JPS6322692B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In diversity reception, the present invention prioritizes diversity antennas and
Reception is performed using the main diversity antenna with a high priority, and when the reception level of the main diversity antenna with a high priority decreases, reception is performed using the auxiliary diversity antenna with a low priority. The present invention relates to a diversity receiving device suitable for use in a vehicle, which monitors the reception level of a diversity antenna, and when the reception level of the main diversity antenna recovers, immediately receives the signal with the main diversity antenna.

Embodiments of the diversity receiving apparatus of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 and 2 are the main antenna and auxiliary antenna for diversity reception, and 3 is a semiconductor switch for switching between the main antenna 1 and the auxiliary antenna 2 to guide the signal to the receiver 24. 17 is a control terminal for switching, 4 is a tuner circuit of the receiver 24, 5 is an intermediate frequency amplification circuit, and 6
1 is an FM detection circuit, 7 is an impulse noise limiting circuit for removing noise generated in the ignition system of an automobile, and 10 is a speaker. Reference numeral 11 indicates a terminal for detecting a reception level from which an output corresponding to the reception level is output from the intermediate frequency amplification circuit 5; and 12 indicates the terminal 1.
1, and in order to obtain a reception level detection output according to the main antenna 1, a control circuit 2, which will be described later, is connected to the main antenna 1.
Only when the level of the main antenna 1 decreases due to the clock pulse from the clock generation circuit 18 of the second clock generator 18, the main antenna 1 is transferred from the auxiliary antenna 2 in a time-division manner.
14 is a sample hold circuit for storing (memorizing) the reception level of antenna 1 obtained by the sample switch 12; 13 is a main antenna; 15 is a sample hold circuit 14 that stores the reception level of the main antenna 1; 15 is a reference voltage source that generates a reference voltage E _S that is set to the permissible detection limit for auditory noise that appears in the speaker 10 when the reception level of the main antenna 1 has decreased; A comparison circuit 16 compares the voltage level of the reference voltage E _S of the reference voltage source 13 with the reference voltage E S of the reference voltage source 13. A comparison circuit 16 obtains the output of the comparison circuit 15 and the output of the antenna switching pulse circuit 19, and when the reception level of the main antenna 1 is high, The changeover switch section 3 is connected to the main antenna 1, and a control signal is sent to the control terminal 17 of the changeover switch section 3 so as to switch from the auxiliary antenna 2 to the main antenna 1 in a time-sharing manner only when the reception level of the main antenna 1 decreases. The driving circuit 22 provided is a control circuit for adjusting the timing in order to operate the circuits of the above-mentioned parts normally. In this control circuit 22, an antenna switching pulse circuit 19 applies an antenna switching pulse to the drive circuit 16 in response to a clock pulse from a clock generating circuit 18.

Sample pulse circuit 20 is connected to antenna switching pulse circuit 19 and provides a signal to sample switch 12 to sample and hold the reception level of main antenna 1 during the antenna switching pulse period. A reset pulse circuit 21 is connected to the sample pulse circuit 20 and provides a reset pulse to the sample hold circuit 14 in synchronization with the start of the sample pulse.

The above 12 to 22 constitute the control section 23 of the diversity receiving device.

Next, the operation of the diversity receiver configured as described above will be explained with reference to the signal waveform diagrams of FIGS. 1 and 2. Note that the signals a to e shown in FIG. 1 correspond to the waveforms in FIG. 2 a to e. Now, assuming that the changeover switch section 3 is connected to the main antenna 1 and that the main antenna 1 is receiving data, the antenna output passes through the tuner circuit 4, the intermediate frequency amplification circuit 5, the FM detection circuit 6, and the main antenna 1.
Sound is generated from a speaker 10 through an impulse noise limiting circuit 7, a stereo demodulation circuit 8, and a power amplification circuit 9.

On the other hand, a signal a shown in FIG. 2a corresponding to the reception level is output to the terminal 11. In addition, the control circuit 22
The clock pulse b shown in FIG. 2B is generated by the clock generating circuit 18 every 5 to 30 msec, thereby causing the antenna switching pulse circuit 19 and the sample pulse circuit 21 to operate in conjunction. That is, in response to the clock pulse b from the clock generation circuit 18, the antenna switching pulse circuit 19 generates an antenna switching pulse c of about 10 to 30 μsec as shown in FIG. An antenna switching pulse c is applied to the antenna switching pulse c. However, the drive circuit 16 receives the other input from the comparison circuit 15, and when the receiver 24 is receiving signals through the main antenna 1, the information from the comparison circuit 15 prevents the drive circuit 16 from operating. Therefore, no time-division antenna switching operation is performed.

