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New Design Technology

  • Thread starter RST Engineering \(jw\)
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RST Engineering \(jw\)

Jan 1, 1970
0
I am thinking about creating a new design for transceiving audio over a
range of a couple of meters. The criteria are as follows:

1. Up to four audio sources each of which must hear all of the other three
stations. (Headset-microphone-earphone) Although I'm not ruling out any
scheme, what I think would work is a "base station" that could be mounted
somewhere in the vehicle, receive up to four separate frequencies, and
retransmit the detected audio over a common transmit channel.

2. Fairly high electromagnetic intensity environment ... tens of watts of
RF at 120-140 MHz. at a meter or so range. Hundreds of peak power watts
(average 5 watts or so) at 1 GHz. also at a meter or so.

3. Entirely possible that in some instances the device will have to operate
in direct sunlight. I'd prefer not to use opto techniques.

4. Whatever the technology and power source, the device will have to be
worn on the head for several hours at a time. It may be possible to mount
the device on the chair the person is sitting on but I'd like to keep my
option open to mount the whole works inside the individual headset.

5. Moderately high noise environment made a little more liveable by the use
of noise-cancelling microphones.

6. If at all possible, I'd like something that will work in an amateur
radio band...the device will only be marketed with proof of amateur license.
2 meters might work, as would 220 or 440. 220 is so quiet that I'd really
like to operate in that band if possible.

I'm not so much looking at a design per se, but more a technology or
device(s) that I could research and see what is available and preferable.
Comments appreciated.

Jim
 
J

John Larkin

Jan 1, 1970
0
I am thinking about creating a new design for transceiving audio over a
range of a couple of meters. The criteria are as follows:

1. Up to four audio sources each of which must hear all of the other three
stations. (Headset-microphone-earphone) Although I'm not ruling out any
scheme, what I think would work is a "base station" that could be mounted
somewhere in the vehicle, receive up to four separate frequencies, and
retransmit the detected audio over a common transmit channel.

I was thinking about a system wherein all car drivers within
line-of-sight would be able to converse, sort of full duplex CB. The
social evolution of that would sure be interesting. I figured it would
be RF or optical. Preferably received sound level would not vary with
distance, at least until the range limit was hit.

I was thinking that everybody would transmit random carrier-modulated
pulses, with pulse density carrying the audio modulation. The receiver
is then just a limiting bandpass amp, a comparator, optional one-shot,
and a lowpass filter.

You could also do some fancy digitized burst packet things, I guess,
with overlapped packets straddling each group of samples, so
collisions could be mostly corrected for. More work.

John
 
M

martin griffith

Jan 1, 1970
0
I was thinking about a system wherein all car drivers within
line-of-sight would be able to converse, sort of full duplex CB. The
social evolution of that would sure be interesting. I figured it would
be RF or optical. Preferably received sound level would not vary with
distance, at least until the range limit was hit.

I was thinking that everybody would transmit random carrier-modulated
pulses, with pulse density carrying the audio modulation. The receiver
is then just a limiting bandpass amp, a comparator, optional one-shot,
and a lowpass filter.

You could also do some fancy digitized burst packet things, I guess,
with overlapped packets straddling each group of samples, so
collisions could be mostly corrected for. More work.

John
Nordic semi has some stuff, such as nRF24Z1, but not exactly suitable,
it might give you some ideas


martin
 
G

Gibbo

Jan 1, 1970
0
RST said:
I am thinking about creating a new design for transceiving audio over a
range of a couple of meters. The criteria are as follows:

1. Up to four audio sources each of which must hear all of the other three
stations. (Headset-microphone-earphone) Although I'm not ruling out any
scheme, what I think would work is a "base station" that could be mounted
somewhere in the vehicle, receive up to four separate frequencies, and
retransmit the detected audio over a common transmit channel.

2. Fairly high electromagnetic intensity environment ... tens of watts of
RF at 120-140 MHz. at a meter or so range. Hundreds of peak power watts
(average 5 watts or so) at 1 GHz. also at a meter or so.

3. Entirely possible that in some instances the device will have to operate
in direct sunlight. I'd prefer not to use opto techniques.

4. Whatever the technology and power source, the device will have to be
worn on the head for several hours at a time. It may be possible to mount
the device on the chair the person is sitting on but I'd like to keep my
option open to mount the whole works inside the individual headset.

5. Moderately high noise environment made a little more liveable by the use
of noise-cancelling microphones.

6. If at all possible, I'd like something that will work in an amateur
radio band...the device will only be marketed with proof of amateur license.
2 meters might work, as would 220 or 440. 220 is so quiet that I'd really
like to operate in that band if possible.

I'm not so much looking at a design per se, but more a technology or
device(s) that I could research and see what is available and preferable.
Comments appreciated.

Jim

I like the idea, very much. If you can get it to work then good luck. I
think you could be on to a winner.
 
B

Ben Jackson

Jan 1, 1970
0
I am thinking about creating a new design for transceiving audio over a
range of a couple of meters. The criteria are as follows:

Bluetooth does this (with digital audio) in the ISM band at 2.45G.
There are probably appnotes out there for the phone/headset sides
of a BT link, eg:

http://focus.ti.com/docs/solution/folders/print/311.html
4. Whatever the technology and power source, the device will have to be
worn on the head for several hours at a time.

Seems like the GHz range has size advantages for that, even if you
want to homebrew.
 
J

joseph2k

Jan 1, 1970
0
RST said:
I am thinking about creating a new design for transceiving audio over a
range of a couple of meters. The criteria are as follows:

1. Up to four audio sources each of which must hear all of the other
three
stations. (Headset-microphone-earphone) Although I'm not ruling out any
scheme, what I think would work is a "base station" that could be mounted
somewhere in the vehicle, receive up to four separate frequencies, and
retransmit the detected audio over a common transmit channel.

2. Fairly high electromagnetic intensity environment ... tens of watts of
RF at 120-140 MHz. at a meter or so range. Hundreds of peak power watts
(average 5 watts or so) at 1 GHz. also at a meter or so.

3. Entirely possible that in some instances the device will have to
operate
in direct sunlight. I'd prefer not to use opto techniques.

4. Whatever the technology and power source, the device will have to be
worn on the head for several hours at a time. It may be possible to mount
the device on the chair the person is sitting on but I'd like to keep my
option open to mount the whole works inside the individual headset.

5. Moderately high noise environment made a little more liveable by the
use of noise-cancelling microphones.

6. If at all possible, I'd like something that will work in an amateur
radio band...the device will only be marketed with proof of amateur
license.
2 meters might work, as would 220 or 440. 220 is so quiet that I'd really
like to operate in that band if possible.

I'm not so much looking at a design per se, but more a technology or
device(s) that I could research and see what is available and preferable.
Comments appreciated.

Jim
AFAIR Ham radio is not allowed to be operated just like that. To be part 97
compliant each transmitter would have to have its own frequency and each
user would have to have multiple (or multichannel) receivers. Some "900
MHz" ISM band radios can do this directly. Moreover, you should consider
motorcycle usage as well. Range should be about 100 m line-of-sight at the
standard 1 W.
 
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