arduino and ham radio beacon

would like some help with this project - this will be for a 10 meter beacon project that i have been working on for some time!!

the radio is an htx-10 made by rs some time ago -- unlike its big brother the htx-100, the htx-10 does not have a cw input ( cw=morse key)

what i want to do is have a wav shield with my beacon string ( morse code ) info on the sd card ( repeating over and over with a 10 second pause in between the message) and output that to the microphone element in the handheld mic ( i sure ill have to adjust the volume out of the wave shield as to not over modulate the signal coming into the where the mic element would be )

the kicker is the PTT ( or switch that you have to push to be able to talk ) -- i want to put a relay in to close the contacts on the PTT switch but time it with the audio from the wavshield or time it where the relay kicks in the PTT line and then a second later the wavshield spits out the audio when the audio is done the relay opens and the switch goes open and 10 seconds later the whole process starts over again!!

can this done what pins need to be activated

I have somewhat of a grasp on this looking at different projects that could be used in this fashion - such as like a xmas light controller using solid state relays and some of the various web searches on arduino beacon controller

Thanks for the help

Chad

what i want to do is have a wav shield with my beacon string ( morse code ) info on the sd card (

That is over complicated, you can generate the morse signal with the tone function of the arduino, no need for any wave shield.

The project should be quite easy.

Does that radio have an AM mode? Does the radio key fast enough that you could use an unmodulated AM carrier for yur beacon? (That's all CW is anyway.)

Problem with either method is going to be getting a proper impedance match between the Arduino Audio and the Radio Audio. A capacitor might do, or you might need a small audio transformer to isolate them.

Finfd out how much (or how little) current you are switching in teh PTT circuit. You might be able to get away with something as simple as a 2N2222.

Grumpy_Mike:

what i want to do is have a wav shield with my beacon string ( morse code ) info on the sd card (

That is over complicated, you can generate the morse signal with the tone function of the arduino, no need for any wave shield.

The project should be quite easy.

Ummm... If I am not mistaken, the tone function generates a square wave which is rich in harmonics which will be transmitted if modulated into an SSB transmitter. This would waste bandwith and probably annoy other ham radio operators listening to your beacon.
BTW I realize this thread is somewhat old

Any SSB transmitter is gong to be bandwidth limited. However a beacon is not normally modulated with SSB. Either way a simple RC filter will remove most of the harmonics.
De G8HBR

Grumpy_Mike:
Any SSB transmitter is gong to be bandwidth limited. However a beacon is not normally modulated with SSB. Either way a simple RC filter will remove most of the harmonics.
De G8HBR

There are FFT programs for computer sound cards.
You could analyze it to see if any of the harmonics are in the ~100-3000hz bandpass.
BTW Since the carrier and other sideband are suppressed, feeding in a pure tone should theoretically result in an output identical to a real continuous wave.

feeding in a pure tone should theoretically result in an output identical to a real continuous wave.

Are you sure?
I would have thought it would result in FSK (frequency shift keying) where as CW is on / off amplitude modulation.

If the rig is tuned to 14000 kHz USB and you feed a 1kHz tone into the microphone, what the radio transmits is a single 14001 kHz tone. If you then switch the tone on and off, you have CW. The only thing you have to be careful of is that the onset and offset of the audio tone is shaped properly so that it doesn't cause any spurious clicks.
If the rig was set to FM then you'd get FSK.

Pete

Grumpy_Mike:

feeding in a pure tone should theoretically result in an output identical to a real continuous wave.

Are you sure?
I would have thought it would result in FSK (frequency shift keying) where as CW is on / off amplitude modulation.

Why would it result in FSK?
There is no significant transmitted energy in a keyed SSB transmitter without modulation. Injecting a pure tone should generate a pure carrier at the normal carrier frequency* plus the audio frequency for USB or minus the audio frequency for LSB.
The normal carrier frequency is where the carrier would be if it were not suppressed.

If the rig is tuned to 14000 kHz USB and you feed a 1kHz tone into the microphone, what the radio transmits is a single 14001 kHz tone. If you then switch the tone on and off, you have CW. The only thing you have to be careful of is that the onset and offset of the audio tone is shaped properly so that it doesn't cause any spurious clicks.
If the rig was set to FM then you'd get FSK.

el_supremo beat me to it and is basically right on.

If the rig was set to FM then you'd get FSK.

I should "modulate" my statement a bit.
Putting an audio signal into the mic when the rig is set to FM generates an FM signal - not FSK.
FSK is when the radio shifts between two frequencies. Many radios these days have a RTTY setting which can generate FSK directly.
For those who haven't got a RTTY setting on their radio, FSK can be generated by putting the rig in USB or LSB mode and feeding into the mic a signal which alternates between two audio tones. This is referred to as audio frequency shift keying (AFSK), although with perfect radios a receiving station wouldn't be able to tell the two methods apart.

Pete