Transmission length (reception)

friis

Senior Member
Hi
I have a 08m which broadcasts the command:

serout C.1, N2400, ( "UUUUUUUUUUU" )
pause 5
serout C.1, N2400, ( "ABC", b2,b0,b1 )

I can see that flashing across the scope.

I have 14m which receives the broadcast:

low C.1
pause 100
serin C.0, N2400, ("ABC"), data1, data1, b16, b17
high C.1

This should also flash across the scope, but instead I see a 7 sec.
transmission, and if I did'nt have the high C.1 disabling the receiver, the
stream would continue.

The RX/TX pair are Dorji 887 and 886

Can anyone explain?

best regards
torben
 

sghioto

Senior Member
Are you sure it's not just random noise pulses? The Rx units are high gain. The noise in the receiver is amplified and might look like data.
 

hippy

Technical Support
Staff member
Start with something simpler, just sending one byte at a time and with the receiver permanently enabled.

Code:
#Picaxe 08M
Do
  For b0 = "A" to "Z"
    SerOut C.1, N2400, ( "UUUUUUUUUUUUUUUUUUUUUUUUU" )
    Pause 5
    SerOut C.1, N2400, ( "ABC", b0 )
    Pause 1000
  Next
Loop
Code:
#Picaxe 14M2
#Terminal 4800
Do
  SerIn C.0, N2400, ("ABC"), b0
  SerTxd( "Got ", #b0, 9, b0, CR, LF )
Loop
Also try T2400 to see if that makes any difference.
 

friis

Senior Member
Hi sghioto and hippy,
As will appear below it was'nt noise.

I tried the simple pgms proposed by hippy and it worked fine. I had to
precede SerIn with low C.1 (enable the RX) and follow it by high C.1.

But looking at the scope I am surprised.

First, the transmission time as measured by the time it takes to receive (not
send) b0 is much longer than I would expect (several secs.)

Second, the sending occurs at the very end of the reception. I suppose that is
because I enable the sender before the transmission arrives and the RX
appears to start receiving (what?) at that point. What appears to be an overlap
is then really a replacement. That could also explain the long apparent
transmission time for reception.

If that is an explanation I wonder why RX appaers to start receiving as soon as
it is enabled. And if disabling by setting the receiving pin high is supposed
to save on the batteries. Well, it stops the apparent sending by RX.

What do you think?

torben friis
 

rossko57

Senior Member
First, the transmission time as measured by the time it takes to receive (not
send) b0 is much longer than I would expect (several secs.)
Not sure what you mean here, hippy's test program is intended to send a little packet at one-second intervals
 

hippy

Technical Support
Staff member
Receivers will often produce output as soon as they are turned on. They simply pick up background noise and their own circuit noise and put this out. What you are observing is expected behaviour.
 
Top