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#155897 - 11/21/08 05:12 PM Re: Advice on FRS/GMRS radio [Re: GoatMan]
Am_Fear_Liath_Mor Offline
Carpal Tunnel

Registered: 08/03/07
Posts: 3077
Quote:
You can't encrypt radio communications with commercial radios. It's illegal and commercial equipment isn't capible of it. That is only something the military and select government offices can do. Even the police can't do it. It is prohibited by the FCC. Most people who think they are using a encrypted, secure, private, etc channel are simply using a digital filter or trunked frequency.

FRS, GMRS, MURS, HAM (VHF/UHF) etc are all in the clear. The digital "filters" or "voice privacy scrambler" is only the CTCSS or DCS tone. It helps you filter out others communication. It doesn't keep yours private. If you are set to the same tone you can hear the communication. But so can everyone who is not using any tone (ex. channel 5 privacy channel 0) or anyone with a scanner.

Even police, airports and most government communications that may be on digitally trunked frequencies can be monitored with a digital trunking scanner. Again, the FCC prohibits anything encrypted from going over the airwaves and most radio equipment can't do it anyway.


Ahah, sounds like a challange for my PIC board.. wink


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#155903 - 11/21/08 05:57 PM Re: Advice on FRS/GMRS radio [Re: Am_Fear_Liath_Mor]
Lon Offline
Member

Registered: 11/14/08
Posts: 115
Loc: middle Tennessee
I can recommend the Midland GXT800 or GXT900 radios. Those are available from Amazon and other sources.
I have had a set of the GXT800 "2-way radios" for a couple of years, and have been happy with them.
For the price, they seem to have a lot of features, a few of which are: can operate on GMRS or FRS, receives NOAA Weather radio, charger stand included. One "backup" feature I really like is that you can use the rechargeable battery, or power the radios with standard AA batteries.
Pay no attention to the stated 26 mile range (or whatever the package claims). You might get that range on a lake, or under special circumstances. But, in most instances, if you hike to the other side of the ridge, or generally put too many obstacles between the 2 radios, your communication will be lost.

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#155914 - 11/21/08 06:34 PM Re: Advice on FRS/GMRS radio [Re: Am_Fear_Liath_Mor]
Eugene Offline
Carpal Tunnel

Registered: 12/26/02
Posts: 2800
Man, I sold all my pic stuff a few years ago, should have kept it

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#155919 - 11/21/08 07:06 PM Re: Advice on FRS/GMRS radio [Re: Eugene]
unimogbert Offline
Old Hand

Registered: 08/10/06
Posts: 837
Loc: Colorado
About 9 years ago I did a true range test with Motorola Talkabout FRS radios. The comparison was against a handheld CB radio paired with a car CB radio.

I put my father on top of the local earthen dam then drove away from him using GPS to check distance.

The CB was unusable at 1/4 mi. (summer daytime)

The Talkabouts were still working full quieting at 7 miles.(True line of sight.)

Have also used it to stay in touch with him while I climbed a mountain. He stayed in the valley bottom and fished. Probably had 2 mile range.

Any obstructions such as trees or building materials would drastically reduce range.

I don't know the specifics of the brands but FRS is really convenient and quite efficient so long as you completely comprehend the limitations of Line Of Sight.
(It's what CB should have been all along.)

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#155920 - 11/21/08 07:08 PM Re: Advice on FRS/GMRS radio [Re: Lon]
benjammin Offline
Rapscallion
Carpal Tunnel

Registered: 02/06/04
Posts: 4018
Loc: Anchorage AK
Well, I was referring to Motorola's Eavesdrop Reducer Technology, which is a very basic analog inversion scrambler of sorts available on their FRS/GMRS radios (like the T6220 model). Voice inversion is an archaic and simple form of encryption, but not entirely effective. The FCC concluded there was just enough intelligence in the transmission that it wouldn't be considered illegal, but a casual listener is not going to be able to follow the conversation that well. I know because I've tried. This form of inversion is quite old, simple, and can be found in many higher end FRS/GMRS radios. Let's make this quite clear, analog inversion of this nature is not the same thing as private tone, PL tone, CTCSS, or any other control tone or digital control tone scheme. It is a processing of the audio signal that alters the content of the audio intelligence, not just adding a low frequency tone to the mix. Digital filters and trunking are something entirely different also. There are also a whole host of public agencies that can and do use some form of encryption, usually digital. DES is supposed to be only for the Federal Government use, but you will find DES units at hamfests on a regular basis. There are also a number of industrial two way communications using DVP encryption, which is perfectly legal.

Here's a site that talks a bit about basic encryption. http://www.fordyce.org/scanning/scanning_info/encrypt.html

I used to do a lot of work on DES encrypted radios for the Feds, and we had some more complicated analog encryption add-ons for a couple of metro drug and undercover units that we put together for local police departments. I also recall adding a couple of split double inversion sweep tone encryption circuits to some industrial radios, but that was way back in the 80s. Stepping into the wayback machine, I saw some pretty interesting encrypted stuff in the Navy, but I was a spook back then, and the Russians were trying everything they could think of to keep our nose out of their business.