On the other hand, the sample pulse circuit 20 connected to the antenna switching pulse circuit 19 takes the time (5 to 20 μsec) from when the changeover switch section 3 is switched until the reception level appears at the tuner circuit 4, intermediate frequency amplification circuit 5, and terminal 11. A sample pulse d as shown in FIG. At the same time, a reset pulse circuit 21 connected to the sample pulse circuit 20 applies a reset pulse e as shown in FIG. 2e to the sample hold circuit 14 to reset it in advance. By doing this, the reception level of the main antenna 1 is stored in the sample hold circuit 14 from the terminal 11 via the sample switch 12.
However, in this case, the switch section 3 is connected to the main antenna 1 and the drive circuit 16 is not operating, so the switch section 3 remains at the antenna 1, and the reception level of the main antenna 1 is set to terminal 11, The signal is stored in the sample hold circuit 14 via the sample switch 12. Then, the output of the sample and hold circuit 14 is added to one input of the comparator 15,
The other voltage is compared by adding a reference voltage E _S set to the audible noise detection tolerance level of the receiver 24, and when the reception level of the main antenna 1 is high, information is given to the drive circuit 16, and the changeover switch section is directly switched. Receive with main antenna 1 without moving antenna 3. When the reception level of the main antenna 1 is higher than the reference voltage _ES , the operation is repeated as it is, and the receiver 24 receives only the main antenna 1 [see operation I in FIG. 2]. Therefore,
Time division of antenna switching is not performed.

However, the reception level of main antenna 1 is at the reference voltage.
If it has decreased compared to E _S [Figure 2 operation]
That is, when the reception level of the main antenna 1 stored in the sample and hold circuit 14 via the terminal 11 and the sample switch 12 becomes lower than the reference voltage _ES , the comparator 15 gives information to the drive circuit 16. A signal is sent to the control terminal 17 of the changeover switch section 3 to switch the antenna from the main antenna 1 to the auxiliary antenna 2. Therefore, the receiver 24 starts receiving signals using the auxiliary antenna 2. At this time, the present invention takes into consideration that the signal is returned to the main antenna 1 as soon as the reception level of the main antenna 1 recovers. That is, during reception by the auxiliary antenna 2, the signal is applied from the antenna switching pulse circuit 19 to the control terminal 17 of the antenna switching switch section 3, and the main antenna 1 is
can be switched to As a result, the control circuit 23 operates at the timing described above and stores the reception level of the main antenna 1 in the sample hold circuit 14 via the terminal 11 and the sample switch 12 only when switching to the main antenna 1 is performed. Here, as before, the reference voltage E _S and the level corresponding to the reception level of the main antenna of the sample and hold circuit 14 are compared to the comparison circuit 1.
5, if the reception level of main antenna 1 is not low, use auxiliary antenna 2 as is to receive receiver 24.
receives the signal, and when the reception level of the main antenna 1 recovers, the receiver 24 operates to receive the signal using the main antenna 1. That is, the sample and hold circuit 14 always stores the reception level of the main antenna 1, and only when the auxiliary antenna 2 is operating, the antenna switching pulse circuit 19, drive circuit 16, and changeover switch section 3 are linked to switch the main antenna 1 to the main antenna 1. The configuration is such that the level of antenna 1 is taken in in a time-division manner.

That is, the present invention normally receives signals using the main antenna, receives signals using the auxiliary antenna only when the receiving level of the main antenna drops, and immediately receives signals using the main antenna when the receiving level of the main antenna recovers. This works most effectively when the main antenna is a monopole antenna installed outside the vehicle body, and the auxiliary antenna is a windshield antenna attached to the car's windshield or rear glass.

