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#1 RCM

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Posted 15 November 2018 - 04:10 PM

I just found something interesting in the GMRS rules. From 95.1771:

 

a. Each GMRS transmitter type must have the capability to transmit F3E or G3E emissions.

b. Only emission types A1D, F1D, G1D, H1D, J1D, R1D, A3E, F3E, G3E, H3E, J3E, R3E, F2D, and G2D are authorized for use in the GMRS.

 

Ok. F3E is FM (frequency modulation) voice. G3E is phase modulation voice; essentially the same as FM. So basically a. states that a GMRS station must be able to transmit FM.

 

Then, b. adds to that. In addition to being capable of transmitting FM, a GMRS transmitter (because the transmitter is really the regulated part) may also have the capability of transmitting the other listed emission types. 1 and 2 refer to digital content. 3 refers to analog content, including voice transmissions.

The third character refers to type of content, with E being telephony: voice or music. Of course music is verboten, so E means voice in the case of GMRS.

 

So looking at the first character, the analog voice modes that are listed are: A3E, F3E, G3E, H3E, J3E and R3E. As already stated, F3E and G3E are FM voice.

 

Here's the interesting part: A3E is AM voice. J3E is SSB voice. H3E and R3E are modified forms of SSB. DSB (Double Sideband, suppressed carrier) also falls under the heading of A3E, so that would be allowed as well.

 

Conclusion: as long as a transmitter meets the rest of the requirements (including the ability to transmit on FM), there is nothing prohibiting the use of SSB or AM on GMRS. If someone would just build a Part 95 type classified multimode transceiver... :)

 

The thing is, on ham radio it is not uncommon to communicate over paths of hundreds of miles, simplex, using 432 MHz SSB. It would seem that availability of a proper radio is the only thing preventing us from doing the same on GMRS freqs.


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#2 berkinet

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Posted 16 November 2018 - 04:16 PM

...The thing is, on ham radio it is not uncommon to communicate over paths of hundreds of miles, simplex, using 432 MHz SSB. It would seem that availability of a proper radio is the only thing preventing us from doing the same on GMRS freqs.

Well, SSB/AM capability AND propagation of UHF beyond line of sight

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#3 RCM

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Posted 16 November 2018 - 07:46 PM

Well, SSB/AM capability AND propagation of UHF beyond line of sight

Meteor scatter, for instance?



#4 berkinet

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Posted 16 November 2018 - 07:59 PM

Meteor scatter, for instance?

Besides meteor scatter working best between 30 & 50 MHz, there is this, from the Wikipedia... Because the presence of a meteor trail at a suitable location between two stations cannot be predicted, stations attempting meteor scatter communications must transmit the same information repeatedly until an acknowledgement of reception from the other station is received.

On a more utilitarian note, GMRS tends to be used more for practical (I.e. where reliability is required) communications, while ham radio, because any commercial use is prohibited, tends to have more experimentation.

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#5 PastorGary

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Posted 17 November 2018 - 04:48 AM

While AM / SSB are listed in the Rules as being acceptable, there is no practical use for them regarding GMRS operations.  If anyone has had an AM CB radio on in a car in the past 5 years or so and heard the 'white noise' generated by the "new and improved" LED traffic signal lights, the noise all but cancels out any signals inbound that you might wish to listen to.  The other noise sources these days that affect AM /SSB are many and getting worse each year. Noise blankers and ANL's help some, but I don't believe that any manufacturer would develop a GMRS  certified radio, which included AM / SSB, with the background noise as it is these days. Also, if the signal is strong enough, AM / SSB at any frequency may occasioanlly demodulate in home electronics equipment, such as stereo systems and computer speaker systems, causing hard feelings with neighbors.


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#6 RCM

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Posted 17 November 2018 - 01:50 PM

Besides meteor scatter working best between 30 & 50 MHz, there is this, from the Wikipedia... Because the presence of a meteor trail at a suitable location between two stations cannot be predicted, stations attempting meteor scatter communications must transmit the same information repeatedly until an acknowledgement of reception from the other station is received.

On a more utilitarian note, GMRS tends to be used more for practical (I.e. where reliability is required) communications, while ham radio, because any commercial use is prohibited, tends to have more experimentation.

That would be sporadic E, not meteor scatter. The meteor showers always bring out the 144 and 432 enthusiasts because they can make some quick DX contacts, even with low powered stations.



