GMRS Trave Frequency?

[WRTC928]

4 hours ago, AdmiralCochrane said:

Seems like many truckers still have CB's but are only using them to communicate the location of a jam and which lanes are open.  

That's the only reason I have one anyway.

[WRUE951]

I used to throw the 10-11 metter in my truck when making frequent trips back and forth between here, (the Desert) and Sacramento..  That all ened back in 23..  I used to catch a lot of truckers, picking them on 58 in Tehacappi all the way north along 99 and back..  Very rarelty did i here them on GMRS and if i did, they were traveling in pairs  on long haul deliveries. 

[AdmiralCochrane]

7 hours ago, dosw said:

Oh I've listened across the CB range using an SDR where it's easy to see the spectrum use. And wow, not just channel 6, but a few others are totally overrun with people who have to be causing brown-outs in their towns when they key up. The funny ones are where you see a big swoop across several channels every time they key up, finally landing on their desired channel, which they fill so broadly that they spill over into adjacent channels. The swoop is wild though. What kind of crazy equipment is sweeping through several channels on its way to landing where it is supposed to be?

You can probably find videos on YouTube.  Pickup trucks with 50 and 80 kw generators in the back and antenna arrays that require another truck to haul.   Lots of stuff to make Randy smile.

[nokones]

10 hours ago, dosw said:

GMRS came into being in 1987.

You are a tad off on that date. GMRS was known as Class A Radio Service and CB Radio was known as Class D Radio Service back in the 60s.

In the 70s, the FCC changed the Class A Radio Service to General Mobile Radio Service (GMRS).

[nokones]

On 8/16/2025 at 5:18 PM, OffRoaderX said:

A road has intersections, stop signs and stoplights.. A highway, aka a freeway, does not.

“Road” means any existing vehicle route.

A “roadway” is that portion of a highway improved, designed, or ordinarily used for vehicular travel.

“Freeway” is a highway in respect to which the owners of abutting lands have no right or easement of access to or from their abutting lands or in respect to which such owners have only limited or restricted right or easement of access.

Highway” is a way or place of whatever nature, publicly maintained and open to the use of the public for purposes of vehicular travel. Highway includes street.

[LeoG]

So what is the advantage if any, of FM CB over AM CB?

[WRUU653]

3 minutes ago, LeoG said:

So what is the advantage if any, of FM CB over AM CB?

To quote Steely Dan “no static at all” 

Perhaps an exaggeration but clearer audio I’m guessing and some might see the lack of traffic as a plus. Just a thought. 

[dosw]

4 hours ago, nokones said:

You are a tad off on that date. GMRS was known as Class A Radio Service and CB Radio was known as Class D Radio Service back in the 60s.

In the 70s, the FCC changed the Class A Radio Service to General Mobile Radio Service (GMRS).

You're probably accurate on that, but Wikipedia doesn't make it entirely clear that GMRS existed before '87: https://en.wikipedia.org/wiki/General_Mobile_Radio_Service#History

 

[nokones]

7 hours ago, dosw said:

You're probably accurate on that, but Wikipedia doesn't make it entirely clear that GMRS existed before '87: https://en.wikipedia.org/wiki/General_Mobile_Radio_Service#History

 

Wikipedia is getting screwed up by A.I.

[nokones]

7 hours ago, LeoG said:

So what is the advantage if any, of FM CB over AM CB?

A tad more communication distance of usable audio because of the noise factor. With 3 1/2 watts that equates to almost a 1/4 mile more in Farz.

[Lscott]

9 hours ago, LeoG said:

So what is the advantage if any, of FM CB over AM CB?

Opportunity for the manufactures to sell more radios with "New Features" for more money.

[WRTC928]

6 minutes ago, Lscott said:

Opportunity for the manufactures to sell more radios with "New Features" for more money.

I've read that it was so the manufacturers could sell the same units in the US and Europe. That may be true because the CB I bought a few months ago has a way to set it to different regions.

