Lscott

I’m not aware of any agency other that the FCC with the authority to enforce spectrum allocations or rule violations. IMHO if a local law enforcement agency attempted to take a violator to court it would likely get dismissed if it even got that far. I don’t see a local DA being that dumb, but surprises do happen. There is an awful lot of stupid going around the last few years.

So the point here is how would you present this to the FCC as a proposed rule change(s)? The FCC will likely take the path of the least resistance. That means if more of the work can be done by us ahead of time, anticipate possible objections etc. then have reasonable solid answers the more likely it will get serious consideration. In other words we have to do their job for them. Don’t forget there will be others out there who likely DON’T want to see any changes. There is always that crowd and that has to be taken into consideration too. Then you have the manufacturers that will likely chime in if they feel a competitor may gain an advantage depending on what selection is made, if any. Who knows the FCC could be persuaded to allow multiple digital voice modes. Based on how this is turning out I’m of the current opinion it was a mistake to even bring up the idea. The debate isn’t over personal preferences. There is nothing to be gained or to facilitate the goal here by trying to prove who knows more except to derail the idea. If others want to continue, fine. But I’m done with.

Yes I have a basic understanding of the concepts. I have some material on it in my personal library. The first photo is a section out of one of my books on digital satellite communications. It’s also allowed in amateur radio by the way. That’s the second photo.

My point, and goal, with this thread are possible rules that would allow digital voice to be used within the current confines of the spectrum currently allocated to GMRS operation. The chances of the FCC adding spectrum is nearly zero. The prior attached file shows the FCC has allowed splitting existing commercial channels into narrower allocations. The same could be done with GMRS all without adding additional spectrum. On the other hand there would be a gain of some extra simplex channels. The practicality of close by stations operating on adjacent 6.25KHz channels is another point. Of course if the stations are geographically separated it likely won’t be an issue. While DMR has some good points it does require coordination between radios utilizing the same frequency to take advantage of DCDM. The occupied bandwidth is still 12.5KHz regardless if one or two slots are used. The 6.25KHz is only an “equivalent” due to the dual slot nature of the transmissions. Trying to squeeze a DMR signal in between let’s say the main repeater channels is exactly the same as the current low power, and basically useless, FM 12.5KHz ones. I was thinking that a true very narrow band digital signal might be used there while resulting in even less interference and and maybe at a higher power for simplex operation. At the moment both NXDN and dPMR are both established digital protocols. There is no necessity to try and standardize a FHSS CAI. This is a necessity if there are going to be multiple manufacturers of these FHSS types of radios. And of course they will have to communicate among themselves too. Utilizing one of the above, NXDN dPMR, is a known standard with lots of field experience and one less item for the FCC to use as an excuse to claim it isn’t proven or accepted by the market place or can’t coexist with current FM technology. Now about DMR, I like it. Yes it can be used however I don’t see how without dedicating specific channels to it. That of course would tick off the FM only users. So the big question is where do you put it or just make it the Wild West and let the users fight it out. The other advantages are the reduced average power, great for hand held radios, and the single frequency repeater operations. Given the number of times you see people asking about setting up their own repeater this would make it almost brain dead simple to do, and no special equipment like tuned cavity filters to deal with.

Using 4FSK I think would be easier than a FHSS. A standard would have to be established so all radios could communicate with radios from other manufacturers. Then you need companies like Motorola to open up their proprietary design they use on their FHSS radios. I’m not confident they would entertain that idea. With 4FSK at least two standards already exist, NXDN (primarily USA) and dPMR (primary European Union). Both are “true” 6.25KHz technologies. Either one would be suitable to use. More than one company manufacturers radios for each of the above already. Also the FCC has moved into splitting 12.5KHz channels into two 6.25KHz. I would vote for NXDN since it widely used in the US already in various sectors. Used commercial radios are not terribly expensive either. In fact, for example, the NX-300’s in the 450-520 band split have FCC Part 95 certification already. They can do wide and narrow band FM along with narrow band digital (12.5 KHz) and very narrow band digital (6.25 KHz). NXDN White Paper.pdf DA-12-10A1.pdf

I hear similar comments from people about cell phones over two-way radios. The point lost on most people are VHF/UHF radios can be used for local communications without any dependency on infrastructure. If the cell sites go down you can communicate only as far as you can yell down the street.

