Can you make a 1Khz from a Walkie-Talkie

[Konton]

Cranium was talking to me about this idea, so I thought I would post the question. I understand that morse code uses a 1Khz signal. This function is usually found on any old $10 walkie-talkie from radio shack. Can you modify these in some way so that one walkie-talkie is connected to the flash contact and the other connected to your audio recorder? Since the 1Khz signal is audio, not an electrical burst, you should not get bleeding into the other track. The walkie-talkie has volume control, so you can even lower the sound you are recording. Plus it's a walkie-talkie, you have a wireless connection, rather than a cord! So . . ummmm . . .what do you all think?

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Konton the Grey

[mattias]

i can't see why it wouldn't work. great idea!

/matt

[Actor]

It should work in theory. Some considerations.
<UL TYPE=SQUARE>
<LI>The PC contact should be across the morse key in the WT. Don't try to lock the key down and key the 1000 Hz.
<LI>The 1000 Hz is approximate. Some use 750 Hz.
<LI>These WTs use either 27 MHz or 49 MHz. 27 MHz is the Citizen's band and 49 MHz is the frequency used by older cordless phones. Both bands are also used for radio control of toy cars, planes and whatever. Any of these could be a source of interference just when you don't want it.
<LI>A 1000 Hz tone keyed 24 time per second sounds awful. If this attracts the attention of CB operators or cordless phone users they may try to jam your signal.[/list]

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[This message has been edited by Actor (edited February 20, 2002).]

[#Pedro]

This idea is not new. In the 1970ies sets like this were offered by several supplyers, I have got 2 sets, one "P?TTER" and one "SYNPUTER". Both work great, the Synputer has more option, such as remote start/stop the tape advance and remote start/delay stop the tape advance. I never recognized interferences or not clean pulses. BUT... they make a great secret of their particular circuits... if you look at the complex printed boards inside, all component lables are grinded off!
And that has a reason: Interferences and signal/noise ratio is a BIG issue when working wireless.
To limit noise and not record noise to tape (only listen to the speaker of a WT any you know what I?m talking about), you cannot directly recod to tape.

The way it works is a little bit different:
The flash contact only triggers the transmission of digital serial pulses to the receiver, not any 1000 Hz tone bursts.
The receiver has an in-built 1000 Hz beeper that is triggered with every digital pulse coming in. So you get a clear and direct signal for recording.

To experiment with a WT, you could do the following: connect on item to the camera (morse button in parallel to the flash socket).
The other one you?ll have to open, too. Disconnect the speaker and connect it?s wires to an interface that creates square TTL pulses out off tone bursts. With the TTL pulses you trigger a beeper (f.e. my 1000 Hz interface) that is recording directly to the tape. This way, you won?t have any noise from the audio transmission on your tape, that probably would disturb the pulse synchronization. If any transmitted pulses get lost or disturbed, depends a lot of the quality of the WT and further interferences.

Theses stores like Radio Shak should also have measuring equipemnt. In measuring technology, there are used wireless data transmissions with special miniature transmitters and receivers, sending directly the digital bit seria (telegrams). I think this would be the better way to re-built wireless pulse transmission.

Pedro

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