sending digital signals over radio

M

margoob

Guest
I've got a 8-bit signal which I want to send over radio - which would
be received & decoded into the 8 bit signal - how do I do it???

I was thinking of taking the signals into a 1 bit shift register - but
decoding that signal from the rx side is getting really complicated...

any suggestions?
 
margoob wrote:
I've got a 8-bit signal which I want to send over radio - which would
be received & decoded into the 8 bit signal - how do I do it???

I was thinking of taking the signals into a 1 bit shift register - but
decoding that signal from the rx side is getting really complicated...

any suggestions?
Click to expand...
Hmm..8 bits..ASCII..Baudot..RS232 ports...sounds simple to me.
 
margoob wrote:
I've got a 8-bit signal which I want to send over radio - which would
be received & decoded into the 8 bit signal - how do I do it???
Click to expand...
What range / frequency / data rate do you need? You can also get
off-the-shelf RF modules for short range serial data links.

I was thinking of taking the signals into a 1 bit shift register - but
decoding that signal from the rx side is getting really complicated...

any suggestions?
Click to expand...
You could use a UART (Universal Asynchronous Receiver/Transmitter). This
chip does it for you. They're used in RS232 serial ports. They work by
adding a "start bit" to the front of your data. From the middle of the
start bit, the receiver counts 8 bit periods to find the centre of each data
bit. Micro-controllers (e.g. PIC) often have a UART built-in.
 
I'd use a UART at the transmitting end (FIFO if you have bursts of data) -
parallel in, formats the data into a serial stream, output serial stream
(+5/0V) can modulate a carrier and be transmitted, demod at other end to
recover the formatted serial stream from the received carrier, and straight
into another UART to recover as 8 parallel bits.

Most UARTS should handle the upper limit of digital speed that a modulated
signal could cope with.

Chris.

"margoob" <margoob@gmail.com> wrote in message
news:1107680899.693178.141850@z14g2000cwz.googlegroups.com...
I've got a 8-bit signal which I want to send over radio - which would
be received & decoded into the 8 bit signal - how do I do it???

I was thinking of taking the signals into a 1 bit shift register - but
decoding that signal from the rx side is getting really complicated...

any suggestions?
Click to expand...
 
He might want to add error-correction/detection - there are chips
around that will add a five bit checksum to the eight-bit data, which
will allow you to correct all single-bit errors, and detect many
multi-bit errors.

There is also the approach used in the Taxi chips, where eight-bt data
is recoded into the 256 ten-bit words that have lowrst DC content .....

-------------
Bill Sloman, Nijmegen
 
<bill.sloman@ieee.org> wrote in message
news:1107690074.825382.148020@f14g2000cwb.googlegroups.com...
He might want to add error-correction/detection - there are chips
around that will add a five bit checksum to the eight-bit data, which
will allow you to correct all single-bit errors, and detect many
multi-bit errors.
Click to expand...
Or you could just send it all twice (normal then inverted) and detect
virtually all errors.

There is also the approach used in the Taxi chips, where eight-bt data
is recoded into the 256 ten-bit words that have lowrst DC content
......
Click to expand...

The method I mentioned above also helps to remove the DC especially if
you interlace the normal and inverted data bit by bit.
 
margoob wrote:
I've got a 8-bit signal which I want to send over radio - which would
be received & decoded into the 8 bit signal - how do I do it???

I was thinking of taking the signals into a 1 bit shift register - but
decoding that signal from the rx side is getting really complicated...

any suggestions?

Yo,
Click to expand...

Check out the units by Radiotronix. Just key the transmitter with
serial output and connect the reciever to a serial input. I have used
these with PIC's all the time.

http://members.cox.net/berniekm/Hot_Parts.html

--
Luhan Monat (luhanis 'at' yahoo 'dot' com)
"The future is not what it used to be..."
http://members.cox.net/berniekm
 
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