443mhz transciver help

mattm_nscc

Hello, Me and my project partner are using a 443mhz transciver (parallax) and we've written a very basic code to send it. but it dosn't work correctly.
Heres what we got, a ADC to the BS2 to the 443 transciver. then to the Rx to the DAC, ive attached the TX and RX code we came up with .
this is a very first code project so any help or suggestions are welcome.

Thanks Matt M

Franklin

Have you established communications using just trying serout / serin with constants and no special cases? How is everything connected together and what are the devices outputting (do you get standby or transmitting from the TX code?)

Beau Schwabe

A couple things that I might try to change:

On the 443ADCv1.0 program, move the PULSOUT so that it's immediately before the SEROUT serdat
...and add a "SYNC string" to the data you are sending... additionally make use of the WAIT command on the receiver side.

 Main:
 HIGH tranre                                              'set transr pin high for Tx
  DO
    GOSUB Read_0831                                       'read the ADC
    SEROUT lcd, baud , [22, 12]                           'turn the display on and clear it
    SEROUT lcd, baud , ["transmitting"]                   '"transmitting" sent to the LCD
    PULSOUT serdat, 1200                                  'Sync pulse for the receiver
    SEROUT serdat, 16468,"!Sync"                          'Sends a "SYNC string"
    SEROUT serdat, 16468, [result]                        'Sends serial data to the transciver throught I/O 6
  LOOP                                                    'continously sends data

On the 433rx program make sure that you are listening for the "SYNC string" ...

main:
LOW tranre                                           ' sets pin 4 low to receive
DO
  LOW serdat                                         ' low on pin 6 which allows data to flow
  SERIN serdat, baud, [WAIT("Sync"), result]         ' Waits for "SYNC string" and recives the data
                                                     ' AND saves it as the variable "results"
  GOSUB shipout
  HIGH serdat
LOOP

mattm_nscc

Thank you both for the replys...

We are sending an audio signal.... our project is a wireless guitar amp...I know the 433 isn't the best choice by far but it's what we have to work with...We got it transmitting something yesterday on the rx side we get "results= 0, 8,16,20,32 ,100, ( random numbers in general ) & lots of 0's....we should expect 0 & 1 ... shouldn't we ?
Also I've built a JFET preamp, that works, but when we hook it up to the ADC0831, we get only 20-100mV on the DO pin and very small digtial blips (time wise) ....any suggestions ?

Thanks Matt M

Beau Schwabe

For Sending Audio, the best you can hope for is close to AM radio quality, but doing this serially won't be fast enough. The most straight forward approach would be to modulate a square wave at the upper limit of the 433MHz transmitter and receiver (close to 10kHz) and send that. On the receiver side, desired but optional, use a low pass filter to remove most of the 10kHz signal... the result is an 'analog' representation of your original audio.

When we first started selling the 433MHz transceivers, I did some early experiments along these lines. With some additional circuitry you can tweak the 10kHz limit for much higher throughput by using the signal strength pin on the receiver INSTEAD of the data pin, but at a cost of proportionally decreasing the effective range between the transmitter and receiver.