Kenwood DMR Tier 2 configuration problem

[hs0zed]

Hello, this is my first post here and indeed my first time to ask a question concerning DMR with which I am very much a newbie.

As a part of a large construction project a client has installed two Kenwood THR-D810-E repeaters for use with some 30 or so Kenwood TK-D340 handhelds for security personnel. They have been allocated 2 frequency pairs and have configured the repeaters to transmit on the higher two frequencies and receive on the lower two frequencies. This is as per the combiner which is tuned appropriately. Handhelds have been programmed in the reverse.

Both repeaters are programmed with channel 1 in timeslot 1 and channel 2 in time slot 2, both are color code 1
Handhelds are programmed with 4 channels, the first two being timeslot 1 and 2 of the first repeater frequency and channels 3 and 4 programmed with the second repeaters timeslot 1 and 2.

For any selected channel keying one handheld results in hearing the signal repeated on the other handheld but with a constant regular chopping as if there is some sort of synchronisation problem.

I am not that familiar with DMR setup so if someone could point to an obvious mistake I would be very grateful. If anyone would be willing to guide me in a step by step way to resolve the issue that would also be most welcome. I have the configuration files for the repeater and the handhelds if that would be useful information.

Many thanks
Martin

 

[buddrousa]

A few Questions.
1 Is this a dealer setup system?
2 What is the Frequencies used?
3 How close are the other walkies to the walkie that is being keyed up?
4 Did you and the Dealer check to POWER out of the duplexers going to the Antenna?
5 How far from the repeater are you when testing?

 

[hs0zed]

Thank you for your reply.
1. No, we purchased the units. Kenwood radios from Radiotronics in UK, duplexer and splitters from a company in Singapore.
2. Two repeater transmit frequencies assigned are 427 and 427.5 MHz, the 2 repeater receiver frequencies are 420 and 420.5 MHz.
3. All handhelds are in the same room, antenna in the ceiling.
4. Dealer not involved in any setup. We have measured the repeater transmit power, approx 40 watts at the repeater output, approximately 10 watts at the duplexer output, circa 6dB loss so in spec.





Note for the repeater channel 2 is slot selection 2

 

[buddrousa]

Loosing 75% of your power through the duplexers is way off. I put in 100 and get 75 to 80 out on the ones I have setup. It sounds almost like you have the RX TX switched. You said Antenna in the ceiling? This should be outside above the building and run on hardline.
Before you do anything it would be time to call a radio shop

 

[hill]

Programmed other DMR radios, but never Kenwood.

Going forward I don't see you have programmed a talkgroup or radio id, as each radio needs a different id.

 

[hs0zed]

Okay well the specification on the duplexer is 6dB loss so I would not expect to see more than 25% out of it. There are 40 antennas in the ceiling spread across the floors of the building which is a hotel. It is a complete distributed antenna system for in building use with -10, -15, and -20dB taps and a number of 3dB splitters. Link budget calculations suggest at least -70dBm at each handheld and around -80 into the repeater with the duplexer receiver ports set for 0dB gain.
We expect to have some drop outs in some areas but the coverage should be sufficient for the 14 floors and 2 basements. There are no outside antennas, it is purely an in-building system. We believe the RF level is sufficient in all cases but especially since we tested it with the handhelds in the same room as the repeaters with an antenna connected directly to the output port of the combiner.

 

[hill]

Also don't know how it is in the UK, but here in the USA repeater outputs are the lower frequency with the input being the higher one.

Plus did you have the duplexers tuned to your frequencies locally, since wouldn't trust anything after being shipped from overseas.

 

[hs0zed]

Before you do anything it would be time to call a radio shop

No radio shops to call for this sort of stuff in Cambodia.

 

[hs0zed]

Programmed other DMR radios, but never Kenwood.

Going forward I don't see you have programmed a talkgroup or radio id, as each radio needs a different id.

Aha, so a talkgroup or radio ID is required? This is when I stsrt to run out of knowledge, how to set up the programming?

 

[chief21]

With DMR, every radio should have a unique ID and every discrete group of users (ie "channel") should have a unique talkgroup number. Most radios allow each talkgroup to be named so that the name can appear on the radio display (ie "security 1", "security 2", etc). Users on any given talkgroup would normally be unaware of users on any other talkgroup.

If you'd like to "study up", you can find lots of DMR-related technical information online.

 

[hill]

Going forward I feel the OP is way over his head in this. Also a hobby website isn't the best to ask on. A lot of people have very much knowledge of this stuff, but it's going to be hard with it being set up on the other side of World.

The antenna setup looks kind of funky.

 

[buddrousa]

The point I tried to make.

 

[hs0zed]

Thanks for all the useful info, it is most helpful.
Way over my head, hmm. I am an RF professional, 40 years experience but predominantly aviation comms, navigation and surveillance systems. So the RF side of it is no problem for me and we have verified the design used here with other non-digital systems.

For those less experienced the antenna system is known as a passive DAS (Distributed Antenna System) and is essentially what you will find in many shopping malls, hotels or large office buildings. They are commonly used in Wi-Fi or cellular distribution and can be active, passive or a hybrid of the two. Most of the Wi-Fi and cellular type today are active but a lot of the older UHF personal radio type are passive.

My real knowledge gap comes in the digital configuration part, though slowly it is coming together. I now know that the radios should have some unique ID and also that one setting we had left at default needed to be changed, that is Dual Slot Direct Mode. Once we have the basics of digital programming for this commercial application understood we can move on to understanding Talk Groups and zones for the different departments.

The duplexer was tuned by the supplier to the allocated frequencies and provided with plots which we have no reason to dispute and indeed measurements of the duplexer do match the published specifications.

 

[racingfan360]

one setting we had left at default needed to be changed, that is Dual Slot Direct Mode.

I'm hoping you're going to say switch this off vs enable it. I've never tried it but from the choppyness you describe it almost sounds like you are trying to mix DSDM (aka DCDM in Motorola speak) - which is only for simplex (and more specifically enables two slot/therefore double channel operation on simplex) - with repeater operation, so you're maybe only getting every other intended timeslot through the repeater.

Like others I've not programed a Kenwood on DMR, but have seen some mention of needing to enable Selcall on PTT too (but perhaps only needed for compatibility with non-Kenwood)

Unique Radio IDs are strongly advised, not essential, but the effort in programming as such will be worth it in the long run. But having a [Talk]group and a [Radio] ID are essential though.

Might sound odd, but if you're still getting nowhere and need to start with a way of simply verifying the basic tech setup, you might want to drop in an analogue channel configuraton and test using that to begin with and then move onto DMR if that's more of your comfort zone.

 

[hs0zed]

Well we turned OFF DSDM and it is all working beautifully so far. All four channels across the two repeaters are functioning as expected. We will no doubt get into talk groups, zones and ID's at a later time but for now it seems to be good. They will do walk tests throughout the building to ensure all floors, basements and other areas are properly covered and what if any blind spots exist.