"Frank Dresser" wrote in message
...

"Telamon" wrote in message
...


Data communications occupy wider bandwidths than the stated clock
rate.
It is not unreasonable to expect harmonics 3 to 5 times the clock rate
because the signaling uses square waves and there is significant power
in the odd harmonics.

--
Telamon
Ventura, California

A square wave, itself, won't convey much information. It needs to be
modulated, and the modulation would have to effect the symmetry and
result in both odd and even harmonics.

I don't know what sort of modulation BPL is using. I can imagine
hundreds of low amplitude sine wave carriers from 2 to 60 Mhz, all of
them phase modulated. In that case, I don't think there would be much
harmonic output.

Digital comms are purely square waves. The modulation is FSK or similar
(generally)... in other words, the on-state is one frequency, the off state
is another. This creates a chain of square waves which themselves are not
modulated. The bandwidth, in this case 75 MHz, is how many on/off states
there are in one second. This is also concurrent with bitrate. Compression
schemes can raise the apparent bitrate, however the actual bitrate is the
same as the frequency used. I'm not sure how they do the band notching that
Japan tried before they tossed out the idea completely.