| 摘要 |
The phase shifter for the auxiliary signal of the diversity system has a quadrature modulator (6, 7, 8, 9). In a power divider (6), the auxiliary signal is divided into two signals with a 90 DEG phase difference. Each of these sub-signals is forwarded to a diode modulator (7 or 8) to which modulation signals s(t) and sigma (t) are applied. The two sub-signals are then vectorially added in a 3dB coupler (9). The modulated auxiliary signal is vectorially added to the main signal in the 3dB coupler (11). This electronic phase shifter can replace a motor-driven rotating phase shifter in a space diversity system designed along conventional lines. In a matching circuit (15), the conventional DC voltage phase correction signal n(t) is converted into the modulation signals s(t) and sigma (t). In the circuit (15), the signal n(t) is first converted into a pulse signal. The pulses are then counted in an up-down counter, the counter reading in each case corresponding to the instantaneously required phase shift. The parallel output of the counter passes to two read-only memories which are programmed in such a way that a cosine or sine function is simulated. The output signals of the memories are applied to digital-analog converters at whose outputs the modulation signals s(t) and sigma (t) appear. <IMAGE>
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