JPS6347098Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an in-vehicle receiver, and more specifically, to a multi-band in-vehicle receiver that prevents deterioration of reception conditions due to movement.

For example, as shown in FIG. 1, a conventional in-vehicle receiving device selects and takes out one of the outputs of receiving antennas 1, 2, 3, and 4 via a switch circuit 5, and the output of the switch circuit 5 is used for reception. The level of the signal received by the receiver 6 is detected by a level detector 7, and the output of the level detector 7 is supplied to sample-and-hold circuits 8, 9, 10, 11.
Antenna 1, 2, 3, by changeover switch circuit 5
Sample and hold circuits 8, 9, 10, 1 sample and hold the output of level detector 7 in synchronization with switching of the output of 4.
1, the outputs of the sample and hold circuits 8, 9, 10, and 11 are supplied to the maximum value selection circuit 12 to select the maximum value, and select the antenna 1, 2, 3, or 4 that showed the maximum value. select. Note that 13 is a control circuit that controls the changeover switch circuit 5, sample-and-hold circuits 8, 9, 10, and 11, and selects one of the antennas 1, 2, 3, and 4 based on the output of the maximum value selection circuit 12. .

In the above, the operation of scanning the outputs of the antennas 1, 2, 3, and 4 and searching for the maximum value is performed almost instantaneously at fixed time intervals.

Since the conventional in-vehicle receiver is configured as described above, it is possible to always select the antenna with the maximum input level.

However, in the above, there is no problem when only one band is being received, but when two or more bands are used for simultaneous reception with the same antenna element, the following problem occurs.

That is, the electric field distribution differs in each band, and even if an antenna element exhibits maximum input in one band, it may be in a dip state in the other band. Therefore, a diversity system is required for each band that is simultaneously received, and antennas are scattered on the roof of the vehicle.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an on-vehicle receiving device that solves the above problems.

The present invention will be explained below with reference to examples.

FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention.

The receiving antennas 21, 22, 23, 24 are supplied to a changeover switch circuit 25. The changeover switch circuit 25 has two systems of switch circuits 25a and 25b.
The outputs of the antennas 21 to 24 are supplied to the antennas 21 to 24b via buffers 25c to 25j that act as distributors, and the outputs of the antennas 21 to 24 are supplied to the antennas 21 to 24 by a switch circuit 25a.
The switch circuit 25b selects one of the outputs of the antennas 21 to 24. The output of the switch circuit 25a is supplied to a receiver 26, and the level of the signal received by the receiver 26 is detected by a level detector 27. Similarly, the output of the switch circuit 25b is supplied to a receiver 28, and the level of the signal received by the receiver 28 is detected by a level detector 29. The outputs of the level detectors 27 and 29 are supplied to a switching circuit 30, and the switching circuit 30 selects one of the outputs of the level detectors 27 and 29 and supplies it to sample and hold circuits 31 to 34. The outputs of the sample and hold circuits 31 to 34 are supplied to a maximum value selection circuit 35 to detect the maximum value among the outputs of the sample and hold circuits 31 to 34. The maximum value selection circuit 35 generates an output corresponding to the sample and hold circuits 31 to 34 that output the maximum value. The output of the maximum value selection circuit 35 is sent to the control circuit 3.
6, the control circuit 36 outputs the sampling pulses of the sample-and-hold circuits 31 to 34, and receives the switching of the outputs of the antennas 21 to 24 by the switch circuit 25a or 25b and the switching of the input of the switching circuit 30 in a time-division manner. The controllers 26 and 28 are controlled accordingly.

In one embodiment of the present invention configured as described above, each output of the antennas 21 to 24 has a buffer 25
c and 25d, 25e and 25f, 25g and 25h,
25i and 25j and supplied to switch circuits 25a and 25b. When the system of the receiver 26 is selected by the control circuit 36, the switch circuit 25a switches between the antennas 21 and 26 at a predetermined timing.
24 outputs are scanned. Through this scanning, the outputs of the antennas 21 to 24 selected by the switch circuit 25a are supplied to the receiver 26, the input electric field strength of the receiver 26 is detected by the level detector 27, and the level detector 27 is proportional to the input electric field strength. Outputs the signal. Similarly, when the receiver 28 system is selected by the control circuit 36, the switch circuit 25b scans the outputs of the antennas 21 to 24 at a predetermined timing. Through this scanning, the outputs of the antennas 21 to 24 selected by the switch circuit 25b are supplied to the receiver 28, and the level detector 29 detects the input electric field strength of the receiver 28 and outputs a signal proportional to the electric field strength. The outputs of the level detectors 27 and 29 are supplied to a switching circuit 30.

On the other hand, the switching circuit 30 selects either the receiver 26 system or the receiver 28 system based on the output of the control circuit 36. The outputs of the level detectors 27 and 29 of the system selected by this selection are output from the switching circuit 30 and supplied to the sample-and-hold circuits 31-34. Here, the sample-and-hold circuits 31-34 correspond to the antennas 21-24, respectively, and the sampling pulses of the sample-and-hold circuits 31-34 are output from the control circuit 36 in synchronization with the switching timing of the antennas 21-24. Ru.