If I had my druthers, I would use spread spectrum transmissions for all my communication needs. Who needs encryption when your signal is bouncing over a 100 Mhz band unpredictably?
_________________________
The ultimate result of shielding men from the effects of folly is to fill the world with fools.
-- Herbert Spencer, English Philosopher (1820-1903)

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#155923 - 11/21/08 07:45 PM Re: Advice on FRS/GMRS radio [Re: benjammin]
haertig Offline
Pooh-Bah

Registered: 03/13/05
Posts: 1841
Loc: Colorado
I've had four of the Kenwood UBZ-LF14 FRS radios for years and they have been great.

http://www.gearqueen.com/gear/comm/2004-04-kenwood-ubz-lf14.html

This model is no longer made, but I think the replacement is the LH14. I bought my FRS radios from here: http://www.bills2way.com/ that was many years ago, but I think they're still in business. Their website is still there.

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#155936 - 11/21/08 09:19 PM Re: Advice on FRS/GMRS radio [Re: Roarmeister]
TeacherRO Offline
Pooh-Bah

Registered: 03/11/05
Posts: 2107
Get a high mile rating 18 or higher. Sets of these are often available on ebay, too.

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#155966 - 11/22/08 02:02 AM Re: Advice on FRS/GMRS radio [Re: Lon]
Roarmeister Offline
Old Hand

Registered: 09/12/01
Posts: 837
Loc: Saskatchewan, Canada
Thanks for the recommendation. I also found a great website that also provided a lot of really good detail. http://www.twowayradioforum.com/forum/index.php

I see they rate the Midland GTX900 as well as the Cobra LI72002WXVP and the Motorola TALKABOUT T9500XLR very highly. The Midland seems to have more features than the Cobra model and cheaper but the Cobra model has awesome battery life. The Midland is more flexible with its power options however and can use either 4-AA or the rechargeable battery pack. The 20 "extra" channels on the Midland are actually preset FRS/GMRS channels with preset codes. Nothing more than what you already have except the quick setting of these channels! A chart mapping the channels/codes has been published on the above website.

I've got a bit more price/feature shopping to do but I expect that with Christmas around the corner, that sales of these radios may be coming very soon.

--
BTW, in Canada, we do not have the GMRS licensing restrictions you have in the States. GMRS radios up to 2 watts output (not input) do not require any licensing. smile

And yes, I don't believe the stated range for a moment! Not unless you are calling from mountain top to mountain top with clear line of sight!

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#156021 - 11/22/08 05:51 PM Re: Advice on FRS/GMRS radio [Re: GoatMan]
KG2V Offline

Veteran

Registered: 08/19/03
Posts: 1371
Loc: Queens, New York City
Originally Posted By: GoatMan
You can't encrypt radio communications with commercial radios. It's illegal and commercial equipment isn't capible of it. That is only something the military and select government offices can do. Even the police can't do it. It is prohibited by the FCC. Most people who think they are using a encrypted, secure, private, etc channel are simply using a digital filter or trunked frequency.


Not exactly true - Mpst police CAN, but choose not to

Originally Posted By: GoatMan

FRS, GMRS, MURS, HAM (VHF/UHF) etc are all in the clear. The digital "filters" or "voice privacy scrambler" is only the CTCSS or DCS tone. It helps you filter out others communication. It doesn't keep yours private. If you are set to the same tone you can hear the communication. But so can everyone who is not using any tone (ex. channel 5 privacy channel 0) or anyone with a scanner.


There is some debate on this - IF you are using a "Known algorythem" and transmit the KEY in the clear, it seems that the FCC considers this to no longer be encrypted, but the average user is NOT capable of decoding - but, as I said, your ID and key have to go 'in the clear'

Originally Posted By: GoatMan

Even police, airports and most government communications that may be on digitally trunked frequencies can be monitored with a digital trunking scanner. Again, the FCC prohibits anything encrypted from going over the airwaves and most radio equipment can't do it anyway.


As I said, Police, Fire etc have no problem getting permission to go encrypted, it's just it's a hassle to do so, so they usually only do it for "tactical" police channels - I own at least for radios capable of AGIS encription, and folks wouldn't be buying a multi hundred dollar option if they weren't using it
_________________________
73 de KG2V
You are what you do when it counts - The Masso
Homepage: http://www.thegallos.com
Blog: http://kg2v.blogspot.com

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#156765 - 12/01/08 05:40 PM Re: Advice on FRS/GMRS radio [Re: KG2V]
GoatMan Offline
Journeyman

Registered: 08/17/07
Posts: 98
Well I clearly stand corrected on the encryption component. Finding information on the web for PIC boards, NPV and AGIS is scarce, but I guess I've never been exposed to them before this. Sounds like something to read up on.

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