Digital Direct Mode (Simplex) on 462 MHz GMRS Channels

[Lscott]

42 minutes ago, WRYZ926 said:

@Lscott I read the last PDF file you posted and you do make a good point about using channels 8-14 for digital. I can se this being done as long as it does not interfere with other channels/frequencies and it is an easy to use system for the average GMRS user to understand and use. DMR on the amateur radio side can be confusing and hard to program radios/repeaters for some.

There will always be some that will stick with analog over digital. I am one that is sticking to analog (for now) due to the complexity of DMR and the different iterations by the different manufacturers.

I know that I am only one person with my own opinion. And we all know what opinions are like. I have never cared for how FRS and GMRS shares the same channels/frequencies. But there is no stuffing that cat back into the bag.

You're one of the examples of those that have no interest digital voice modes, at least DMR, on GMRS. That's perfectly fine. Any implementation has to take those kind of interests into consideration. Undoubtedly, and from other posts, you aren't the only one.

NXDN is not very complex to use. It can be used without talk-groups, unlike DMR. That deceases the complexity for the user. 

The attached images are screen shots of the programming software for the example Kenwood dPMR radio in that file. As you can see it's very simple. One is for the analog channels while the other is for the digital ones.

[WRYZ926]

13 minutes ago, Lscott said:

You're one of the examples of those that have no interest digital voice modes, at least DMR, on GMRS. That's perfectly fine. Any implementation has to take those kind of interests into consideration. Undoubtedly, and from other posts, you aren't the only one.

I am not against DMR and I would definitely be interested in a simpler to use system. 

[Lscott]

Just now, WRYZ926 said:

I am not against DMR and I would definitely be interested in a simpler to use system. 

So do I! When I was first messing with DMR my initial reaction was WTF?

[WRYZ926]

I might get into DMR once we figure out the issues we are having with our 70cm repeaters. We get a lot of noise on the analog side when someone is using DMR. Plus that would mean buying more radios too. The wife might not be happy with that 

It will be interesting to see if DMR gets implemented on GMRS.

[intermod]

46 minutes ago, Lscott said:

You're one of the examples of those that have no interest digital voice modes, at least DMR, on GMRS. That's perfectly fine. Any implementation has to take those kind of interests into consideration. Undoubtedly, and from other posts, you aren't the only one.

NXDN is not very complex to use. It can be used without talk-groups, unlike DMR. That deceases the complexity for the user. 

The attached images are screen shots of the programming software for the example Kenwood dPMR radio in that file. As you can see it's very simple. One is for the analog channels while the other is for the digital ones.

I had not seen NXDN programming before.  Was is the "Common ID" field?   Is that the "RAN"?

Completely agree that this is easier than DMR.  I hope some of the the DMR settings (not the slot, CC, Talkgroup) that nobosy ever plays with will get accepted and not be present eventually. 

But also, Kenwood makes things much easier compared to the others.  

G

[intermod]

4 hours ago, Lscott said:

That annex is huge. I think the relevant section starts on page 92 of the linked document. Most of that annex after that is just the specific test conditions for each mode.

https://fasma.org/wp-content/uploads/TSB-88.1-D-Wireless-Communications-Systems-Performance-in-Noise-and-Interference-Limited-Situations-Part-1-Recommended-Methods-for-Technology-Independent-Performance-Modeling-Includes-Access-to-Additional-Content.pdf

See attached.  This is the key table for determining what the required C/I ratio is for a given voice quality and technology.   Much of the other data was use to generate this table.   DAQ3 column is what should be used from commercial and GMRS. 

For others who have not used this, it shows that:

1.  Analog FM ± 5kHz (25 kHz) requires a Carrier-to-Interference (C/I) ratio of 17 dB (e.g., any interfering signal, regardless of type, must be 17 dB weaker than the signal you are trying to receive for good voice quality)

 2. ETSI DMR 2 slot TDMA (AMBE +2) (12.5 kHz) requires 14.3 dB

This indicates that DMR and other digital signals can tolerate more interference than Analog (2.7 dB greater interference tolerance in this case).

