JPS5943640A - Receiver - Google Patents

Abstract

PURPOSE:To improve the received output, by providing two antennas to a different position, connecting a tuner to each antenna, and selecting the output not subject to multi-path distortion among the outputs. CONSTITUTION:Multi-path detecting circuits 4a, 4b extract a part of signals from intermediate frequency detecting circuits 3a, 3b to detect the presence of multi-path distortion. Each output of the circuits 3a, 3b is given to a same pattern extracting device and a switch circuit 6. The extracting device 5 extracts only the same pattern component in each output of the circuits 3a, 3b and an output of the extracting device 5 is given to the circuit 6. Any detecting output signal is selected at the circuit 6 and given to a speaker 9 via a stereo demodulating circuit 7 and a sound amplifier 8.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a receiver, and more particularly to a receiver that is mounted on a car and receives FFL broadcasts while moving.

For example, in mobile receivers such as car radios, especially FM
When receiving broadcasts, multipath distortion occurs in areas such as built-up areas or mountains, which often causes significant reception interference. On the other hand, with fixed receivers installed in homes, attempts have been made to eliminate interference waves by using directional antennas or by measuring the delay characteristics of reflected waves in multipaths. However, in a mobile receiver, the multipath state itself changes every moment due to movement, so the countermeasures used in home receivers are useless. Therefore, in order to reduce this multipath distortion, we forcibly switch to monaural reception when receiving stereo broadcasts,
Secondary methods have been used, such as cutting off the high-frequency components of the demodulated output to remove annoying noise components, and attempts have been made to use diversity reception. Even in this diversity reception, the reception outputs of the two systems often include multipath distortion (,'S), and the improvement in reception quality is often not noticeable.

Therefore, the main object of the present invention is to provide a receiver that can reduce multipath distortion as much as possible.

To summarize, this invention provides at least two antennas on a mobile body with a predetermined interval, a tuner is connected to each of the at least two antennas, and multipath is detected based on the received output of each tuner. , when multipath occurs in the output of any of the tuners, the same pattern signal is extracted from the output of any of the tuners or the received output of each tuner.

The above objects and other objects and features of the present invention will become more apparent from the detailed description given below with reference to the drawings.

The figure is a schematic block diagram of an embodiment of the present invention. This embodiment is composed of two systems of receiving devices. That is, antennas 1a and 1b are provided at different positions of the vehicle (for example, left and right, front and rear, etc.). Each antenna 1a and 1b is individually connected to a front end 2a and 2b, respectively. The respective outputs of the respective freons 1 to ends 2a and 21) are connected to intermediate frequency and detection circuits 3a and 3b. Note that one tuner is constituted by the front 1 to end 2a and the intermediate frequency and detection circuit 3a, and another tuner is constituted by the front 1 to end 2b and the intermediate frequency and detection circuit 3b. The respective outputs of intermediate frequency and detection circuits 3a and 31] are given to multipath detection circuits 4a and 4b. These multipath detection circuits 4a and 4b are constituted by, for example, a high-pass filter and an amplifier, and have an intermediate frequency.

Part of the signal is extracted from the detection circuits 3a and 3b, and the presence or absence of multipath distortion is detected from the magnitude of the high frequency component. Further, the respective outputs of the intermediate frequency and detection circuits 3a and 3b are given to the same pattern extractor 5 and the switch circuit 6. The same pattern extractor 5 has an intermediate frequency and a detection circuit 3a.
It extracts only the same pattern components in the respective outputs of 3b and 3b, and can be easily extracted, for example, as an output of an EXOR gate or exclusive OR gate in digital signal processing. The output of this same pattern extractor 5 is also sent to the switch circuit 6. The switch circuit 6 is supplied with respective detection signals from the multipath detectors 4a and 41). Therefore, the switch circuit 6 has a multipath saving factor of 3 input to the switch circuit 6 according to the respective detection outputs of the circuits 4a and 4b.
output one of two signals. That is, for example, when the multipath detection circuit 4a detects multipath distortion and the multipath detection circuit 4b does not detect multipath distortion, the switch circuit 6 is composed of the antenna 1a or intermediate frequency, and the detection circuit 3a. The output of the receiving section is selected and applied to the stereo 411 circuit 7. Conversely, when the multipath detection circuit ff14b detects multipath distortion, it selects the output of the other receiving section consisting of the amplifier circuit 1b or the intermediate frequency and the detection circuit 3b, and outputs "high". When multipath distortion is detected in any of the detection output signals f84a and 4b, the switch circuit 6 selects the output of the same pattern extractor 5.In this way, any one of the detected output signals is selected by the switch circuit 6. is,
The signal is applied to a speaker via a stereo'A demodulation circuit 7 and an audio amplifier 8.

As described above, according to the present invention, at least two antennas are provided at different positions on a moving object, each antenna is connected to a tuner, and an output that is not subjected to multipath distortion is selected from among the outputs of each tube. , if the output of any tuner is subject to multipath distortion, only signals with the same pattern are extracted from the output signal containing relatively slight multipath distortion. It is possible to obtain improved reception output compared to city reception.

[Brief explanation of drawings]

The drawing is a schematic block diagram of an embodiment of the invention. In the figure, 1a and 1b are antennas, 2a and 2b are front ends, 3a and 3b are intermediate frequencies, a detection circuit, and 4a
4b is a multipath detection circuit, 5 is an identical pattern extractor, and 6 is a switch circuit.

Claims (1)

[Scope of Claims] A receiving device provided on a moving object, comprising: at least two antennas provided on the moving object, each having a predetermined interval, and each individually connected to the at least two antennas. same pattern extracting means for extracting only the same pattern signals from the reception outputs of the at least two tuners; and multipath detection means connected to the outputs of the at least two tuners and each detecting multipath. and a switching means for outputting either the output of the at least two tuners or the output of the same pattern extraction means according to the detection signal of the multipath detection means.