 time slots in the repeater and the subscribers can pick from one of among four repeated timeslots to receive.

    I looked at the catalog sheet and found that though they claim DMR tier 2 compliance, they pass 4 time slots for purpose of linking and broadcasting from several repeaters. Further the spec says 25 KHz . Not sure if DMR tier 2 specs 4 time slots in 25 KHz, but this would pose some regulatory problems in the US at 470 MHz and below. Maybe a waiver is doable. Because this show was in Florida and there are South American participants, this may have been the target market.
    Were they available in 800/900 MHz? Neither of those bands were subjected to the 12.5 kHz mandate, and OpenSky (4-slot TDMA) is permitted on both bands. TETRA is also permitted on 800, not sure about 900.
    "The Girl Scouts found several hungry REACT members at the finish line..."

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    Default SUBJECT HyTera E-pack100

    Quote Originally Posted by motorola_otaku View Post
    Were they available in 800/900 MHz? Neither of those bands were subjected to the 12.5 kHz mandate, and OpenSky (4-slot TDMA) is permitted on both bands. TETRA is also permitted on 800, not sure about 900.
    You can download a spec sheet here. This seems to cover 350-400 and 410-470 bands only. It clearly says DMR Tier II. It could be multicarrier, in other words, two 12.5 KHz carriers and aggregated 4 slots. If anyone learns more I would like to know.

    http://www.hytera.com/resourceSearch.htm?columnId=416&searchType=driver& resourcesKeyWord=100&resourceType=2#page-index



    http://www.hytera.com/epProduct.htm?...Type=newDetail

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    This is something Moto is rumored to be working on too. They are using 2 phase-coherent 12.5 kHz transmitters spaced right next to one another, essentially. That gives a 25 kHz wide signal that carries 4 timeslots. This also maintains 6.25 kHz "channel equivalency" so it would be allowed similarly to trunked systems to use wide band, legally.

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    If you need some kind of emergency backup portable repeater you can build it just with two radios in DCDM mode. You will have to program subscriber units to scan for downlink time-slot and transmit on uplink time-slot of selected channel. Yes, you will have only single common talk group but usually this is what is required in emergency scenarios. Such repeater can be built with portable radios as well and it's even possible to use a single antenna with Tx-power controlled PIN-diode antenna switch. Here are repeaters we built.

    https://goo.gl/photos/UkmhGU7nsr1eZfLA8

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    Quote Originally Posted by Oles View Post
    If you need some kind of emergency backup portable repeater you can build it just with two radios in DCDM mode. You will have to program subscriber units to scan for downlink time-slot and transmit on uplink time-slot of selected channel. Yes, you will have only single common talk group but usually this is what is required in emergency scenarios. Such repeater can be built with portable radios as well and it's even possible to use a single antenna with Tx-power controlled PIN-diode antenna switch. Here are repeaters we built.

    https://goo.gl/photos/UkmhGU7nsr1eZfLA8
    That is actually pretty cool. Do you have schematics for this? Is it a commercial product? How do get the signal for timing the PIN switch properly?

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    Quote Originally Posted by Alpha View Post
    This is something Moto is rumored to be working on too. They are using 2 phase-coherent 12.5 kHz transmitters spaced right next to one another, essentially. That gives a 25 kHz wide signal that carries 4 timeslots. This also maintains 6.25 kHz "channel equivalency" so it would be allowed similarly to trunked systems to use wide band, legally.
    Isn't this called TETRA ?

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    Perhaps they were "borrowing" the idea from Tetra, but no, it's some specific new experimental DMR mode. I can't remember the exact term my contact used, but I think it was something with "Quad" or "Four" in the name, or something suggestive of the 4 simultaneous voice channel capacity. It has been at least 2 years since I heard about that, make of it what you will.

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    A certain vendor is offering their new repeater mesh solution in the new firmware release. I dont really have any details other than it only works in the non-trunking digital modes and reduces the amount of advanced features that the repeaters support. Make sure to catch the new firmware release webinar. FB

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    Quote Originally Posted by Fatboy View Post
    A certain vendor is offering their new repeater mesh solution in the new firmware release. I dont really have any details other than it only works in the non-trunking digital modes and reduces the amount of advanced features that the repeaters support. Make sure to catch the new firmware release webinar. FB
    With a few manufacturers and technologies being discussed in this thread, mind mentioning which certain vendor you're referring to?

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    New product is called MOTOTRBO Link. FB

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    Fatboy, do we have any more information on Mototrbo Link? The Motorola website does not have any information on the subject.

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    Give it until the first of June. My understanding is it will be part of the new firmware. FB

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    The French gas industry is using proprietary (3) time slots "eDMR".
    Interesting approach, but no further documentation publicly available.

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    Quote Originally Posted by RFI-EMI-GUY View Post
    That is actually pretty cool. Do you have schematics for this? Is it a commercial product? How do get the signal for timing the PIN switch properly?
    Sorry, I had not received notifications from the forum and missed your question.
    I use just RF power detector to switch PIN diodes, no need to get any signal from the radio.
    The radio's programming was described here https://communications.support/threa...1367#post81367
    Only DIY kits for mobiles-based are available outside EU. There is also available a repeater controller board to build a backup repeater with two portables, antenna switch is optional, it will work just with native portable's antennas. Any XPR series RSM can be connected for local operator.
    20180530_143246.jpg