Digital Direct Mode (Simplex) on 462 MHz GMRS Channels

[intermod]

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.    

[Radioguy7268]

Again, if you want to use DMR for Digital simplex, the FCC already offers you a service for this choice. Go get a part 90 license, talk on DMR simplex all day long. Make sure you license it as an MO6/FB6 Private Carrier, and then all your friends and family (plus anyone else you want to count as a 'subscriber' under your license) can join along for one 10 year term. As a bonus, you can use encryption, run a repeater, and even pump out more than 50 watts.

There are no GMRS  Part 95 radios that will do Digital today, so unless you want to wait for a possible rule change, wait for manufacturers to respond to the changes and build GMRS digital radios, you would end up using Part 90 equipment anyway.

I really don't understand the resistance to using what's already available today. If you want to use DMR, then use DMR - it wasn't like you were going to be using it to talk with existing analog GMRS users anyway.

 

[SteveShannon]

I have used simplex DMR on 70 cm amateur radio. It works well and gives me a fairly wide segment on radio spectrum to operate uninterrupted. 
Like RadioGuy, I don’t understand the desire to make GMRS something different when ham radio offers so much variety. The only thing it doesn’t allow is operating under the familial license. 

[DONE]

There is an 8 page discussion on this topic elsewhere on the board.

It's the same dead horse with a different bridal. 

Here's a thought.  Why don't YOU petition the FCC for a rule change allowing digital modulation on GMRS? 

And I have NO idea where you got the idea that DMR is somehow better suited to deal with analog signals than other analog signals.  Any type of signal getting into a DMR receiver will raise the BER and cause artifacting and digitization of the audio.  That's if it comes through at all.  Public Safety is discouraged by the FCC from using any sort of DMR because of the issues with it not playing well with analog signals and the fact that the public safety frequencies were issued multiple times in an area, sometimes within the same county and the end users would just run different PL's to filter out the other users traffic. 

There is a requirement under part 90 that a user much first monitor the frequency in use to be sure that there isn't another user on it.  That is what the MONITOR button is for, and why there is a 'Hub defeat's PL' that turns off the PL requirement on a mobile radio when you take the mike from the hanger.  Now I don't believe that GMRS has such a requirement.  It's also why there is a channel free and color code free setting in DMR radios.  When using a DMR programmed channel it's suppose to be set for channel free if there is another user close enough that their licensed coverage area overlaps your coverage area.  GMRS doesn't have 'licensed coverage area's.  We are power limited but that's it, as long as your transmitter is 50 watt's or less, the sky's the limit on antenna height and antenna gain.  Yes, if your tower is over 200 feet you have to have it registered and have obstruction lighting, but that's not a height limit, it's an additional requirement by the FAA not the FCC for towers exceeding a certain height. 

You ant DMR, go get a part 90 license, go get a ham license.  DMR is prevalent in both of those services.  It's not allowed on GMRS currently and I really don't see that ever changing.

 

[Raybestos]

Another person trying to turn GMRS into "ham radio lite".  If you want to do ham stuff go get your ham license and do ham stuff.  We already have the eight 50W Simplex/Repeater channels clogged up with "networks" and linking by wannabe hams in too many locales.  No need to jam up GMRS with more digital noise.  Or if you really want to play digital mode on simplex, do it on one of the five MURS channels.

[WRYZ926]

I have to agree with everyone that GMRS should be left alone as is. My local club runs digital repeaters on the 70cm repeaters and those repeaters are constantly having issues. If things are not setup correctly then anyone using analog will hear a bunch of noice when someone transmits using digital. And as mentioned , there are man different digital modes and none of them are 100% compatible. I'm at the point right now that I won't even buy hand held or mobile radios with digital modes.

If you want to use digital modes then get your amateur radio license. You will find that there are quite a few of us that have both amateur and GMRS licenses and we like the simplicity of GMRS and analog amateur bands.

[Flameout]

There is a GMRS DMR repeater in my area, but right now I don't have a digital radio so haven't been able to test it out. I do hear weird, loud noise occasionally on the frequency using my analog radio. I'm guessing it's IDing?

https://mygmrs.com/repeater/8051

[radiozip]

36 minutes ago, Flameout said:

There is a GMRS DMR repeater in my area, but right now I don't have a digital radio so haven't been able to test it out. I do hear weird, loud noise occasionally on the frequency using my analog radio. I'm guessing it's IDing?

https://mygmrs.com/repeater/8051

Could be someone "quick keying" the repeater in DMR, thus the brief digital hash that's not a conversation. Typically a repeater ID is analog morse code, or sometimes analog voice.

