JPH03254225A - Diversity receiver for automobile - Google Patents

Abstract

PURPOSE:To allow the receiver to use only one transmission cable between an antenna conductor and the receiver and to simplify the constitution of an automobile reception system by providing plural antenna conductors and a diversity reception circuit on a window glass, selecting a best reception signal among plural reception signals induced in the plural antenna conductors and leading the selected signal to the receiver. CONSTITUTION:Plural antenna conductors 3, 4 and a diversity reception circuit 22 selecting a best quality signal among plural reception signals from the antenna conductors 3, 4 are provided on a window glass face. The diversity reception circuit 22 is provided with tuner circuits 30a, 30b converting a received RF signal into an IF signal, a switching control circuit 33 forming a switching control signal based on the IF signal and a changeover switch 23 selecting one reception signal among the plural reception signals from the antenna conductors 3, 4 with the switching control signal and leading the selected signal to the receiver. Then the tuner circuits 30a, 30b receive channel selection information from the receiver. Thus, one transmission cable 13 is enough between the antenna conductors and the receiver and the comparatively inexpensive diversity reception circuit with high performance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a diversity receiving device for an automobile that uses a plurality of antenna conductors provided on a window glass surface.

[Conventional technology]

In-vehicle AM by attaching an antenna conductor to the car window glass
Window glass antennas are known that supply received signals to radio receivers, FM radio receivers, television receivers, and the like. In a reception system using such a window glass antenna, in order to prevent the quality of the received radio waves supplied to the in-vehicle receiver from deteriorating when the reception condition changes as the car moves, Diversity reception methods have come into use.

[Problem to be solved by the invention]

In the diversity reception method, two or more antenna conductors are installed on the window glass surface, and the receiver compares the carrier level, distortion amount, noise level, etc. of the received signal from each antenna to find the best quality reception. Select a signal and perform demodulation. Therefore, it is necessary to wire the same number of signal transmission cables between the window glass and the receiver as there are antenna conductors provided on the window glass (generally, the rear window glass), which is one of the causes of high costs.

In addition, the receiver requires a switching circuit for the received signal, and a level, distortion, etc. detection circuit and comparison circuit for discriminating good received signals and forming a switching control signal, resulting in high cost.

SUMMARY OF THE INVENTION In view of these problems, it is an object of the present invention to provide a diversity receiving device that requires only one transmission cable between an antenna conductor and a receiver, is relatively inexpensive, and has high performance.

[Means to solve the problem]

A diversity receiving device for an automobile according to the present invention is provided with a plurality of antenna conductors and a diversity receiving circuit for selecting a signal having the best quality from among a plurality of received signals from each antenna conductor on a window glass surface. The receiving circuit includes a tuner circuit that converts the received RF signal into an IP signal, a switching control circuit that forms a switching control signal based on the IF signal, and a switching control circuit that converts the plurality of received signals from the antenna conductor using the switching control signal. and a selector switch for selecting one of the channels and outputting it to the receiver, and the tuner circuit is characterized in that it receives channel selection information from the receiver.

[Effect]

The received signals of the plurality of antenna conductors are selected into one output on the glass surface and guided to the receiver through one transmission cable. A tuner circuit is provided on the glass surface to discriminate relatively low frequency IF signals in the reception level discrimination circuit required for diversity reception.
A high-performance diversity receiving circuit can be obtained at low cost.

〔Example〕

FIG. 1 shows a car reception system to which the present invention is applied.

In FIG. 1, a defogging heater wire 2 is provided on a rear window glass 1 of an automobile, and first and second FMs are arranged in the upper and lower margin areas from an inverted T-shaped element and a horizontal single element.
A receiving antenna conductor 3.4 is provided. The first and second antenna conductors 3.4 are arranged close to the heater wire 2 and receive received power from the heater wire 2. The shapes and installation locations of these two antennas are not particularly limited.

The heater wires 2 are divided into two groups, upper and lower, and a busbar 5.6 is provided at one end of each group, and a common busbar 7 is provided at the other end, and power is supplied in a folded manner.

A high-frequency choke coil 10.11 that is antimagnetically coupled is inserted into a feeder line 8.9 connected to the bus bar 5.6.

These choke coils 10, 11 have high impedance in the RF band, and prevent the power received by the heater wire 2 as an antenna from escaping to the power supply side and the ground side.

