Pulse emitter long range data comm?

[Day Brown]

It seems that Zeners could be used to just clip the steepest part of a
sine wave and port that power to a Yagi tuned to resonate with the
effective frequency.

Which is to say, put out a series of pulses, either pos or neg, zero
as neg, 1 as pos. No carrier wave. No IF. No conventional AM/FM/VHF/
UHF tuner would pay any attention to it.

I like living in my neck of Ozark woods, but none of the commercially
available long range wireless communication devices can penetrate the
canopy. When the wavelength gets down to the length of pine needles,
thru put is zero.

The 1/4 wavelength of 200 mhz is 37.5 cm, longer than any pine
needles. Which seems like it could be turned into 200,000kbps, and
even with error correction give me as much as my LAN port can handle.

But I would havta gate it with a mosfet or something. Then detect it
on the other end. Zat reasonable?

 

[Frank Raffaeli]

It seems that Zeners could be used to just clip the steepest part of a
sine wave and port that power to a Yagi tuned to resonate with the
effective frequency.

Which is to say, put out a series of pulses, either pos or neg, zero
as neg, 1 as pos. No carrier wave. No IF. No conventional AM/FM/VHF/
UHF tuner would pay any attention to it.

I like living in my neck of Ozark woods, but none of the commercially
available long range wireless communication devices can penetrate the
canopy. When the wavelength gets down to the length of pine needles,
thru put is zero.

The 1/4 wavelength of 200 mhz is 37.5 cm, longer than any pine
needles. Which seems like it could be turned into 200,000kbps, and
even with error correction give me as much as my LAN port can handle.

But I would havta gate it with a mosfet or something. Then detect it
on the other end. Zat reasonable?

http://www.uwbforum.org/
http://www.alereon.com/

It's called ultra-wideband: although you may have over-simplified it.

Frank

 

[Bob]

It seems that Zeners could be used to just clip the steepest part of a
sine wave

The steepest part of a sine wave is at the zero crossing point.
I think you mean the highest amplitude.

and port that power to a Yagi tuned to resonate with the
effective frequency.

Hmm, I'm not sure what the point of trying to square the sine wave.
Why not just use a sine wave at the resonant frequency of the yagi,
or just generate square pulses with the right period.
Squareing a sine wave is mainly going to result in a signal with
energy at multiples of the original frequency, the third harmonic
being strongest. Tehh yagi isn't going to work very well at three
times its operating frequency, the radiation pattern looses
directivity and you won't get a good impedance match.

If you want to multiply up to reach the yago frequency the usuall
active multiplier circuits in radio comms books are likely to be more
use.

Which is to say, put out a series of pulses, either pos or neg, zero
as neg, 1 as pos. No carrier wave. No IF. No conventional AM/FM/VHF/
UHF tuner would pay any attention to it.

You need a low noise amplifier on the front end of the reciever.
The problem is that the wider the bandwidth you are trying
to receive at once the more thermal/atmospheric/electrical noise
you will pick up and you have to get your signal back out
of that noise.

Picking up a single pulse thats been band limited by the
yagi in amongst 10's of MHz of WHF background noise needs
a lot of signal to get a worthwile s/n ratio. With
practical transmitter power and typical path loss encoding
a bit as a single pulse is generally not practical.

I like living in my neck of Ozark woods, but none of the commercially
available long range wireless communication devices can penetrate the
canopy. When the wavelength gets down to the length of pine needles,
thru put is zero.

The 1/4 wavelength of 200 mhz is 37.5 cm, longer than any pine
needles. Which seems like it could be turned into 200,000kbps, and
even with error correction give me as much as my LAN port can handle.

The maximum data rate of a radio link, assuming a perfect
encoding scheme, can be calculated with Shannon's law
which gives max bit rate from channel bandwidth and signal
to noise ratio.
Wifi for example does 11MBps or more in a 30Mhz wide channel
but needs a fairly high signal to noise ratio.


Bob