Talking about expensive for the XPR7550e’s….. https://www.ebay.com/itm/354082232848?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=TlfnglliRoC&sssrc=2349624&ssuid=j_t98fioS_6&var=&widget_ver=artemis&media=COPY

That’s not a bad idea. I was thinking along the line of using the nearly useless narrow band channels 8 to 15. Currently at 0.5 watts many GMRS radios don’t even include them. If the digital mode was restricted to those channels at 2 to 5 watts and 6.25KHz bandwidth the interference to the adjacent wide band repeater channels would be minimal.

I was thinking here tonight about digital voice modes on GMRS. I’m sure it will happen sooner or later. What I haven’t seen is a good discussion on how it should be done. If there is any chance the FCC would be receptive to the idea then a good reasoned plan on the implementation I think would help push it along. So what would be a reasonable plan be and what mode(s) make sense? I’m going to guess the one thing the FCC won’t do is expand the spectrum. They might would entertain splitting existing 25KHz channels into two 12.5KHz or four 6.25KHz ones.

Well he has spent more on his various high end Motorola radios than I have on my Kenwood stuff. Other than my D74A, and the D578UVIII Pro, I’ve paid maybe a bit over $200 for some of the digital radios. The analog stuff was well under $100, more like $30 to $80 range. I have a photo in the gallery showing most of my radio collection sorted out and boxed up in plastic tubs for storage. It’s grown a bit since then.

Do you have a link for that? I would like to read it and see specifically what was done out of curiosity. I have some HT's that I specifically looked for, and purchased, with the 400-470 band split so no re-tuning was required. I was also gifted a NX-820HG mobile from a buddy, it was left over from a project that was canceled, nobody wanted it so he took it home otherwise it was going to get junked, which also had the 400-470 band split. The mobile shows up on eBay every once in a while. https://comms.kenwood.com/common/pdf/download/10_NX-720HG&820HGBrochure.pdf I had looked at some of the TK-480's for use on the 33cm band at one point. The info I read highly recommended swapping out the IF filters. The replacements where not an exact fit and required tweaking the pins to fit the PCB pads. I'm wonder if something along those lines might have to be done with the 880's.

A very good point for newbies out there. Power isn't everything. Having a bullet proof receiver that won't overload and maintains selectivity in a high RF environment is critical. This is why you'll see people like gman1971 spending big bucks on commercial radios, his favorite are Motorola models. I also have a collection but I'm mainly into the Kenwood stuff. People get tempted by the cheap, or cheaper, Chinese radios. For some people they might be OK for their intended usage, occasional non-critical communications. I'll admit I have a few as "beater radios" and you get what you pay for, if you're lucky. If you want something you're going to bet your life on look at buying a better radio. There is a reason why those radios carried by police and firefighters cost in the $1,000's, their life is on the line. Those radios CAN'T afford to fail.

Which band split does your radio have? The brochure I have in my electronic library shows three, 400-430, 450-490 and 485-512. From my experience with various Kenwood HT’s they will function out to 3 to maybe 4 percent beyond the stated band split. For example the 450-490 split you might get it phase lock down to around 440 or a bit higher. The repeater section of the 70cm Ham band is 440-450, which I’m going to guess is what you’re interested in. There is more to it than just tweaking the VCO voltage to extend the lock range. The radios typically have band pass filters in the input section that are electronically tuned on the fly as the radio changes frequency. The radio’s micro generates the voltage fed to either a number of varactor diodes or inductors that vary their inductance based on a small bias current. I don’t recall seeing any adjustments in these type of circuits.

That doesn't help in my case. I'm monitoring the local mall security frequency about a 1/2 mile away from my office on analog FM . There is a hospital on the same frequency using DMR some miles away. I used the mall's repeater tone to block the DMR station, but it doesn't work consistently and the squelch will open at times.

