IEEE 376-1975 pdf free.IEEE Standard for the Measurement of Impulse Strength and lmpulse Bandwidth.
IEEE 376 of the impulse as a concept in engineering work has come about not only because of the extensive useof pulses in many types of communication systems, but also because many sources of interference or radio noise are“impulsive” in nature. By an impulsive source one generally means a source of electromagnetic energy which can berepresented by a series of discrete disturbances of low duty cycle.Usually, it will have a relatively broad frequencyspectrum.The importance of the impulse is related to the fact that where the duration of the pulse generated by a givensource is sufficiently short’ in comparison with the reciprocal of the center or tuned frequency of a “narrow-band“network responding to it, the waveform at the output of the network is of a very definite shape practically independentof the input waveform, and has a peak value proportional to its “impulse strength.”Because of these relations, animpulse generator is useful for calibrating the network response, and the networks themselves may be characterized interms of their equivalent “impulse bandwidth.”
Because the impulse has a broad spectrum, a quantitative measure of the “spectrum amplitude”is also a usefulquantity.
spectrum intensity: (For spectra which have a continuous distribution of components (components are not discrete)over the frequency range of interest).The spectrum intensity is the ratio of the power contained in a given frequencyrange to the frequency range as the frequency range approaches zero. It has the dimensions watt-seconds or joules andis usually stated quantitatively in terms of watts per hertz.
lt is this form that is used as the basis for calibration of commercially available impulse generators.
A practical impulse is a function of time duration short’ compared with the reciprocals of all frequencies of interest.lts spectrum amplitude S(f) is substantially uniform in this frequency range and is equal to twice the area under theimpulse time function or 2o. At frequencies higher than this it is still of interest to define the spectrum amplitudewhich will usually be less than 2o.
In most broadband impulse generators adc voltage is used to charge a calibrated coaxial transmission line. The pulsesare produced when the line is discharged into its terminating impedance through mechanically activated contacts.These mechanical contacts may be parts of either a vibrating diaphragm or mercury wetted relay switches. By properchoice of transmission line length and resistive termination, it is possible to produce impulses having a predictableuniform spectrum amplitude range.
The advent of solid-state switches has made it possible to switch on a sine wave for a precisely measurable timeinterval (t), producing in the frequency band in the vicinity of the sine wave a spectrum simulating that produced byan impulse. The spectrum amplitude at that particular frequency can be measured in terms of a measurement of theamplitude of the sine wave when not switched, and a measurement of the on time for the switch.IEEE 376 pdf download.