Hi, I'm trying to design a low-cost digital radio interface to communicate with a robot. I'm not interested in exchanging a lot of data, or doing it at high speeds. This design will work well if I can get even 300 baud out of it since I never exchange more than about 1K bytes during a conversation. Although I've had fair success up to 1200 baud. Unfortunately the system doesn't seem to be real dependable and I'm wondering if anyone has any ideas of how I might change my simple circuit to make it more dependable. I'm designing around the following low-cost receiver and transmitter modules: Receiver: http://www.rentron.com/remote_control/RWS-434.htm [Broken] Transmitter: http://www.rentron.com/remote_control/TWS-434.htm [Broken] I have a schematic of my own simple circuit on my web site at: http://www.csonline.net/designer/ [Broken] I'm using RS-232 serial connectors to connect a standard IBM type PC to my transceiver circuit. Then I have an identical transceiver circuit at the robot end which uses an 8051 Microcontroller. So far the thing works but doesn't seem to be stable. I send repeated characters at the beginning of each message for sync. Like A5A5A5A5A5A5 and that seems to help but doesn't solve the problem completely. It seems to be an asynchronous timing problem. Once it's on track it seem to work fine. But often I just get garbage because it gets off by a bit or two at the beginning of the run it seems. I thought that the MAX232 chips would take care of all that timing. I use one at each end. Maybe I need some kind of buffers between the MAX232 chip and the I/O of the transmitter and receiver modules? Any suggestions (whether hardware or software) would be welcome. Thanks in advance for any responses.