Diversity reception having a plurality of antennas for use with moving vehicles
AssigneesHitachi, Ltd., Hitachi Video and Information Systems, Inc., Hitachi Automotive Engineering Co., Ltd.
InventorsKazuhiro Ooyagi, Nobutaka Hotta, Keiro Shinkawa
Life of this patent
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Abstract
A diversity reception apparatus which has a plurality of antennas and in which one of the antennas having the best receiving condition is automatically selected and connected to a broadcasting signal receiver. The diversity reception apparatus has a feature in that after demodulated signals, obtained by the receiver respectively corresponding to the plurality of antennas, are converted into digital signals by an A/D converter, the best demodulated signal and the antenna corresponding thereto are selected by comparing the digital signals with each other, and that the width of a switch driving pulse from a switch driving pulse generator is made not more than 3 .mu.s.
Claims2
A diversity reception apparatus comprises:
- a plurality of receiving antennas;
- a receiver for receiving an analog demodulated broadcasting signal;
- an A/D converter for converting said analog demodulated signal from said receiver into a digital signal;
- a change-over switch for selecting one of said plurality of receiving antennas and connecting said selected receiving antenna to said receiver;
- a switch driving pulse generator for generating a switch driving pulse for sequentially selecting one of said plurality of receiving antennas;
- a comparator for comparing demodulated signals output by said A/D converter which are obtained when said plurality of receiving antennas are sequentially connected to said A/D converter to thereby detect a receiving antenna corresponding to a demodulated signal of the highest level;
- and
- control means responsive to said switch driving pulse and an output of said comparator, for controlling said change-over switch so that said receiving antenna corresponding to said demodulated signal of the highest level is selected for a period of time in which said switch driving pulse is absent while a receiving antenna corresponding to said switch driving pulse is selected for a period in which said switch driving pulse is received by said control means;
- wherein the pulse width of said switch driving pulse output from said switch driving pulse generator is no longer than 3 .mu.s.
A method of removing audio distortion from a diversity reception apparatus having a plurality of receiving antennas, said method comprising the steps of:
- receiving an analog demodulated broadcasting signal from said receiving antennas into receiving means;
- converting said analog demodulated signal into a digital signal;
- selecting one of said plurality of receiving antennas;
- connecting said selected receiving antenna to said receiving means;
- generating a switch driving pulse;
- sequentially selecting each of said plurality of receiving antennas according to said generated switch driving pulse;
- comparing the digital signals with one another to thereby detect a receiving antenna corresponding to a demodulated signal of the highest level;
- and
- controlling said selection of a receiving of antenna of said plurality of receiving antennas such that a receiving antenna corresponding to said demodulated signal of the highest level is selected for a period of time during which said switch driving impulse is absent, while a receiving antenna corresponding to said switch drive impulse is selected for a period of time during said switch driving pulse is received by said control means,
- wherein a period of time for which one of said receiving antenna is selected in response to a corresponding switch drive impulse is no longer than three (3) microseconds.
Dependencies are inferred from the claim text.