Sun Oct 18, 2020 9:40 am #1803751
gaznav wrote:PaulisHome wrote:...
It's a fairly complicated problem. It's not as simple as less power = less range. At these frequencies, range can be up to line of sight (we know we can pick up Flarm signals from gliders > 100km away with a suitable antenna, and Flarm is the lowest power of the systems we're discussing). Often the driver of whether you can see a signal at a receiver in a congested network, is the signal to noise - and the noise is the contribution from everything that's emitting in line of sight).
So I think we need to be quite specific about the question we're trying to answer, and look closely at the modelling which is used to answer it. Do we have these?
Finally, power is most definitely linked to range in the most simplest of equations - free space path loss. Yes, antennae design can also assist with this so-called problem (which can also be fed into the free space path loss equation if required). Further, receiver design can also improve things. Technology shifts on this all of the time (normally incremental gains) and certainly filters for noise on 1090Mhz have come a long with digital processing. So it may be that in the 6-8 years that this study was completed that matters have improved over what the study reported. Further, the removal of more of the non-selective Mode A transponders since will most certainly have cleaned up 1090Mhz.
Thanks. I understand that. What I said was "It's not as simple as less power = less range." Although that's broadly true, there are other things you need to consider. [There's a big difference between a congested and an uncongested network - an analogy might be how far away you can hear someone talking in a field when it's just you and them, compared with when there's a crowd, also talking].
I understand one of the three reports that you mention is in CAP1391 (referenced by @rjc101 earlier). Do you have links to the other two?
Last edited by PaulisHome on Sun Oct 18, 2020 9:46 am, edited 1 time in total.
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