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GMRS / FRS - Discussions related to GMRS (General Mobile Radio Service) and FRS (Family Radio Service) communications

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Old 08-31-2016, 3:56 PM
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Default GMRS help

So I can't find another thread about this, I think this is the closest to what I am looking for. I am fairly new to the radio world. I have used CB before but only with not really knowing what I was doing. I recently purchased a scanner and began to learn more about the world of radio. Just wanted to give y'all a little background. I am looking to get my GMRS license for myself and my family to use in emergency situations and maybe a little everyday use (ex: long trips, hunting camp, etc etc...). I have been reading on these forums and others about the way GMRS works. Although it still does not make a whole lot of sense to me. What I am wondering is if anyone can tell me a good "starter set" for lack of better wording. I am a hands on learner, so getting the equipment and essentially teaching myself to program it and work it would be what I would do. (of course with help from the internet haha) Any help would be greatly appreciated.
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Old 08-31-2016, 5:21 PM
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Depends on exactly what you are looking for.

You can purchase consumer grade FRS/GMRS hybrid radios at most retail stores. Programming is done from the front panel and you are pretty much limited to programming the CTCSS or DCS codes, and maybe a few other options like ring tones, alerts, etc.

If you are looking to get some commercial radios, it's a bit more of a challenge. There is only one consumer grade mobile radio out there, made by a Chinese company. I've never used one, but did see it at a trade show a few years back.

For a professional grade radio, you'll need a PC, programming software and programming cable. Before you pick a radio, you need to have a budget, as you can spend a lot of money really quick.
Back when I was active on GMRS, I used a couple of Icom F-4 portables and Icom F-420, Icom F-2020 and F-221 mobiles. Programming software was either DOS based or Windows based depending on the model.
They were not terribly difficult to program, but it does take some knowledge. Since they are professional radios they don't come with in-depth instructions intended for someone who hasn't programmed a radio before. There is some terminology that can be difficult to grasp at first, and there are things you can do to the radio, either on purpose or accidentally that can cause the radio to not function or even work outside the limitations of your license. Worst case is you can cause interference to other users, public safety users, etc.

But, don't let that scare you off. Finding a basic UHF commercial radio that has the necessary Part 95 certification can be a bit difficult. There are some active discussions on this site about finding the right ones, so I won't go into that.

The software takes some knowledge, but people here will help you out.
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Old 08-31-2016, 6:11 PM
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So basically what I'm wanting to do is have an area about 30 miles wide covered for close friends and family. I've talked to some people that have done just that. I know the price on that is fairly high, but i live in the baton rouge area and my friends and family live well outside of a 10 mile radius type of thing. So im willing to spend some but of course not go completely overboard so i guess a mid level system with repeater is where i want to start. Thank you for the help also
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Old 08-31-2016, 8:24 PM
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You will need a repeater to cover that sort of territory.
Repeaters can be had for a few hundred bucks. Trouble is they are not easy to set up. You'd do much better buying one pre-built with pre-tuned duplexers. It requires some specialized test equipment to properly set up a repeater system, and the right gear isn't cheap.

The other issue is to get that sort of coverage your repeater needs to be up high. I'm not familiar with the terrain there, but what you need is a hill or mountain in the area where you can place the repeater.
Short of that, you'll need a tall tower or building, and that isn't cheap.

You'd do better to check around and see if there is an existing GMRS repeater in your area. That will save you a LOT of money. Check with the repeater owner and find out what it would take to access their system. GMRS repeaters are private property and some owners will not allow others to use them, or charge for access.

Another option is amateur radio, but unless you can get each and every user to take their licenses test, that won't be an option.
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Old 09-01-2016, 5:04 AM
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Not hilly at all around here more low lying marsh than hills. I do have a friend that is also looking at getting his license, his grandparents house is probably the highest point that we can easily access (and cheaply). So if I bought a repeater that was pre-programmed and all, what kind of programming does it take on the units end. I have read and like you said the power variances and all can be changed on the units. But is there any major programming that has to be done between the repeater and the units themselves?
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Old 09-01-2016, 9:28 AM
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There is a website: (myGMRS.com - GMRS Repeater Directory) that provides information on GMRS repeaters. You might want to check the website for repeaters in your area that might be accessible. Keep in mind that many GMRS repeaters are to be used by permission only. I sent off an e-mail to a few of the repeater trustees in my area and all that responded gave me the go ahead. It's certainly worth a shot unless you have your heart set on setting up your own.
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Old 09-01-2016, 10:16 AM
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Quote:
Originally Posted by ChitheadDeSo View Post
Not hilly at all around here more low lying marsh than hills. I do have a friend that is also looking at getting his license, his grandparents house is probably the highest point that we can easily access (and cheaply). So if I bought a repeater that was pre-programmed and all, what kind of programming does it take on the units end. I have read and like you said the power variances and all can be changed on the units. But is there any major programming that has to be done between the repeater and the units themselves?
I agree with bharvey, check your area first to see if there is something available. Repeaters can be difficult to do right. Not impossible, but doing it right can get expensive.
For fairly flat terrain, your repeater antenna would need to be well over 100 feet high to get the sort of coverage you'd want. Towers are expensive, good coax is expensive, doing it all right so it doesn't fail is expensive.

