Help with correct radio frequency for project

[Gradio]

Hi Folks,

I am a complete radio knob and need your expert help with a project.

I need to figure what radio frequency is the correct and legal one to use for something I want to make.

Basically I want to have two hand held FRS type radios that have the Call function, and nothing else. So it has a button, you push it, and the other radio gets a beep. But I don't need to send any message of voice over the signal. Ideally they would be smaller than existing FRS radios, with small batteries and small antennas.

But I need to make sure there are no false calls from other radios. So they need to be on some sort of secure signal together.

And the distance the signal needs to work is a maximum of 500 feet, but it needs to work perfectly at that distance or less, on a clear line of sight.

So is the FRS signal the right one to use? Are there other radio frequencies that are legal without a license to use over that distance that would be more appropriate since I don't need to send voice?

Thanks so much for your help.

 

[Moleculo]

You could do that with FRS radios that have the CTCSS feature. Some radios call CTCSS "sub bands" or "privacy channels" or other names. You should be able to find one with a call feature also. Keep in mind that this does not make the radio completely secure...others *could* use your same channel and CTCSS tone. However, if there are not a lot of people around you using FRS radios, the chances of that happening are probably pretty slim. Unless you get a license of some type, you're going to have to use one of the public unlicensed services, which means that others can use them too. The trick is to just find a frequency that not many are using. That can be a real challenge in a big city, but is real easy in a smaller town.

Something like this would probably do what you want:

NEW Motorola EM1000 EM1000R 2-WAY FRS/GMRS RADIO NiMH - eBay (item 200403358766 end time Mar-07-10 10:21:34 PST)

 

[packrat]

Sounds nefarious to me.

 

[GLR]

If you really require everything you listed, good luck. I don't see this ever working the way you are hoping.

Problems:

1. handheld frs radio with call function and nothing else - not going to be easy
2. Ideally they would be smaller than existing FRS radios, with small batteries and small antennas - uhhh those radios are pretty small already, I've seen one that doubled as a wrist watch
3. I'm bored, I'm sure there are others though...

 

[GLR]

Sounds nefarious to me.

It doesn't to me but perhaps your meaning of the word is much different than mine and Webster's.

nefarious

- 3 dictionary results
ne·far·i·ous


–adjective extremely wicked or villainous; iniquitous: a nefarious plot.


Use nefarious in a Sentence


—Synonyms
flagitious, heinous, infamous; vile, atrocious, execrable.


—Antonyms
good, honest.


Wait...Gradio are you currently or have you ever been a terrorist?

 

[packrat]

Nope. Same definition as Mr. Webster.

 

[GLR]

uh oh....

 

[packrat]

Think about it. He wants a very small radio with 500 ft range that cant be inadvertently accessed by outsiders, and doesn't need to do anything but one radio transmit a tone and the other receive a tone. Tell me that doesn't sound nefarious to you.

 

[Robb]

Think about it. He wants a very small radio with 500 ft range that cant be inadvertently accessed by outsiders, and doesn't need to do anything but one radio transmit a tone and the other receive a tone. Tell me that doesn't sound nefarious to you.

I saw your point when you first made it. I agree.
Such a thing can trigger b___s
Surveilance is another possibility...

 

[GLR]

I see no other option but for the admins here to ban this potential terrorist immediately!

packrat thank you for seeing what I was unable to see, I will do better in the future

 

[GLR]

I gave the terrorist negative rep points. I suggest everyone else do the same.

GOD BLESS AMERICA

 

[GLR]

Currently Active Users Viewing This Thread: 3 (3 members and 0 guests) GLR, Robb

And now we have an invisible member... Is this the end?

 

[packrat]

 

[mackmobile43]

I see no other option but for the admins here to ban this potential terrorist immediately!

packrat thank you for seeing what I was unable to see, I will do better in the future

it's there duty to report this to home land tierany.

 

[GLR]

screw this, I'm putting on my karate gi

if the terrorists are coming I plan on being prepared