#7 RCM

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Posted 17 November 2018 - 02:15 PM

While AM / SSB are listed in the Rules as being acceptable, there is no practical use for them regarding GMRS operations.  If anyone has had an AM CB radio on in a car in the past 5 years or so and heard the 'white noise' generated by the "new and improved" LED traffic signal lights, the noise all but cancels out any signals inbound that you might wish to listen to.  The other noise sources these days that affect AM /SSB are many and getting worse each year. Noise blankers and ANL's help some, but I don't believe that any manufacturer would develop a GMRS  certified radio, which included AM / SSB, with the background noise as it is these days. Also, if the signal is strong enough, AM / SSB at any frequency may occasioanlly demodulate in home electronics equipment, such as stereo systems and computer speaker systems, causing hard feelings with neighbors.

I disagree. No, it wouldn't be practical for mobile use, but it would between base stations. I'm talking primarily about SSB btw, not AM.

As for hard feelings with neighbors, lots of hams run high power (500+ up to 1500 watts) even in suburban environments with no such problems. The fact that GMRS is limited to 50 watts makes it even less likely.

I've never had a complaint from a neighbor, even when I was running 1200 watts in a suburban neighborhood. On ham radio, of course.

 

The main thing about SSB is that you can hear a much weaker signal than you can on FM. The other advantage is that it transmits more efficiently with a given power level.  Of course you need a clear frequency. Whether or not those are available depends on where you live, time of day etc.

 

I don't think it would be out of the question for manufacturers to provide multi-mode radios if they saw a demand. CBs are type classified too, and there are SSB CBs despite the fact that it is a limited market. And the radios already exist. All it takes is a programming change and type classification. The Yaesu FT-817 for example could easily be programmed for channelized operation on UHF and receive-only everywhere else.

 

Not saying it's going to happen; just that it legally could.

 

ETA: Let me give an example, since I mentioned the FT-817. We have 5 channels on 60 Meters. That is the only channelized ham band, and it's fairly new. Allowable specs are at least as tight as on GMRS as far as frequency stability, etc. The only approved mode of voice operation on 60M is USB (upper sideband).

The FT-817 did not include the 60M channels when it was introduced (because 60M wasn't yet available to hams). Mine doesn't, because it is a very early one. The first one in Huntsville, as a matter of fact.

But when we gained 60 Meters, Yaesu was quick to add those channels to new FT-817s via a programming change.



#8 berkinet

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Posted 17 November 2018 - 04:56 PM

I disagree. No, it wouldn't be practical for mobile use, but it would between base stations. I'm talking primarily about SSB ...

I think you may be missing the main point here. This is not a technological issue, it is about the basic nature of GMRS. GMRS was designed for short distance, reliable communications that can, and are, used for personal, family and commercial communications. Unlike ham radio, you can tell someone to pickup a six pack of beer, or make reservations at a restaurant for you. For those who want to experiment with different forms of radio communications, the ham bands are available for exactly that purpose.

Adding unreliable modes to GMRS would totally defeat its purpose, raise the cost of equipment, and change the basic nature of the service.
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#9 RCM

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Posted 17 November 2018 - 06:47 PM

I think you may be missing the main point here. This is not a technological issue, it is about the basic nature of GMRS. GMRS was designed for short distance, reliable communications that can, and are, used for personal, family and commercial communications. Unlike ham radio, you can tell someone to pickup a six pack of beer, or make reservations at a restaurant for you. For those who want to experiment with different forms of radio communications, the ham bands are available for exactly that purpose.

Adding unreliable modes to GMRS would totally defeat its purpose, raise the cost of equipment, and change the basic nature of the service.

I agree about the nature of GMRS.  And yes, amateur radio is far more suited to experimentation. I brought up this subject to highlight something that I didn't realize is legal. Obviously I'm not the only one who was unaware of that. Would I try it if I had a Part 95 classified radio that included those modes? Absolutely. But I'm not holding my breath.

 

I won't get into the discussion of the reliability of AM and SSB, although suffice it to say that airlines use HF SSB every day on transoceanic flights.


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#10 RickW

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Posted 17 November 2018 - 08:22 PM

I think you may be missing the main point here. This is not a technological issue, it is about the basic nature of GMRS. GMRS was designed for short distance, reliable communications that can, and are, used for personal, family and commercial communications. Unlike ham radio, you can tell someone to pickup a six pack of beer, or make reservations at a restaurant for you. For those who want to experiment with different forms of radio communications, the ham bands are available for exactly that purpose.

