The present invention relates to a diversity reception apparatus having a plurality of antennas, in which one of the antennas, which is in the best receiving condition is automatically selected and is subsequently connected to a broadcasting signal receiver. The invention particularly relates to a diversity reception apparatus suitable for application to a television receiver mounted on a mobile body such as a car.
As a conventional mobile television diversity reception apparatus, for example, there is known an example disclosed in JP-A-57-14224. FIG. 3 is a block diagram illustrating this diversity reception apparatus.
In FIG. 3, television RF signals 1, 2 and 3 received by respective antennas are led to an RF switch 4. In the RF switch 4, the RF signals 1, 2 and 3 from the antennas are sequentially switched in time division by RF switch driving signals 5, 6 and 7 after a television vertical synchronizing signal in a vertical blanking interval An RF signal 8 switched in the RF switch 4 is supplied to an input terminal of a television receiver 9.
A television video signal 10 is extracted from the television receiver 9 and supplied to a peak hold circuit 31 so that each of the respective levels of the RF signals 1, 2 and 3 subjected to switching is detected from the flat-portion level of the video signal by the first peak hold circuit 31. A detected level signal 32 obtained thus, is sampled in a switch circuit 33 by using level sampling pulses 34, 35 and 36 corresponding to the input RF signals 1, 2 and 3.
Sampled level signals 37, 38 and 39 of the respective antennas are converted into DC-voltage signals 44, 45 and 46 in a second peak hold circuit 40. The reference numerals 41, 42 and 43 represent reset signals for the second peak hold circuit 40, by which a hold voltage is reset before sampling.
In a level comparator 47, the level of each of the DC voltage signals 44, 45 and 46 is compared at a timing of a timing pulse 48 after completion of level sampling, and level comparison signals 51, 52 and 53 (of these three signals, only a signal having the highest level is made to be in a high level, and the other signals are made to be in a low level) are output and combined with a level-sampling RF switch driving signal in a controller 50 so as to produce the RF switch driving signals 5, 6 and 7. As a result, antennas other than the antenna corresponding to the high level signal of the comparison signals 51, 52 and 53 are connected with the television receiver 9 only for a driving period by the RF switch driving signal, while the antenna corresponding to the above-mentioned high level signal is connected with the television receiver 9 for the whole period other than the above driving period.
Reference may be further made to JP-A-57-127339 for a related prior art technology.
USPTO Backgrounds
USPTO Backgrounds