Interoperability between separate FRS and GMRS radios

[davidotoole]

Hello and thanks for letting me join. My name is David O'Toole and I have just gotten a new GMRS license and callsign, after having had a license from 2015-2020 using the old style "hybrid" FRS/GMRS radios which are no longer being sold. While I believe I understand the new GMRS rules after reviewing them, I would like to ask if anyone could help clarify the rules regarding interoperability between what are now separate (non-hybrid) FRS and GMRS radios. In particular, Section 95.1731 "Permissible GMRS Uses" mentions that GMRS and FRS radios can talk to one another, but the rules of interoperability are not made explicit (there or elsewhere) in a way that I was able to discover on my own.

My use case involves leading a small group of volunteers into local wetland, park, and trail systems in our town in order to clean up trash and monitor adverse conditions such as mud, flooding, dumping, downed or hanging branches, animals, or vandalism. We will have two licensed GMRS users including myself, and we wish to invite guest volunteers who can use unlicensed FRS radios.

I spoke with an FCC representative on the phone today, and came to the understanding that we could communicate between GMRS and FRS radios provided that:

1. We must use only channels 8-14
2. We must limit power to no more than 0.5 watts.
3. GMRS call signs can be given by licensed operators per GMRS rules.
4. The GMRS radio must be "compatible" with FRS.

However, as the rules regarding FRS and GMRS radios have changed in recent years, I thought I would reach out to the community and ask for clarification of some points that remain unclear to me:

1. Now that FRS devices are no longer limited to 0.5 watts on some channels, is it still correct that we must limit power to 0.5 watts when a conversation involves both licensed GMRS users and unlicensed FRS users?
2. Now that so-called "hybrid" FRS/GMRS radios are no longer being sold, what does it mean exactly to say that the GMRS radio must be compatible with FRS, as in point 4 above? Does this mean only that the manufacturer has provided compatible channels and frequencies? 
3. Given that channels 8-14 are limited to 0.5 watts, does this mean that a GMRS+FRS conversation would need to use a different channel to use the 2 watts now available to FRS?

This last point would seem to contradict what the representative said to me on the phone, but as she also mentioned combination FRS/GMRS radios, I wondered if we might have been discussing out of date information. The points in question would be at 47 CFR 95.1761(d) and (e), also at 47 CFR 95.1791(a) where the sale of these radios are prohibited. So there is the additional issue of whether the rules we discussed apply only to existing hybrid radios manufactured before 2019 (which I no longer have) or whether it applies to my new radios which are either GMRS or FRS, but none are hybrid units.

I would greatly appreciate any help you could offer in clarifying the new rules for us with regard to the points I have raised above. I would also be happy to answer any questions you may have. 

Thank you. 

--David

[axorlov]

1 hour ago, davidotoole said:

• We must use only channels 8-14
• We must limit power to no more than 0.5 watts.

That's weird. Are you sure that you understood correctly? It supposed to be like "when you are using channels 8-14, make sure you limit power to 0.5W".

FRS and GMRS radios and operators are absolutely allowed to talk to each other on all simplex channels. FRS operators can't use repeaters, FRS operators (radios) are limited to narrowband. But other than that, channels 1 - 22 can be used by both GMRS and FRS, taking power limits in account.

The old what you call "hybrid" FRS/GMRS radios are now FRS radios. https://en.wikipedia.org/wiki/General_Mobile_Radio_Service

[wrci350]

55 minutes ago, davidotoole said:

However, as the rules regarding FRS and GMRS radios have changed in recent years, I thought I would reach out to the community and ask for clarification of some points that remain unclear to me:

1. Now that FRS devices are no longer limited to 0.5 watts on some channels, is it still correct that we must limit power to 0.5 watts when a conversation involves both licensed GMRS users and unlicensed FRS users?
2. Now that so-called "hybrid" FRS/GMRS radios are no longer being sold, what does it mean exactly to say that the GMRS radio must be compatible with FRS, as in point 4 above? Does this mean only that the manufacturer has provided compatible channels and frequencies? 
3. Given that channels 8-14 are limited to 0.5 watts, does this mean that a GMRS+FRS conversation would need to use a different channel to use the 2 watts now available to FRS?

This last point would seem to contradict what the representative said to me on the phone, but as she also mentioned combination FRS/GMRS radios, I wondered if we might have been discussing out of date information.

I will give the representative the benefit of the doubt and go with "looking at old information".  

