| 摘要 |
<p>A single phase locked loop based device 21 is used to detect alert tones and to decode data in caller display services signalling systems. The device 21 has two sets of components (resistors) 24,25 to configure the device to perform tone detection and data decoding. One or both of the sets of components are connected to the device by an electronically controlled switch 26,27,28. <IMAGE></p> |