This table also indicates why you really don't want to use analog narrowband.  Narrowband analog (Analog FM ± 2.5kHz (12.5 kHz)) requires a C/I of 23 dB, which is 8.7 dB worse than DMR and most other digital technologies.   Anyone that has used narrowband has already realized this.    

So - if the FCC ever proposes narrowband analog, I would hope they would also allow digital so we could maintain the range and performance of our radio systems.  

TSB-88.1-D-Annex A Table.pdf

[WRQI583]

On 11/25/2023 at 6:47 PM, intermod said:

Has anyone considered asking the FCC to permit digital direct-mode (simplex) such as P25, NXDN, DMR, on the 462 MHz channels?  Some posters in other threads have been concerned about digital repeaters causing more interference than analog ones (although nobody has yet been able to show how this occurs).  So why not allow it on the eight 462 MHz channels?

We already have many people using digital in this manner daily here anyway - listening to them tells me they are commercial users.   

Digital radios are less susceptible to interference from analog or other digital signals, so this would be of great benefit in areas subjected to all the commercial 2-watt bubblepack radio traffic.   Range would be limited so it would not disrupt a significant number of analog users - particularly those using CTCSS/DCS. 

I am not suggesting requiring anyone to use digital - it would just co-exist with legacy analog radios and be another buying choice.  

This would apply to both portable and vehicular radios.

They would not be permitted to transmit on the 467 MHz repeater input/uplink channels.    

Have you ever listened to digital where analog is supposed to be?
Have you ever tried to use analog when digital is taking up the space?
Have you ever been booted right off of a frequency or repeater because of digital ?

I have! It's called Ham Radio!

Just because you are running digital, does not mean you wont interfere with someone using a CTCSS tone. Analog tones, digital tones, analog voice, digital voice, encrypted voice.................. It doesn't matter. It is all a raw radio signal in the end and if you mix them all, you will all interfere with each other. You can take a plain analog radio and key it up near a digital one that someone is actively listening to and totally blank out the radio to where they dont hear anything.

I have found that some people who use digital, whether legally or illegally, are very smug about it, they dont care if they are interfering with another analog station because in their mind, digital is the way of the future and people need to get used to it and deal with it because, to them, analog is so last year. If the FCC wanted digital on GMRS they would have made a provision for it. Every person on this forum who wants digital voice on GMRS should go out and get your Ham Radio license and go play with digital voice over there. I am very irritated with Ham Radio because of everyone abandoning the VHF and UHF bands for HF and then I come over to GMRS just to hear a bunch of people wanting digital voice on GMRS? I don't think so!

Ham bands have over 1 GHz worth of space to go play digital voice however you want and if you live in an area like I live where very few people use VHF and UHF, then you are in luck because you can play digital all you want without interfering with anyone. Its bad enough MURS is clogged with NXDN and P25 in my area, I sure dont want to hear digital on GMRS.

Here is another thought I have had for awhile - Since most Hams in this country have a nice rotten attitude about the UHF band, how about a bunch of digital voice GMRS people go petition the FCC to take a portion of the 440 Ham band away from Hams and create a DMR GMRS band where you can all play? That should work well. The FCC wouldn't lose any money, Hams wouldn't lose any space, since none of them use it anyhow and those who want to fill a band with digital, can go play digital GMRS however you want. Win Win all the way around.

