What radio frequency for handheld pager to pager device?

[Pradio]

Hi Folks,

I am a total radio knob, needing help with a project. So thanks in advance for your help and patience.

So I have this idea for a new game that requires a very simple remote control radio device. Basically I want to have a person to person pager, that runs off some form of radio band. Essentially I want to have the function of the call button on a walkie talkie, that makes another unit vibrate. And vise versa. But I don't need any voice communication. So a handheld device, battery powered, and very small, that has a button that pages an identical device via radio, and makes it vibrate. Initially I thought I would use the FRS radio band, but after looking into the FCC rules I believe I discovered that they will not allow that without the ability to transmit voice back and forth.

The travel range I need these to work within is fairly short, say a maximum of 300 to 500 feet, all in line of sight. The only requirements I have is that the devices be as small as possible, have as short of antenna as possible while still working very reliably, and a small battery. So I am assuming to get a short antenna I will need a higher frequency of radio transmission?

So my question to you is, with all your experience with radio, what do you think would be the best radio frequency band to use that would be legal with the FCC without any license? Do you know of a similar product that uses this band that I could check out and see if it would work?

Thanks for your help with this.

[gewecke]

You CAN use an frs radio for this legally and with no problem! Many of them will allow vibration pages only. IF you are a ham then there are many ham talkies which allow you to page privately over much longer distances as well.
n9zas

[kcoleman]

How about the small customer pagers that many restaurants are using? I'm not sure of the cost (I imagine a system is not cheap!) but something like this sounds like it might fit your needs.

Good Luck,
Keith

[rescuecomm]

Check out the TriSquare 900 mhz walkie talkies. They can do what you are describing rather inexpensively.

Bob

[Pradio]

gewecke - thanks for your help. I am aware that many FRS radios have this function. But for the device that I want to create, that does not have voice communciation, I believe it would not be allowed via FRS.

I may be reading this incorrectly, but below is the quote that leads me to believe this from this link
FRS FAQ

"May I use my FRS radio to transmit one-way paging messages?

Yes, but only voice paging messages [95.193(a)]. You may not transmit "tone-only" pages (a tone-only page consists of tones communicated in order to find, summon or notify someone)."

I believe that is what I would be doing, transmitting "tone-only" pages to notify someone. Since the FRS is setup for two way voice communication I don't think what I want to do will be in line with the rules about it. There is also the issue that since I will not have a speaker and cannot listen and monitor to so if the FRS channel I am on is free to use (no one else using it), my device will not be correct for the purpose of the FRS frequency.
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kcoleman - Thanks also for your suggestion. I may look into the restaurant pager devices. My only issue is that they utilizes a higher power base unit (I believe 2 watts and above), and it is also not two way communication. So while I may learn something from it, it is not a portable transmitter that works with low power.

Thanks for the ideas so far. Anyone other ideas? It has been suggested to me that the 2.4ghz band would be appropriate to use. Any suggestions there? Does anyone know what frequencies that car remote car door locks use? Or remote control door bells?

[Pradio]

Originally Posted by rescuecomm

Check out the TriSquare 900 mhz walkie talkies. They can do what you are describing rather inexpensively.

Bob

Thanks Bob. I am aware that walkie talkies can do what I want, but I am interested in designing a new type of product that is much simpler in function and smaller than the walkie talkies available. And I believe that for what I want I will not be able to use the FRS band (read my post above). But please do keep the suggestions coming.

[N_Jay]

At that range I would bet some of the RF remote control type designs would be perfect.

I think they are 390 to 410 MHz

[Pradio]

So it looks like I have options, in the 400mhz range, 900mhz range and a good option sounds like the 2.4ghz range.

What would be the benefits of those different bands?

Would the antenna length change much between those three bands?

Is the 2.4ghz much more directional? Meaning would I have to make sure and point the antenna at each other with the band?

What about the power needs? Would one band take less power to work the distance I want vs another?

Thanks again

[N_Jay]

All very good questions to discuss with the design firm you hire.