Which Digital Voice Modes Do You Have Equipment To Operate?

[WRKC935]

Lots to think on here.

Selling spectrum as opposed to the continued increase of license holders and their money.  I don't know what the agreements are for 'selling' spectrum.  Is it a forever thing, as long as it's occupied or is it a lease with some fixed length of time?  Reason I ask is this.  GMRS and HAM are both a continuing revenue stream.  This is from both new licenses and renewals of old licenses.  If the sale of spectrum is done without a term then it's just done.  Here's your money, and I can do as I please there as long as I want for no additional cost.  Again, I don't know how that works.

DMR on GMRS and interference.

Would I like to see DMR made legal on GMRS.  Yes, but I also realize, like others have and mentioned, the level of interference on the limited repeater spectrum could cause serious issues.  I have seen the issues with DMR and analog trying to co-exist first hand on public safety frequencies and it didn't work.  And the systems were several COUNTIES away from each other.  There would be NO way that it could exist in the same county or city.  Simply NOT possible.   And they would interfere with each other,,, not just the interference from DMR to the analog, but the analog to the DMR as well.  The interference from DMR is obvious, it puts noise on the air that the analog stuff would pick up.  But the analog would cause increased BER on the DMR subscribers as well causing issues with pixelation of the audio and drop outs. 

How COULD it be addressed?  Coordination would be a BIG part of it.  Coupled with the DMR repeaters being limited to only PART of the repeater spectrum.  DMR repeaters being REQUIRED to be high profile and FREE access to all licensed users would also need to be a requirement.  In addition, because of the way DMR works, the coordination would not only need to be for the frequencies but the time slots, and talk group assignments as well.  And that is where it would all fall apart.  The equipment isn't hard to find.  And groups could assemble to fund the repeater purchase.  So, no big deal there. 

But Talk Group assignments and management would need to be figured out.  That would most likely fall on the repeater owners to do.  And ongoing management of that could turn ugly quick.  As long as the person was available and willing to do it, things would be fine.  But once that person wanted his life back, then the problems with getting ID's and talk group assignments would become a problem.  And that's not something that anyone is going to want to do.  We see this here to some extent getting repeater node numbers assigned.  It's not automated, requiring ONE person to manage all that.  And I am not complaining, but it's not a 24 hour process to get it done.  Which is what people would want.  And if that person sells off the repeater, then it's up to the new owner to manage it or NOT.  They can very easily flip it to analog and it's just gone.  Now if you bring LINKING into the mix, it gets MORE complicated.  Not only can subscriber ID's not overlap, but repeater ID's can't either.  So MORE management is required.  If someone was profiting, then it's manageable.  But we can't profit from it, because that's the GMRS rules.  So it's just not even feasible to attempt linking.  And even managing a single repeater in a big city with hundred's of users would be more than I would ever want to take on personally.  You may have time for that.  I don't. 

P25 on GMRS.

Slightly more feasible.  Can be linked flat (no talk groups but COULD be done).  Still some management, but just at an infrastructure level.  Could be relegated to one or two repeater pairs nationwide.  Doesn't interfere as bad with analog.  Still would create issues with analog repeaters however.  Doesn't use the pulsed transmission that the subscribers do so the analog receivers don't have to deal with the constantly changing SNR that is present with DMR.

Ham spectrum reallocated to GMRS.

Yeah, not gonna happen.  We don't even have a group to go lobby for something like this where the ham's have the ARRL.  Then there are the technical issues that you would face with being 20 something Mhz apart and needing super broadband EVERYTHING to make that work.  Too many reasons that will not work.  Coupled with if you want MORE spectrum to communicate on, you can go get a ham license and do that.  And once you have a ham license you can do MANY things we can't do on GMRS. 

But  I will say this.  If all the GMRS operators on this board were to figure out where their local AllStar node was and we were to link them all together and have a net some Friday night on that network, the hams would flip the hell out.  It would be more traffic than their repeaters had seen in years.  ANd it could be echo link or allstar.  It would only require the linking.  My guess is they would never allow it again due to the traffic load. 

