Hello,
We are currently using the CC1120EM-868-915 to transmit frames to a receiver designed in our lab.
The frame are transmitted using ASK/OOK modulation, at 1kbps, without preamble, sync and CRC and only one byte of payload. So actually only 1 byte should be transmitted by the radio.
Using an oscilloscope, we can observe the data received by the receiver, and we always observed three bits high before the payload. For example, if we want to transmit '10101010', what is actually transmitted is '11110101010'.
We test our received using a CC430 and it works fine, i.e. the first 3 bits are not added.
In order to check if it was not a misconfiguration of the registers, we set the CC1120 to transmit a preamble (3 bytes of 0xAA), and what we observed on the oscilloscope at the receiver side was:
111+PREAMBLE+PAYLOAD
that is the first 3 bits high are still present BEFORE the preamble.
Can we get rid of these 3 bits ? What did we miss ?