The diversity receiver having a plurality of antennas and one receiver comprises a detector means to detect a signal voltage responsive to an antenna output from an intermediate frequency amplifier of the receiver, and a comparator unit to receive two separated components of the signal voltage from the detector unit through two separated paths, so that one of the antennas which is in the best receiving condition is selected in response to an output from the comparator unit.
A diversity receiver includes first and second antennae for receiving an RF signal, and an antenna switching circuit for selecting one of the first and second antennae. A first detection circuit having a high sensitivity, and a second detection circuit having a low sensitivity are provided, each detecting a noise signal contained within the received RF signal in different sensitivity. A field strength detection circuit is provided for detecting a field strength of the received RF signal, and a selection circuit is provided for selecting either one of the first and second detection circuits according to the output signal of the field strength detection circuit, and for providing a switching signal to the antenna switching circuit. Thus, when the field strength is relatively strong, the first detection circuit with high sensitivity is used for the noise detection, and when the field strength is relatively weak, the second detection circuit with low sensitivity is used for the noise detection.
In a space diversity receiver for receiving broadcast signals and having first and second antennas coupled to first and second receiving circuits, respectively, for supplying first and second output signals therefrom to a switching circuit which normally selectively supplies the one of the output signals detected to have a superior or better signal to noise ratio; a judging circuit is provided for comparing the better signal to noise ratio of an output signal with a predetermined value and for producing a stop or inhibiting signal when the signal to noise ratio is lower than the predetermined value, and such inhibiting signal temporarily causes the switching circuit to stop switching between the output signals and to continuously supply one of the output signals.
A space diversity system capable of operating accurately over a wide range of received input electric field strengths. With a middle or high received electric field strength, a search operation for the antenna with the highest strength is commenced in response to noise detected in the output of the antenna presently selected. With a low received electric field strength, the search operation is carried out in response to noise such as white noise at all times.
Disclosed is a mobile radio-receiver system built-into an FM radio-receiver set installed in a vehicle, wherein a reproduction characteristic of a reception signal, such as a sound signal, having noise superimposed thereon is improved. The mobile radio-receiver system includes a space diversity unit which receives two reception signals and selects one reception signal on which noise is smaller than on the other reception signal, and a signal prediction unit which ignores the selected signal for a predetermined time in which large noise remains in the selected signal, and predicts a reception signal for the ignored selected signal for the predetermined time, so that a quality of a reproduction sound from the FM radio-receiver set is greatly improved.
A tuned radio apparatus includes a tuned radio receiver and a tuned antenna apparatus both of which are tuned to the same frequency. The antenna apparatus may include a varactor similar to a varactor used in the receiver and receiving the same tuning voltage for tuning at least one antenna. The tuning voltage may be supplied from the receiver to the antenna apparatus and the received radio frequency output may be supplied from the antenna apparatus to the receiver over an antenna cable connected to a single antenna terminal.
