Communication equipment



PURPOSE: To use the communication equipment without remodeling even when the system is revised by enhancing the accuracy of a 90° phase difference of a carrier so as to improve the modulation accuracy when an orthogonal modulation circuit is used to generate a digital modulation signal and the signal is transmitted. CONSTITUTION: An orthogonal modulation circuit 2 being one device is provided with a local oscillator 2F oscillating a frequency of a multiple of two or four of a carrier frequency and its output is frequency-divided by a 90° phase shifter 2C to obtain a carrier of 90° phase difference. I, Q signals received from input terminals 1A, 1B are respectively multiplexed with the carrier of 90° phase difference from the 90° phase shifter 2C at mixer circuits 2A, 2B respectively and the results are added by an adder 2D and a carrier from a 1st local VCO 2 is multiplied with the sum at a mixer circuit 2E to obtain an orthogonal modulation signal as a transmission signal. COPYRIGHT: (C)1996,JPO
(57)【要約】 【目的】 直交変調回路を用いてディジタル変調信号を 生成し送信する際、搬送波の90度位相差の精度を高め て変調精度を良好にし、かつシステムを変更してもその まま使用できるようにする。 【構成】 1つのデバイスとしての直交変調回路2に、 搬送波の2倍ないし4倍の周波数で発振するローカル発 振器2Fを設け、その出力を90度位相シフタ2Cで分 周して90度位相差の搬送波を得る。入力端子1A,1 Bから入力されたI,Q信号は夫々、ミクサ回路2A, 2Bで90度位相シフタ2Cからの互いに90度位相差 の搬送波と積算され、加算器2Dで加算された後、ミク サ回路2Eで第1のローカルVCO2Gからの搬送波が 積算されて、送信信号としての直交変調信号が得られ る。




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