Direct measurement of bandwidth

SINCE the field of communications had its beginning, the width of the band of frequencies that could be passed by any piece of equipment has been important. Advances in the field have put more rigorous demands on the fidelity of response of some systems, consequently requiring greater pass-bands, and at the same time progress has demanded that other systems become more and more selective with an appropriate limitation of pass-band. Notwithstanding, the specification of bandwidth is not standard, nor has its measurement been simplified greatly.