CAR Short Range Radar (SRR)
Murray Niman G6JYB
Bear in mind when you read this that Ofcom less than a year ago approved
the move of the Amateur 76Band into this new 77GHz+ area!
What also annoys me on 76 more from a professional point of view is...
a) There are/planned to be other users/applications on the
76Ghz bands which Ofcom ignored, as its ideal for 'Long' range radar.
It's an ideal low loss band , <1dB/km in the atmosphere
b) If you want a 100 cars with radar on in close proximity, you
want maximum frequency reuse and a good way to do this is to put them
on a high absorption band to limit their range, say near to the 60GHz
absorption peak. 1GHz BW is more than enough for the doppler and a chanellised
system
c) CAR SRR is fundamentally a safety related system, so having
it in a unprotected de-regulated area overlapping with other stuff is
frightening, especially for next generation systems which support 'platooning'
on motorways.
d) UK Car telematics development (car-car, car-roadside comms/data
links) have previously been on 63GHz based on the reasoning of c) and
consistent with radiolocation being permitted on the 59-64 band
e) I presume the new German systems are trying to do 'mm-wave
imaging' but I dont know for sure. Its better to do this with pulse compression
in DSP recievers and/or timegating the return rather than the bruteforce
very narrow wideband pulses on transmit
I need to confer with a few people on this but for now I still find the
4-5GHz bandwidth requirement not only amazing, but hardly conducive to
low cost commercial systems which is what the Car people would want, and
could block some other useful commercial and other systems in that area.
If we can go back to keeping 75.5-76 for amateurs as primary all well
and good but that should'nt stop us pointing out the technical flaws on
SRR as there are so few engineers left in the relevant halls of Ofcom/CEPT
to realise the consequences of their actions
Who believes that car radar on the 21-26 band will be a
short term thing if they are let onto there?!
Murray G6JYB
NB The Astronomers also have allocations in the 76-79
and probably wont be very pleased
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