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What band would YOU use for basic, conventional digital voice up in the mountains?

I live up in the mountains and have been using VHF (150s) the whole time. Generally speaking, I can get farther range-per-watt up here using VHF than UHF or 700/800, right?

With all these new networks I see going up in 700/800 digital, just has me thinking about things. Seems 700/800 digital is the hot ticket item nowadays.

EVERYTHING is VHF up here, and - ironically, there is a new P25 trunking network up here that is in the low 160s, lol. I guess those should be my clues, right?

I recall an article in MRT several years ago after the rash of California wildfires stating that the general consenus was that VHF highband was the most reliable in your mountainous areas.

I'd stick to high band. UHF, 800, and 900 are well suited for plains and urban, but suffer in mountainous terrain.

I second VHF as well; its the standard!

Are you married to the idea of digital? Low Band VHF has some spectacular range. However, because of the antenna size, portables aren't the best for this. A decent mobile antenna and you're going to out-range anything else watt-for-watt. I've used low band simplex full-quieting in places high-band VHF wouldn't cut the cheese at all.

Is there a radio that has digital in the VHF low band spectrum?

VHF Analog all the way!

Renamon wrote:What band would YOU use for basic, conventional digital voice up in the mountains?

First off, I wouldn't use digital at all "up in the mountains".
I'd use Low Band all the way. Second choice would be VHF Hi.
Conventional Analog VHF

Forget about UHF and 700/800 unless you have millions to spend on a simulcast system (about 1 million a site) plus the million or better for the control system.

VHF high and low have pro's and con's

High band gives you digital ability, and digital will work better than analog.
High band equipment is readily available used if you desire it for cost savings.
High band 100 watt equipment is readily available for mobile application (unlike UHF or 700/800) there ARE UHF 100 mobiles, but not for 800
High band has a bit less long distance and 'SKIP' ability so interference will be lower with it than low band VHF

Cons are lack of channels, does get some skip depending on atmosphere

Low band does have skip issues, so interference is possible.
There are no low band VHF digital radios
Antenna's are large, gain antenna's are huge
Used equipment is not as available

Pro's are low band has long range, even in mountainous area's
Power requirements aren't as high for long distance communication
Channels are easy to get in most area's as everyone moves off to trunked systems.
Distance if superior to any other band.


Not knowing what service this is for, what requirements there are by the customer, solid answers can't be made.
But this is a good starting point for considering your options.

Wouldn't a 100 Watt 800 MHz cause some harm to one? I mean wouldn't it fry you?

CAPTLPOL wrote:Wouldn't a 100 Watt 800 MHz cause some harm to one? I mean wouldn't it fry you?

Only if you stand right in front of it. In rough calculations, isotropics loss of Rf at 800MHz through free-space (air) gives approximately 50 db loss at 10 meters of horizontal separation. So at that point the 100 watts is more like .001 watts. Vertical separation is roughly greater by a factor of 10, so even much less exposure if 10 meters up a tower & you're on the ground. Make sense?

I imagine he was referring to a mobile power level, yeah up on a tower no real issue. Personally I use the fully shielded NMO with double shielded coax in my vehicles, most of the NMO's have the coax attaching to the mount with a blob of solder and a plastic cover over this (no RF shielding at all into the vehicle interior). On my standard cab pickup I noticed the bottom of my NMO mount was about a foot from my head, that's when I started seeing the need for shielded mounts and with todays heavily electronic controlled vehicles doesn't hurt to keep the stray RF out either. Far as the original topic like everyone else VHF is the way to go, I'd only add to stick with 1/4 wave antennas on the mobiles, the narrower beamwidth gain antennas go in and out on anything but mostly level terrain.

I am not married to digital, just all my equipment is capable and I use P25 unless I have range/interference issues, then use analog.

I messed around with VHF-LO a couple years ago. While the range was great, the need to have a VRS so I could use a handheld was not worth it. Was cool for a while (felt like CHP), but ended up selling it all off.

The smaller antennas on higher bands are nice, but not a problem. Have a 5/8 3db and a 1/4 unity on my car right now, works well; one for over and one for out. Widebands on the portables.

If it ain't broke, don't fix it. Nothing is broken here now, works great actually. Just have had the itch to change something up.

What do you think?

Since you asked what band, I certainly concur that VHF high band seems like a good choice. Just for fun, you might want to consider programming your VHF high band frequency with one analog channel and one digital channel. Then you have the questions of carrier squelch, PL, or DPL. My vote is for analog PL. I seem to recall reading in the past that a DPL channel might need a little bit more signal than a plain analog PL channel. That way after you compare and contrast analog vs. digital modulation you can post your results here.

The other thing I have just know began to wonder about is how simplex P25 would compare to MOTO TRBO on VHF high band. Does anybody know if they would perform virtually the same or might their be differences on simplex? Just wondering.

As far as the digital (Astro CAI) vs analog, digital will beat it hands down.
Assuming that this is a discussion about a commercial system, when you narrowband, you WILL loose coverage on analog.

