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1887

Radio and Electronic Engineer

Volume 39, Issue 3, March 1970

Volumes & issues:

Volume 39, Issue 3

March 1970

Television measuring techniques
An experimental laser-photochromic display system
An optical fixed data store
  • Author(s): R.J. Botfield  and  A.N. Hill
  • Source: Radio and Electronic Engineer, Volume 39, Issue 3, p. 130 –138
  • DOI:  10.1049/ree.1970.0020
  • Type: Article
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  • p. 130 –138 (9)
    An optical fixed data storage system is described which is designed to hold 4 M bits of information on each exchangeable photographic plate. The store, intended as an integral part of a computing system, enables any of 65,536 69-bit words to be retrieved with a random access time of a few microseconds. Writing time for each data plate is approximately 1 hour. To record and retrieve the data, a spot is positioned on the face of a high resolution electrostatic cathode ray tube, and multi-imaged on to a photographic plate by means of a lens/square cross-section mirror tunnel/lens system. Word readout is achieved using one 11-stage photomultiplier as detector for each bit of the word.
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Six new delay functions and their realization using active rc networks
Instantaneous and time-varying spectra—an introduction
Letters: Advertisements in the Journal
A function generator using hybrid techniques
  • Author(s): R.N. Barnes
  • Source: Radio and Electronic Engineer, Volume 39, Issue 3, p. 153 –160
  • DOI:  10.1049/ree.1970.0024
  • Type: Article
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  • p. 153 –160 (8)
    The principle of operation of a novel function generator is outlined and some applications are reviewed. The basic function produced by the generator is a ‘box-car’, or discrete, type function having fixed thresholds with respect to the input voltage, and output voltage levels that may be independently set in any segment. By using a sampling technique, linear interpolation may be applied across any of the discontinuities in the ‘boxcar’ function to produce an ‘analogue’, or continuous type function. This arrangement allows for the independent adjustment of the value of the function for input voltages midway between the threshold voltages. In the discrete mode, good accuracy is maintained for full amplitude input swing up to 80 kHz and in the continuous mode up to 5 kHz.
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Cyanide gas lasers for sub-millimetric wavelengths
  • Author(s): E.J. Becklake  and  M.A. Smith
  • Source: Radio and Electronic Engineer, Volume 39, Issue 3, p. 161 –166
  • DOI:  10.1049/ree.1970.0025
  • Type: Article
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  • p. 161 –166 (6)
    Progress is outlined in the design of c.w. and pulsed lasers, using methyl cyanide, dimethylamine and a mixture of methane and nitrogen, for use at wavelengths in the 337 μm region. Output stability is stated to be a function of cathode material, gas type and pressure and discharge current for any given laser design. Brass appears to be the best cathode material. With input power at 1 kW, outputs of 7 mW (c.w. laser) and 1 W (pulsed laser) were obtained, the gas used making no significant difference to these figures. An optimum working pressure of 0.55 torr was established using a mixture of 60% methane and 40% nitrogen. Tube life with all three gases is typically 100 hours. Initial investigations into transmission properties of various materials at sub-millimetric wavelengths show that p.t.f.e. and t.p.x. (polyolefin thermoplastic) make the best lenses and windows, and that black polythene makes the best attenuator. Investigations into atmospheric absorption at this wavelength indicate that, dependent on temperature and relative humidity, attenuations of between 36 dB/km and 204 dB/km can be expected.
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Semiconductor diodes as detectors and mixers at sub-millimetric wavelengths
The two-frequency m.t.i. system
  • Author(s): J. Kroszczyński
  • Source: Radio and Electronic Engineer, Volume 39, Issue 3, p. 172 –176
  • DOI:  10.1049/ree.1970.0027
  • Type: Article
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  • p. 172 –176 (5)
    Clutter motion relative to the radar may seriously degrade the efficiency of moving target indication (m.t.i.) systems used in radio location. This problem arises in shipborne radar, airborne radar, or when the clutter is being carried by the wind. Although various methods have been devised to overcome the effect, the problem still exists because these have their inherent drawbacks. As another approach, the two-frequency m.t.i. system has been proposed occasionally in the past few years, but it seems that a more detailed consideration of this method is as yet not available in the literature. A basic theory of the two-frequency m.t.i. system, together with a discussion of its significant characteristics, is presented in this paper.
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