What would the optimum bandwidth for a WWVB receiver be? For the AM signal, there are three different symbols, 0.8 seconds on/0.2 sec off; 0.5 sec on/0.5 sec off; and 0.2 sec on, 0.8 seconds off. This suggests to me that the two non-symmetrical symbols have strong modulation sidebands at +/- 2.5 Hz, or a minimum (AM-DSB) bandwidth of 5 Hz, plus any frequency tuning error requirements. This would give me a soft edge with a 100 ms rise and fall time.
The next stop for significant improvement would be to catch the third harmonic of the AM modulation component, which would require a 15 Hz total filter bandwidth, plus any frequency tuning errors, and an edge rise and fall time in the 33 ms range. Am I looking at this correctly? I am assuming that any phase modulation sidebands would fit inside the AM filter requirements. --- Graham == _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