Adding unreliable modes to GMRS would totally defeat its purpose, raise the cost of equipment, and change the basic nature of the service.

From my perspective, GMRS is reasonably equivalent to 440 FM ham radio, except the users in one extended family do not need to all be separately licensed. While full carrier AM would not be that useful, having the enhanced technology of SSB would be significant. I live in a fairly rural area, but at this moment am monitoring CB channel 39 LSB and can consistently talk to some stations 30+ miles away with me running legal power (12 watts PEP) with a Uniden Bearcat 980SSB rig. This is somewhat beyond what some might consider to be line of sight. I can sort of do it on AM, but SSB really helps. Same thing on VHF and UHF.

 

The problem with SSB is that it is a bit more difficult for non technical folks and would significantly add to the cost of the rigs. I have talked to a station on 2 meter SSB with my 4 element beam at only 10 feet off the ground into northern Illinois from SE Wisconsin, if the other station has a fairly elaborate station with a high gain beam well up in the air. This is well over 100 miles simplex. And I can also talk to a station off the side of the beam around 25+ miles north of me when we had a three way.

 

The FCC has loosened up the regulations on incidental use of ham radio for what we used to think of as commercial use. It would be completely acceptable to say, ask my wife to pick up some groceries via ham radio, but I personally would not make this an everyday practice. 

 

By the way, today is opening season of deer hunting and this has been the busiest I have heard the GMRS/FRS channels. 


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#11 RCM

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Posted 17 November 2018 - 11:12 PM

20+ years ago, a friend and I made a 2M SSB contact between our respective homes that were about 15 miles apart. Each station was running a single moderate Yagi: Brian was running a Cushcraft 13B2 at about 50 feet, and I was running an old Cushcraft 10 element at 20 feet. I was running 3 watts with a modified (for lower power) TS-700A, which is not known to have a super receiver. Brian was running an FT-736. I don't remember how much power he started out at, but he had a set of switched, calibrated attenuators that he switched in incrementally until I lost the signal. I could still hear him down to 50 microwatts. That is 0.00005 watt, or 1/20,000 watt!

 

QRP-ARCI has a "1000 mile per watt" award. This was 300,000 miles per watt! :D

 

FM doesn't work as well for that, but I did once work another friend with 50 milliwatts (1/20 watt), standing in my backyard with an Icom HT and a quarter wave antenna, on 446.100 FM simplex. Range for that one was a bit farther; about 20 miles. To be fair, he was running stacked Yagis at a pretty good height.

 

The same ham told me he had worked a ham on the Texas coastline 3 or 4 times over the years on 432 MHz CW. The Texas ham was running less than 5 watts!

People who haven't tried it, would be amazed what can be done on VHF and UHF. And microwaves, too. I've never tried 5 GHz, but I've read some wild stuff about an experiment between mountaintops in California and Mexico.



#12 Hans

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Posted 18 November 2018 - 12:39 AM

communications that can, and are, used for personal, family and commercial communications. Unlike ham radio, you can tell someone to pickup a six pack of beer, or make reservations at a restaurant for you.


This has to be one of the biggest appeals of GMRS for me. We use the service for a mixture of these types of communication each and every day. Five nights a week, my adult son gets off of 2nd shift work in a distant town. We talk each night on his way home on a local GMRS repeater that has a huge coverage area. We discuss dinner plans for the night (usually fast food because we both hate to cook our own food). We briefly discuss his day in a public communication appropriate manner. I re-route him via Google Maps if there is heavy traffic. Some locals have taken to listen in of an evening to these conversations and occasionally throw out a howdy. That is the way we like GMRS. It fits our usage perfectly. When we had our family farm, it was so very useful for over more than 20 years. Even if members of my family eventually get Amateur Radio licenses, we could never properly use that service in the manner that best serves us. Amateur Radio satisfies my itch to experiment and allows me to hone my on air radio technique. GMRS is where our family actually does its daily radio work.

ETA: A few minutes ago, I heard a grandfather and adult grandson using GMRS on another local large footprint repeater in the same way as we do. It was almost 2 am. The grandson was on the road and the grandfather was keeping him company on the air. I had to smile. smile.png
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