One of the issues with narrow band is that you are putting the same amount of information in half the space.
To do this you amplify the information on the carrier twice as much to recover it.
This means that you amplify the noise floor twice as much as well.


Personal experience is that talking to a person at a fixed station in wide band analog, right at the noise floor and barely readable, when we switch to ASTRO CAI
the other station is clear. If that station were narrow band analog, due to being just above the noise floor, there would be nothing intelligible from them.

Because Astro uses less bandwidth to begin with, it can be recovered with greater reliability with everything else being equal.

We have noticed marked improvements with coverage with MOTOTRBO as well, for the same reason.

RadioSouth wrote:I imagine he was referring to a mobile power level, yeah up on a tower no real issue.

I've never heard of a 100 watt 800MHz mobile, so I assumed he meant Quantar repeater or similar.

I haven't either, when he expressed concerns over RF exposure at 100 Watts on 800 MHz could see that being a problem if it existed in a mobile setting but not up on a tower (unless you live in a high rise next to the antenna). I've had a few 800 MHz mobiles (Moto and EFJ) only 35 watts on the high power one's, 15 on the low. all the portables were 3 W max.

LOW band all the way

Hello:
I was wondering why only two others besides my self wasnt saying lo band all the way.
In all honesty isnt the 42 to 50 mhz or any of the other lower bands the better choice over all of the higher bands ?
I realize skip can be an issue on lower freqs but if your looking to get the best performer in mountainous areas id have to believe lo band is the answer accepting some skip issues.
Id like to hear everyones experience and iedas on this original postees qestion as i too have been asked what freq band would be best in canadian type fishing terrain .
I know there is the legal licensing issues ect but that not being a problem which band is best suited for that type of terrain and use ?
Satelite

Low band is kick especially in mountains. The ground wave hugs every curve and laughs at green leaf attenuation. But! Getting the antenna right on some vehicles is difficult, and getting the noise floor down is more difficult.

Well, there are mountains all around me, but a BIG lake in the middle (so lots of nothing for miles). Most of the time, we are all within a few miles of each other, so p25 (OFB to boot!) usually works fine.

Satelite wrote:Hello:
I was wondering why only two others besides my self wasnt saying lo band all the way.
In all honesty isnt the 42 to 50 mhz or any of the other lower bands the better choice over all of the higher bands ?

It's the pain-in-the-arse factor.

For sheer distance outdoors, yes, low band will generally out perform VHF high by a significant margin. Some issues, which others have touched on, is general unavailability of modern equipment...repeater duplexers and antennas tend to be HUGE...the need to cut portable antennas for a specific frequency if you expect it to work well at all, thus limiting what frequencies it can operate on. Tuning a mobile antenna can be very tricky! You cannot do it inside an install bay, and you need to be outdoors a good 50 feet away from any metal sided buildings, and even then, with your wattmeter on you can see the VSWR changing with the passing of large trucks on a nearby road...craziness! Start by cutting your whip at least 4 inches longer than the chart recommends, as each vehicle will be different, then work your way to your best VSWR in 1/4-inch increments, then by 1/8-inch or less when you get close. On top of all the pain in the arse things mentioned above, low band is much more negatively affected by atmospheric conditions than other bands...I've seen overall range vary as much as 20% depending on the weather...mind you even at 80% it's much farther than VHF high, but still hard to explain to a customer why it is so.

Motorola still sells low band CDM and HT if anyone wants it

They sell a VHF-LO HT!?!?!?!

Yes, among several low-band HT's there is the HT1250. Here are two examples of low band HT1250's, along with the model numbers:


as stated from "M" -



•AAH25BEF9AA5-N
HT1250 Display-Limited Keypad Low Band (29.7-40MHz) 128 Channel 1-6 Watt Portable Radio
•AAH25CEF9AA5-N
HT1250 Display-Limited Keypad Low Band (35-50MHz) 128 Channel 1-6 Watt Portable Radio

So yes, they DO exist, but there are NOT many around. Occasionally you will find a few on E-B@! as well.

Low band VHF works well out in the open. One other problem is that low band portables and pagers don't work well in buildings with steel and reinforced concrete, or inside vehicles. I had FD radios/pagers on 33.98 and 46.12 that didn't work well in the truck or in hospital ER depts. I had to have an external mobile antenna on 33.98 for the pager or I would miss calls.

On 52.525 using 5 watt Ten-Tec radios, a buddy of mine and I could work 30 miles base/mobile simplex around Fairbanks AK which included hilly areas. Unless we had whips on the portables, coverage with helical antennas on low band portables stunk.

So, low band base-base, base-mobile, and mobile-mobile coverage in rural areas is great. Typical portable/pager operation is not so good. If you can afford low band duplexers, repeaters can have phenomenal range.

If you want portable/repeater operation, coverage in buildings, smaller antennas, stick with VHF high band. That's what we use for SAR in Alaska where operation is predominately portable.

-Pierre