The outputs of the level detectors 27 and 29 by the sample and hold circuits 31 to 34 are sent to the antennas 21 to 34.
Sampled and held corresponding to 24,
The outputs of the sample-and-hold circuits 31 to 34 are supplied to a maximum value selection circuit 35, the maximum value of which is detected, and the output corresponding to the sample-and-hold circuit 31, 32, 33, or 34 that outputs the maximum value is the maximum value. It is output from the selection circuit 35 to the control circuit 36. The control circuit 36 stores the sample-and-hold circuits 31, 32, 33, and 34 that output the maximum value upon receiving the output of the maximum value selection circuit 35, and stores the sample-and-hold circuits 31, 3, which have output the maximum value.
Antenna 21, 2 corresponding to 2, 33 or 34
Reception continues until the next selected operation period with the antenna with output No. 2, 23, or 24, that is, the maximum input electric field strength.

Now, the receiver 26 system is a receiver that receives television signals, and the receiver 28 system is an FM receiver.
If it is a receiver, television broadcast waves have a high frequency and the Rayleigh distribution has a shorter period than FM waves, so the antenna selection speed needs to be high.
In addition, in the case of a television receiver, the antenna 21~
It is preferable that the selection operation of 24 be performed during the retrace period so as not to affect the screen, and the timing may be determined using a synchronizing signal.

Therefore, in this case, the output timing of the control circuit 36 is set to a basic timing corresponding to the television receiver system as shown in FIG. 3a, and as shown in FIG. 3c corresponding to the basic timing. It may be used as a selective operation timing signal for the antennas 21 to 24, as shown in FIG. In Figure 3c, a ₀ , b ₀ ,
c ₀ , d ₀ and e ₀ represent sampling pulses of the sample-and-hold circuits 31 to 34 and comparison timing pulses of the maximum value selection circuit 35, respectively. Further, the switching timing of the switch circuit 25a may be generated slightly before the sampling pulses _a0 to _d0 , and the antenna may be switched at this timing.

Furthermore, when the FM reception system is selected, the basic timing shown in FIG. 3a may be divided and the FM reception system, ie, the switch circuit 25b, may be switched once every several basic timings.

FIG. 3b shows the waveform of the switching signal output to the switching circuit 30. When the receiver 28 system, that is, the FM receiving system is selected by the switching signal shown in FIG. The output of the detector is sampled and held, and the maximum value selection circuit 35 uses the pulse e to select the sample and hold circuit 31.
It is only necessary to compare the outputs of the switch circuits 25b to 34, and the switch circuit 25b
All you have to do is switch. In this case, as described above, the interval between the sample pulses a to d shown in FIG. 3d and the next generated sample pulse may be once every several basic pulses shown in FIG. 3a.

In addition, in one embodiment of the present invention described above, the case where the number of antennas is four is illustrated, but it is not limited to this, and the receiver also has two receivers.
Although the case in which two systems, 6 and 28, are provided is illustrated as an example, the configuration is not limited to this, and it is obvious that a similar configuration can be made even if there are two or more systems.

Furthermore, some reception bands do not require diversity reception, and in such cases, one of the plurality of antennas may be fixedly connected to that reception band.

Furthermore, in the above embodiment, a system was explained in which the antenna exhibiting the maximum input is selected from among a plurality of antennas. A method such as switching to the other antenna may also be used.

As explained above, according to the present invention, the two-system diversity system is configured with one set of antenna systems, so diversity reception is possible without arranging antennas on the roof, trunk, windows, interior of the vehicle, etc. Become.

Furthermore, since diversity reception can be performed on two or more bands at the same time, the optimum received signal can always be obtained.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of a conventional in-vehicle receiver, Fig. 2 is a block diagram showing the configuration of an embodiment of the present invention, and Fig. 3 is an example of the output of a control circuit in an embodiment of the present invention. FIG. 21 to 24...Antenna, 25...Switch circuit, 25a and 25b...Switch circuit,
25c-25j...Batsuhua, 26 and 28...
...Receiver, 27 and 29 ...Level detector, 3
0...Switching circuit, 31-34...Sample and hold circuit, 35...Maximum value selection circuit, 36...
...control circuit.

Claims (1)

[Scope of utility model registration request] In a vehicle-mounted receiving device that includes a plurality of antennas and selects and receives the output of one of these antennas, a distribution means for distributing the output of each antenna to a plurality of groups, and an antenna in each group distributed by the distribution means. Antenna changeover switch means for selectively outputting an output by switching the output; and a receiver corresponding to each set, each receiving the antenna output outputted from the changeover switch means, and detecting the input level of each receiver separately. a level detector, a switching means for switching the output of the level detector, an antenna indicating means to which the output of the switching means is supplied and indicates an antenna that can best receive data from the output, the antenna switching means, the switching means, An in-vehicle receiver comprising: control means for time-sharingly controlling antenna instruction means corresponding to the plurality of receivers.