Before anyone on here decides to post questions like this, I want you all to get together with the following or a combination of the following - 
Analog radios running no tones
Analog radios running CTCSS tones, one with decode and one without
Analog radios running DCS tones, one with decode and one without
Digital radios running DMR, one with encryption and one without
Digital radios running NXDN
Digital radios running P25
Digital radios running Yaesu Fusion 

and I want you all to key up your radios randomly and see if you the others are able to communicate. Maybe the ones running analog can place the radio to their ear and crank up the volume real loud while a digital radio transmits. I guarantee, after that, you will see why putting digital voice on GMRS is a bad idea. I've been on the receiving end of listening to digital garbage come flowing through the speaker on my analog radio because of a smug digital radio operator who thought he could act arrogant and transmit with his much superior digital radio and not care what he did to someone else. The funny thing about all of this, is that I am not against digital. I personally own a DMR hotspot, I operate DMR (or I used to). I own two DMR radios. I just dont mix my DMR where analog is meant to be.

So, if you want digital voice? HAM RADIO! HAM RADIO! HAM RADIO! You have the capability of 5+ different digital voice modes and that number is probably growing.

Thanks to HF and all of its contesting garbage, Hams have abandoned the VHF and UHF bands to go have an ongoing competition for the most contacts. This is your opportunity to go get your Ham license and start flooding the VHF and UHF bands with activity!!! Trust me, you have PLENTY of space and the most that will happen is that Ham radio operators will try and try to coerce you into operating HF. Grow a strong backbone and ignore them! Please leave GMRS alone. GMRS is the last band that many of us have that isn't tainted.

[intermod]

2 minutes ago, WRQI583 said:

 

I am sorry to have triggered you.  So I understand - are you suggesting I try amateur radio?

[Lscott]

7 hours ago, intermod said:

I had not seen NXDN programming before.  Was is the "Common ID" field?   Is that the "RAN"?

Completely agree that this is easier than DMR.  I hope some of the the DMR settings (not the slot, CC, Talkgroup) that nobosy ever plays with will get accepted and not be present eventually. 

But also, Kenwood makes things much easier compared to the others.  

G

The programming example is for a dPMR radio. NXDN programming isn’t too bad. 

[WRQI583]

6 hours ago, intermod said:

I am sorry to have triggered you.  So I understand - are you suggesting I try amateur radio?

Well, I wouldn't go saying triggered, but the subject has been brought up many many times as many people have said and I have personally watched most Hams "empty out of the room" so to speak when it comes to using the VHF/UHF bands where these digital voice modes are used. Not only has that happened, but many Hams will straight up talk very badly about these bands right over the air and get other new Hams to trash talk these bands. What is really sad is that they have added many different digital voice modes, DMR being one of them, to these bands and not only does it cause Hams to trash talk the bands even more, some fly off into a rage about how digital voice is not real Ham radio and they will go as far as having certain feelings (not good) about those who use it. Like I said, there is literally over 1 GHz worth of space to play with on these bands where you can do digital voice. DMR only takes up 6.25 KHz per channel (utilizing time slots). There are some places where some of these bands are dead. There is literally no one on them at all. You could set up pirate radio stations (not condoning that) and no one would know, as in, that dead.

So when people get on here with ideas about DMR on GMRS and someone like me has seriously watched Ham bands, where this is more than allowed, dry up in front of his face, yes, it can be pretty irritating to see the posts. So, Yes, Ham Radio all the way. Just dont get sucked down the HF rabbit hole when the Hams with higher class licenses come around coercing you to upgrade your license to join the HF crowd in contesting, otherwise, you will become like every other Ham abandoning the VHF and UHF bands to talk around the world doing contesting.

GMRS is meant to be analog for people just simply trying to communicate between family and friends. Would I personally love to see DMR on GMRS. Absolutely. But not with the limited space and lack of control over the band the way it is now. Ham Radio is the place to be for digital because you have all sorts of freedom to experiment with it any way you want, minus encryption. 

[Lscott]

4 hours ago, WRQI583 said:

GMRS is meant to be analog for people just simply trying to communicate between family and friends. Would I personally love to see DMR on GMRS. Absolutely. But not with the limited space and lack of control over the band the way it is now. Ham Radio is the place to be for digital because you have all sorts of freedom to experiment with it any way you want, minus encryption. 

