433 MHz Receiver Random Data on Serial Terminal

Hi,

I bought these cheap (￡2) 433 MHz Tx and Receiver modules from ebay. I wanted to try them out without the antenna first.
Firstly I decided to connect the Receiver to my PC through the USB to TTL serial cable. I used a serial terminal program to monitor the data as soon as I opened the port I started to get lots of random data, my baud rate is set to 600 bps (remember the Tx is not powered up yet).

I am not sure why I am getting this random data through. I would expect occasional random data but not continuous stream of data. Can somebody shed some light on this, it will be a great help. Thanks in advance.

In general these receivers needs to receive a stream of bytes (preamble) in order to adjust the AGC of RF stage, therefore it is an expected behaviour. I believe that you could shorten the interval between the characters transmitted to avoid variation in the gain.

Thanks for the quick response, I just had both of them communicated by sending 4 bytes every 100 ms.