| 摘要 |
<p>The cordless phone has a base unit and one or more handsets. Both fixed and portable units are equipped with a PLL synthesiser which can operate in a channel-scanning mode to detect an attempt to establish communication. Scanning is controlled by a microprocessor, which executes a routine (SCNN) which directs the PLL to tune the receiver to a series of channels (N). If the channel currently being received is free, the scanning routine is resumed. If a carrier is detected, the processor enters a wait mode (D2) then a test (M is executed for the presence of data. If no data is detected, scanning is again resumed, while the presence of data causes the processor to enter a further wait mode (D3). Communication link request data includes data (L) relating to the channel on which it is transmitted, and in another test (L this data is compared to the current channel designation of the synthesiser. Communication (CO) is immediately initiated if the two channel indicators match, otherwise the synthesiser is reset to receive the transmitted channel, on the basis that a valid set-up request has been received as a spurious signal on another channel.</p> |
