Crossband Repeat

[scott931]

Ok, so I know some HTs are capable of crossband repeat.  So, could I "in theory" say, transmit on a MURS channel and recieve on a GMRS frequency? 

Or am I overthinking this concept?

[OffRoaderX]

Yes, you are overthinking it...

[scott931]

So, that's not possible?  Then what exactly does crossband repeat accomplish?

[Lscott]

8 minutes ago, scott418 said:

Ok, so I know some HTs are capable of crossband repeat.  So, could I "in theory" say, transmit on a MURS channel and recieve on a GMRS frequency? 

Or am I overthinking this concept?

In theory yes. Legally no. 
 

On the Ham bands it’s done. In fact I helped a buddy install just such a system on top of an apartment building about a year or so ago. It cross-banded between the VHF 2M and UHF 70cm bands. 

[Lscott]

1 minute ago, scott418 said:

So, that's not possible?  Then what exactly does crossband repeat accomplish?

It’s just not legal to operate this way on GMRS and MURS. That’s just the way the rules are written, like it or not. Some have gone and setup cross-band repeaters between MURS and GMRS anyway. NOBODY is going to guarantee FCC won’t come looking for you.

[scott931]

Ok, so here's the situation.  I am both Ham and GMRS licensened. My son has a Baofeng GM-15 Pro. and I have a Baofeng UV21 Pro. So his radio only transmitts on GMRS but can recieve  VHS as well.  My will transmitt on both. So, since I can do a 2 meter simplex to transmit, and then set his to transmit on GMRS and recieve said 2 meter frequency.  please explain where the legality issue comes in.

[Lscott]

8 minutes ago, scott418 said:

Then what exactly does crossband repeat accomplish?

The reason it’s done is the elimination of the heavy, bulky and expensive cavity filters required for an in-band repeater. This applies to analog radios.

The filters are required because the RX and TX frequencies are close together. Without sufficient isolation the transmitter will overload the receiver such that it effectively become deaf. Remember the receiver is feeding every it hears to the transmitter at the same time.

A cross-band repeater the frequencies are space far enough apart that a far simpler and cheaper filter can provide the isolated required.

[Lscott]

6 minutes ago, scott418 said:

Ok, so here's the situation.  I am both Ham and GMRS licensened. My son has a Baofeng GM-15 Pro. and I have a Baofeng UV21 Pro. So his radio only transmitts on GMRS but can recieve  VHS as well.  My will transmitt on both. So, since I can do a 2 meter simplex to transmit, and then set his to transmit on GMRS and recieve said 2 meter frequency.  please explain where the legality issue comes in.

As a Ham you’re limited to ONLY making contact with other stations which are licensed and operating in the amateur service of the US, or of the country the station is located in. Obviously GMRS is NOT a Part 97 service. As a Ham you should know this. I would recommend you get a copy of Part 97 rules and throughly read it. It’s pointless to waste time on something you can easy research yourself.

[scott931]

Ok, I probably am overthinking this, but one more question. All I'm basically wanting to do is transmit on vhf and recieve on uhf, even if only on VFO, but I'd like to be ably to put it in a memory, as, like a split channel. 

[scott931]

Ok, gotcha. thanks for your input.  So basically, I need to keep both channels within the same service.  Got it. thanks sir. 

[SteveShannon]

3 minutes ago, scott418 said:

Ok, I probably am overthinking this, but one more question. All I'm basically wanting to do is transmit on vhf and recieve on uhf, even if only on VFO, but I'd like to be ably to put it in a memory, as, like a split channel. 

You can do that if both vhf and uhf frequencies are in the ham bands. 
 

[BoxCar]

The FCC rules generally prohibit transmissions from one service to another. This means you can't cross-band from part 97 to any other service such as Part 95 or from one service under the same part. This prohibits CB being crossbanded to GMRS, FRS, or MURS and any combination of the services.

[Lscott]

1 hour ago, BoxCar said:

The FCC rules generally prohibit transmissions from one service to another. This means you can't cross-band from part 97 to any other service such as Part 95 or from one service under the same part. This prohibits CB being crossbanded to GMRS, FRS, or MURS and any combination of the services.

That’s what generally foils the whole idea not to mention repeaters, including cross-band types, are prohibited in MURS.

A variation of the cross-band idea is an in-band spilt frequency operation. Many radios can be programmed to receive on one frequency and transmit on another within the same band using an arbitrarily frequency offset.

The idea would require the GMRS user to transmit on a legal GMRS frequency and receive on a frequency in the Ham 70cm band. 

The Ham radio user would then transmit on a legal 70cm simplex frequency, which is programmed into the above GMRS radio for receive only, and receive on the GMRS transmit frequency programmed in the GMRS radio.

Nether radio requires modifications nor dual band operation. Just the ability to program in spilt UHF frequencies with an arbitrarily offset.

This operation in not legal either for the prior mentioned rules. The Ham station shall only contact other stations in the Amateur service. Also it could fall under the general prohibition to engage in one-way communications since the other station is NOT in the Amateur service. 

I wanted to point this scenario out before somebody dreams this case up and tries a convoluted argument this would pass under the rules. It won’t. 

[BoxCar]

Our firm coordinated many public agencies to allow cross-band repeaters. The fire service is one of the major users of these for fire ground communications. But again, these were all operating in the same service under Part 90.20.

[jwilkers]

Ok, so here's the situation.  I am both Ham and GMRS licensened. My son has a Baofeng GM-15 Pro. and I have a Baofeng UV21 Pro. So his radio only transmitts on GMRS but can recieve  VHS as well.  My will transmitt on both. So, since I can do a 2 meter simplex to transmit, and then set his to transmit on GMRS and recieve said 2 meter frequency.  please explain where the legality issue comes in.

You are basically making a one way transmission. Your conversation is split between 2 services. One way communications are forbidden by regulations.

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[WQAI363]

On 9/11/2023 at 7:25 PM, scott418 said:

Ok, so I know some HTs are capable of crossband repeat.  So, could I "in theory" say, transmit on a MURS channel and recieve on a GMRS frequency? 

Or am I overthinking this concept?

What are you going crossband too? There's only a single band on GMRS, it's not like Amateur Radio or the LMR, where there's VHF Low VHF High and UHF. Obviously Crsss banding from GMRS to 2m Amateur is a Big No No. even on simplex. You could attempt it on MURS and GMRS, but that's still violates FCC R&R under 95 E & J. I think that the PEG SYSTEM uses GMRS simplex to crossband to VHF low band on some of PEG Radio Systems, but is it totally in compliance with FCC R&R. I'm not sure.  

If I where going to, but I wouldn't. I would use 462.5750  pl 85.4 / 154.6000  pl 146.2.  However, unless there's urgent need to this, I rather follow protocol.

[WRYS709]

On 9/11/2023 at 4:52 PM, scott418 said:

Ok, so here's the situation.  I am both Ham and GMRS licensened. My son has a Baofeng GM-15 Pro. and I have a Baofeng UV21 Pro. So his radio only transmitts on GMRS but can recieve  VHS as well.  My will transmitt on both. So, since I can do a 2 meter simplex to transmit, and then set his to transmit on GMRS and recieve said 2 meter frequency.  please explain where the legality issue comes in.

FCC rules allow your son to use your GMRS license, including when talking to you on GMRS.

Use your GMRS certified radio to talk to your son on his GM-15Pro either simplex or through a GMRS Repeater.

Then work with your son to get his Technician Ham License and then you can cross talk on 2 meters and 70 cms Ham bands, if that is important to you.