The FM antenna conductor 3.4 is connected to a hybrid IC 12 for diversity reception provided on the glass surface, and the hybrid IC 12 selects the best reception output of these two antenna conductors 3.4. Ru. The selected received signal is transmitted through a coaxial or other transmission cable I.
3 to an FM radio receiver 14 on the driver's side of the vehicle.

The heater wire 2 is used as an AM receiving antenna, and its received power is led out from a coupling wire 15 connected to the bus bar 5 to the transmission cable 13 via an impedance matching circuit in the hybrid IC 12.

The reason why the hybrid IC is arranged on the glass surface is to reduce the number of cables between the antenna conductor 3.4 on the rear window glass l and the receiver 14. A matching circuit is also provided within the hybrid IC 12 to reduce power loss due to impedance mismatch between the antenna conductor 3.4 and the transmission cable 13.

As shown in FIG. 2, the antenna conductors 3.4 are coupled to active matching circuits 20.21, and the respective received outputs 2O3
, 21S are supplied to the changeover switch 23 of the diversity receiving circuit 22 via these matching circuits 20, 21. The changeover switch 23 selects the better one of the signals 20S and 215 in accordance with the control signal from the changeover control circuit 24, and outputs the selected output to the transmission cable 13.

On the other hand, the AM reception signal of the heater wire 2 is received by the hybrid IC 1.
The signal is supplied to an impedance matching (IM) circuit 25 in 2. The output of the matching circuit 25 is the transmission cable 1
3 and transmitted to the receiver 14 together with the FM reception signal.

On the other hand, the receiver 14 controls the DC control 11, which is changed according to the channel selection operation, by transmitting the voltage E (tuning voltage) through an element having sufficiently high impedance in terms of high frequency, from the antenna input terminal to the window glass via the cable 13. 1 to the hybrid IC 12 on the top.

The active matching circuits 20 and 21 in the IC 12 have, for example, a series or parallel LC resonant circuit, the capacitance elements of which are comprised of variable capacitance diodes, the capacitance values of which are controlled by the DC control voltage E.

Thereby, the resonant frequency of the resonant circuit is controlled to correspond to the frequency tuned in the receiver 14. At this time, regarding the received signal during tuning from antenna conductor 3.4,
The resonant circuit is capacitive or inductive, so that the active matching circuit 20.21 operates to cancel the reactance of the antenna conductor 3.4 and improve the matching with the subsequent receiving circuit.

Figure 3 shows the antenna switching control circuit 24 and the switching switch 2.
3 is a block diagram showing the configuration of the second
The received signals 2O3 and 21S, which are the outputs of the active matching circuits 20 and 21 in the figure, are subjected to IF multiplication signal conversion to form an IF multiplication signal revealing antenna switching signal.

The received signals 203 and 213 are supplied to tuners 30a and 30b, and are subjected to IF multiplication signal conversion. Each tuner 30a,
30b has an RF tuning circuit, a local oscillator, and a mixer;
Deriving the selected IF multiplied signal. Each tuning frequency and oscillation frequency of the RF tuning circuit and the local oscillator are transmitted from the receiver 14 via the transmission cable 13 to the DC control 1.
11FEB to correspond to the frequency to be tuned.

The IF output of the tuners 30a and 30b is provided by the IF amplifier/I
Through the F filter circuits 31a and 31b, the detector 32a,
32b, and the carrier level or carrier distortion amount at the IF frequency is detected as a DC signal. Here, the IF amplifier and IF filter may be equivalent to those built into a normal FM radio receiver, and the frequency characteristics,
No special specifications are required for the Q value, etc.

The outputs of the detectors 32a and 32b are given to a control circuit 33, and a switching control signal 33S for selecting a better received signal is formed by comparing the levels of the two signals. Based on this control signal 33S, the received signals 2O3, 21
One of S is selected by the changeover switch 23 and led out to the transmission cable 13.

Figure 4 shows the antenna switching control circuit 24 and the switching switch 2.
FIG. 3 is a block diagram showing a modified example of No. 3; In this example, first, one of the received signals 2O3 and 21S is selected by the changeover switch 23, and one system of tuner 3 is selected based on the selected output.
0. A switching control signal 33S is generated in a detection system consisting of an IF amplifier/■F filter circuit 31, a detector 32, and a control circuit 33. This switching control signal 33S is supplied to the switch 23, and one of the better received signals is selected. Tuner 30. IF amplifier/IF filter circuit 31,
The operation of the detector 32 is the same as that shown in FIG. 3, and in this example as well, a DC control signal E is supplied from the receiver 14 via the transmission cable 13 to the tuner 30. Control circuit 33
can be composed of, for example, a comparator that compares the IF multiplied signal carrier level and a predetermined threshold level.

