FM多重波によるウオッチ型情報受信端末の受信システム Message Watch Receiver using FM Subcarrier
Watch type redio apparatus is a symbolic one and a dream merchandise as well in the future world. As the first step of ideal two way radio apparatus, we have developed a message watch receiver by use of FM subcarrier system. The Message Watch Receiver has the following features; 1) Using custom IC's for minimizing watch size:These are each for FM receiver, data decoder and CPU. FM receiver is of single-heterodyne type which receives the U.S. and European FM band (87.4 to 108MHz). A image cancelling Mixer is included. 2) Duo-binary technique for acheving higher bit rate (19kbit/sec):Data synchronized 19kHz clock signal can be transformed. This technique makes data decoding much more simpler than binary system. 3) Special tuning technique for watch band anntena:Since loop antenna is in the watchband, special tuning technique is used to adjust the band length and tune correct frequency. Antenna is tuned to make receiving signal level maximum. 4) Long battery life over 1.5 year:40ms receiving period and nearly 120s receiving cycle achieve very small average current consumption. This keeps battery life of the watch 1.5 years. Basic technique for achieving these features are described here. we can use this message watch in the U.S. snd Europe at present.
日本時計学会誌 155(0), 23-37, 1995