Originally Posted by
Wensleydale
GMP,
....
My statement of "low PRF" is of course relative - I don't want to go into the current system in this forum. However I must take issue with you about the performance of the "Offset Pair of Bo****cks" - sorry Parabolics. You have fallen for the GEC line about road traffic. If this is the case then the Shetland Islands have a huge number of articulated trucks driving over them. The problem was the very large first sidelobe which painted land as moving targets due to the too small clutter notch. Hence the UK coastline and oil rigs being tracked as huge formations of aircraft doing 47 Kts. This is the reason that we could not directly illuminate the coastline within 120 nmi without crashing the computer.
I also disagree about the tracker which gave appaulingly short track life if the aircraft turned. I refer the Gentleman to the results of the final trial before the decision to scrap where the AEW 3 was trialled against a common datum (E-3A flown the day after). The results are classified so I cannot say too much, however the results were damning.
We're a bit off thread here but let's close it off.
PRF rating isn't relative, it's absolute. There are clear definitions for what constitutes a low, medium or high PRF system. No ifs ands or buts. Low is range and velocity unambiguous; medium is both range and velocity ambiguous; high is range ambiguous velocity unambiguous.
MPRF resolution in range is achieved by examining the modulo of PRF event. If you haven't an engineering degree you won't have come across modulo - it's a part of mathematical number theory. (Stay away from it unless you're an insomniac).
I saw first hand the results of the offset parabolics compared to the cassegrains, in design and test reports, independent assessments, and from my own observations in flight. They made a huge difference. If we'd started with them, as GEC was advised at the outset to do, the outcome might well have been completely different. The lessening of the height line was not large - it was utterly immense, measured in tens of dB.
I'm afraid the rest of your analysis is simply wrong, save for the fact that there were massive numbers of vehicles on UK roads that were picked up by the radar in main and sidelobes. I flew a number of overnight flights using the TWT drivers only (not using main power) and the road map of UK emerged from 2am and by 6am the whole of the landmass was alive and the radar unusable.
Back to the MRA4 please.