Marine Electronics Forum - Scrambled/Secret Frequencies

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View Full Version : Scrambled/Secret Frequencies

Capt Phil
06-11-2002, 06:28 AM
Fishermen in my neck of the woods use there own special frequencies to communicate with their buddies with no risk of anyone listening.

Anybody do this sort of thing ?? It sure would be nice to be able to talk openly on the VHF. Cell phones always have issues.

It sure would be nice to have a "scanner" of some sort to pick these frequencies up. Is there 12V equipment out there for this ?

06-11-2002, 07:03 AM
Do you mean the so called "expansion channels?" Some radios can be modified to use some illegal channels, most can actually, its just a matter of finding someone to do it for you. I have hunted for the instructions for doing it and have had no success, though I've found a dealer or two that will do the mod for a charge. On the west coast there are a lot of guys using 2-meter ham radios, which operate in the same general frequency range that our VHF radios do. In order to use one of those leagally you have to have your HAM license (which would also be true of using the 'expansion'channels). There are also scramblers available for most high end radios and in some areas they are in common use. As an example if you were fishing out of Hatteras and listening in on channel 1 you'd often hear an annoying humm breaking squelch, that would be the boys with their scramblers. Actualy because there are only 124 codes in use (sequential numbers beginning with 001) its not big brain activity to find which one they are using.

Anyway, if its truly non-standard VHF channels they are using you can get to them by simply buying a 2-meter radio and modifying it for full range operation. I have one of them in my truck I modified. Its an ICOM and is about the same size as the old M-59, in fact uses the same mounting bracket, mine has all the bells and whistles, sends and receives on the Marine frequencys, can pick up all the weather channels (and could transmit on them too if I wanted to) and has a power output of 55 watts. All this and it costs less than $200.



"I command thee, O fish of the ocean, rise to my bait"

First Light
06-11-2002, 07:26 AM
Concur with what Thom said, but I would guess the anglers in your area are using "Standard Horizon" brand VHF radios with scramblers, which is the simplest of all methods of scrambling a VHF signal because it is a dealer "add-on." Standard Horizon has been offering a scrambling option as an add-on for 10-12 years now and a friend in Key West and I had them on our Standard brand radios. Cost was around $120 and as I recall the dealer had to order them for the specific channel we wanted to use.

Even if you have a scanner I don't believe a scanner will unscramble their transmissions - you'll need to know what frequency they are using and get scrambler for that particular frequency installed on your radio.

Capt Phil
06-11-2002, 07:59 AM
There are 2 different tjhings going on. Some guys scramble others have there own frequencies.

In fact they are usually ICOM 59's which is what I have. A friend of mine bought one at a yard sale and suprise ! he is able to hear all of the local highliners. That is worth some money !

06-11-2002, 08:26 AM
I know of one marine electronics shop that will modify your radio to receive the expansion channels for $50, and I have been told of another that will do it but I don't know how much they would charge.

You can buy the scrambler unit for any ICOM radio for about $100, its a simple plug in, not much different than adding memory to a computer actually. I think it took me all of 5 minutes to stick on in my M-127. Once you've got it all you do is park your butt on a channel that guys are using and start with it set to 001, if that doesn't break into their ever-so-secret stuff go to 002, and so on. I shouldn't take you over an hour to hit the code number they are using. After that, of course, your have to act just like the current administration, and share your valuable knowledge with noone.

On the frequency question, once again the modified 2-meter radio to the front of the line - all you have to do is take the modified 2-meter radio and hit the scan button. If they are out there it will find them.

I don't know if you all are aware of it or not but there was a Federal Register publication about a year ago from the FCC for comments on a proposed rule that would have cut the channel separation for marine VHFs in half, meaning that there would then be room for twice as many channels minus one. I never heard anything else about it ... and didn't really care to tell the truth /infopop/emoticons/icon_cool.gif


"I command thee, O fish of the ocean, rise to my bait"

06-11-2002, 10:48 AM
I think alot of guys are using the relatively innexpensive 10-meter radios, there are many on the market. These are 11-meter cb-radios that also have 10-meter channels installed. Most have 25-100 watts of power and ssb for long range communications. This setup gives you over 360- channels, 1080 if you consider the ssb option. These are of coarse illegal, but unregulated or checked. Prices for these radios run $200+ and you can run a regular 8' shakespeare cb antenna.

202 Scout Sportfisher, mainly fish Point Judith, Block Island, and Charlestown.

Capt Phil
06-11-2002, 11:07 AM
Thanks for your information. It sounds like I need "expansion" channels installed.

We have a great marine electronics shop nearby that can probably do it for me.