[WRQC527]

38 minutes ago, Flameout said:

I don't have a digital radio

Here's a serious, honest question for anyone who can provide an honest answer. Instead of brazenly claiming there are none, I'll ask if there are there any commercially-available FCC-certified GMRS transceivers that one can purchase that are capable of digital voice transmissions? Not that I want or would buy one, but for the edification of anyone here who is interested in communicating through the experimental WN2XFO DMR-enabled GMRS repeater or any others like it. You can provide links if you're so inclined.

[Lscott]

15 hours ago, Radioguy7268 said:

There are no GMRS  Part 95 radios that will do Digital today, so unless you want to wait for a possible rule change, wait for manufacturers to respond to the changes and build GMRS digital radios, you would end up using Part 90 equipment anyway.

If you’re referring to recent manufacture yes. There are some older radios that will do digital and have FCC Part 95 certification. I own a few of those. Of course I can’t use the digital part under the current rules.

The attached file is the FCC grant for one of my NX-300 radios with certification for Part 95 for all modes it has the capability to transmit. The various radio features are listed in the attached brochure.

NX-300 FCC Grant - 1.pdf NX-200_300.pdf

[intermod]

15 hours ago, Sshannon said:

I have used simplex DMR on 70 cm amateur radio. It works well and gives me a fairly wide segment on radio spectrum to operate uninterrupted. 
Like RadioGuy, I don’t understand the desire to make GMRS something different when ham radio offers so much variety. The only thing it doesn’t allow is operating under the familial license. 

I have operated amateur DMR since 2011 and legacy analog repeaters since the 1990's.  What I increasingly find in amateur are many abusive people with closed minds that lack loyalty to friends.   Also very cliquish.  They want to consider amateur an exclusive club...no thanks.  I find those in GMRS - many very new to radio - as more open-minded and less abusive (except for here . )    

I am guessing that of all the people that want or need a radio, likely ~90% will never get their amateur license.  So we miss out on all of them.  GMRS is a great service for the vast majority of these people.   The familial license is just the right amount of regulation to keep business and large incompatible organizations from monopolizing it and running legit GMRS licensees off.  

But the other nice thing is less content moderation by the government.   I can actually conduct my small business communications over GMRS legally.  The ability to hand a radio to another family member for quick comms is also great. 

Lets expand GMRS capabilities, not cripple it with inflexible rules.   

[intermod]

12 hours ago, WRKC935 said:

.....It's the same dead horse with a different bridal. 

And I have NO idea where you got the idea that DMR is somehow better suited to deal with analog signals than other analog signals.  Any type of signal getting into a DMR receiver will raise the BER and cause artifacting and digitization of the audio......   

Of course, but we are comparing analog to digital.  Your statement is a bit too broad.   Empirical tests have proven that for a given digital voice quality (BER-related), DMR, NXDN and P25 are about 1-3 dB better at rejecting interference than legacy wideband analog signals are (See TSB-88.1, Annex A).  Its 6-8 dB better than narrowband analog.  This is the same data the Part 90 frequency coordinators often refer to when licensing those systems.   

[intermod]

12 hours ago, WRKC935 said:

...There is a requirement under part 90 that a user much first monitor the frequency in use to be sure that there isn't another user on it.  That is what the MONITOR button is for, and why there is a 'Hub defeat's PL' that turns off the PL requirement on a mobile radio when you take the mike from the hanger.  Now I don't believe that GMRS has such a requirement.  It's also why there is a channel free and color code free setting in DMR radios.  When using a DMR programmed channel it's suppose to be set for channel free if there is another user close enough that their licensed coverage area overlaps your coverage area.  GMRS doesn't have 'licensed coverage area's.  We are power limited but that's it, as long as your transmitter is 50 watt's or less, the sky's the limit on antenna height and antenna gain.  Yes, if your tower is over 200 feet you have to have it registered and have obstruction lighting, but that's not a height limit, it's an additional requirement by the FAA not the FCC for towers exceeding a certain height.....

Correct - GMRS does not have that requirement, but it more broadly states that users should avoid interference and cooperate.   But the "listen-before-talk" (LBT) concept generally remains. 