Here are the answers to your questions:

1) No.  Nowhere in the CURRENT rules does it say that.  FRS can use up to 2 watts (depending on the channel).  GMRS can use 5 or 50, but in the situation you are describing you're probably better off sticking with 2 or 5 since it probably doesn't do you any good if the FRS users can hear the GMRS users but not talk to them!

2)  No idea where "compatible" came from.  Out of the box, GMRS radios and FRS radios have the same 22 channels programmed in them.  Other than power levels and narrow vs wideband the only difference is that GMRS radios have the repeater channels programmed too (and FRS radios cannot do the offset needed to use a repeater).

3)  This one is actually YES.    Channels 8-14 are limited to .5 watt and in the GMRS world to HT (hand-held) radios only.  So just use 1-7 or 15-22 instead.

As far as IDing?  The rules do seem to say that the licensed GMRS users need to ID.  An easy solution?  Grab an FRS radio and use that instead.  I have never read any FRS rule that says you have to ID on FRS if you have a GMRS license!

[Sshannon]

13 minutes ago, wrci350 said:

1) No.  Nowhere in the CURRENT rules does it say that.  FRS can use up to 2 watts (depending on the channel).  GMRS can use 5 or 50, but in the situation you are describing you're probably better off sticking with 2 or 5 since it probably doesn't do you any good if the FRS users can hear the GMRS users but not talk to them!

Maybe I’m misunderstanding your point, but here’s what the FRS rules say about power:

§ 95.567 FRS transmit power.

Each FRS transmitter type must be designed such that the effective radiated power (ERP) on channels 8 through 14 does not exceed 0.5 Watts and the ERP on channels 1 through 7 and 15 through 22 does not exceed 2.0 Watts.

It’s true that output power may be different from ERP.

[wrci350]

3 minutes ago, Sshannon said:

Maybe I’m misunderstanding your point, but here’s what the FRS rules say about power:

Yes, you misunderstood my point.  

The OP asked

1. Now that FRS devices are no longer limited to 0.5 watts on some channels, is it still correct that we must limit power to 0.5 watts when a conversation involves both licensed GMRS users and unlicensed FRS users?

The answer is NO, you aren't limited to .5 watts.  Didn't I say that?

[axorlov]

1 minute ago, wrci350 said:

The answer is NO, you aren't limited to .5 watts.  Didn't I say that?

467.xxx5 MHz channels are limited to 0.5W and narrowband for both GMRS and FRS. That are channels 8-14.

[davidotoole]

Hi everyone, I want to thank you so much for your help in clarifying this situation. I will continue following the thread and let you know if I have any other questions. We'll be doing our first on-trails test as soon as the snow melts a little more here in New England. I'll be sure to post an update then, and perhaps offer some review thoughts on the waterproof Baofeng GMRS radios we will be using. I still haven't purchased the FRS units I've been wanting to use, I want them to be waterproof and Baofeng doesn't seem to make a waterproof FRS handset, so I'm probably going with Cobra.

[wrci350]

8 minutes ago, axorlov said:

467.xxx5 MHz channels are limited to 0.5W and narrowband for both GMRS and FRS. That are channels 8-14.

And your point is what?  That wasn't the question.  The question was "are we limited to .5W if we are using both FRS and GMRS radios".  And the answer is still NO.

On channels 8-14?  Yes.  So pick a different channel.

[axorlov]

3 minutes ago, wrci350 said:

And your point is what?  That wasn't the question.  The question was "are we limited to .5W if we are using both FRS and GMRS radios".  And the answer is still NO.

Yes, you're right. You mentioned it in your other post anyway. Sorry for the noise.

[Sshannon]

1 hour ago, wrci350 said:

1) No.  Nowhere in the CURRENT rules does it say that.  FRS can use up to 2 watts (depending on the channel).

Somehow I missed the first period.

I read:  Nowhere in the CURRENT rules does it say that FRS can use up to 2 watts (depending on the channel).

Definitely my mistake. 

[wrci350]

LOL.  No apology neccesary!  I can see how I could have done the same thing very easily!!  

[Lscott]

4 hours ago, davidotoole said:

I spoke with an FCC representative on the phone today, and came to the understanding that we could communicate between GMRS and FRS radios provided that:

1. We must use only channels 8-14
2. We must limit power to no more than 0.5 watts.

That's not a "requirement" as such. It's in the rules that GMRS radios must use narrow band FM on channels 8-14 and no more than 0.5 watts. This is the exact same technical requirements for FRS radios. The FCC rep likely mentioned the above because the two radio services would be compatible on a technical level.

