| 摘要 |
PURPOSE:To make it possible to know easily a sweep direction even as to a receiver provided with a small number of display elements corresponding to all frequency divisions on a scale, by enabling the discrimination of whether a sweep or down sweep is in process by sound. CONSTITUTION:During an up sweep, a signal of high frequency 2f, for example, is supplied from channel selection control part 23 to low frequency amplifying circuit 19, where it is amplified to send sound out via loudspeaker 20. During a down sweep, on the other hand, the sound is generated as to a signal of frequency (f) a half that in the up sweep, for example, and on the basis of the difference in the pitch of the sound, whether the up sweep or down sweep is in process can be discriminated. Consequently, the sweep direction of a receiver equipped with a small number of display elements corresponding to all frequency divisions on the scale can be known, the cost of the whole receiver can be reduced, and its operation can be improved. |