 

 

[SteveShannon]

1 hour ago, WRKC935 said:

Yeah, not gonna happen.  We don't even have a group to go lobby for something like this where the ham's have the ARRL. 

This is a key factor. Without some kind of organization representing us, I doubt much will change. And based on the vast diversity of ways people use GMRS, it would be a challenge forming such an organization. 

1 hour ago, WRKC935 said:

If all the GMRS operators on this board were to figure out where their local AllStar node was and we were to link them all together and have a net some Friday night on that network, the hams would flip the hell out.  It would be more traffic than their repeaters had seen in years.  ANd it could be echo link or allstar.  It would only require the linking.  My guess is they would never allow it again due to the traffic load. 

I must be missing something. How would hams even see the traffic? 

[MichaelLAX]

5 hours ago, BoxCar said:

The money paid for spectrum, like fines and fees, goes to the treasury, not the FCC. They only get the headache of enforcing it.

Plus no one pays for spectrum when it is shifted from one service; e.g., Ham Radio to another; e.g., GMRS.

[Lscott]

This is encouraging, somewhat back on the thread's topic and people expressing some interesting ideas and opinions.

Some of the issues, with at least DMR, is the proliferation of mainly Chinese radios, cheap and not so cheap. The cheap ones tend to give users a poor impression of the mode's performance. The commercial radios are much better, but of course more expensive.

IMHO the issue with DMR causing interference to analog users I believe can be traced to poor receiver design and channel separation. For example the common bandwidth quoted for DMR is 6.25KHz "equivalent" which is not the same as a true 6.25KHz signal. DMR is in fact a 12.5KHz signal, and due to TDMA, two voice streams can occupy the channel, that's the equivalent part.

Some radios cheap out by using 25KHz IF filters in the radio while limiting the FM deviation to 2.5KHz to meet the FCC's 12.5KHz occupied bandwidth. Locating a adjacent  transmitter closely to such a receiver will result in the DMR signal spilling over in to part of the pass band of the affected receiver.

[Lscott]

I forgot to mention there are also problems with "clock drift" of the internal oscillators in digital radios and DMR also has to deal with range limitations due to slot timing too.

See page 110 section 10.1.4, and page 113 sections 10.2.3.1.2 through 10.2.3.2.3 in the following link.

https://www.etsi.org/deliver/etsi_ts/102300_102399/10236101/02.02.01_60/ts_10236101v020201p.pdf

[WRKC935]

1 hour ago, Sshannon said:

I must be missing something. How would hams even see the traffic? 

This is only if we were to as ham operators shift our net to ham repeaters ( of course only those of us that have a ham license) that were AlStar linked.  I guess I didn't specify that before. 

 

Lscott

Pertaining to what you said regarding interference.  I was specifically referring to the repeater pairs that were used multiple times in a similar geographic location.    Obviously if two analog repeaters are close enough together they will interfere with each other.  The issue really begins when the DMR modulation starts hitting analog signals on the same frequency and are close to capture in the receiver.  DMR carries further than analog.  I have tested this several times.  These tests were against both wide and narrow band FM on VHF and UHF.  With an analog receiver, the DMR signals were intelligible at the greatest distance, and the DMR radios would communicate a greater distance with all other factors (used the same repeater and antenna system) being equal.  I have not tested the interference issues specifically.  But We did have a DMR system in Fayette County Ohio and an analog narrow band FM system in Licking County Ohio.  The FM system significantly interfered with the DMR system.  The DMR system was built out to replace an FM wide band system in the same location in Fayette county.  Both users had that same frequency for years and had never experienced issues with it prior to the conversion to DMR.  At that point the DMR system had significant drop outs and the analog system was hearing the DMR digital transmissions in their receivers as the repeaters would drop (Licking county system was 6 site simulcast). 

I have never seen adjacent channel interference with DMR.  Most likely since it's requirements for better frequency correctness than analog FM.  (Can't remember the correct term here.)  I have seen FM wide band radios off as much as 1200 Hz from center and work fine.  DMR will exceed the acceptable BER long before the frequency drift gets that bad. 

