Selective Calling on CB

[CSL126]

I know that the FCC says that you can play tones over a frequency in the CB range to "tone call" someone or a group of people. How do you tone call someone? Does it come standard in some radios, or is it an addon? Does anyone know of any websites that have schematics for circuits that do selective calling on CB radios? or just any information about selective calling on CB in general... thanks for the help guys...

 

[kc4jgc]

I have never seen a CB rig with PL encode/decode or any other selective calling technique.

The simplest way to do this is with an external box. I don't know off the bat where one can be found; I'll look around.

 

[HighOnAtower]

Back in the late 1960's Lafayette Radio produced many C.B. Radios that had Selective Calling. There was a socket type jack on the rear of the radio. You had to purchase a seperate small box that plugged into the jack to encode and decode the selective call feature. It allowed the radio to sit muted untill the proper code was recieved. then it would sound an audible tone alert and un mute the audio. I also belive you could get it to flash your headlights and beep your horn . If it was in a mobile. Not many of these boxes were sold so they will be hard to find. It would be easy to buy a pl
incode decode board and install it in the radios you want to communicate with.

 

[CSL126]

Thanks for the replies guys... Where might I find one of these PL encode/decode boards at hightower? or will I have to make it?

 

[fmon]

CSL,

I shall try to copy the circuit (if i can find it) of a 1963 Sonar FS23 CB which had Tone Call. I was stationed in GTMO Cuba for three years and they had a microwave telephone system for calls from one side of the bay to the other (all one Naval Base) but divided by international water. Anyway, this Microwave system left a lot to be desired, it often failed.

I worked on the Leward Pt side of the base and road a Ferry back and forth to the main side where I lived with my family. I had two of these radios set up with tone call so we didn't have to put up with the skip and other worldly noises, one at our residence and the other in my office, The one in my office also had a phone patch, so when the cross bay phone system failed, people would call me if they needed to conduct business on the other side. I would tone my wife and patch the call from my side, she would take notes on what was needed, (this often included aircraft parts from main supply) then call the location on her side and pass the message, then return confirmation back through my patch. It wasn't long before CB's started showing up in various locations on the main side so the second middle man (my wife) could be left out. Crude, crude, crude, but make out with what you got.

BTW, if anyone wants to zoom in using Goggle Earth the location is:

19 degrees 54’00” N
75 degrees 11’00” W

Oh, and the FCC in GTMO is the communications officer, would he dare defy the need...not likely.

 

[HighOnAtower]

Selective Call Encoder/decoders will be more expensive than a PL or CTCSS type encoder/decoder.
For a cheap $38 pl or ctcss encoder/decoder try http://www.hobbytron.com/R-QT-1.html For a better unit try http://www.com-spec.com/index1.htm or http://www.transcendient.com
If you want a 2 tone encoder/decoder try http://www.norcommcorp.com/two-tone.htm also Ham Radio Outlets have various Pl CTCSS units.

 

[N5RLR]

For historical reference, Handic of Sweden also offered selective calling on/for some of their radios.

Their S12 selective calling unit with Model 1235:

[Credit: CB Museum.De. [click] Image hotlinked for illustrative purposes.]

With the proliferation of CTCSS and DTMF encoders and decoders, selective calling should be fairly simple to implement on CB [I'm surprised that manufacturers haven't offered it lately]. The problem is that making any changes/additions to the internals of a CB rig is technically against FCC Part 95.

 

[CSL126]

Ok, I have a Midland radio... how would i go about putting a PL tone encoder/decoder on the radio? Do you think that would be included in the instructions to the encoder by any chance?

 

[HillbillyUHF]

Ok, I have a Midland radio... how would i go about putting a PL tone encoder/decoder on the radio? Do you think that would be included in the instructions to the encoder by any chance?

Why Bother???????and risk doing something against the rules????with everything availible today on ham radio.....WHY BOTHER AT ALL???

 

[Joseph11]

It's not against the law to add a CTCSS encoder/decoder to a radio as long as you don't modify the inside of the radio.

 

[Skypilot007]

Ok...so you go and put this PL encoder/decoder on your midland CB. Does anyone else you know have a CB with the PL setup in it? Chances are, unless some of your freinds have their radios set up like yours you will be hard pressed to find anyone else these days running a setup like that. Most CBer's around here(very active CB area)seem more interested in running on FM and SSB and out of band(above ch40 and below ch1). Something to think about before adding such an option to your radio.

 

[HillbillyUHF]

It's not against the law to add a CTCSS encoder/decoder to a radio as long as you don't modify the inside of the radio.

I said"and risk doing something against the rules"
I never said anything about adding a ctcss ENCODE /DECODE to a radido was aginst the law were did you read that in my post???I don't remember typing that?I made a blanket statement bout modifying CB radio's in general was bein against the rules.Your to quick to jump the gun always trollin to stir up things.

 

[CSL126]

well see, me and a few of my friends have bases at our houses. we just wanted some way to tune everyone else out, because there are A LOT of people around here that use CB. I dont have a problem with getting a ham license, but I dont think the other guys would. We just want some way to either do selective calling or PL encode/decode.