[Northcutt114]

3 hours ago, nokones said:

A tad more communication distance of usable audio because of the noise factor. With 3 1/2 watts that equates to almost a 1/4 mile more in Farz.

Uh... unless I'm mistaken this is not correct. AM CB will talks more fars than FM, no?

As to @LeoG's question as to what is the difference? FM is a little cleaner, sounds a little warmer. But nobody, en masse, is talking on it so unless it's you and someone else you plan to have comms with, there's no need to get one. I have one. It stays on AM band 24/7.

 

[amaff]

4 minutes ago, Northcutt114 said:

unless it's you and someone else you plan to have comms with, there's no need to get one. 

Hey just like GMRS!

[hxpx]

43 minutes ago, Northcutt114 said:

Uh... unless I'm mistaken this is not correct. AM CB will talks more fars than FM, no?

IIRC both are primarily line of sight so performance should be roughly the same, especially with HTs. You can take advantage of troposheric ducting with 11m/CB for the occasional long distance connection (whereas UHF just punches through the atmosphere) but you can't rely on that for regular communications.

[LeoG]

I do tropospheric ducting with GMRS.  Just takes the right conditions.  And I've never really gotten huge distances.  Just impossible connections.  Where I am and where I connected has a huge mountain in between that makes it impossible to have any sense of LOS.  It's only about 70 miles and it only happens in the summer.  And it's only happened once this summer and I'm not sure if it's conditions or from me going from a 7.2dBi to a 9.8dBi gain antenna.

There was one night were I was able to connect and talk with several people with my HT and they said it was R9.  Very unlikely unless you live in SoCal....

[WRUE951]

4 minutes ago, LeoG said:

I do tropospheric ducting with GMRS.  Just takes the right conditions.  And I've never really gotten huge distances.  Just impossible connections.  Where I am and where I connected has a huge mountain in between that makes it impossible to have any sense of LOS.  It's only about 70 miles and it only happens in the summer.  And it's only happened once this summer and I'm not sure if it's conditions or from me going from a 7.2dBi to a 9.8dBi gain antenna.

There was one night were I was able to connect and talk with several people with my HT and they said it was R9.  Very unlikely unless you live in SoCal....

I have traveled and spent time camping all over the place.   The only place i have encountered 70CM tropospheric ducting is right here in the Indian Wells Valley or the foot of the Sierras.  And the traffic i was picking up was coming form Southern California, just a mere 140miles south.  Although i tried a couple times, i never was able to make a contact with someone 'ducting' in but their conversions were coming in like there were sitting next to me.  

[hxpx]

Just now, LeoG said:

I do tropospheric ducting with GMRS.  Just takes the right conditions.  And I've never really gotten huge distances.  Just impossible connections.  Where I am and where I connected has a huge mountain in between that makes it impossible to have any sense of LOS.  It's only about 70 miles and it only happens in the summer.  And it's only happened once this summer and I'm not sure if it's conditions or from me going from a 7.2dBi to a 9.8dBi gain antenna.

Neat! Probably a bit of both, plus a dash of luck.

[AdmiralCochrane]

1 hour ago, Northcutt114 said:

Uh... unless I'm mistaken this is not correct. AM CB will talks more fars than FM, no?

As to @LeoG's question as to what is the difference? FM is a little cleaner, sounds a little warmer. But nobody, en masse, is talking on it so unless it's you and someone else you plan to have comms with, there's no need to get one. I have one. It stays on AM band 24/7.

 

Theoretically yes, but in practice the opposite has often proven to be the result.   What happened was that FM dropped out at essentially the same distance that AM became unintelligible.  AM broke squelch farther away, but was completely unreadable at max distance.  If I recall FM was full readable where AM was 50/50.

[Northcutt114]

2 hours ago, amaff said:

Hey just like GMRS!

Pretty much. Except GMRS can do repeaters.