Continuation of question about analog and DMR repeaters on the same frequency

[patrickdickey52761]

My question is a continuation on a closed thread DMR and Analog Repeaters on the same frequency.

The question that I have is would it help to put a PL-tone on the DMR Repeater to reduce the amount of interference from an analog repeater (or radio) on the same frequency? Or would that stop the DMR repeater from receiving any transmissions? I realize that DMR uses color codes in place of PL-Tones, so I want to make sure that the PL-Tones aren't used in any fashion to open the repeater input.

Thanks.
Patrick.

 

[jaspence]

I have not seen any option in the DMR software for several different radios I have programmed to add PL tones. That is why there are repeater coordinators to help avoid situations where repeaters are close and on the same frequency or a different mode.

 

[popnokick]

CTCSS / PL / DCS tones are not used in any manner with DMR. DMR receivers simply ignore them. Which also means you cannot “put a PL tone on the DMR Repeater”.

 

[buddrousa]

You can run in mixed mode DMR will only hear DMR and ANALOG with PL TONES will only hear ANALOG but both can not talk at the same time.

 

[popnokick]

The question that I have is would it help to put a PL-tone on the DMR Repeater to reduce the amount of interference from an analog repeater (or radio) on the same frequency? Or would that stop the DMR repeater from receiving any transmissions? I realize that DMR uses color codes in place of PL-Tones, so I want to make sure that the PL-Tones aren't used in any fashion to open the repeater input.

Thanks.
Patrick.

You didn't specify whether you were asking about two different, separate repeaters on the same frequency, or one single repeater operating in "dual" mode (DMR / FM Analog). I think some of the replies you received assumed two separate repeaters (as I did).... but I think at least one reply is referring to a single repeater operating in dual mode DMR / FM.

 

[patrickdickey52761]

Ok, a little clarification on the subject. We have a DMR only repeater that has some issues. The one thought that I had was since it's running on an old Motorola repeater that analog signals on the same frequency might be causing interference. Which brought me to the original forum post. So, I'm wondering if I should go into the hardware with the Motorola CPS programming software and put a PL-Tone on the hardware. I understand that DMR uses Color Codes in place of PL-Tones and CTCSS.

And, I'm fully aware that I'm most likely barking up the wrong tree with the issues. The main issue is digitalization in conversations (which I also attribute to people doubling on each other) and portions of the conversation dropping out. Other people in the mix are saying it's our Internet, but we have a sister repeater running on a crappy Internet connection and it works fine. This leads me to believe it's something to do with configuration, the repeater itself, or interference. I'm trying to eliminate the easy stuff before I tell them they need to buy a new repeater. Especially when the guy who got the radio and built it can be sensitive.

Have a great day.
Patrick.

 

[sallen07]

The one thought that I had was since it's running on an old Motorola repeater that analog signals on the same frequency might be causing interference. Which brought me to the original forum post. So, I'm wondering if I should go into the hardware with the Motorola CPS programming software and put a PL-Tone on the hardware. I understand that DMR uses Color Codes in place of PL-Tones and CTCSS.

The fact that it's "an old Motorola repeater" isn't relevant. If anything, that "old Motorola repeater" is probably a better choice than things you can buy new.

Could an analog signal on the same frequency as the repeater input cause interference? Sure.

But if you go into CPS and program a DMR channel, that's what it is: a DMR channel. The repeater will only 'repeat' a DMR signal with the correct color code. It will ignore an analog signal. The options to set PL/DPL aren't even active on a DMR channel.

The main issue is digitalization in conversations (which I also attribute to people doubling on each other) and portions of the conversation dropping out. Other people in the mix are saying it's our Internet, but we have a sister repeater running on a crappy Internet connection and it works fine.

Sounds like a signal strength issue to me, like one or both stations are at the fringes of the repeater's range.

Are both parties talking directly through the repeater, or is one side coming in via the Internet? What happens if you use Local TG (9) and talk directly through the repeater only? Is this a Brandmeister node? What kind of signal strength and packet loss are you seeing on the dashboard?

 

[popnokick]

And adding to what sallen07 asked: What kind of duplexer are you using on the DMR repeater? Who tuned the duplexer and with what instruments? And what level of rejection / isolation are you seeing from the duplexer? A mistuned duplexer (or none at all) can cause the symptoms you describe on the DMR repeater.

 

[16b]

Since we don't know the exact nature of your repeater setup this could be easier said than done. But, one thing you could do is temporarily configure the repeater for analog operation with carrier squelch (no PL). No DMR. If interference is indeed the problem, you will likely know in short order.

 

[prcguy]

I have not done this with DMR yet but I've run an analog FM, Yaesu Fusion and P25 repeater, all on the same frequency at the same site. All repeaters used the same receive antenna and the transmitters were combined onto one antenna. People on this repeater pair have a choice on what mode they want to use and its never keyed up the wrong repeater at any time.

Getting interference from other users on the same frequency trying to get into another distant repeater is one thing. Someone on analog FM somehow keying up a DMR repeater by accident is another and should never happen under any circumstances.

