| 摘要 |
A radio broadcast receiver is disclosed for sequentially scanning and monitoring a plurality of preselected broadcast channels to determine the presence of a radio signal in any one of the preselected broadcast channels. Selector means are provided for each preselected channel to enable the user to individually select the mode of operation for each preselected channel. Three modes of operation are provided for each channel as follows: (1) the scan mode; (2) the bypass mode; and (3) the select mode. Structurally, the receiver comprises a two pole, three-position switch associated with each channel. With the switches in their "scan" position, the receiver automatically scans each channel in sequence, stopping only on a channel which is broadcasting, and resumes scanning when such station terminates broadcasting. If any switch is moved to a second "bypass" position, the scanning proceeds as above but without stopping on the bypassed channel. The third position, called the "select" position, permits selection of a subgroup of one or more channels to be scanned. A principal advantage of this arrangement is that automatic scanning can be provided between any selected channels by a positive selection process. The user need not work backward to achieve the same result, that is, by bypassing all channels he wished not to scan. In addition, this radio receiver includes a scanning speed control circuit for adjusting the speed of the scanner according to the mode of operation of each channel. Thus, when a preselected channel is encountered with its selector switch positioned in an unused mode, that is either the bypass mode or the non-select mode when another switch is in the select mode, the speed of the scanning is increased to effectively eliminate the scanning period.
|
