IEEE 376:1975 pdf download.IEEE Standard for the Measurement of Impulse Strength and Impulse Bandwidth.
The importance of the impulse as a concept in engineering work has come about not only because of the extensive use of pulses in many types of communication systems. hut 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 be represented by a series of discrete disturbances of low duty cycle. Usually, it will have a relatively broad frequency spectrum. The importance of the impulse is related to the fact (hat where the duration of the pulse generated by a given source is sufficiently short1 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 independent of the input waveform, and has a peak value proportional to its “impulse strength.” Because of these relations, an impulse generator is useful for calibrating the network response, and the networks themselves may be characterized in terms of (heir equivalent “impulse bandwidth.”
Because the impulse has a broad spectrum, a quantitative measure of the “spectrum amplitude” is also a useful quantity.
2. Definitions
impulse strength: The area under the amplitude-time relation for the impulse.
In most broadband impulse generators adc voltage is used to charge a calibrated coaxial transmission line. The pulses are produced when the line is discharged into its terminating impedance through mechanically activated contacts. These mechanical contacts may he parts of either a vibrating diaphragm or mercury wetted relay switches. By proper choice of transmission line length and resistive termination, it is possible to produce impulses having a predictable uniform spectrum amplitude range.
The advent of solid-state switches has made it possible to switch on a sine wave for a precisely measurable time interval (t), producing in the frequency band in the vicinity of the sine wave a spectrum simulating that produced by an impulse. The spectrum amplitude at that particular frequency can be measured in terms of a measurement of the amplitude of the sine wave when not switched, and a measurement of the on time for the switch.
impulse bandwidth: When an impulse is passed through a network with a restricted passband. the output generally consists of a wave train, the envelope of which builds up to a maximum value and then decays approximately. exponentially. The impulse bandwidth of such a network is defined as the ratio of that maximum value (when properly corrected for network sine wave gain at a stated reference frequency) to the spectrum amplitude of the pulse applied at the input. In networks with a single humped response. the reference frequency is taken as that at which the gain is maximum. (Overcoupled or stagger-tuned networks should not be used for measurement of spectrum amplitude of impulses.)
IEEE 376 pdf download.