IMHO the argument for digital voice on GMRS has nothing to do with trying to make it a "Ham Lite" type hobby service or experimenting. I believe it it would improve the quality of the service, better with less noise communication. That is the primary reason why somebody would want to use the service, they have a communication need, the clearer the better, while digital voice provides that out closer to the range limits compared to analog FM.

The key to the whole thing is how to go about it without creating a major disruption to the existing user base.

[WRYZ926]

4 hours ago, WRQI583 said:

Just dont get sucked down the HF rabbit hole when the Hams with higher class licenses come around coercing you to upgrade your license to join the HF crowd in contesting, otherwise, you will become like every other Ham abandoning the VHF and UHF bands to talk around the world doing contesting.

This is true. A lot of the members of my local club keep bugging me to get on HF along with using FT8, etc. But I have kept to using the VHF and UHF bands. Our 2m repeater is quite busy since it has a large coverage area, possibly the biggest in Missouri. A few of us are getting more members to use the analog side of our 70cm repeaters too. I prefer having a good analog setup since it will be more reliable than digital in severe conditions/emergencies.

[BoxCar]

Mixing digital and analog services on the same frequency just doesn't work. It works in Part 90 because the channels and coverage areas are coordinated to prevent one service from interfering with the other. GMRS/FRS is an uncoordinated service meaning you can use any of the frequencies at any time and any place. Also, as there are so few channels available you can't help but have the modes interfere with each other.

[WRQI583]

1 hour ago, Lscott said:

IMHO the argument for digital voice on GMRS has nothing to do with trying to make it a "Ham Lite" type hobby service or experimenting. I believe it it would improve the quality of the service, better with less noise communication. That is the primary reason why somebody would want to use the service, they have a communication need, the clearer the better, while digital voice provides that out closer to the range limits compared to analog FM.

The key to the whole thing is how to go about it without creating a major disruption to the existing user base.

Well in that case, either ya make it all ONE digital standard or keep it all analog. Dont give anyone the option to run both, otherwise it creates problems and shoves everyone away from the band. Remember, we are only playing with 8 and in some cases 6 repeater pairs. That isn't a lot of room. I am not against digital. I love running it. It makes better use of the band, but if it ends up like Ham Radio and you add the unregulated nature of GMRS to that equation, that will mean people will be able to just set up whatever they want wherever they want. Sadly, you wont be able to do it without disrupting the current users. I know on Ham Radio, Digital repeaters have really shoved a lot of Hams off of the bands in some places. It doesn't accomplish anything good. Straight up, there needs to be organization. It needs to be regulated. What I would love to see is to have more frequency pairs added to GMRS. 

[WRQI583]

50 minutes ago, WRYZ926 said:

But I have kept to using the VHF and UHF bands. Our 2m repeater is quite busy since it has a large coverage area, possibly the biggest in Missouri. A few of us are getting more members to use the analog side of our 70cm repeaters too.

I prefer having a good analog setup since it will be more reliable than digital in severe conditions/emergencies.

I wish I could say the same over here. These bands are really quiet to the point where I disconnected my 2 meter radio so I could use the antenna on my SDR's full time.

I found that digital doesn't work well as far as distance unless you have an external antenna with a good amount of power. I love digital voice, however, I only have portable radios and I am over 20 miles from the nearest repeater.

[Lscott]

50 minutes ago, BoxCar said:

Mixing digital and analog services on the same frequency just doesn't work. It works in Part 90 because the channels and coverage areas are coordinated to prevent one service from interfering with the other. GMRS/FRS is an uncoordinated service meaning you can use any of the frequencies at any time and any place. Also, as there are so few channels available you can't help but have the modes interfere with each other.

That's one of the key areas that has to be examined and the potential interference issues resolved. I covered that in the attached opinion paper in my prior post in this tread. 

