New Direction-Finding In strument for Naval Vessels

Radio Record, Volume II, Issue 53, 19 July 1929, Page 2

New Direction-Finding In strument for Naval Vessels

A NEW wireless direction finder has been developed by the Research Department of the Marconi Company for use primarily on all:classes of naval | ships as a navigational instrument. ~ Experience has shown that a wite- . less direction: finder, ‘to meet: naval requirements, must. be capable ‘of tak- . ing accurate bearings from a continuous +. wave, interrupted’ continuous | wave, spark or, telephone ' ‘transmitters over a. wide range of Wavelengths.’ ' The new .type equipment comprises . three units-the frame antenna, the . radio-geniometer, and the.tuner, .and . amplifier. The frame. antenna,. working on a well-known. principle, consis of two -fixed loops : totally enclosed, i strong metal tubes, mounted: on. a- pedes- ., tal. This is rigidly. fixed to the.deck and the leads to the receiver are well protected by being: taken‘ ‘through ‘the centre of the pedestal... oe In the receiver the. tuner’ ‘and amplifier are combined as.one compact unit and coyer. a range.of. from 300 to 4000 metres. To obtain this. waye-’ range three sets of coils are employed and by means’ of a singlé switch mounted on.the front of ‘the’ receiver: any one set: of:these cdils can be switched into circuit. -An indicator shows which coils are-in use-and their’ waverange. Three shielded valves are’ used to: provide -high-frequency.. ‘amplification: and four tuning condensers which: are ‘calibrated:in metres are’ used to ‘tune the grit circuits of the high-frequency ‘and detector valves... Each of these condensers can be adjusted "independently, but a common eontrol: enables ‘them*to be varied: overia range of approximately 10 percent. on’ either side of the w avelength to: which they. are set. Tor reception of ‘cotinuous waves a. separate heterodyne mounted in the amplifier is employed. In all seven valves are used, three ‘high-frequency ampli-, fiers, one detector, one note magnilfier,, one local oscillator. generator, which’ can be used as an additional note,mag-. nifier if requiréd, and one coupling valve. In. order that the "sense". of bear-. ings over the whole wayeband ‘of the receiver can be obtained with the use of only a short vertical aerial a‘stage of valve amplification using the caunling valve is employed for the vertical component. The arido-goniometer is ‘eonstructed 4 as a separate unit-..which can be fixed: in any convenient position. ‘Two calibrated scales from which the bearings are read are mounted on the face of the unit. The inner, scale. is -fixed and bearings taken from this ‘scale are relative to the centre line of the:ship. The outer scale can be rotated until the figure indicating the shin’s true course is at the top. of the dial. opposite the zero mark of the inner seale, aud then, if the ship is steady on her course, the bearings réad: from the outer scale are true: bearings.