Off topic. Started engineering college with a new HP-45 I got for graduation from high school. Now I have the HP-41C emulator on the company iPhone. Over the years I always loved giving people my HP when they wanted a calculator to use for a few minutes. Just stood there while they looked at all the buttons trying to find the "equals" key. They give up after a few minutes and handed it back. They just couldn't get the hang of a "stack" and "RPN" operation to do even simple stuff like add, subtract, multiply or divide numbers.

I've read some comments where DMR seems to screw with analog CTCSS when it falsely will open the squelch at times when you really don't want to hear the digital noise.

Yup. Talking face to face you get to read the other person's body language and not form your opinion on what just come out of the mouth or the fingers on the keyboard. Some people say things in jest, but you can't tell unless you read their body language. There is a lot of nonverbal communications that's lost when using messaging apps etc. Maybe that's why this county is going to crap. People don't talk to each other in person so much any more.

I pretty much agree with your points. Sooner or later digital voice will happen. I would much rather have the FCC get ahead of the game and institute some regulations to keep order rather than let things go and end up with the wild west of various modes trashing each other.

Yeah, DMR does sounds good, but a bit funky. My issue is with those who know better but run digital voice anyway simply because they can and screw the rules. They set a bad example for everyone. Most people honestly want to follow the rules. The few who have the “don’t give a sh*t” mindset, believing the FCC will never enforce the rules, harbor a very narcissistic view where their wants are more important and don’t care who else has to put up with the mess their actions cause. That’s what ruined 11M through the 70’s and 80’s, linear amplifiers, free-banding etc. as an example. Now some of those idiots have discovered GMRS.

He was behind and in front several times during the trip.

All I can say is I drove down to the Dayton Hamvention with a couple buddies. One drove his truck alone since he need to leave before the other two of us planed. We used GMRS channel 20 on the ride down since he didn’t have his Ham license, just the GMRS license. Anyway he had one of those ghost antennas mounted on the front hood up by the windshield. I had a simple 1/4 wave magnet mount on the roof of my buddies car connected to a 4 watt HT. The ghost antenna couldn’t reach more than a mile or two, and that was running around 40 to 50 watts using a mobile radio. My buddy driving the truck commented before we started the drive down that’s been his experience with it, very poor range.

I think we’re going to hear more digital voice activity. There are plenty of choices for radios to use from the cheap Chinese models and the older but very useable commercial types all with digital voice features People are buying them and programming them up for GMRS and digital, either out of ignorance or just plain don’t give a sh*t attitude because I’m not going to get caught. My feeling is the FCC will ignore it as long as possible until it reaches the point where the chaos on the band seriously degrades the usability. At that point they will have to make a tuff choice, either officially allow it with specific rules on where it can be used or get serious about enforcement. That’s what the FCC did with the rule changes back in 2017/2018 with the FRS/GMRS combo radios. The FCC gave up, though in the towel and just made the wide spread practice legal.

That would be disappointing. I think it’s going to happen with or without the FCC’s official blessing. They already look the other way with people using Part 90 radios on GMRS. Of course they can just ignore it like they did with 11M for decades then finally figured out the rest of the world moved on and allowed FM. I have several commercial radios that are Part 95 certified and digital capable. Would be nice to use their full set of features on something other than the Ham bands.

I scan the GMRS/FRS channels while sitting at my desk at work using a cheap radio. Sporadically I catch some DMR activity. It might persist for a day or so then it’s gone. I verified it was DMR by using my D878 I brought in and setup for promiscuous mode. Nothing was said that one could infer who or where the transmissions were originating from at the time. Has anybody else noticed DMR, or other digital voice modes, on GMRS/FRS? As the service becomes more popular the temptation to run digital voice increases as the price for “cheap” or used digital radios comes down. Perhaps it’s time to put the squeeze on the FCC to authorize some form of digital voice before it gets out of hand like they did with the former GMRS/FRS combo radio mess. Something like DMR, or NXDN, maybe both, are allowed. DMR would likely be the favorite while NXDN might be the lower cost solution. Note in Europe dPMR is very popular, similar to NXDN, and is used for their license free radio service. https://en.wikipedia.org/wiki/Digital_private_mobile_radio

I don’t know if they have one in an NMO type mount.