Programming is the easy part compared to this.
To communicate through a repeater, you would need to program:
Transmit frequency. This would match the input frequency of the repeater. It would be 467.xxx
Receive frequency. This would match the output frequency of the repeater. It wold be 462.xxx
Since you don't want your repeater getting triggered by every stray noise it hears, your repeater would be programmed with a CTCSS or DCS code to filter out what you don't want it to repeat. So your portable, mobile and base radios would need to be programmed to transmit that same tone to activate the repeater.
And, preferably, you don't want to listen to all the unnecessary crap on the repeater output frequency, so ideally you'd program the repeater to transmit a CTCSS or DCS code out with repeated traffic. your mobiles, portables and bases would all need to listen for that tone.

There are other settings on the radios that you'd want to program. You'd want simplex (radio to radio) channels. You'd want to program the radio function buttons for various features, like scan, squelch code defeat, etc.
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Old 09-01-2016, 12:19 PM
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I looked at the website that bharvey posted and of course there is none around me. The house that I am talk about is somewhere around the ~70-80 feet to the roof (that is a rough guestimate) which would put the antenna around ~90-100 ft I believe, I will double check on that before I would put it up to make sure I am close to the 100' mark.

"Programming is the easy part compared to this.
To communicate through a repeater, you would need to program:
Transmit frequency. This would match the input frequency of the repeater. It would be 467.xxx
Receive frequency. This would match the output frequency of the repeater. It wold be 462.xxx
Since you don't want your repeater getting triggered by every stray noise it hears, your repeater would be programmed with a CTCSS or DCS code to filter out what you don't want it to repeat. So your portable, mobile and base radios would need to be programmed to transmit that same tone to activate the repeater.
And, preferably, you don't want to listen to all the unnecessary crap on the repeater output frequency, so ideally you'd program the repeater to transmit a CTCSS or DCS code out with repeated traffic. your mobiles, portables and bases would all need to listen for that tone."

That doesn't seem to terribly bad, especially after having figured out how to manually program a digital trunking system into my scanner (that was about a weeks worth of work cause I started from not knowing anything). But based on that, I know in the rules that you cannot "own" a set of frequencies, but how often do other people catch your repeater? Are there enough CTCSS or DCS codes that the likelyhood of many other people being on the correct frequency and correct codes high? Thank y'all again for all the help, been very helpful.
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Old 09-01-2016, 1:41 PM
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You've got the general idea down on the programming but as mmckenna said, that is the easy part. If you go the repeater route and decide to use one antenna for both transmit and receive, you'll need a duplexer that should be tuned once the antenna, feedline and radios are in place. Alternatively you could go with two antennas and separate them vertically, horizontally or both. The first alternative requires the use of specialized equipment, The second increases the cost as two antennas and feedlines are required. The latter scenario is more DIY friendly.
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Old 09-01-2016, 1:51 PM
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With the two antenna setup what kind of programming or tuning is left for that? It seems like it would take out the harder part(ie tuning the duplexer, which sounds like a chore in and of itself).
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Old 09-02-2016, 8:47 AM
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The radio programming aspect doesn't change although there is still repeater controller to contend with. Keep in mind that a repeater is both a receiver and and transmitter. It isn't uncommon to use two separate transceivers (especially in the HAM crowd) and dedicate each to a specific function - one to receive and one to transmit. The repeater controller causes the transmitter to engage when the receiver receives the proper signal (and CTCSS or DCS tone if desired). The transmitter is operating at the same time that the receiver is. If they are sharing an antenna, a filter must be used to prevent the power emitted from the transmitter from overloading and destroying the input circuitry of the receiver. This filter needs to be tuned precisely and it isn't easily accomplished without the proper tools. The alternative of using two antennas and separating them can mitigate the need for that filter if the antennas are far enough apart.

As mmckenna stated, a purpose built repeater would make many things simpler. If you go the two radio route, you have to keep in mind that most radios aren't built to transmit continuously. The output power is usually turned down substantially and an amplifier with the proper duty cycle is employed.

