| 摘要 |
<p>The invention relates to a device identifying traffic on a paired cable. The different types of traffic are characterized by different levels and frequency ranges. The device comprises a limiter connected to the paired cable and delivering an output signal having substantially constant amplitude and a frequency corresponding to the strongest frequency component of the input signal. The limiter may be constructed of inverters coupled as an amplifier or of an amplifier having a Schmitt trigger. The limiter is connected to a frequency indicator indicating what frequency ranges within which the strongest frequency component lies. The frequency indicator may consist of monostables or counters and decoders. The decoder interprets the output signal of the counter and may be constructed of a fixed gate network or of a programmable memory. The output signal of the frequency indicator is connected to an indicator indicating the frequency range in question, e.g. by means of flashing light-emitting diodes.</p> |
