| 摘要 |
1,217,204. Frequency changing systems; radio signalling. TELETTRA, LABORATORI DI TELEFONIA ELETTRONICA E RADIO S.p.A. 16 Feb., 1968 [29 March, 1967], No. 7714/68. Headings H3F and H4L. Frequency changing and amplification of angle modulated waves of frequency F and modulation #F is effected by amplifying dividing and shifting the waves to produce a signal of frequency F/n + f/n with a modulation #F/n and amplifying and multiplying this signal frequency by n to produce an output F + f modulated by #F. Fig. 5 (not shown) illustrates a radio repeater in which the signal is amplified, divided, shifted by f/n in that order, further amplified and then multiplied. In Fig. 6 (not shown), the shift of frequency (by an amount f) is effected before division while in Fig. 7 (not shown), the incoming signal is divided before subsequent amplification and shift. Amplification and division may be effected by a locked oscillator and multiplication by a varactor diode circuit. The looked oscillator may have a common input circuit using a circulator of appropriate filters (Figs. 2 and 5, not shown). |
