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Radiolocator

Page history last edited by Alan Hartley-Smith 5 years ago

 

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Introduction

An extract from "The Origins of Baddow" by Roy Simons-

 

Immediately post-war there was a requirement for the Marconi Marine Company to attempt to enter the merchant marine radar market and there was an order to fit the LMS (London Midland and Scottish railway) ships, which sailed between Heysham and Belfast daily.

The Marine Company did not have its own development staff and sub contracted development to the Telegraph Company.  The marine development team at New Street under James Watt was only expert in depth sounders and marine communications so the work was placed on Research at Baddow.

Shortly after this R. J. Kemp increased his responsibilities as Deputy Chief of Research (to J. G. Robb) and B. J. Witt was put in charge of the section, (plus Lambert and Golding, all of whom had worked directly for Marconi)

At about this time, Fred Garrett returned from secondment to the Admiralty, bringing expertise in modulators and Roger Shipway, (previously a lecturer at Marconi College) returned, bringing a significant amount of expertise in the latest circuit techniques, gained in the RAF at Malvern and which prior to that time were only known to secure projects especially H2S and the work of Blumlein.

 

Radiolocator 1

 

The first Radiolocator was effectively a rework of the American Type 268 or Canadian 972 - a 1938 design searchlight control radar, peak power 50Kw, pulse width 7-15 microsecs, prf 4098, frequency 206 MHz.

 

The display of the 268 was generated using an area balanced waveform resolved in three phase by a synchro with the stator of another synchro placed round the neck of a CRT.  We used rather better resolvers and coils than the original, but the design suffered from providing only a centred picture, with only fractional off-centering possible using external deflectors. There was also a difficulty in generating a fast scan of say 10  microsec for a 1 mile presentation, as the waveform had, in principle, to travel up and down the mast on the way to the display.

Some members of Section K and Section E left to join L. H. Bedford who had arrived to launch the English Electric Company into domestic television and the 1550 TV receiver was designed and put into production.

 

Radiolocator 2

 

The Radiolocator Mark 2 was a totally revised design.  All units were new and used the latest technology available and the latest valves.  This design required up to date test equipment and as a by-product we designed an oscilloscope which had much better performance than any available and which was for many years the standard in the laboratories and in production test.  Again this used ‘modern’ circuit technology to great effect.  The radar display used a rotating coil as part of the deflection system, driven via a gearbox, which incorporated compass correction from an M-motor and electro mechanical auto alignment of the display to the ship's head.

 

Radiolocator 3

 

The Radiolocator Mark 2 was the prototype of the Mark 3, which was subsequently engineered by Marine Development in New Street and had a successful market life.

 

There followed a long series of improved designs to provide increasingly comprehensive navigation facilities to mercantile marine customers. Details can be found through the MIMCO wiki

 

An interesting note

The following is a note from the archives of a probable development by MIMCo based on the Radiolocator which shows the benefits of radar:

 

ADDITIONAL INFORMATION ON PREDICTOR SELF-PLOTTING MARINE RADAR

 

The first installation of Predictor in the liquid-gas carrier Methane Progress has already accumulated nearly 7,000 hours of operations in the twelve months since it was fitted.

 

Summarised, this is what one user has to say about Predictor in operational service: 'There can be no doubt that the chosen form of presentation is of great value. Both true and relative situations can be fully appraised in about half-a-minute, even when some ten to fifteen targets are on the screen. Changes of course or speed are readily noticed, and in true mode the antics of fishermen, for example, a considerable problem in some places, ­can be appreciated at once.

 

When the screen is really full of targets, full appraisal takes longer, and it is sometimes advisable to use a shorter plotting interval, e.g. three-minute tracks, to reduce the risk of confusion. Nevertheless, one can assess the immediate hazards just as readily as in the simpler situations, and while one is doing this, the next hazards are quietly plotting themselves so that when it is necessary to assess them, the plot is already there. This really is the essence of the method, that without any manual intervention, a six, three or one-and-a-half minute plot of all targets can be available at all times; a situation quite impossible to achieve by manual methods and by no means easy to obtain by computer methods. Further, it provides a continuously up-dated four-point plot, greatly reducing the chance of over-looking a course or speed change that is inherent in a two-point plot.

 

To build the complete four-point plot requires four scans, taking ten seconds. A simple trick enables the user to compare true and relative plots even more quickly if he wishes. This is done by changing mode immediately after the 'now' scan. The next scan displays the oldest 'history' plots and thus gives a quick assessment within one scan.

 

The effect of a proposed course or speed change can be judged in a few seconds using the 'Predicted Relative' mode.

 

Marconi have produced a system which meets most of the navigators' needs, and which is extremely easy to learn and officers handle it with ease in a matter of hours. It does not attempt to predict Courses, but provides data in such a way that extrapolation is easily done by eye and cursor. Thus the user still has to think about what he is doing, but this is seen as no disadvantage, maintaining as it does full human involvement. Some people may find their understanding of true/relative motion refined by it. A plot is available at any time without detaching a man to observe radar continuously, and furthermore all targets are plotted, a situation often not possible for a human observer.

 

There is no need to select potentially dangerous targets before an automatic plot can be developed. In short, here is a real asset to safety.

 

 

 

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Comments (1)

Ian Gillis said

at 2:57 pm on Feb 14, 2016

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