I hope this makes sense.
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Old 09-02-2016, 8:55 AM
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Determine the frequencies you will be using before ordering a duplexer. Almost always the company selling the duplexer will tune it for you before shipment.

Contrary to what many might expect, the most critical (and expensive!) parts of a repeater system are (in order) height, antenna gain, and coax. Do not try to be "cheap" on the antenna system or you will be disappointed...
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Old 09-02-2016, 7:15 PM
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Ok, so i didnt know what antenna gain was (very new haha), so i looked it up. However that confused me a little i somewhat understand what it means, but what im confused on is whether its better to go with high or low gain. Also, with the coax what kinds are good?
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Old 09-02-2016, 8:25 PM
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Depends on the application. Gain isn't free and usually comes at the cost of directionality. In the case of omnidirectional antennas its in the vertical pane of the radiation pattern. So a high gain antenna may not be suitable for all situations. However when you are trying to maximize coverage, it is often the best solution. Gain works with both receive and transmit though, power only works one way.


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Old 09-02-2016, 8:41 PM
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So a high gain antenna may not be suitable for all situations. However when you are trying to maximize coverage, it is often the best solution. Gain works with both receive and transmit though, power only works one way.


So if I'm understanding you correctly the gain allows for some of both transmit and recieve distances? But the higher power would be for transmit only?
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Old 09-02-2016, 8:57 PM
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Quote:
Originally Posted by ChitheadDeSo View Post
So a high gain antenna may not be suitable for all situations. However when you are trying to maximize coverage, it is often the best solution. Gain works with both receive and transmit though, power only works one way.


So if I'm understanding you correctly the gain allows for some of both transmit and recieve distances? But the higher power would be for transmit only?
Yes. For every 3 dB of gain you roughly double your radiated power. So a 25 W repeater through a 9 dBd antenna (assuming no line loss here) would perform identically to a 200W repeater on an antenna with no gain. However, any signal being receiver by that same antenna would also be 9 dB stronger.
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Old 09-03-2016, 7:44 AM
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Just a word of caution regarding repeaters... I've experimented with ham and GMRS repeaters, using both purpose-built and modified equipment, and have never been very happy with my residential locations. I used to live on the side of a small mountain so I had a pretty good height advantage. Even though I used large, high-quality coax and a large, commercial exposed dipole antenna, I was never able to get anywhere near the kind of coverage that you're looking for.

With repeaters, height is KING! The repeaters with the best coverage always seem to be located on tall towers, really tall buildings, or mountain-top locations where the antennas are totally in the clear and very prominent. They also seem to use high-quality, commercial (ie expensive) equipment almost exclusively. Anything less often results only in "local" coverage.

My experience.

John
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Old 09-03-2016, 10:11 AM
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Just a word of caution regarding repeaters... I've experimented with ham and GMRS repeaters, using both purpose-built and modified equipment, and have never been very happy with my residential locations. I used to live on the side of a small mountain so I had a pretty good height advantage. Even though I used large, high-quality coax and a large, commercial exposed dipole antenna, I was never able to get anywhere near the kind of coverage that you're looking for.

With repeaters, height is KING! The repeaters with the best coverage always seem to be located on tall towers, really tall buildings, or mountain-top locations where the antennas are totally in the clear and very prominent. They also seem to use high-quality, commercial (ie expensive) equipment almost exclusively. Anything less often results only in "local" coverage.

My experience.

John
I think a lot of it depends on terrain. I know a location on a hill 300 ft above valley floor that would work as well (if not better) as the site the local SO uses 3,000 ft above the valley floor for covering the valley…doesn't cover the into the ranges like the SO site does though. Every now and then I make it out to Colorado and New Mexico and go skiing, usually take a portable repeater with me. Ski Apache and Wolf Creek both provide resort coverage from a vehicle mounted repeater in the parking lot. Monarch and Sipapu are configured similarly and should cover similarly. You'd have trouble at Ski Cooper, Angle Fire, Red River and TSV due to a good portion of their runs being on the back side. I think that would pretty much eliminate Park City, the Canyons and Breck as well.
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Old 09-03-2016, 11:23 AM
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"The house that I am talk about is somewhere around the ~70-80 feet to the roof (that is a rough guestimate) "
I would point out that a normal "story" is only ten feet high. So you're talking about a seven to eight story tall building. If it is a two story house with an attic, it is more likely 35' to the peak of the roof.

And if you want to have a system that will live through a good storm, and need to use a tower or other high location, remember that it will have to be very much more robust (and expensive) than the usual consumer grade installation.

If you have a two-way radio company in the area, you might want to ask them about consulting or selling you a package. It won't be cheap, but there are a lot of important little things that you might not get right on a first time DIY project for this.
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