Programming GMRS

[Artsifrtsi]

Anyone have a really good USEFUL list of the frequencies to program into radios for offroading and travel? For the trip I did, I threw in all the GMRS/FRS freqs, Race Radio, and the MURS (? Handhelds) freqs, but when I was scanning on the road, and even in Moab, I rarely ever heard anybody on. Don't get me wrong, it was nice communicating with the other vehicle and spotter without radio chatter, but would have been nice to hear others.

I have a Radioddity DB-25 pro, and 2 of the Baofeng UV-5R.

Other problem I really had, was I could barely reach out 1/4 mile, if even that far... so I'm sure I do not have the programming completely correct. The UV-5Rs I was using the long whip they come with, and the DB25 I used the antenna it came with...Better options?

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[Teqsand]

Nothing on this ?

 

[bd100]

Where is the vehicle antenna mounted? It may be a ground plane issue. You probably want some horizontal metal beneath it, and keep the whip away from other metal.

 

[Artsifrtsi]

Where is the vehicle antenna mounted? It may be a ground plane issue. You probably want some horizontal metal beneath it, and keep the whip away from other metal.

That could be possible for the truck mount, as I mounted the antenna on a side cowl mount. The handhelds though, are a little puzzling...

 

[Minty JL]

Antenna placement is key for maximum range CB, GMRS and HAM all have considerations in regards to LoS. Mounting antennas on the cowl or hood might look cool or be easy to install, but is not deal for either Rx or Tx

 

[Artsifrtsi]

Antenna placement is key for maximum range CB, GMRS and HAM all have considerations in regards to LoS. Mounting antennas on the cowl or hood might look cool or be easy to install, but is not deal for either Rx or Tx

I put it there completely out of no other areas to mount it to where it would be out of the way. I may experiment and maybe try it on the actual cowl, with some aluminum ducting wrap affixed to the backside, or maybe one of the panel edge mount brackets.

 

[Radio Guy]

Antenna placement is key for maximum range CB, GMRS and HAM all have considerations in regards to LoS. Mounting antennas on the cowl or hood might look cool or be easy to install, but is not deal for either Rx or Tx

The hood is not as bad as other vehicles since much of the upper part of a Gladiator is fiberglass or very wide spaced pillars and roll cage. Its very transparent to UHF signals. I've seen a hood or trunk mount antenna outperform a fiberglass roof mounted antenna that had no ground plane. The ground plane helps pull the radiation pattern down towards the horizon and when you remove it the pattern usually raises upwards away from the horizon a bit affecting distance. If you go for a high antenna mounting location on a Gladiator you must include an adequate ground plane.

 

[Artsifrtsi]

How big of a plane should there be?

Also, what is the consensus of NGP antennas?

 

[Radio Guy]

How big of a plane should there be?

Also, what is the consensus of NGP antennas?

12" diameter or square is adequate ground plane for GMRS. A halve wave no ground plane antenna can work ok without a ground plane because it inherently puts the signal near the horizon. A non NGP antenna with no ground plane is asking for both tuning problems and reduced performance at the horizon.

 

[bd100]

For the handhelds, if there are signals bouncing all over the place they can interfere with each other such that moving a few inches left or right can make all the difference. Try this. One person standing still, the other person a quarter mile away. Have the other person move around a few feet left or right or forward or back while the first is transmitting. You may find a certain spot where the signal is strong, another spot a few feet over where it is entirely gone, and everything in between. I found this to be the case in a suburbia setting, but it may be less so out in the open.

 

[Radio Guy]

For the handhelds, if there are signals bouncing all over the place they can interfere with each other such that moving a few inches left or right can make all the difference. Try this. One person standing still, the other person a quarter mile away. Have the other person move around a few feet left or right or forward or back while the first is transmitting. You may find a certain spot where the signal is strong, another spot a few feet over where it is entirely gone, and everything in between. I found this to be the case in a suburbia setting, but it may be less so out in the open.

That would be multipath distortion and at GMRS frequencies 1ft is about 1/2 wavelength and moving 1ft can potentially make the signal fade under the right conditions. Its not the signal fading due to low signal level, its the signal from the transmitter taking more than one path to the receiver and one of those paths is delayed 180deg from the direct path. A perfect 180deg out of phase signal of similar level to the main path can almost completely cancel out reception.

You have probably experienced this many times in the past listing to your FM stereo in the car. You slow down to a stop light and the station fades slowly as you come to a stop. When you stop its really weak and fuzzy sounding so you put the car in reverse and go backwards a couple of feet until it sounds clear again because your favorite song is playing. The light eventually changes and your on your way and don't really notice the rapid fading at high speed.

Congratulations, your experiencing multipath and you probably never thought about it before. 6ft is about 1/2 wavelength at FM broadcast frequencies and if you have multipath moving 6ft can take you from a good signal level to a very bad one.

 

[sarguy1941]

I spent a week in MOAB last summer as well as Bolder CO and Grand Canyon. I scanned all the GMRS stuff and only heard a little chatter in Arches National Park. Most folks use the radio for talking on a trail.

 

[Mash5]

With GMRS (and other FM bands) you need to pay attention to wide and narrow in your programming. If one station/radio is wide and the other is narrow you will not have good reception because the other station is effectively filtering out some of your signals. As I recall, some GMRS channels are wide, and some are narrow.
Also as others have eluded, moving your antenna mount a few inches can have a big effect on signal. If, for instance, your cowl mount is half a wave or one and a half waves or whatever away from your A-pillar, the reflection from the pillar can be canceling out a significant portion of your signal.
It is also possible there is just not a ton of traffic in remote areas. If you are used to a city repeater with people always chatting, Moab is going to sound kind of dead most of the time. I have rolled around all week talking vehicle to vehicle on 2m calling at 50w daring someone to come up and announce themselves... nothing.

 

[Radio Guy]

With GMRS (and other FM bands) you need to pay attention to wide and narrow in your programming. If one station/radio is wide and the other is narrow you will not have good reception because the other station is effectively filtering out some of your signals. As I recall, some GMRS channels are wide, and some are narrow.
Also as others have eluded, moving your antenna mount a few inches can have a big effect on signal. If, for instance, your cowl mount is half a wave or one and a half waves or whatever away from your A-pillar, the reflection from the pillar can be canceling out a significant portion of your signal.
It is also possible there is just not a ton of traffic in remote areas. If you are used to a city repeater with people always chatting, Moab is going to sound kind of dead most of the time. I have rolled around all week talking vehicle to vehicle on 2m calling at 50w daring someone to come up and announce themselves... nothing.

All GMRS channels are wide band 5KHz deviation as well as FRS ch 1-8 in the 462MHz range. FRS ch 9-14 are narrow band 2.5KHz deviation in the 467MHz range.

 

[sarguy1941]

All GMRS channels are wide band 5KHz deviation as well as FRS ch 1-8 in the 462MHz range. FRS ch 9-14 are narrow band 2.5KHz deviation in the 467MHz range.

While I agree with most of what @Radio Guy helps with this is missleading in the fact of that may be the rules but we know all midland radios (mobile and portable) are narrowband on all channels. Until the MTX500 you could not program them for wide v narrow. I actually run a GMRS repeater in narrowband as the MTS275 works much better on the repeater now. We went round and round with midland in the past over this.

Most FRS units are all narrowband on all channels which now include GMRS. My T600 are narrow band on all channels. 1-22

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