I found that the vast majority of Part 95 analog radios lack a Busy Channel Lockout (BCLO) feature - and in practice, nobody uses or remembers how to use the Monitor button.  And many new bubbleplack radios come with CTCSS/DCS enabled on their receivers.

In contrast, all DMR radios have BCLO, and many have dual-mode capability that allows monitoring of digital or analog signals on the same channel. 

DMR repeaters also have BCLO built in, and you can manually fine tune the lockout threshold.   Few analog repeater ever had such a feature.   

So the DMR radios and repeaters are much better at channel-sharing and protection than analog radios.   

[intermod]

3 hours ago, WRYZ926 said:

....If things are not setup correctly then anyone using analog will hear a bunch of noice when someone transmits using digital. ...

Is this a digital problem or a poorly-design analog radio problem (e.g., is the analog radios CTCSS/DCS decoder to apt to false on digital noise)?  We have run dual-mode on our repeaters and have not experienced that - except with a few Boafengs that were really low-end.   We were able to false those decoders by just talking on analog - they would open their speakers intermittently.   

Yea - the thing that sucks is that all the digital modes are incompatible.  But do you think that the world is headed towards a digital radio nirvana (one standard - all compatible) or is the trajectory in the other direction?

[intermod]

10 hours ago, RayP said:

 Or if you really want to play digital mode on simplex, do it on one of the five MURS channels.

MURS does not permit common digital voice modes like DMR.   See § 95.2771 MURS emission types.

Another reason why GMRS is the right place for digital.  

But thanks for suggesting the idea.  I had forgotten whether MURS allowed this or not. 

But both MURS and GMRS permit DMR, P25 and NXDN data, such as for texting.   Or maybe GPS...not sure about this one though.  

Retevis made one last year - could not remember the model.   DMR on GMRS, but only for texting.  Analog voice.

 

[SteveShannon]

1 hour ago, intermod said:

I can actually conduct my small business communications over GMRS legally.  The ability to hand a radio to another family member for quick comms is also great. 

Sounds like the perfect reason for a business license. 

[gortex2]

We go over this topic monthly. Unless a big manufacture goes after the FCC it wont change. None are going to spend the time, research and funding to do this because folks with $20 portables want to use DMR, Fusion, P25 etc. Look at the ham world. Tell me how many manufacturers sell gear that does DMR ? Or P25 ? Fusion is made by Yasue only. DSTAR ICOM. They can't even have a standard there where it would semi work. Never going to happen in GMRS. As said in about 50 different threads on this topic just go use a ham cannel if you want DMR, or license a Part 90 Frequency and do what you want. 

[WRYZ926]

21 hours ago, intermod said:

Is this a digital problem or a poorly-design analog radio problem (e.g., is the analog radios CTCSS/DCS decoder to apt to false on digital noise)?  We have run dual-mode on our repeaters and have not experienced that - except with a few Boafengs that were really low-end.   We were able to false those decoders by just talking on analog - they would open their speakers intermittently.   

Yea - the thing that sucks is that all the digital modes are incompatible.  But do you think that the world is headed towards a digital radio nirvana (one standard - all compatible) or is the trajectory in the other direction?

It is definitely a digital problem since everyone hears the noise no matter what type/brand of radio they are using. The noise is not heard all of the time. It is either a hardware or software issue with the repeaters running analog and digital.

[DONE]

17 hours ago, intermod said:

Of course, but we are comparing analog to digital.  Your statement is a bit too broad.   Empirical tests have proven that for a given digital voice quality (BER-related), DMR, NXDN and P25 are about 1-3 dB better at rejecting interference than legacy wideband analog signals are (See TSB-88.1, Annex A).  Its 6-8 dB better than narrowband analog.  This is the same data the Part 90 frequency coordinators often refer to when licensing those systems.   

Still didn't answer the question about why YOU don't bother to go petition the FCC about making a rule change allowing DMR on GMRS. 

And again, as myself and others have said in this thread.  This is a dead horse being beaten again.  This has been rehashed over and over again.  No one is going to petition the FCC for the rule change, including members here who have actually successfully petitioned the FCC for rule changes.  And the reason is simple.  DMR on GMRS will cause nothing but problems for the current users.  It's about as dumb as when the FCC decided to change CB radio from 23 channels to 40 channels making everyone's equipment obsolete when the change took effect.  The actual part 95 radios that are in service will be unable to operate with DMR.  Same issue exists for adding channels to GMRS or making GMRS narrow band. 

