| 摘要 |
<p>The apparatus has a probe (13) for collecting a small portion of a carrier signal on a pair of wires (37). The collected portion of the carrier signal is mixed with a local oscillator (17) signal so as to produce a heterodyned signal having a low frequency component and a high frequency component. The frequency of the local oscillator signal is selected to be within a few Kilohertz of the carrier signal so that the low frequency component is within an audible range. A low pass filter (19) removes the high frequency component. The low frequency component is amplified (21) and converted to sound. The audible signal is a representation of the carrier signal and allows a technician to determine the relative strength of the carrier signal and to identify the type of carrier signal on the wire pair.</p> |
