I'm using a 18F452@20MHz to collect data from several sources.
Once a "full data-set" has been collected it is transmitted via a standard 433MHz TX-Module.

The "Remote-PIC" (18F252@20MHz)) is connected to a 433MHz RX-Module
and picks up the data to display it on an LCD.

I have got the Manchester Encoding/Decoding, Timing, Balancing and CRC working.

With a simple lambda/4 antenna I get the required range
and at the given Bandwith of the RF-Modules
I get a reliable communication at 1200 Baud.

The Problem:

The RX-Module Data output pin idles LOW, so Im using TRUE polarity (Mode $432D).

As long as my transmitter sends data continuously I receive the data errorfrree on the remote PIC.

If the transmitter does not send data for about a minute or more the Receiver hangs
(sitting in the SERIN2 Statement)

-------------------
Serin2 Rxpin,Baud,TimeOut,NoInput,[Wait(Synch),STR RX\50\13]
-------------------

To me it looks like RF noise is causing that problem.
With no noise (RX data pin low) the SERIN2 Timeout works fine
and the Program does what it is expected to.

As there will always be noise on 433MHz I verify the received data
using CRC and discard invalid telegrams.

If a random sequence of bits (Noise) is received it hangs and only a MCLR helps to restart it.

How to solve that "hanging problem"?

regards:

Ralph