If you want to petition the FCC for a rule change, and get it to the point that it's open for public comment, we will certainly comment on the change.  Until then, be happy with what you have, and if it doesn't suit your purposes use a different service. 

Because while your numbers are correct, they apply to DMR being effected by Analog signals.  Not the effects of DMR on the ANALOG signals of the multitude of users out there currently using the service within the rules as they are now.

 

[Lscott]

20 hours ago, intermod said:

The familial license is just the right amount of regulation to keep business and large incompatible organizations from monopolizing it and running legit GMRS licensees off. 

When the rules changed to allow license free FRS radios to run 2 watts isn't going to help matters considering business are free to use them.

[Lscott]

20 hours ago, intermod said:

Of course, but we are comparing analog to digital.  Your statement is a bit too broad.   Empirical tests have proven that for a given digital voice quality (BER-related), DMR, NXDN and P25 are about 1-3 dB better at rejecting interference than legacy wideband analog signals are (See TSB-88.1, Annex A).  Its 6-8 dB better than narrowband analog.  This is the same data the Part 90 frequency coordinators often refer to when licensing those systems.   

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

[Lscott]

12 hours ago, WRKC935 said:

Still didn't answer the question about why YOU don't bother to go petition the FCC about making a rule change allowing DMR on GMRS. 

Before even petitioning the FCC there needs to be some general concuss about how to do it. Without that the FCC mostly would just deny it at the outset. So far can't really get to that point yet. DMR might not even be the mode to use. I haven't really read any good debate if there are better digital voice modes that could potentially be used. I believe there are. I posted an opinion paper I wrote outlining my thoughts. If anyone is interested doing some searching on the forum should turn up references to it.

From various posts on the Internet digital voice is being used in pockets around the country. I don't expect that to change without some huge FCC enforcement action, which at this point in time doesn't seem to be high on their agenda. What's more likely to happen is the practice will continue and grow. Once it gets out of hand the FCC can do what it's done before, throw in the towel and make it legal. They did it with the combo GMRS/FRS radio mistake. Buggered around with the rules such that what people were already doing illegally is now legal.

[SteveShannon]

40 minutes ago, Lscott said:

Before even petitioning the FCC there needs to be some general concuss about how to do it. Without that the FCC mostly would just deny it at the outset. So far can't really get to that point yet. DMR might not even be the mode to use. I haven't really read any good debate if there are better digital voice modes that could potentially be used. I believe there are. I posted an opinion paper I wrote outlining my thoughts. If anyone is interested doing some searching on the forum should turn up references to it.

From various posts on the Internet digital voice is being used in pockets around the country. I don't expect that to change without some huge FCC enforcement action, which at this point in time doesn't seem to be high on their agenda. What's more likely to happen is the practice will continue and grow. Once it gets out of hand the FCC can do what it's done before, throw in the towel and make it legal. They did it with the combo GMRS/FRS radio mistake. Buggered around with the rules such that what people were already doing illegally is now legal.

The only way to do digital is to make a complete switchover. After some date stop certifying new products for 95B and 95E. People who have them can continue to use them but there will be no analog replacements available. 
There ought also to be a complete overhaul that does away with the convoluted mess of channels we now have. Get rid of FRS and GMRS completely and replace both services with a single unlicensed digital service. There might even be a very simple digital mode that is selected for this that is represented by a simple channel. I.e. no color code, no time slot, no encryption, etc, just a way to carve more very narrow channels out of the existing section of the spectrum. 

[Lscott]

5 minutes ago, Sshannon said:

The only way to do digital is to make a complete switchover. After some date stop certifying new products for 95B and 95E. People who have them can continue to use them but there will be no analog replacements available. 

The issue you'll have the owners of those radios will soon realize the channels will become crowded with digital users rendering them almost impossible for analog FM use. That could happen quickly. Digital TV is a case in point.

Also once people see no new analog FM radios are being sold they will most likely hang on to them much longer than otherwise might be the case. There are those who hate the sound quality of various digital voice modes and have zero desire to use any of them. If a large enough group objects to digital voice all over the channels, with their objection filed with the FCC, that's going to be a problem that needs a solution.

I did a quick update to my opinion paper on how it could be done and some suggestions on how to deal with some of the potential objections by existing users.

 

GMRS Digital Voice - 20231127.pdf

[WRYZ926]

@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.