Abstract: In a tuning method, a commanded-tuning loop (CTL) tunes a receiver (REC) on the basis of a tuning command (TC) and a self-tuning loop (STL) tunes the receiver on the basis of a reception signal. To resolve a tuning conflict between the loops, one of the loops (CTL or STL) is calibrated (CAL) with respect to the other loop (STL or JKR CTL). Preferably, the commanded-tuning loop (CTL) is in an active state when the self-tuning loop (STL) is in-lock. This allows good reception under dynamic reception conditions.

Abstract: Manually tunable analog receivers with AFC have the drawback that the AFC exhibits hysteresis and that in the event of fading pulling to an adjacent station may occur, whereas receivers with PLL electronic tuning have the drawbacks that tuning is comparatively slow and also inaccurate because of the tuning in discrete steps by a microprocessor. The present receiver combines the advantages of both analog manual tuning and electronic tuning. It includes two cooperating frequency loops, one loop (L1) being an AFC loop and the other loop (L2) having a frequency counter (13) for measuring the frequency (f.sub.0) of a tuning oscillator (6) which is controlled by both loops. Cooperation between the loops is provided by a control circuit (16) responsive to control signals supplied by both loops: an in-lock signal (in-1) and an in-window signal (in-w). Preferably, when the desired tuning is achieved, the power to a tuning section (12) of the receiver, forming part of the frequency loop (L2), is interrupted.

Abstract: A tuning detection circuit for a high-frequency modulated RF signal which is within the frequency band of a receiver. A level signal (1e) is derived which is a measure of a level of the modulated RF signal, and is combined with a signal from a window comparator (20, 21) to which a filtered demodulated signal derived from the modulated RF signal is applied. The detection circuit supplies an in-channel signal (in-1) which indicates whether a desired tuning state has been reached. To prevent that upon detection of stations in a busy frequency band incorrect in-channel signals (in-1) are generated, i.e., signals indicating that the tuning process has been completed even though tuning is actually between two stations instead of to one station, the detection device also combines the level and in-channel signals with output signals of the window comparator, compared by means of a phase comparator (50).

Abstract: A level shifting circuit in which the collectors of a first transistor and a second transistor (T.sub.1, T.sub.2), which are coupled together as a differential pair, are each connected to a load resistor (R.sub.o) and to the base of a third transistor and a fourth transistor (T.sub.3, T.sub.4), respectively, which are connected as emitter followers. In order to obtain a low dissipation for a specific gain and bandwidth, the collector of the third transistor (T.sub.3) is coupled to a tapping (7) on the load resistor (R.sub.o) of the second transistor (T.sub.2) and the collector of the fourth transistor (T.sub.4) is coupled to a tapping (6) on the load resistor (R.sub.o) of the first transistor (T.sub.1).