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1887

Radio and Electronic Engineer

Volume 45, Issue 4, April 1975

Volumes & issues:

Volume 45, Issue 4

April 1975

Promoting non-glamorous technologies
A noise-protected digital heart ratemeter
  • Author(s): R.J. Twizell
  • Source: Radio and Electronic Engineer, Volume 45, Issue 4, p. 155 –160
  • DOI:  10.1049/ree.1975.0029
  • Type: Article
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  • p. 155 –160 (6)
    In many experimental and diagnostic studies of heart rate, a simple averaging ratemeter is not satisfactory. This is due to the difficulty of obtaining an instrument response sufficiently fast to follow the rapid changes in rate, and at the same time keeping the ripple to an acceptable level.This paper describes an instantaneous-frequency cardiotachometer with some unique design features. It focuses particular attention on the digital period-to-frequency converter and a protection system designed to reject spurious noise pulses, such as those caused by muscle artefacts during exercise studies and those occurring during foetal heart rate monitoring.
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Object identification from multi-frequency radar returns
  • Author(s): A.G. Repjar ; A.A. Ksienski ; L.J. White
  • Source: Radio and Electronic Engineer, Volume 45, Issue 4, p. 161 –167
  • DOI:  10.1049/ree.1975.0030
  • Type: Article
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  • p. 161 –167 (7)
    Methods are presented for identifying object classes from a limited number of radar measurements. The radar measurements are the backscattered signal amplitudes at up to twelve harmonically related frequencies in the lower portion of the object's response spectrum. These amplitudes constitute a set of features upon which classification is based.The maximum and average probabilities of misclassification are computed for various classes represented by test samples corrupted by Gaussian noise. Various methods are derived which reduce classification errors.Results are presented which demonstrate that reliable classification can be obtained in the presence of noise.
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Britain's first X-ray astronomy satellite
Computers chosen for ESRO Meteosat project
Series-parallel generation of m-sequences
A design for a low-cost high-speed m.o.s. associative memory
  • Author(s): R.M. Lea
  • Source: Radio and Electronic Engineer, Volume 45, Issue 4, p. 177 –182
  • DOI:  10.1049/ree.1975.0034
  • Type: Article
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  • p. 177 –182 (6)
    A design for a 128-bit m.o.s. associative memory is described. The memory array can be integrated on a 1.6 × 2.9 mm (63 × 114 mil) chip using standard silicon-gate m.o.s. fabrication technology. The basic memory cell is dynamic in operation, but external refresh circuitry is not required. Computer simulation studies predict match and read access times of 10 ns, and a write ‘toggle’ time of 25 ns. A design for a cheap interface buffer circuit is also described. With these two designs it is possible to build a low-cost associative memory array, organized as 256 words of 256 bits each, which is TTL compatible and will operate with a 100 ns cycle time.
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A double phase sweeping system for diversity reception in mobile radio
  • Author(s): A.J. Rogers
  • Source: Radio and Electronic Engineer, Volume 45, Issue 4, p. 183 –191
  • DOI:  10.1049/ree.1975.0035
  • Type: Article
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  • p. 183 –191 (9)
    Fading due to multi-path propagation is a serious problem in mobile radio communications. Consideration is given to the theory of an effective means for combining the signals from a twin antennae space diversity arrangement using phase sweeping in opposite directions for the two antennae. An analysis is presented for various modulation methods.The resulting system should be compatible with existing receivers. Some experimental results for acommercial v.h.f. a.m. system are included.
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