For what I understand in the thread this repetition is valid for oldest transponders, whereas new RC4 transponders always change numbers every time. Also, three in a row is ok from a single transponder in the loop, but does this work with multiple transponders? Anyway I'll investigate further if I have something to optimize in my design in order to minimize this bit misalignment... OR implement CRC check of the packet. By the way...this is my prototype, on top right is your loop amplifier... the rest is in the board, with a USB serial port. It's pretty impressive that I'm reading something since this is my first project with this hardware... Next is a camera shot for the amp waveform (old technology, I know....)