| 摘要 |
<p>Portable, plugable electrical test equipment signals the presence or absence of radio frequency energy within a predetermined frequency spectrum, as on a CATV or MATV video distribution system. The equipment comprises a cascaded bandpass filter, radio frequency amplifier, coupling-detector network, and operational amplifier to selectively energize a light emitting diode when a sufficient level of energy in the requisite frequency range is sensed.</p> |
