GMRS forest adventures and GIS mapping

[davidotoole]

Hi everyone, first I just want to thank you for welcoming me to the site and for your help with my various questions. I thought I'd share our GMRS experience from today. My little group which I've recently started, called "Trails Adventure Team", made our first mission into a local trail system to clean up trash and report trail conditions. We hiked to the summit of Edmund Hill here in Northborough, Massachusetts, and then split up on two different trails on the way back down. While separated, we tested our new waterproof Baofeng GMRS-9R radios with our newly issued callsigns. Although Edmund Hill Woods isn't large enough to do a proper GMRS range test, we did find that transmissions were loud and clear in the forest at about 0.25 miles apart. In a few weeks we're going up to Mount Pisgah which is a significantly larger area and with more varied terrain. We are planning to conduct more tests then, using both wideband and narrowband modes (since we will be using the latter whenever unlicensed FRS users are in the mix, and we want to know how both perform) and will try to test reception at a distance of 0.5 miles or greater.

We also used QGIS and QField to record some GPS data points on the trails (see attached image), although a few of them were inaccurately placed; I think I need to buy a tablet with a more precise GPS than my low-end mobile phone. 

Does anyone else use GMRS in woodland areas? What kind of range are you capable of getting with a 5 watt handheld? (Although, I've heard these GMRS-9R don't actually reach the 5 watts advertised.)

[73blazer]

Last summer i did extensive testing in heavily forested areas with some mild hills. The KG-935G at 5.5w and a Nagoya 771G antenna was by far the best setup for penetrating heavy foliage. I found we could get 1.25mi-1.5mi reliably (or farther in some conditions or  if you don't mind some hearing every other word). I also tried some Boeganf uv5r (rated 5, puts out 3.8-4w) and a Retivis 4w and a KG-905G (5w) and a MURS radio and a Yeasue FT-65R ham (4w) . I had high hopes for MURS in the lower frequency, but MURS sucked.  1/2mi at most in the forest. The Retivus and ham radio (in a UHF range ahhem near a GMRS frequency) got near a mile and then was unreliable past that. The 905 was reliable to 1.25mi but never got to the 1.5mi mark without some interferance . All were tried with their included rubber ducks and again with a 771G (except the MURS). The 771G added about .1-.25mi of reliability in the forest.

Alot of people will say a 2w radio will do the same as a 5w radio, and out in the open or atop a mountain to someone in a valley that's likely true. For for penetrating heavy foliage while your standing under canopy.... my testing has shown that wattage is a factor. The 935g by far sounds the best and gets the best range and the 771G antenna is a great investment for heavy foliage use.

[davidotoole]

Hi @73blazer thanks so much for sharing this information! I really appreciate your help. I'm guessing we will need to plan to have our distance top out at about 1.25 miles when planning multi squad trips. I'm so happy I joined this forum and I hope to make a positive contribution. Nice to meet you.

[davidotoole]

@73blazer One additional question: did you get a chance to compare narrow versus wide band?

[73blazer]

I have only tried narrowband one time for fun and it was slightly worse but not too bad, where I tried IIRC I was about 1.1-1.2mi away in the woods I didn't try it on all radios and it wasn't included in my testing, I just always used wideband.  Mostly because from what I read about it, it's not gonna make much difference unless your in a radio congested area and where we use them, there is literally nothing else and the more frequencies (wideband)  to carry my signal the better chance it has.

In case you didn't know because GMRS channels 8-14 are shared with FRS (among others) and required by part 95e (gmrs) radios to be narrow band.They also can only transmit 0.5w on those channels. I always use the GMRS channels 15-22 in wideband.

[davidotoole]

Hi and thanks again for your report. My Beofeng GMRS-9R radio complies with the regulations regarding power and bandwidth on channels 8-14, and we'll be using channel 18 on narrowband when 2-watt FRS handsets are in the mix. It is good to hear that range shouldn't suffer dramatically with narrowband. 

[73blazer]

If you have true FRS radios in the mix, their power on the 15-22 channels (usually only newer frs radios have those) is 2w, that will reduce their transmission range in heavy forest, coupled with their usually crappy antennas, the transmission range may be reduced significantly with an FRS. FRS radios are narrowband on all channels so yes, your GMRS radio should be set to narrow on those channels if communicating with them because there is some quality issues with narrow to wide etc.

[davidotoole]

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If you have true FRS radios in the mix, their power on the 15-22 channels (usually only newer frs radios have those) is 2w, that will reduce your range in heavy forest, couple with their usually crappy antennas, the range may be reduced significantly with an FRS. FRS radios are narrowband on all channels so yes, your GMRS radio should be set to narrow on those channels if communicating with them because there is some quality issues with narrow to wide etc.

Interesting. I'll have to choose my FRS model carefully then. Actually, I'm starting to wonder if I should even bother with FRS for this use case, because we only need one person on each squad with a radio, and we already have 3 GMRS licensees in the group.

[WRWE744]

I have used my Baofeng GM-15 Pro with an outdoor antenna across about 6 miles of woods and uneven terrain from my house to my brothers house. It worked fine for a few days but we haven't been able to establish a very good connection through that area since. Any ideas on anything that might help?

[73blazer]

1 hour ago, davidotoole said:

Interesting. I'll have to choose my FRS model carefully then. Actually, I'm starting to wonder if I should even bother with FRS for this use case, because we only need one person on each squad with a radio, and we already have 3 GMRS licensees in the group.

