Showing papers on "Impulse noise published in 1971"
59 citations
TL;DR: An optimal signal design of the classical smeardesmear technique for combating impulse noise is demonstrated and it is shown that the smear-desmear channel can be considered superior except for very high noise levels or repetition rates.
Abstract: An optimal signal design of the classical smeardesmear technique for combating impulse noise is demonstrated. The signal design makes use of calculus of variations to derive an integral equation to which several solutions are given, along with a technique for generating additional solutions. A computer simulation and an evaluation of Rice's triple integral pdf for impulse noise are used to analyze the error probability of a smear-desmear data channel and a standard data channel. This is the first known publication of a general evaluation of Rice's integral for the intermediate repetition rate case. The error rates show that the smeardesmear channel is superior only for the lower repetition rate and/or lower level impulse noise cases. An analysis is then made of a clipper before the receiving filter. It is shown that this improves the system error rate to a degree, depending on the clipping level and the preclipper bandwidth-with the wider bandwidth giving greater improvement. The smear-desmear channel experienced a greater improvement than the conventional channel, so that the smear-desmear channel can be considered superior except for very high noise levels or repetition rates; practical considerations in the preclipper bandwidth and clipping level are the limiting factors.
19 citations
Patent•
08 Jul 1971TL;DR: An impulse noise blanking circuit for decreasing the impulse noise in a receiver includes a level sensing circuit coupled to a stage in the signal path following the blanking elements, and to at least one amplifier stage in noise amplifiers which amplify the impulse noises.
Abstract: An impulse noise blanking circuit for decreasing the impulse noise in a receiver includes a level sensing circuit coupled to a stage in the signal path following the blanking elements, and to at least one amplifier stage in the noise amplifiers which amplify the impulse noise signals. The level sensing circuit senses the level of the on-channel and adjacent channel energy in the signal path and develops a level sensing signal. The level sensing signal is coupled to the noise amplifiers to vary the gain in accordance with the level sensing signals, thereby reducing the blanking rate and the resultant receiver degradation due to an excessive blanking rate. The level sensing circuit includes a field effect transistor amplifier stage and feedback circuitry to minimize the production of undesired intermodulation producing signals therein.
10 citations
Journal Article•
8 citations
TL;DR: In this paper, temporary threshold shift (TTS) measurements resulting from exposures to live and tape recorded impulse sounds were carried out on four subjects, and the results show that there is a significant difference between the two measured values of TTS 2, and that the rise time and frequency response of the reproduction system are important factors in determining this difference.
4 citations
TL;DR: A method is described for suppressing impulse interference in a signal detection system by recognizing it as a non-Gaussian contribution, not possessing any of the expected signal characteristics.
Abstract: A method is described for suppressing impulse interference in a signal detection system by recognizing it as a non-Gaussian contribution, not possessing any of the expected signal characteristics. A digital implementation of the method is presented in detail. The performance of a complete signal detection system employing signal integration together with impulse interference suppression is discussed.
1 citations
TL;DR: In this article, the effect of steady-state noise and the combined effect of it with impulse noise (peak sound pressure 125 dB, time constant 10 ms, i.e. duration of the impulse, frequency every 4 seconds, exposure for 30 minutes) on the temporary threshold shift (TTS) was studied on 5 healthy young men.
Abstract: The effect of steady-state noise (88 dB, exposure for 30 minutes) and the combined effect of it with impulse noise (peak sound pressure 125 dB, time constant 10 ms, i.e. duration of the impulse, frequency every 4 seconds, exposure for 30 minutes) on the temporary threshold shift (TTS) were studied on 5 healthy young men. TTS at both test frequencies of 1kHz and 4kHz was much larger in the latter case. This seems to show that the ability of the steady-state noise to arouse acoustic reflex is just of temporary nature.
TL;DR: This preliminary study of noise conditions associated with the use of explosive-actuated tools found that differences in the impulse characteristics, dependent on the physical and acoustical features of the environment, may be expected.
Abstract: Explosive-actuated tools are used extensively in the construction industry. Recent hearing loss claims prompted this preliminary study of noise conditions associated with the use of these tools. Flush-mounting piezoelectric blast pressure gauges coupled to an FM tape recorder and a General Radio impact analyzer were used to obtain measurements of the impulses. Peak sound pressure levels for high-velocity tools were in the range 150 to 160 dB with rise times in the order of 200 microseconds. Differences in the impulse characteristics, dependent on the physical and acoustical features of the environment, may be expected.