 

[patrickdickey52761]

One of the guys in our club tuned the duplexers on both this and the sister repeater. He got the radios and duplexer tuned down into the microvolts range for everything. This was something he did in his professional life, so I'm pretty confident that he did it correctly.

As for the signals, one is from in town (maybe about five to ten miles tops from the repeater, which has an antenna sitting at 265' AGL) and the rest are over the Internet through Brandmeister. Every once in a while, we'll get a "Repeater Not Found" on our radios. It mainly happens on Sunday night during the Iowa 3119 net, but we do notice it at other times. Especially if there's been a long conversation going on. I partially suspect the radio because it's a repeater that he had to do a lot of repair work to get running.

In re: 16b's reply, I'm not sure what exactly you need for information. We have a DMR only repeater that was built from an older Motorola analog repeater. Basically, we programmed in 444.1250/449.1250 for the frequencies on the Motorola repeater. Then, we connected an STM32 from repeater-builder on a raspberry pi running pi-star to the repeater to act as the controller. The duplexers were bought off of eBay. As for the repeater, someone else in the club acquired it and our "repeater guy" tuned the duplexers and fixed receiving issues on the repeater using his Service Monitor, along with a Bird 443. We're running it from a tower at our local college and using an AREDN mesh for the Internet (which is still running better than the sister repeaters' Internet connection).

Tomorrow, I'll see about getting a few people to go on LCL 9 and try it. We'll see if we have any issues with digitalization, dropping out, or "Repeater Not Found". As I said above, *I think* it's the repeater itself. Just because we don't know where the original member got it, he's SK so we can't ask, and the other member had to do a lot of work to get it running again (receive issues for sure, possibly transmitting issues too). I have to eliminate all other possibilities before I tell them they bought a lemon.

Hopefully, I gave you enough information. If not, please tell me what you want specifically. I understand the networking/IT side of this, but the repeater side isn't my strong suit.

Have a great night.
Patrick.

 

[patrickdickey52761]

I have not done this with DMR yet but I've run an analog FM, Yaesu Fusion and P25 repeater, all on the same frequency at the same site. All repeaters used the same receive antenna and the transmitters were combined onto one antenna. People on this repeater pair have a choice on what mode they want to use and its never keyed up the wrong repeater at any time.

Getting interference from other users on the same frequency trying to get into another distant repeater is one thing. Someone on analog FM somehow keying up a DMR repeater by accident is another and should never happen under any circumstances.

If it's analog interference, my guess is someone is trying to get into another repeater or just trying to get into ours not realizing their radio won't do it. In truth, I don't know if this is the issue at all. I'm grasping at straws because of things I hear during the nets and my limited knowledge of all of this. The guy who knows repeaters says that it's an issue with pi-star, the raspberry pi/mmdvm board, and the Internet. I think it's something on the radio side of things.

At the end of the day, the question is this: If I key up my Baofeng BF-F8HP on the input or output frequency of the DMR only repeater, will someone listening to the traffic on a DMR talkgroup even notice that I did? Will they get interference from my POS radio? And if so, what should I do to eliminate that possibility?

Have a great night.
Patrick.

 

[patrickdickey52761]

The fact that it's "an old Motorola repeater" isn't relevant. If anything, that "old Motorola repeater" is probably a better choice than things you can buy new.

Could an analog signal on the same frequency as the repeater input cause interference? Sure.

But if you go into CPS and program a DMR channel, that's what it is: a DMR channel. The repeater will only 'repeat' a DMR signal with the correct color code. It will ignore an analog signal. The options to set PL/DPL aren't even active on a DMR channel.



Sounds like a signal strength issue to me, like one or both stations are at the fringes of the repeater's range.

Are both parties talking directly through the repeater, or is one side coming in via the Internet? What happens if you use Local TG (9) and talk directly through the repeater only? Is this a Brandmeister node? What kind of signal strength and packet loss are you seeing on the dashboard?

On the dashboard (pi-star), we notice good signal strengths from radios that are connecting via RF and low (<2) BER for the most part. Occasionally, we'll have someone connecting via RF that has high BER. The problem is both on RF and the net side of things. We'll hear digitalization as well as dropped portions of the conversation. Like, if I said "The sky is blue and the grass is green.", you might get "The is blue grass is green." Occasionally we'll get "REpeater Not Found" when you try to connect. If you try it again right after, you most likely get through.

Hopefully, I'll be able to get some people to try LCL 9 and see what happens on there tomorrow or the next day.

Have a great night. And, thank you all for your help in this.
Patrick.

 

[sallen07]

Occasionally we'll get "Repeater Not Found" when you try to connect. If you try it again right after, you most likely get through.

OK when you said "older Motorola repeater" I thought you meant something like an XPR8300 or 8400, which would be an older Motorola DMR repeater.

But "repeater not found" says that the mobile or HT is not talking to the repeater, perhaps because it is out of range.

I'm running an XPR8300, and use Parrot to do range testing. What you described ("They sky is blue and the grass is green" -> "The is blue grass is green" sounds exactly like what I get back from Parrot when I am at the fringes of my repeater's footprint.