[Lscott]

17 minutes ago, WRQI583 said:

Well in that case, either ya make it all ONE digital standard or keep it all analog. Dont give anyone the option to run both, otherwise it creates problems and shoves everyone away from the band. Remember, we are only playing with 8 and in some cases 6 repeater pairs. That isn't a lot of room. I am not against digital. I love running it. It makes better use of the band, but if it ends up like Ham Radio and you add the unregulated nature of GMRS to that equation, that will mean people will be able to just set up whatever they want wherever they want. Sadly, you wont be able to do it without disrupting the current users. I know on Ham Radio, Digital repeaters have really shoved a lot of Hams off of the bands in some places. It doesn't accomplish anything good. Straight up, there needs to be organization. It needs to be regulated. What I would love to see is to have more frequency pairs added to GMRS. 

It's going to take some careful thought to figure out how to do it. IMHO for the moment we should just forget running digital voice on repeaters. I think the major gain is digital voice on simplex. The logic there if you need a repeater the analog FM types seem to do a very good job of providing good coverage. The digital voice modes would primarily benefit HT to HT, or HT to mobile/base communications.

Also remember UHF spectrum is limited. The FCC mandated most services move to narrow band in an attempt to free up more spectrum.  Asking the FCC to allocate more spectrum to GMRS is very likely dead on arrival. We would be lucky to keep what we have now.

https://forums.mygmrs.com/topic/6478-digital-direct-mode-simplex-on-462-mhz-gmrs-channels/?do=findComment&comment=66329&_rid=1908

 

[BoxCar]

As GMRS/FRS is an unregulated, uncoordinated service, just like CB, you'll never be able to control who installs what where. As the service is well established as a low-power, uncoordinated service, you'll never be able to get the cat back into the bag -- period! Hams got it to work in VHF/UHF because they saw how Part 90 was done and had a national organization to act as a clearing house to spread the word on the frequency assignments. The only way to accomplish your dream would be for the FCC to allocate new unlicensed spectrum and the chance of that happening is slim and none, (Oh, Slim had already packed his bags and that truck left town 5 years ago.)

[WRXB215]

I'd prefer to keep GMRS analog. I can't afford new equipment. 

[intermod]

2 hours ago, Lscott said:

It's going to take some careful thought to figure out how to do it. IMHO for the moment we should just forget running digital voice on repeaters. I think the major gain is digital voice on simplex. The logic there if you need a repeater the analog FM types seem to do a very good job of providing good coverage. The digital voice modes would primarily benefit HT to HT, or HT to mobile/base communications.

Also remember UHF spectrum is limited. The FCC mandated most services move to narrow band in an attempt to free up more spectrum.  Asking the FCC to allocate more spectrum to GMRS is very likely dead on arrival. We would be lucky to keep what we have now.

https://forums.mygmrs.com/topic/6478-digital-direct-mode-simplex-on-462-mhz-gmrs-channels/?do=findComment&comment=66329&_rid=1908

 

Lscott's proposed plan using a narrow NXDN or dPMR type emission (~4K00 - if am I correct) is absolutely the easiest way to approach this when we have a federal bureaucracy to deal with.   And the manufacturers will jump all over digital in any form to sell more equipment or differentiate their products (ant least temporarily).   So he would likely have both GMRS licensee and manufacturer support.   And all the hate that comes with mentioning the D-word.

As we have many mountains here in our Northern California area (repeater signals travel great distances), GMRS interference and capacity issues can only be dealt with by addressing repeater use.  So that is why I focus here. 

Agree that getting more spectrum is unlikely.        

If we eventually have to discontinue use of DMR, the two main users groups (on Slot 1 and Slot 2) will now have to share a common (single) repeater channel, but they are more likely going build a second repeater on a different channel, in an attempt to get the same level of service.   This will create as much or more interference than the single DMR repeater did before and eat up more of our limited spectrum.  So these things need to be looked at broadly to really understand the overall picture.

The horse has expired. 

[Lscott]

22 minutes ago, intermod said:

The horse has expired. 

A while ago. You can still smell it. A few will still try to kick the bones around for a bit