 

[Joseph11]

HillbillyUHF: You quoted the post that CSL126 wrote about adding a CTCSS Encoder/Decoder box. When you quote a post, you're supposed to be replying or talking about that post. You, sir, are trying to stir things up.

 

[HillbillyUHF]

HillbillyUHF: You quoted the post that CSL126 wrote about adding a CTCSS Encoder/Decoder box. When you quote a post, you're supposed to be replying or talking about that post. You, sir, are trying to stir things up.

:roll:
Notgettin into this as per Mr B's orders today!
Case closed.
nuff said
HillbillyUHF
Southbound en DOWN

 

[KB8UYC]

well see, me and a few of my friends have bases at our houses. we just wanted some way to tune everyone else out, because there are A LOT of people around here that use CB. I dont have a problem with getting a ham license, but I dont think the other guys would. We just want some way to either do selective calling or PL encode/decode.

I believe that the CB rules are you cannot construe your message. So having Encode/Decode on a CB would be illegal. Besides, in order to put Encode/Decode into a CB radio of any sort would require modfing the radio. Again that is against the rules. If you dont want anyone to hear your conversations, perhaps dial your CB radio back down to 4 watts and use a different channel.

Besides, having Encode/Decode would be a rediculous function to have in a CB radio. Encode/Decode was not designed for CB. If you want privacy there is alway the telephone, otherwise enjoy the airways that is why they are called CITIZENS BAND!!

Eric

 

[grem467]

Would PL even work over AM? With all the noise and heterodynes, i think a decoder would have a hard time with that.

Of course there is FM, but that is outside of what is permissible anyway.\

What we used to do was use one of those speech inversion boxes, worked great, required zero modification to the radio. Of course this isnt DES level security, but it worked enough to keep most people out of the loop. The downside was the audio quality was horrid.

 

[gr8amp]

I believe that the CB rules are you cannot construe your message. So having Encode/Decode on a CB would be illegal. Besides, in order to put Encode/Decode into a CB radio of any sort would require modfing the radio. Again that is against the rules.

You dont seem to have a solid understanding of what tone squelch is. How does using a tone squelch, or some other type of selective calling "construe" your message? There is no privacy provided by using tone squelch, other people on the frequency will still hear what is being said.

Also, adding a selective calling function does not require making any internal modifications to the radio. Everything can be added externally.

If you dont want anyone to hear your conversations, perhaps dial your CB radio back down to 4 watts and use a different channel.

Where did anyone say anything about running higher levels of power, and what does that have to do with anything?? Trying to stir the pot?

Besides, having Encode/Decode would be a rediculous function to have in a CB radio. Encode/Decode was not designed for CB. If you want privacy there is alway the telephone, otherwise enjoy the airways that is why they are called CITIZENS BAND!!

C'mon..get real people. Please do explain why it would be a "rediculous function to have in a CB radio." I think it would be a great function to have, and there is nothing wrong with what CSL126 wants to do.



FYI....There is a specific section in the part 95 rules/regs that ALLOWS the use of selective calling. The only restriction being that audible tones can only be transmitted for a short period of time. Subaudible tones can be transmitted continuously. If you dont believe this, please do spend a few minutes and browse the regs at fcc.gov.

However, I must add that the use of CTCSS on CB is generally unreliable. Due to the nature of AM, beat tones created when multiple signals are present at the receiver will often cause falsing. It will work, but don't expect a great level of reliability. (as grem was saying)

Although I am not aware of any currently available "plug and play" options for CB, it wouldn't be terribly difficult to implement. Audio can be injected at the micropone input, and the decode end can be connected to the external speaker output (perhaps with a relay to provide the "squelch" function). Of course, if the frequency response of the TX/RX audio stages have a high pass cutoff which would filter subaudible tones, you may need to use tones in the voice range. In this case, there are DTMF encoders and decoders available (ramsey has one I think) that could work as well.

Good luck and have fun!
-Jim

 

[fmon]

grem467

Would PL even work over AM? With all the noise and heterodynes, i think a decoder would have a hard time with that.

It would be very unusual for these tones to be duplicated randomly, either intentionally or by nature.

This is the note in the service manual for the 1963 Sonar FS-23

The FS-23 operation can be enhanced by eliminating all of the objectionable reception through the use of a Sonar-Call two-tone squelch (an accessory). The receiver will remain quite and inoperative until the proper two tones are received by the FS-23. The use of Sonar-Calls provides a high degree of interference-free operation.

A second enhancement for the radio was VOX (also an accessory), which I did not have.

Over the years, I have cannibalized one radio to keep the second going but in reality quit trying to keep either in operation. I refused to modify the radio to go beyond the legal frequency and power out range. However, it would be very easy to do both. Bleeding all over my neighbors is not in my sea bag, which is the real reason for laws.

 

[fmon]

http://www.cb-museum.de/index2/Mikro-Mic/-/page1_g/page2/Herst_-_Manuf/R_-_S/Sonar/sonar.html
This link provided by Mike N5RLR in "For historical reference, Handic of Sweden also offered selective calling on/for some of their radios" shows the FS-23 without the Sonar-Call feature installed. However, note the location for a slide switch in the lower right (Standard Normal Call).

BTW, I have the G model also (bottom picture). 1960 vintage.
Thanks for the ->, Mike