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Author Topic: Wilderness Hiking - Inter-group communications  (Read 6741 times)
K1WMT
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Posts: 27




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« on: June 29, 2015, 07:41:39 PM »

Hey everyone,

Long time hiker.  
For starters, I'm a licensed Ham Extra and GMRS operator.  I have an ACR transponder.  I even have a whistle.   Whew, that's out of the way.
Often my hiking groups split into two, a faster and a slower group.   As the leader I need to keep in touch with both groups when on the move / on the trail.  Very often we are under the forest canopy.

For the last few years, I used GMRS @ 2 watt.  It wasn't bad, but it was choppy.  So I grabbed a chinese HT and pump out GMRS @ 5 watt.  From a technical point of view, would there be any value in going to VHF /2 meter?  Please put aside the license issues for a moment and just focus on the technical merits.  Is the VHF going to punch through the forest any better than GMRS/UHF?  

My groups are usually between 1/4 and 1 mile apart.   I recognize that every time a group goes up, under and around a hill, rock or other immoveable object we are impaired.  However we have been fairly successful because we hike somewhat steep mountains, rather than horizontal topology.

I see counselors at lots of overnight camps for kids using VHF business class HT.  But since most of the camps are on a pond and the facilities surround the pond, line of sight usually isn't a problem.

Maybe an easier way to ask the question is, with all things equal, and you were told you could only take one pair of HT radio into the woods with you, for talking to another group, would you pick a  GMRS or a 2meter HT?

Thanks!
« Last Edit: June 29, 2015, 07:53:54 PM by K1WMT » Logged
WB6BYU
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Posts: 18389




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« Reply #1 on: June 29, 2015, 11:33:23 PM »

Quote from: K1WMT

Maybe an easier way to ask the question is, with all things equal, and you were told you could only take one pair of HT radio into the woods with you, for talking to another group, would you pick a  GMRS or a 2meter HT?


I'd take a better antenna.


Actually I've spent a lot of time in the woods with a radio, both working for the
Forest Service and as a Search and Rescue volunteer.  I also chase radio signals
through the woods as a sport.

I've never used UHF in such conditions, but VHF-HI band 130 - 170MHz usually
has no problems covering up to a mile in most terrain:  sometimes less, but often
much more, especially with a good antenna.

I never used a rubber duck with the Forest Service.  The pack set radios had
a flexible whip that bent over inside the canvas case.  Later HTs had a telescoping
whip:  they received well enough with the whip down for monitoring, then
you would stop and extend the whip to transmit.  (The whips didn't last long if
you walked around with it extended.)   Coverage was usually several miles at
least:  the first Forest I worked on used primarily simplex, though you could
call a fire lookout and ask them to turn on a repeater if needed.  In Alaska
we had a pretty good repeater system, but local conversations still used simplex.

For Search and Rescue we used rubber ducks and coverage was somewhat less,
but we usually could manage 1 - 5 miles when the radios were working properly.
Part of our coverage area was a rugged canyon, where we might cover 1/2 to 1
mile between handhelds, or 3 miles from a mobile, depending on the number of
bends between us.  One of the first things we did when sending a team up the
canyon was to send a relay team up to a nearby ridge - that gave pretty good
coverage for the first 7 miles until they got behind the next ridge over.


So 2m should work, with these guidelines:
1. Understand the limitations.  Take advantage of high points to contact the
other station.  Sometimes you might have to walk up the side of a hill a bit
to get a better shot in their direction.  And have a plan what to do when you
can't make radio contact.

In one case my crew was on the back side of a ridge from a repeater and
couldn't hit it to call the helicopter to pick us up.  I climbed 30' up a spruce
tree with the radio: I still couldn't hit the repeater, but I could hit the
dispatcher's remote base 100 miles away (direct shot between the islands)
on simplex, and she relayed the message.

2.  Use an effective antenna.  The telescoping 1/4wave whips actually
worked well. If you need more gain use a 1/2 wave whip, but don't try to
walk around with it extended.  Do NOT use a 5/8 wave whip - they are poor.
A hanging radial wire can help, too.

The best antenna I used was a half wave end-fed mounted on my pack frame
to give it some height.  It was quite effective, though still didn't give 100%
coverage at all times.  Well, actually the 3-element yagi I use for transmitter
hunting while running through the woods has higher gain...
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N9BH
Member

Posts: 109




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« Reply #2 on: June 30, 2015, 05:12:50 AM »

I agree, better antenna. You might even consider something like a 1/4 wave ground plane made out of solid house wire you could mount on a short hand held pole for when signals get weak. Crunch it up when not in use. Though not good in the woods, I once made a 1/4 wave ground plane for 2 meters and used some PVC and strapping to mount it on my back, over my head.  Worked much better than the rubber duck.
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N7EKU
Member

Posts: 1037




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« Reply #3 on: June 30, 2015, 10:38:15 PM »

Hi,

Don't CB HT's go farther than those little GMRS radios?  There are tons of used super cheap Realistic ones on ebay all the time.  Most use plain AA batteries which is nice.  Might be worth a try?

Got this off some "Zombie Apocalypse" site:



The solid red line and first distance number is for "90% reliable" communications,  The next distance number on some of them is for 75%, and the yellow line is for 25%.

73,


Mark/n7eku
« Last Edit: July 01, 2015, 11:24:36 AM by N7EKU » Logged

Mark -- N7EKU/VE3
G8YMW
Member

Posts: 750




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« Reply #4 on: July 01, 2015, 03:15:43 AM »

UHF (and higher) have problems with foliage absorbing the signal that VHF and lower doesn't suffer from.
On that chart, I would say that 2 metres would perform better than the chart suggests unless the aerial supplied is a cheapo rubber duck. A full length flexy Quarter wave will WELL out perform a handy's stock aerial
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73 de Tony
Windows 10:  Making me profane since March 2017
N7EKU
Member

Posts: 1037




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« Reply #5 on: July 02, 2015, 09:23:11 AM »

UHF (and higher) have problems with foliage absorbing the signal that VHF and lower doesn't suffer from.
On that chart, I would say that 2 metres would perform better than the chart suggests unless the aerial supplied is a cheapo rubber duck. A full length flexy Quarter wave will WELL out perform a handy's stock aerial

For sure g8ymw,

I'm pretty sure those charts were made up based on stock antennas -- they were trying to show what consumers could expect from standard purchased radios.

I just found some other posts on those Reaslistic CB HT's.  The user had 5W ones with the longer Radio Shack (mid point loading coil) CB BNC whips.   He was saying the reliable minimum range was 5-6mi and long range with clear terrain was about double that.

I guess for the OP it depends on if they want occasional or frequent communication, because I wouldn't really actively hike with an antenna like that extended and those HT's are not small.

73,



Mark/n7eku

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Mark -- N7EKU/VE3
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