為了提高現代工廠設備的調度效率，降低儀器儀表等測控數據的傳輸成本，壓縮設備體積等。利用收發芯片TH7122和分離器件相結合的方式設計了一款通信頻段為438～470 MHz的無線音／數兩用小型收發信機。數字調制方式采用MSK調制，同時可切換到音頻模式。其中接收機采用超外差一次變頻結構，結合PIN管帶通調頻濾波器和外接LNA，用于鏡像抑制和降低噪聲。發射部分采用晶振拉動的方式間接調制VCO輸出，經過芯片內部放大、外接功率驅動電路和功率放大電路將發射功率增至5 W，再經諧波濾波發射。經過仿真實驗，輸出功率5 W，中頻10.7 MHz，接收靈敏度為-110 dB，鏡像抑制40 dB，均達到設計要求。

Abstract:

?In order to improve the dispatch efficiency of modern factory devices ， reduce the transmission cost of observe and control datas of instrumentation， and compress equipment volume， this paper designed a small wireless voice/digital dual purpose transmitter receiver which used transmitter receiver IC TH7122 and discrete device，and it worked in the frequency of 438~470MHz. The digital modulation system adopted MSK modulation， it also can be switched to the audio mode. The receiver adopted superheterodyne once frequency conversion， which combined with the PIN controlled bandpass filter to inhibit mirror frequency and the extral LNA to reduce noise figure. In the transmitter section，the crystal pulling way was used to indirectly modulate the VCO’s output. Through the internal amplifier enlarged and the external power driver and power amplifier circuit， the output power was increased up to 5W and transmitted by the harmonic filter.The simulation and testing results show that the output power is 5W， the medium frequency is 10.7MHz ， the rx-sensitivity is -110dB， and the mirror frequence restrain is 40dB. All the design requirements was reached.