Danny continues his story from #5902 p.296 (roll on 6,000).
For a description of the AR-1, I cannot do better than put in the following (filched) text (bold type mine) from:
"THE DECCA LEGACY"
"Air Traffic Radars"
"6.6. AR – 1 AIRFIELD APPROACH RADAR"
"In 1959, the MOD was already conducting trials of a radar system against their own performance requirement specification and they were not content with the results. The Decca Radar Company was given 10 months to produce a competitive radar system; a product that was to become known as the AR-1 achieved this.
The AR1 was configured by bringing together elements of existing radars. The antenna and turning gear design was taken from the AWS-1. A variant of the ‘LOTUS’ Transmitter/Receiver would be produced to power the system with a peak power of 650 KW. operating at S-band, with a 1.0 microsecond pulse length and a prf of 700 pps .
The standard system was configured with two transmitters operating in frequency diversity (alternatively, in a single transmitter configuration). The receiver utilised a travelling wave tube RF amplifier from English Electric".
"The double curvature antenna was designed (cosec2 pattern) to give coverage out to 70+nm with a maximum height of 40,000 ft, (using a calibration aircraft such as the Canberra or commercial airliner of equivalent radar surface area). The antenna rotation rate was 15 rpm and circular-polarisation, at S-band, was introduced for the first time. The AR-1 was designed to meet both military and civil airfield approach control requirements with many different display configurations, utilising the new Mk.5 Fixed Coil Display".
"The AR- 1 radar became an international success with sales reaching 108 systems, of which 32 were to the U.K. MOD for use on RAF and Royal Naval stations in the UK and overseas. Much of this success can be attributed to the introduction of the transistorised Moving Target Indicator system - a world wide first into production. Details of both MTI and Display technology employed on the AR-1 are given in Chapters 14 and 12 respectively".
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The enormous height and range (almost double what we had previously) swept by the huge radar lobe transformed life for the operator: he could "see" high level QGHs approaching the overhead (although there was always the "dark area", as in the old D/F "cones of silence"), outbound, turning and inbound, and warn Approach of (apparently) conflicting traffic. Cases like my Ahmed at Strubby ten years before were now impossible, for you could see what he was up to most of the time.
But remember, "the operator" in this case means "Talkdown" (who was his own "Director"): he could only help "Approach" (sitting next to him), when the former was not doing a PAR, or otherwise engaged. At other times Approach was on his own with just the CA/DF as before.
In fact, Radar had everything that an operator could possibly want (except a height-finder), and that would not be of much use when you are dealing with multiple targets which might be hopping up and down. They were fine when you needed only to find the height of the next wave of Heinkel 111s coming over the Channel (say), but in Area Radar the only answer is the radio Transponder (in universal use today) - but we had nothing like that.
And now both operating "heads" were far away from the Tower, over on the other side of the airfield. AR-1 was the usual large radar array on top of a high lattice tower, PAR was a separate structure on a turntable, so that it could be rotated to "look" up the line of approach to either 16 or 34 (control for selection was in the Tower). Of course, your radar mechs spent their time, and had their workshop, over there, and would only come across to you if the displays were giving trouble.
Radar Heaven ? Well no, not quite. The enormous depth of the radar lobe meant that it was showing everything in the skies. You could have two "blips" seemingly on collision course, but one might be at 5,000 ft and the other at 10,000 - but there was no way of knowing this unless you had identified both and were in radio contact with them.
Lower down, the very effective MTI (Moving Target Indicator) almost completely cancelled ground returns. But then the extremely sensitive radar gave such high definition that it was not unknown to find yourself talking to a bird rather than the aircraft you thought you had under control. If you could "zoom in " far enough, you could probably see bumble bees in your garden. Truth to tell, it was too good a radar for our purposes.
IIRC, you could "zoom" in from the 70 (?) miles of full screen down to 20 (?), with range rings every ten (every 2 at full zoom ?). And there was a wonderful new toy. You could displace the point-of-origin of the time-base (the "sweep") anywhere on the tube. So you could put your "centre spot" on Teeside airport (14 mi), zoom in to 20 mi, put your strobe onto 043 (or whatever), and so give an aircraft a far better PPI talkdown than they could possibly do with their puny ACR-7D.
That'll do for the PAR/AR-1. What else ? Well, Leeming had an ILS on 16, but it wasn't used much (did the JP have ILS - I should know !) And we had a Ghost. And that was about it.
More interesting stuff next time.
Goodnight, all.
Danny42C.
Embarass de Richesse !
Last edited by Danny42C; 7th Jul 2014 at 17:18.
Reason: Spacing.