[SteveShannon]

1 hour ago, WRKC935 said:

This is only if we were to as ham operators shift our net to ham repeaters ( of course only those of us that have a ham license) that were AlStar linked.  I guess I didn't specify that before. 

So for purposes of this thought exercise, a bunch of hams would network their ham repeaters and then discuss GMRS?

Of course to be compliant we wouldn’t allow any GMRS repeaters to connect to the common network, right?

 

[gortex2]

So to be fair this thread started about digital on ham. Now we want to change GMRS again.... 

Back to digital on HAM one of the issues now is the poor CCR radios on the systems. If it was not a market for CCR stuff they wouldn't build it. This goes back to me "cheap" comment in the past. People dont spend money on good gear anymore when they can get a CCR for the cost of one battery. 

 

[BoxCar]

15 minutes ago, gortex2 said:

Back to digital on HAM one of the issues now is the poor CCR radios on the systems. If it was not a market for CCR stuff they wouldn't build it. This goes back to me "cheap" comment in the past. People dont spend money on good gear anymore when they can get a CCR for the cost of one battery. 

 

Perhaps if the major manufacturers had DMR radios the CCR market wouldn't have as deep an inroad into the ham market. Each has their own digital scheme and they are incompatible with the others. The CCRs provide hams with equipment that works across brands and, once it's configured, works well enough. Yes, they could buy public safety grade radios but they lack the flexibility to connect with a multitude of available DMR repeaters.

[gortex2]

I agree. The problem is and was Kenwood or Yaseu wasn't going to create a radio that would compete with the LMR world. Remember Yasue Vertex was part of MSI for a short period. I'm surprised ICOM never got on board with DMR but they and Kenwood were working on IDAS/NXDN at the time and went that direction. Even in the LMR world no one could standardize on one platform. It seems its leveled out and NXDN and DMR are the preferred digital vendors in the LMR non public safety world. MSI never was in the Amateur Radio world other than a few HF rigs that were basically built for EMO/SEMO applications. When MARC-DMR got started they were the only group working with digital and all equipment was LMR branded gear. I don't recall other LMR manufacturers adding DMR until recently to be honest. I think the entire Hytera incident may of caused some of the CCR folks releasing DMR also. Who knows but agree none of the main ham radio manufactures produce DMR gear to my knowledge ? 

Does ICOM, Kenwood or Yaesu have a DMR radio in the market ? 

From what I've read, Yaesu has Fusion (c4fm varriant), Icom has DSTAR and Kenwood has APRS and one handheld with DSTAR and that's it.  

[tweiss3]

43 minutes ago, BoxCar said:

Perhaps if the major manufacturers had DMR radios the CCR market wouldn't have as deep an inroad into the ham market. Each has their own digital scheme and they are incompatible with the others. The CCRs provide hams with equipment that works across brands and, once it's configured, works well enough. Yes, they could buy public safety grade radios but they lack the flexibility to connect with a multitude of available DMR repeaters.

This statement is confusing and possibly incorrect. For ham use, all the manufacturers that offer DMR conventional (not trunking) are compatible with each other. Ham takes many things out of the picture that are not necessarily compatible (encryption, RAS, etc.). But for conventional DMR in the clear, Motorola, Hytera, Kenwood, etc. are all directly compatible. 

As for the CCRs, I would say they are the ones that are truly incompatible. The don't offer some of the beneficial features DMR offers. I have even asked many of them if they could/would implement conventional roaming (offered by any public safety manufacturer) and was told it's not a thing, and no, they won't even look into it.

Is there something I am missing in your statement above?

[Lscott]

1 hour ago, gortex2 said:

So to be fair this thread started about digital on ham. Now we want to change GMRS again....

Yeah, should get back on topic.

[gortex2]

I think what @BoxCar meant were none of the major ham manufacturers ie: icom, kenwood, Yaesu. All went different directions with digital. I may be wrong but thats the way I read it. 

In the LMR world your right Kenwood, Motorola are both compatible with each other as long as we stay away from specific features. 