If you have a choice, as in have enough GMRS radios, I personally would certainly ditch the FRS radios. We used to use them for years in a hunting area, heavily forested, and you could never get more than 1/2mi from them, or less. The choked off transmission wattage is one thing, the irremovable usually very short crappy antenna is another reason.

45 minutes ago, WRWE744 said:

I have used my Baofeng GM-15 Pro with an outdoor antenna across about 6 miles of woods and uneven terrain from my house to my brothers house. It worked fine for a few days but we haven't been able to establish a very good connection through that area since. Any ideas on anything that might help?

6 miles sounds pretty good to me in the woods. I've never gotten anywhere near that. I think sometimes peoples definition of "woods" differs. I've seen videos of people testing radios in the "woods" and their standing in an a field with a patch of woods 50 yards away talking to someone else in open park on the other side of said "woods".  When I say woods, I mean, woods,100% 50-80' oaks maples hickories birch popples & pines with alot of ground scrub as well, no homes, no fields,no yards,  no open areas at all, dead of summer full foliage,  and your transmitting from under canopy of said woods to another person under canopy in said woods and nobody is at any significant elevation change and there may be some small 50-70' ridges/hills in between people.    Even the GIS picture in the 1st post shows homes, and I would consider that alot more open (aka probably get more range) than what I listed and tested.

If you used to be able to get it, and now don't, something changed. Day to day experience can differ somewhat , temperatures, rain, humidity etc can all affect, but not usually to a point of we were talking no issues and now we can't at all. I have seen foiliage do that if you were on the edge already then the leaves grow in, it can block you entirely.  I would say somebodies radio suddenly stopped puttin out, (did the radios get married by chance? )

[davidotoole]

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Even the GIS picture in the 1st post shows homes, and I would consider that alot more open (aka probably get more range) than what I listed and tested.

@73blazer Yes, this forest isn't so big or deep, encompassing about 100 acres, and the amount of wetlands means that some areas (particularly the area where we did our test yesterday) are partly devoid of trees. But at Mt. Pisgah here in town we should be able to separate up to about 0.75-1.0 miles in denser forest if we straddle town boundaries, and we'll explore transmitting from the 715 foot high peak to a trail head about 0.8 miles south as well. Nearby Upton State Park should be an even more more interesting testing ground... it's 2,600+ acres! I will let you know what happens. 

[73blazer]

Elevation difference between radios of that magnitude (715') will change the game completely. Now your talking 10's of miles of range pretty easily. But yes, every terrain is different and you never really know what your gonna get.

[davidotoole]

1 minute ago, 73blazer said:

Elevation difference between radios of that magnitude (715') will change the game completely. Now your talking 10's of miles of range pretty easily. But yes, every terrain is different and you never really know what your gonna get.

Whoa. I just checked the map and the trail head I was planning to use for this test, is only actually about 175 feet lower than the peak. But if what you are saying is true, then I could possibly talk to someone at my house from Mt. Pisgah over 2 miles away. Since my elevation is about 400 feet lower than the peak, I might be able to make it happen. 

[73blazer]

17 hours ago, davidotoole said:

Whoa. I just checked the map and the trail head I was planning to use for this test, is only actually about 175 feet lower than the peak. But if what you are saying is true, then I could possibly talk to someone at my house from Mt. Pisgah over 2 miles away. Since my elevation is about 400 feet lower than the peak, I might be able to make it happen. 

With 175' of elevation difference and no major obstacles like other 200' hills in between, I would think 2miles would be pretty easy. I can hit a repeater about 6miles away on what I believe is about 150' tower in flatlands where I'm at from my house in fairly heavy woods, without any issue. Well, until the repeater went offline  a few weeks ago

[KAF6045]

On 3/27/2023 at 2:22 PM, davidotoole said:

Interesting. I'll have to choose my FRS model carefully then. Actually, I'm starting to wonder if I should even bother with FRS for this use case, because we only need one person on each squad with a radio, and we already have 3 GMRS licensees in the group.

As mentioned by others -- if you have enough GMRS licensees (remember, the license covers "immediate" family members, so if your group has such...), stick with the GMRS radios.

FRS radios compliant with the 2017 reorganization will approach 2W on 1-7 and 15-22. 8-14 is restricted to 0.5W ERP as they are splitting the GMRS repeater INPUT frequencies (1-7 split the GMRS output frequencies, but were also GMRS interstitials BEFORE FRS ever existed -- GMRS is allowed up to 5W on channels 1-7). A "proper" FRS will NOT have access to repeater inputs (23-30; aka rp15-rp22 and variations thereof).

I'd have to question the selection of channel 18 if using FRS radios in the mix -- that just smells of potentially interfering with repeater outputs. I'd probably stick with 1-7 as they are simplex only. I'd tend to "save" 15-22 for GMRS units that might be reaching repeater (of course, if there are no repeaters [open or closed] within miles of the locale, go ahead with that range).

If you do have FRS and GMRS in the mix, and if the GMRS radios have a medium power (or just are weak -- as both my BTech HTs are; just over 2W even though the V2 is supposed to be 5W -- the V1 was only 2W to start with), I'd suggest using medium (or whatever is near 2W) just to equalize the reach between FRS and GMRS units. At the least, it should extend battery life a bit on the GMRS stuff.

[davidotoole]

@KAF6045 Thanks so much for your advice. Yeah, we've decided to drop the FRS idea for now. And I'll use Channel 4 instead.