You can legally program your GMRS radio to use narrow band FM on all channels thus you can use any of the 22 to communicate with FRS radios. The radio I use, Kenwood TK-3170, has "zones" which are logical grouping of memory channels. I have one zone programmed for wide band when talking to other GMRS radios, and another zone with the same channels programmed for narrow band to talk with FRS radios. Since the radio can't be turned down to 0.5 watts, minimum is 1 watt, I don't use 8-14 to talk with FRS radios.

[davidotoole]

I checked and my Baofeng GMRS-9R's allow setting narrow band on channels other than 8-14, so I'll program that (and 2.0 watt power level) and we should be good to go for GMRS/FRS! Thanks everyone for your help.

[Lscott]

12 minutes ago, davidotoole said:

I checked and my Baofeng GMRS-9R's allow setting narrow band on channels other than 8-14, so I'll program that (and 2.0 watt power level) and we should be good to go for GMRS/FRS! Thanks everyone for your help.

If you have a GMRS license there is no requirement you have to use 2 watts or less on 1-7 and 15-22. That ONLY applies to FRS radios. GMRS radios can use up to 5 watts on 1-7 and up to 50 watts on 15-22, and that includes when talking to FRS radios.

FRS-GMRS combined channel chart.pdf

[davidotoole]

Thanks for clarifying this @Lscott. My main reason for limiting to 2 watts when communicating with FRS radios is to avoid having FRS radios not be able to respond to GMRS when just out of transmit range, and so that the volume difference is eliminated. So I will keep in mind that higher power can be used on GMRS when communicating.

[Lscott]

1 hour ago, davidotoole said:

My main reason for limiting to 2 watts when communicating with FRS radios is to avoid having FRS radios not be able to respond to GMRS when just out of transmit range, and so that the volume difference is eliminated.

The power level has nothing to do with the audio volume when using FM for communications.

[davidotoole]

Quote

The power level has nothing to do with the audio volume when using FM for communications.

Oh, thank you for fixing this error in my brain . I wonder if you could explain why this is? 

[Lscott]

3 hours ago, davidotoole said:

Oh, thank you for fixing this error in my brain . I wonder if you could explain why this is? 

The radios we use employ FM, frequency modulation. In other words the transmitted frequency is varied to convey the audio information. The amplitude of the transmitted signal, power, is not used to convey any audio information.

This is why you see references to wide-band verses narrow-band on these forums. What is being referred to is how much the transmitted frequency varies, called deviation, for a given audio signal level. The wide-band can vary the transmitted signal by as much as 5KHz, while a narrow band signal will only vary by 2.5KHz.

If we use wide-band on transmit to communicate with a narrow-band radio the audio will sound very loud and likely will be distorted. The reverse case a narrow-band radio transmitting to a wide-band radio the audio will sound very weak, low volume.  This is why it's important to ensure that all radios are set to use the same bandwidth, deviation, and thus the FCC's comments you got.

[UncleYoda]

8 hours ago, Lscott said:

The power level has nothing to do with the audio volume when using FM for communications.

Wrong.  It's very common on 2m for HAMs to turn up the power to get louder voice audio.  There's a difference between theory and practical experience.

[Lscott]

1 hour ago, UncleYoda said:

Wrong.  It's very common on 2m for HAMs to turn up the power to get louder voice audio.  There's a difference between theory and practical experience.

Wrong. I've operated VHF and UHF FM for over 20+ years. It doesn't work that way. If you want to talk about SSB on 2M that's a different story.

https://en.wikipedia.org/wiki/Frequency_modulation

[Sshannon]

2 hours ago, UncleYoda said:

Wrong.  It's very common on 2m for HAMs to turn up the power to get louder voice audio.  There's a difference between theory and practical experience.

Clearer, perhaps, because of signal to noise ratio, but I have never heard anyone tell people to turn up their power if their audio is simply low.  We’ll tell them to turn up their mic gain, or maybe engage compression, or to speak more directly into the microphone.

[Lscott]

6 minutes ago, Sshannon said:

Clearer, perhaps, because of signal to noise ratio, but I have never heard anyone tell people to turn up their power if their audio is simply low.  We’ll tell them to turn up their mic gain, or maybe engage compression, or to speak more directly into the microphone.

That's the usual reason, you're correct on that point. FM receivers incorporate a "limiter" stage for the sole function of eliminating any amplitude modulation in the RF signal.