| 摘要 |
<p>A ring scheduling apparatus for use in a digital multiplexed telephone communication system. The apparatus utilizes a controller (36) which sorts messages indicating which telephone lines are being run and what frequency and DC signal level is required for this ringing signal. The messages are sorted into voltage and frequency compatible groups. Digital data is then sent to a ring signal generating circuit (54, 42, 36, 88, 24, 66, 56, 44, 38, 26) to control the frequency of ring signal generated and the polarity of the DC signal upon which the ring signal is superimposed. A multiplexer (42, 44) and line interface circuitry for use in this system is included as well as a self-test circuit for testing the audio circuitry of idle telephone lines.</p> |