I'm not up on the radio communications terminology. Sorry if I saked the same question twice.


Capt Phil
06-11-2002, 11:09 AM
Where would I get a "modified 2 meter radio" ?

The shack ??


06-11-2002, 11:38 AM
Capt. Phil,

They show up on E-Bay all the time or you can simply buy a new radio and do the modification yourself - its that easy to do. I am using an ICOM 2100H which sells new for around $175 these days. In order to modify it for operation on the marine frequencys you simply remove two screws to pull the face plate off and then remove one diode that is well marked and put it back together. It has 100 memory channels that you can preset and give your own names to - which is what I've done with mine with the marine frequencys. It has three power outputs and if I remember them correctly they are 1, 10 and 55 watts - I know about the 55 watts, its the lower ones I'm not sure on. Its actually a very nice radio, very compact and very clear. I put the same power plug on mine that my M-127 has (and its the same ne I put on my M-59 as well) so all three are interchangable if the need be. I've only pulled it out of the truck once to use on the boat. I did that while my 127 was back at ICOM to have the MMSI programmed into it. Other than that I just use it to listen in on the marine frequencys when I'm on the road, to check the weather on those channels, and of course I have my HAM license so I continue to use it as a 2-meter.

Thom (KC8NID)

"I command thee, O fish of the ocean, rise to my bait"

06-11-2002, 12:51 PM
Get yourself one of these and you can listen to anything you want!! /infopop/emoticons/icon_biggrin.gif

Birdman, Capt of

Capt Phil
06-11-2002, 02:29 PM

Do I understand you correctly? With this scaning radio I would choose the marine band.... and it scans all available frequencies even the private ones ?

I like the sound of that. My guess is that I would need to use a 8' antenna for offshore ??

THANKS, I'm going shopping.

06-11-2002, 03:06 PM
Two points I might add to this discussion:

1. The Icom IC2100H will RECEIVE outside of the amateur bands without the modification Thom described. Unlike the Icom marine radios, it does not have provisions to plug in a descrambler (it's not weatherproof either). But, they are super radios at a great price (I have two of them)

I would NOT recommend one of these as a replacement for a regular marine VHF radio, especially for someone who is not a licensed amateur radio operator - with the out-of-band transmit modification, it's too easy to transmit on some frequency that could easily get someone into big trouble with the FCC. Also, the IC2100H is NOT FCC type accepted for use on marine frequencies.

2. NewMoon - don't count on a lack of enforcement on the 10M amateur bands. A local trucker recently received a visit from the FCC after his use of some "expansion channels" (within the 10M amateur band) on an imported CB radio was heard, located, and reported by local amateur radio operators. Since it was fairly obvious that his illegal operation was not intentional, he wasn't prosecuted, otherwise he probably would have received a fine for $10K or more.

Bryan, K4IOA

06-11-2002, 06:50 PM
Hi Capt Phil...

There's a few captains in Mass. waters using rather expensive but off the shelf sideband radios. It's not blackbox stuff but, you can hear them modulating after they use the secret handshake to go up or down on the "standby"...
As for scanners, ask the propeller heads at radio shack if their stuff is programmable to catch sideband etc...


06-12-2002, 06:34 AM

As I stated in my post that these 10/11 meter radios are in fact illegal, and yes on occassion somebody will be nabbed with them. But the fact is there are tens of thousands of these radios out there being used on a daily basis. The radios perform well give you a wide variety of channels, and can allow you to talk cross country if conditions are right.

The ham guys are the first to complain about these radios all the while they have the illegal 11-meter mods done to their radios and amps....Kind of amusing...

The modification of VHF radios I think would be illegal, as would running the 2-meter rigs without a ham license. So yes there are legal issues, but hey it's illegal to drive over 55mph in most states...

202 Scout Sportfisher, mainly fish Point Judith, Block Island, and Charlestown.

06-12-2002, 10:04 AM
NewMoon, no argument, there are probably thousands of 10/11 meter radios being used illegally every day, and probably several 2M rigs being used illegally as well.

I must take exception to your statement that:
quote:The ham guys are the first to complain about these radios all the while they have the illegal 11-meter mods done to their radios and amps....Kind of amusing...

I would find it very hard to believe that the very same hams who are complaining about illegal 10/11 meter radios are also operating illegally on 11M CB. Even if they have modified their rigs to operate on that band (which in and of itself is not illegal), I doubt seriously that they actually operate there. I won't deny that there are a few bad hams that do operate illegally on CB bands with amateur equipment - several got busted here in NC about a year ago - but they do not represent the amateur radio community in general.