FIG. 3 shows a specific example of the configuration of the main parts of the present invention. This is a part of the control section 23 shown in a dotted frame in FIG. 1, and 25 in the figure is an input amplifier for receiving a signal from the terminal 11 in FIG. The analog switch 26 is the sample switch 12 in FIG.
corresponds to Operational amplifiers 27 and 29, diode 28, transistor 30, and capacitor C correspond to sample and hold circuit 14 in FIG. Operational amplifier 31, diode 32, inverter 33
corresponds to the comparator circuit 15 in FIG. In the figure, E _S corresponds to the reference voltage E _S in FIG. NAND gate circuit 34 and inverters 35, 36 and 37 correspond to drive circuit 16 in FIG. Inverter 38
and 39 correspond to the clock generation circuit 18 in FIG. Inverter 40, NAND gate circuit 4
1 corresponds to the antenna switching pulse circuit 19 in FIG. Inverters 42 and 44 and NAND gate circuit 43 correspond to sample pulse circuit 20 in FIG. NAND gate circuit 45 and inverter 46 correspond to reset pulse circuit 21 in FIG. In this case, since the potential relationship between the receiving level of the receiver and the terminal 11 for detecting the receiving level is of opposite polarity, that is, the voltage at the terminal 11 decreases as the receiving level increases, so the sample switch circuit Even the sample hold circuit and comparison circuit operate with reverse polarity. Further, in this circuit, a sample and hold circuit performs peak hold, and the operation is exactly the same as that in the basic block diagram of FIG. It goes without saying that the portion corresponding to the control circuit 22 in FIG. 1 may be changed in any way as long as the timing relationship in FIG. 2 is maintained. Further, the reference voltage E _S is semi-fixed. Further, in order to increase the stability against electric field fluctuations, it is also possible to apply it from the terminal 11 via an integrating circuit.

Another configuration example is shown in FIG. To explain this, operational amplifier 47 is an input amplifier similar to 25 in FIG. Analog switch 48 corresponds to sample switch 12 in FIG. Operational amplifier 49 and capacitor C correspond to the sample and hold circuit shown in FIG. Operational amplifier 50 and diode 51 correspond to comparator circuit 15 in FIG. In the figure, E _S corresponds to the reference voltage E _S in FIG.
NAND gate circuit 52, inverters 53, 54
and 55 correspond to the drive circuit 16 in FIG.
Inverters 56 and 57 correspond to clock generation circuit 18 in FIG. inverter 58,
NAND gate circuit 59 corresponds to antenna switching pulse circuit 19 in FIG. Inverters 60 and 62 and NAND gate circuit 61 correspond to sample pulse circuit 20 in FIG. In this case, the input is of opposite polarity as in FIG. 3. Also, by removing the peak hold in Figure 3 and performing ordinary sample hold, the first
Since the reset pulse circuit 21 shown in the figure is eliminated, a simpler diversity receiving device can be realized. This is also operationally exactly the same as the case shown in Figure 1, and in particular, in diversity reception for car-mounted FM radios, the main antenna is a monopole antenna attached to the outside of the car body, which has good sensitivity, and is attached to the glass. If the wind seal antenna is used as an auxiliary antenna, diversity reception can be performed with a simple configuration and reliable operation, and is effective against skip noise, picket fencing, and multipath.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of essential parts of an embodiment of the present invention.
2a, b, c, d, and e are signal waveform diagrams of each part in FIG. 1, and FIGS. 3 and 4 are specific circuit configuration diagrams of main parts that can be used in the present invention. 1... Main antenna, 2... Auxiliary antenna, 3... Selector switch section, 11... Terminal for detecting reception level, 1
2...Sample switch, 13...Reference voltage source, 14
...Sample hold circuit, 15...Comparison circuit, 16
...Drive circuit, 18...Clock generation circuit, 19...Antenna switching pulse circuit, 20...Sample pulse circuit, 21...Reset pulse circuit, 22...Control circuit, 23...Control unit, 24...Receiver.

Claims (1)

[Claims] 1. A main antenna and an auxiliary antenna for diversity reception, and a selector switch section that selectively switches between the main antenna and the auxiliary antenna;
The receiver is provided with an antenna output from the changeover switch, and a diversity reception control section that controls the changeover switch section in response to the output from a reception level detection terminal provided in the receiver, and The city control section includes a drive circuit that drives the changeover switch section, a sample hold circuit that holds the reception level of the main antenna from the reception level detection terminal, and an output of the reception level detection terminal that is sent to the sample and hold circuit to receive the main antenna. a sample switch that inputs only the level; a comparison circuit that compares the output level of the sample and hold circuit with a reference voltage and supplies the output to the drive circuit; and a comparison circuit that operates the sample switch, the sample and hold circuit, and the drive circuit. The control circuit includes a control circuit that generates a sample pulse, a reset pulse, and an antenna switching pulse, so that when the reception level of the main antenna is high, the main antenna receives the signal preferentially, and when the reception level of the main antenna is low, the auxiliary antenna receives the signal preferentially. It is characterized by being configured such that the signal is received by the antenna, and the control circuit monitors the reception level of the main antenna in a time-sharing manner, and when the reception level of the main antenna recovers, the signal is automatically switched to receive by the main antenna. Diversity receiver.