[Lscott]

11 hours ago, WRKC935 said:

This is only if we were to as ham operators shift our net to ham repeaters ( of course only those of us that have a ham license) that were AlStar linked.  I guess I didn't specify that before. 

 

Lscott

Pertaining to what you said regarding interference.  I was specifically referring to the repeater pairs that were used multiple times in a similar geographic location.    Obviously if two analog repeaters are close enough together they will interfere with each other.  The issue really begins when the DMR modulation starts hitting analog signals on the same frequency and are close to capture in the receiver.  DMR carries further than analog.  I have tested this several times.  These tests were against both wide and narrow band FM on VHF and UHF.  With an analog receiver, the DMR signals were intelligible at the greatest distance, and the DMR radios would communicate a greater distance with all other factors (used the same repeater and antenna system) being equal.  I have not tested the interference issues specifically.  But We did have a DMR system in Fayette County Ohio and an analog narrow band FM system in Licking County Ohio.  The FM system significantly interfered with the DMR system.  The DMR system was built out to replace an FM wide band system in the same location in Fayette county.  Both users had that same frequency for years and had never experienced issues with it prior to the conversion to DMR.  At that point the DMR system had significant drop outs and the analog system was hearing the DMR digital transmissions in their receivers as the repeaters would drop (Licking county system was 6 site simulcast). 

I have never seen adjacent channel interference with DMR.  Most likely since it's requirements for better frequency correctness than analog FM.  (Can't remember the correct term here.)  I have seen FM wide band radios off as much as 1200 Hz from center and work fine.  DMR will exceed the acceptable BER long before the frequency drift gets that bad. 

I'll take your word for it. You have the real world experience to back it up.

Was there anything that was, or could be done, to mitigate the interference issues?

[tweiss3]

9 minutes ago, gortex2 said:

I think what @BoxCar meant were none of the major ham manufacturers ie: icom, kenwood, Yaesu. All went different directions with digital. I may be wrong but thats the way I read it. 

In the LMR world your right Kenwood, Motorola are both compatible with each other as long as we stay away from specific features. 

Ok, got it.

Yes, in the amateur market, Kenwood went with Icom for D-Star, Yaesu made their own YSF, and some of the CCRs tried to copy DMR. I'm still not convinced they meet the DMR standard, or use the correct AMBE+2 codec.

On the commercial side, in terms of use on amateur radio, P25 is compatible with P25 across the board, NXDN is compatible with NXDN across the board as is DMR.

[Lscott]

Here is a question I haven't seen talked about.

On many of the commercial grade digital radios they can be operated in analog only, digital only, or in mix mode. The later would have the radio programmed to receive in either analog or digital on a given frequency while automatically detecting which mode is in use and demodulating the signal as necessary. The transmit mode is usually set for either analog or digital exclusively. 

I don't have any of my radios programmed for mix mode. Other than monitoring a frequency for activity has anyone else found it beneficial?

[tweiss3]

10 minutes ago, Lscott said:

Here is a question I haven't seen talked about.

On many of the commercial grade digital radios they can be operated in analog only, digital only, or in mix mode. The later would have the radio programmed to receive in either analog or digital on a given frequency while automatically detecting which mode is in use and demodulating the signal as necessary. The transmit mode is usually set for either analog or digital exclusively. 

I don't have any of my radios programmed for mix mode. Other than monitoring a frequency for activity has anyone else found it beneficial?

Yes, I have. There are a handful of repeaters that do Analog/P25 or Analog/NXDN. For these radios, I put 2 versions in the radio, both are dual mode RX, but the first is strapped Digital transmit, the second is strapped analog transmit (then only 1 is included in the zone scan). 

[SteveShannon]

19 minutes ago, Lscott said:

Here is a question I haven't seen talked about.

On many of the commercial grade digital radios they can be operated in analog only, digital only, or in mix mode. The later would have the radio programmed to receive in either analog or digital on a given frequency while automatically detecting which mode is in use and demodulating the signal as necessary. The transmit mode is usually set for either analog or digital exclusively. 

I don't have any of my radios programmed for mix mode. Other than monitoring a frequency for activity has anyone else found it beneficial?