It is not illegal for a licensed ham to modify any radio or amplifier for his own use on the 10M amateur band. It is illegal, however, to commercially manufacture or modify amplifiers for use on 10M or 11M. This prohibition came about during the CB craze years ago because most of the amplifiers being used illegally on CB were in fact being "marketed" as "10M amateur amplifiers" that could be modified very easily (clip one diode or resistor)to operate on CB.

Just don't want to encourage any fellow Hull Truth'ers to do anything illegal....or get busted for illegal operation....although some 2M rigs can be modified for marine frequency use, if the untrained user happens to hit the wrong key or dials in the wrong frequency by mistake, they could get into serious trouble

[This message was edited by Overcurrent on June 12, 2002 at 12:12 PM.]

06-12-2002, 10:35 AM

You're absolutly right and I should have put more emphisis on that.

There is nothing illegal about the modification to the 2-meter rigs and I can listen in all I want on mine. I can put it on the boat and use it there as either 2-meter (which I am licensed to do) or as a marine VHF, so long as I have it set to low power, nothing wrong there either. But if I were to key the mike while I had it tuned into one of the weather channels - a set of frequencys on which it will now transmit - I would be breaking the law. What is much more important than the fact that I would be breaking the law itself is that I would be stepping on the broadcast by NOAA and that would impede anyone nearby from receiving that weather information - which is potentially extremely important information for a boater to have.

So, yes, its possible to use a modified radio illegally but just its possession or even performaning the modification itself is not illegal. Of course if I was driving down the road chatting with guys on the marine frequency's that too would be illegal, but in fact its would be no worse than the fools who hog the airwaves while they are out there on their boats.


"I command thee, O fish of the ocean, rise to my bait"

06-12-2002, 11:28 AM
Capt. Phil,

Yes, you understand correctly. No, you don't need an 8' antenna, the 6" ruber ducky antena included will pick up anything your VHF radio will (with an 8'er on it) and more. The receivers in most scanners are much more sensitive.

Not to mention you can pick up cordless phones, cell phones, police, marine police, fire dept's, utilities companies, McDonalds, Burger King.....
(disclaimer: Listening to cell phones and cordless phones is illeagal in most states). Even though I think that is rediculous, how canthey tell me I'm NOT allowed to listen to something sent right into me? That's like throwing water at somebody and saying, you're NOT allowed to get wet with it!! Give me a break!

Birdman, Capt of

Capt Phil
06-12-2002, 11:32 AM

Thanks a million for the information. I always kind of knew there must be a way. Thats why this is such a good web site. I'll let you know how it works out.



06-12-2002, 11:34 AM
Thanks, Thom. You made the point a lot better than I did. Also, as we both know, the IC2100 is not particularly user-friendly to program, especially to an untrained user. Great radio, though.

Bryan (K4IOA)

Booby Trap
06-15-2002, 08:42 PM
You can "listen" legally to any frequency on the two meter ham radios....most will receive from 144mhz to 174mhz.......xmitting, well that's another story.

Many police frequencies fall within this band.

Thom, It's illegal for you to xmit on the marine bands with your icom 2 meter radio because it is not fcc approved for that band.

Newmoon, I can't imagine a ham radio operator thinking of using an 11 meter (CB) radio after working so hard to get a ham license and having endless other more interesting frequencies to use although I must admit that I do listen to it (CB) on the road traveling to and from Fla. and RI to get road info.

I use a Yaesu 2400 which can be used from 144-174 mhz and have seen them on e-bay for $100.00.....I paid more than $300.00 some years back.

Good luck all.....KA1K ham since (1976)

[This message was edited by Booby Trap on June 15, 2002 at 10:50 PM.]

06-16-2002, 08:05 AM
(CB raidos) maybe a cb raido would work? i've used them, summer time in the tuna bite the vhf gets stepped on a lot. they worked for me. but the other guys you fish with have to have them also.(kind of a code group thing)

06-17-2002, 04:17 AM
Seaswan, the capt "sideband" transmissions you refer to are not ssb, you can't hear ssb signals on a fm radio, they are in fact simple "voice inversion" scramblers used on a standard marine radio. Easy to decode /infopop/emoticons/icon_biggrin.gif My business /infopop/emoticons/icon_biggrin.gif

If I ever caught someone out there transmitting illegally out of band they would be bluefish chum...I have found many illegals over the easy I can drive to their a $2500 doppler direction finder in me truck /infopop/emoticons/icon_biggrin.gif

06-17-2002, 08:25 AM
Well the ham guys do in my area on occasion. They are bumping down 2000+watt Ameritrons on channel 6 to try and prove their superiority over the high power cb stations in the area. They also tend to appear on the typical ssb 11-meter channels when the DX is good.

