Hello, I have been searching for a simple frame detection scheme for GNURadio for a while, but everything I've found either doesn't work or it is more complicated than I expected.
What I needed was a block that would be searching for a predetermined sequence used by the transmitter. While it doesn't find this sequence, it should give no output. Once it is found, it should output everything that came after the sequence and discard the rest as "garbage". I tried using the simple framer and simple correlator. I created a simple example that just took a random source, created a frame, converted it to float, added some delay and then the correlator would try to find the sequence. But this didn't work. I got a constant zero signal as output. The documentation on these blocks is really poor and I couldn't find any good example to clarify its usage. On the other hand, I found plenty of examples of the header/payload demux. But it seems more complicated than what I need. I don't quite understand the tags and streams portion of GNURadio and I am not sure on what I should use as header data. I have been trying to create a block that will try to check for a known sequence in the incoming stream. Once it is detected, it will read the next L samples (L will be the message length defined by the user) and create a frame, which will be sent as a message. Everything before the detection of the known sequence will be ignored. The message will then be read by further blocks as the received frame. Unfortunately, creating a message passing block from scratch is turning out to be way harder than I expected. Is there any easier way to do this? Thanks in advance, Dan Franch
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