My Yaesu FT5DR has automatic mode select.  I tried to use it. Once I was listening to an analog net and when I tried to check in it switched to digital when hit the PTT.  It’s entirely possible that I had it configured incorrectly, but it was sure annoying to everyone else listening.  I turned AMS off and haven’t had any problems since. 

[Lscott]

Thanks for the comments. This was something I was curious about.

[Lscott]

2 hours ago, gortex2 said:

Who knows but agree none of the main ham radio manufactures produce DMR gear to my knowledge ? 

If Kenwood ever started to produce the TH-D74A again in a DMR format they likely couldn't keep them in stock on the shelf. I would be interested in buying one just to get away from the Chinese stuff.

[SteveShannon]

3 hours ago, gortex2 said:

Does ICOM, Kenwood or Yaesu have a DMR radio in the market ? 

Not in the ham market.

Although not considered one of the big three, Alinco has both handheld and mobile radios in DMR, which appear to be Anytone OEM.  All are type 90 certified. I like mine.

[WRKC935]

3 hours ago, Lscott said:

I'll take your word for it. You have the real world experience to back it up.

Was there anything that was, or could be done, to mitigate the interference issues?

Well, yes and no.  And the FCC actually did the main one when issuing licenses in the PS band that had the emission designator for DMR.  And that is significantly limiting ERP to pull the coverage footprint of the transmitted signal into a reasonable distance.  Part of the problems that were created by DMR was the old school mentality of repeater systems for communications.  That was put it as high as possible and run as much ERP as was legal.  That mentality is why VHF low band is all but abandoned today.  That stuff went up with 500 watt amplifiers to cover one county and it actually covered 8 or 10 counties.  Then when the atmospheric conditions were favorable, you were talking to Arizona From Ohio and of course, the interference issue became a real problem. 

So, can you take a bunch of guys that have a CB radio mentality getting into GMRS that is further pushed forward by the guys that are already using the service where a 1.5 to 1 antenna match is TOO high, even though it's a .18dB signal loss and has ZERO effect on performance, to run a repeater with reduced power?  And of course the answer is no.  Because the rules say 50 watts, and by God, I can run 50 watts so I will run 50 watts.  And I am not picking on the GMRS crowd here, this was an issue with professional radio techs doing it the way they always had done it, so there is zero reasonable expectation that hobbyist's are gonna do it the way it would need to be done.  

The FCC reacted to the issue on the public safety spectrum due to a glut of complaints they were getting from agencies and commercial radio shops fighting the interference that started as some agencies moved to DMR from analog.  At one point they would not issue a license to any PS agency with an either a ERP or transmitter power level of 10 watts.  I can't remember which it was, probably transmitter power level.  For those that don't understand ERP (Effective Radiated Power) that is the realized effective signal level of a repeater SYSTEM including the feed line and antenna.  So a system with a 50 watt transmitter, a 3dB loss in the cable and a 3dB gain antenna is 50 watts.  But that same transmitter and line with a 6dB gain antenna would be an ERP of 100 watts due to the additional 3dB of antenna gain. 

GMRS and HAM radio doesn't have an ERP regulation, GMRS transmitter power is regulated at 50 watts and ham of course for most bands is 1500 watts.  But a ham or GMRS operator can build any amount of gain into an antenna (as long as there is no additional active amplification) and have any ERP that system can produce.  Ham's use this methodology to bounce signals off the moon and back to earth with large antenna arrays that produce ERP's in the ten's of thousands of watts. 

 

 

[SteveShannon]

34 minutes ago, WRKC935 said:

GMRS and HAM radio doesn't have an ERP regulation,

The interstitial channels do in GMRS:

(b) 462 MHz interstitial channels. The effective radiated power (ERP) of mobile, hand-held portable and base stations transmitting on the 462 MHz interstitial channels must not exceed 5 Watts. 

(c) 467 MHz interstitial channels. The effective radiated power (ERP) of hand-held portable units transmitting on the 467 MHz interstitial channels must not exceed 0.5 Watt. Each GMRS transmitter type capable of transmitting on these channels must be designed such that the ERP does not exceed 0.5 Watt.