I think on a strictly entertainment factor, listening to the channel 6 stations beating each other up, and the comments made are worth the price of listening admission...LOL. There are some real characters on there.

202 Scout Sportfisher, mainly fish Point Judith, Block Island, and Charlestown.

Eric S
06-17-2002, 08:31 AM
Does anyone know if the scramblers in VHF radios are digital or analog. You can buy a descrambler if they are analog. Also, does anyone know if the typical scanners will monitor "expansion channels" on VHF radios.

Eric S
06-17-2002, 08:32 AM
Forgot one question. Does anyone know the frequency range of the "expansion channels" on VHF.

06-17-2002, 01:41 PM
analog. simple voice inversion. What it does is split the voice band by adding a pilot tone, anything above the tone is made the inverse and vise versa. So it makes you sound like donald duck. You can retrain your brain to understand voice inversion, and it has been done easily enough, it's just that your brain has only been trained to understand normal voice not inverted.
Digital scramblers make you either hear straight squelch noise or just a hiss.

06-25-2002, 10:20 AM
In regards to voice-scrambled VHF's, most VHF mfgrs have approx 128 codes per channel on their scramble chips. If you have a Standard-Horizon, it can't unscramble a Motorola, which can't unscramble an Icom, which can't unscramble a Raytheon, which can't unscramble a Standard-Horizon and so on. You have to have the same brand radio on the same VHF channel on the same scramble code (of 128) to listen in on someone's private comms.

With the exception of professional electronics guys and the pros at such places as NSA, no regular Joe is going to be able to listen in on you.

Even if he has the same brand radio, scanning thru all the channels and then switching thru 128 codes is a real PITA and 99% not worth the effort. It's usually some guy bitching to his buddy about the crappy re-frozen ballyhoo he got at XYZ Bait Shop. /infopop/emoticons/icon_biggrin.gif

Five of my friends have the same brand scrambled VHF and we "go to scramble" all the time if we happen across a buncha tuna crashing baits on the surface, birds working a school of stripers, etc. We got these radios so we could get each other on the meat and not have a hot bite ruined by the kind of knucklehead(s) who regularly crashes right thru said school instead of trolling or casting from the perimeter and picking them off.


Member, I-Went-Lesbian-Fishing Club

06-25-2002, 10:59 AM
Heads up.

Digital scrambling of Sat Mobs..

Those with the gear (Read CIA / MI6 etc) can even unscramble digitally encoded sattelite transmissions using either "echelon" or "carnivore" program.

The scramble software encoder contains a surreptitiously "inserted" sub program that includes a microdot containing the encryption key in the scrambled transmission!

This is captured by "Echelon" (MI6) or "Carnivore" (CIA) and the microdot containing the encryption key examined and the text decrypted...real time.

Soo - even stuff like international bank all available to "those with the desire to know!".

Big bruther is watching all of us! /infopop/emoticons/icon_eek.gif

Like locks on houses - encryption only keeps the honest theives at bay! /infopop/emoticons/icon_wink.gif

Cheers n beers! /infopop/emoticons/icon_biggrin.gif ...sheesh - maybe I shoulda encrypted this /infopop/emoticons/icon_rolleyes.gif

06-28-2002, 12:17 AM
Actually, Trouty, it is a lot worse then that.
But who really cares? Unless you are doing some serious level stuff, no one really wants to know about your girlfriends . (Except maybe your wife)

06-28-2002, 03:03 AM

WOT could possibly be worse than big bruther listening on on your fav fishing hole GPS location? /infopop/emoticons/icon_eek.gif /infopop/emoticons/icon_biggrin.gif /infopop/emoticons/icon_wink.gif /infopop/emoticons/icon_razz.gif


06-28-2002, 05:12 AM
You can't use a scanner to listen in on a scrambled channel/frequency unless you enjoy listening to static/garble.

Also, if you use a scrambled radio, you can only communicate with someone else with a radio from the same vendor. This means ICOM can talk with ICOM and Standard can talk with Standard but ICOM can't talk with Standard and vice-versa.

It is also not easy to listen in on a scrambled channel even if you have a compatible radio because there are 127 different codes in my radio for example and you can NOT scan the scrambled codes to receive the transmission. You have to turn the radio off and then on again putting it in a mode where you can change the code number. Unless a conversation is taking place for a long time, probably in the neighborhood of 20 minutes, I imagine it is possible to find the code unless of course you get lucky enough to hit the code "lottery." The scrambled radios are designed to prevent this easy eavesdropping.

Happy communicating

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