| 摘要 |
<p>To permit mass-production of coders selectively usable in various types of transmitter installations, and regardless of whether designed for stereophonic or monophonic transmission, in which a subcarrier of non-audible frequency (57 kHz) is radiated, amplitude modulated by separate recognition signals characterizing intelligence information (AR, or announcement recognition) and a specific transmitter (region or radio station recognition, RR), a memory element (36) such as a PROM is provided, connected to a selector switch, the memory element having stored therein data representative of (1) frequency of amplitude modulation of the subcarrier of the announcement recognition (AR) signal; (2) frequency of amplitude modulation of the radio station recognition (RR) signal; (3) degree of modulation by the (AR) signal; (4) degree of modulation by the (RR) signal, and, preferably, data to provide a visual indication of a respective frequency channel and modulation degree, the memory element (36) being programmed for selective control of a frequency divider chain (31,32,33,34) including a programmable divider (30) as controlled by the selector switch. The degree of modulation of the subcarrier as between the respective AR and RR frequencies can be changed in dependence on whether only the RR modulation signal is present, or the AR and the RR signals are both present.</p> |
