[MLB-WIRELESS] [TIB] A new offer has been added to TIB-23/01 /2003

Tony Langdon tlangdon at atctraining.com.au
Tue Jan 28 10:03:18 EST 2003


> sorry? 5 channels? the sideband interference is 5 channels 
> wide?  Are you 
> sure? Hmmm. not much of a frequency band selection then...
> hang on, that is only 4 channels seperation, 1(2,3,4,5)6(7,8,9,10)11
> 5 channels apart, 4 channels seperation.

The channels are 22 MHz wide, and are spaces at 5 MHz intervals.  That makes
the signal 4.4 channels wide.  You have to go 5 channels (25 MHz) higher to
ensure the signals from two transmitters don't overlap (assuming no
significant out of band emissions).

Now one thing that hasn't been discussed is how much overlap is acceptable?
> 
> anyone know what shape the off-channel frequency response looks like?

It would be a truncated sin(x)/x frequency envelope (typical for PN sequence
modulated carriers).

> I guess you could have all 14 channels operating at once if 
> you were willing 
> to put up with really crap transfer rates...  

Yeah, maybe. :)

> if the channel seperation is indeed 4 channels, then that 
> stuffs that a bit, 
> but the same principal applies. 1 or 2,  7, 13 or 14 seems 
> the best in that 
> case

The basic idea makes sense.

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