[WRKC935]

4 hours ago, gortex2 said:

I think what @BoxCar meant were none of the major ham manufacturers ie: icom, kenwood, Yaesu. All went different directions with digital. I may be wrong but thats the way I read it. 

In the LMR world your right Kenwood, Motorola are both compatible with each other as long as we stay away from specific features. 

OK in the ham realm here's who does what with digital.

YEASU.  Wires-X or Fusion which is C4FM, the same modulation scheme that is used in P25 but is not compatible with the commercial P25 offerings from any manufacture.

ICOM.  D-Star is their digital offering that is a fully ham system.  The entire design of the system caters specifically to ham radio and has no commercial equivalent.   This is a lined radio system that runs through various servers across the world.  Call signs are registered and act as the radio ID.  The system supports group and private calling (call sigh to call sign) across the entire system.  The system is not band specific, meaning if an area has a full infrastructure roll out in place, users with VHF, UHF and 1.2Ghz radios call ALL talk to each other and anyone else on the system world wide. 

Kenwood has now adopted the D-Star technology as their digital offering for ham radio. 

Oddly, none of them are making a DMR radio that works with the MOTOTRBO DMR that is dominant in Amateur Radio currently.  Those offerings are going to be commercial and the CCR's like BaoFeng, Anytone and Woxsun.

 

Back to digital on ham and what's out there.  I am gonna leave out discussion of hot spots.  I know they are prevalent.  I have one sitting here.  But I personally don't consider talking 2 feet from my portable to my hot spot as real radio communications.  So I will limit this to REAL (IMHO) radio systems with real infrastructure (repeaters with antenna's on towers).

DMR is prevalent.  Most hams know of this and many use it.  Based on DMR repeaters, and a device called a C-Bridge there are two main systems.  DMR-MARC and Brandmeister.  These of course are both world wide systems using the Internet as a linking medium to connect the sites together.  System is Talk Group based requiring not only the programming of a frequency and Color Code (similar to PL/DPL) in a Radio but a time slot and talk group ID as well to communicate.  Bands supported are VHF, UHF and 900Mhz

D-Star.  Common in major metro area's.  Build on all ICOM infrastructure.  Specifically designed for ham radio from the ground up.  Uses call signs as radio ID's to simplify management.  System is also connected via the Internet.  System is able to group and private call and has data transfer abilities.  Bands supported are VHF, UHF and 1.2Ghz.

P25.  There is a lesser known P25 system that uses all Motorola infrastructure (Quantar repeaters) that is talk group based and Internet linked.  This is the P25.link system.  This system uses Cisco routers and software running on a Raspberry-Pi to link repeaters together across the internet.  It uses reflectors similar to the MMDVM system (hot spots) for talk group support.   This is a system requires more knowledge to connect to (must know Cisco router configuration and some level of Linux to load and configure the R-Pi.  Has both internal Talk Groups that are PURE P25 and access to many MMDVM reflectors that allow for access for hot spots that can be configured for DMR, D-Star or any other digital mode supported by a hot spot.

 

 

[Lscott]

8 minutes ago, WRKC935 said:

DMR is prevalent.  Most hams know of this and many use it.  Based on DMR repeaters, and a device called a C-Bridge there are two main systems.  DMR-MARC and Brandmeister.  These of course are both world wide systems using the Internet as a linking medium to connect the sites together. 

This is the one thing that bugs me, mostly with DMR. That's the multiplicity of networks. 

I try to program up my radios and every repeater seems like they have to use a different network for linking. If you're lucky the talk group numbers are the same, but not always. Then you have to jump through hoops to link from one network to another if the one you want is on the "other" network.

DMR is enough of a pain as it is to program up a radio without the above BS on top of things.

Here in Michigan for example a number of local repeaters use the Mi5 network. Dah!

https://w8cmn.net/mi5-sites-talkgroups/

And a de-funked network.

https://dmrx.net/dmrx-core.html

And this is an example of a repeater that's a bit more changeling to program. It uses several different networks and talk groups.

http://n8noe.us/DMR/dmr.html