| 摘要 |
<p>Low frequency signal generator esp. for telephone tone generation. The generator is based on the use of a single stable oscillator feeding two programmable frequency dividers providing outputs which are practically equal to a multiple of telephone selector identification signals. The maximum frequency error due to the use of a ceramic oscillator (1) is 0.25% for the generators eighth output frequencies. The baseline frequency is 530388Hz. This is fed to two frequency (2,3) one providing l.t. outputs and the second h.t. outputs, both being controlled via a decoder (5) from the telephone number generating mechanism (4). The two dividers (6,7) are fed both from the oscillator and the decoder and provide an output (F) to a six line series input, parallel output, shift register (8).</p> |
