| 摘要 |
<p>A conversion circuit 20 for use with digital telephone switching equipment for converting pulse amplitude modulation (PAM) signals on line 19 into pulse code modulated (PCM) signals on line 31 and for converting PCM signals on line 30 into PAM signals on line 18. When these conversions are done it is desirable to adjust the magnitude of the signals involved to take into account the differing losses in the associated analogue circuitry. The present invention employs digital pads 25, 42, in the digital portion of the conversion circuit and controlled by a storage register 26, in order to introduce variations in the signal levels. <IMAGE></p> |