FIG. 5 shows yet another example of the antenna switching circuit 24. In this example, tuners 30a, 30b, IF amplifier/IF
The antenna switching control signal 33S is formed by the filter circuits 31a and 31b, the detectors 32a and 32b, and the control circuit 33, which is the same as in the example shown in FIG.
IF signal JF output from IF filter circuits 31a and 31b
a and IFb are supplied to the changeover switch 23, and the better one is selected and sent to the transmission cable 13.

In this configuration, since the IF multiplied signal is transmitted to the receiver via the transmission cable 13, there is little signal deterioration during transmission.
Another advantage is that inexpensive signal cables can be used. Note that since the receiver 14 only needs to include a circuit for detecting and demodulating the IF multiplied signal, it can be manufactured at low cost.

FIG. 6 shows a modification of FIG. 5. In this example, detection circuits 34a and 34b are added to detect the IF signals IFa and IFb output from the IF amplifier/IF filter circuits 31a and 31b, and these outputs are The audio signal of the changeover switch 23
The configuration is such that the selected signal is selected by the user and sent to the transmission cable 13.

Therefore, in this example, since the audio signal is transmitted through the cable 13, signal deterioration during transmission is further reduced.

Moreover, since the receiver 14 only needs to include a decoder for stereo demodulation, the configuration becomes even simpler.

〔Effect of the invention〕

As described above, the invention of claim 1 includes a plurality of antenna conductors 3.
．． 4 and the diversity receiving circuit 22 are provided on the window glass, and the best one is selected from the received signals induced by the plurality of antenna conductors 3.4 and outputted to the receiver 5114. Transmission cable 1 between
Only one number 3 is required, which simplifies the configuration of the automotive reception system.

In addition, a tuner circuit 3 converts the RF received signal into an IF multiplied signal.
0a, 30b on the glass surface diversity receiving circuit 2
2 is provided, and the antenna switching control signal is formed based on the IF multiplied signal. Since the frequency of the IF multiplied signal is lower than that of the received RF signal, it is easy to manufacture a bandpass filter for carrier extraction, for example, and there is an advantage that the one used in a normal receiver can be used as is. Furthermore, since the receiver does not require a tuner circuit, the configuration becomes simple.

In the invention of claim 2, a plurality of RF reception signals are selected by the diversity reception circuit and transmitted to the receiver, so a normal receiver can be used, and therefore the system configuration has a high degree of freedom and is inexpensive. .

In the invention of claim 3, since the switching control signal is formed based on mutual comparison of the IF multiplied signals of the tuner output, accurate switching is possible, and in the invention of claim 4, one system of tuner and switching control circuit is used. Therefore, the circuit configuration is simplified.

In the invention of claim 5, since the plurality of IF signals output from the tuner corresponding to the plurality of antenna conductors are switched and derived to the receiver, the deterioration accompanying signal transmission is less than in the case of RF transmission, and noise contamination is reduced. There are also few. Furthermore, since the receiver does not need to include a tuner circuit, the configuration is simplified.

In the invention as claimed in claim 6, since the detection output signals from the plurality of detection circuits are switched and transmitted, deterioration and noise contamination accompanying signal transmission are further reduced, and the configuration of the receiver is further simplified.

[Brief explanation of drawings]

Fig. 1 is a system diagram of an automobile receiving system to which the diversity receiving device of the present invention is applied, Fig. 2 is a block diagram of the internal circuit (diversity receiving circuit) of the hybrid IC shown in Fig. 1, and Fig. 3 is an antenna switching control diagram. A block diagram showing one example of the circuit, and FIGS. 4 to 6 are block diagrams showing other examples of the antenna switching control circuit. In addition, in the symbols used in the drawings, 1-・--1----------Rear window glass 2-
・ 3.4 011 12-1------・ 20.21--・ 3 24---・------・ 25--・ 30a, 30b 31a, 31b 32a, 32b 33----- -- is. Heater wire Antenna conductor Chigok coil - Hybrid IC - Active matching circuit changeover switch - Antenna changeover circuit Impedance matching circuit Tuner 1F amplifier / IF filter circuit - Detector control circuit embedded Masaru Ueya

Claims (1)

[Scope of Claims] 1. A plurality of antenna conductors and a diversity reception circuit for selecting the one with the best quality from among the plurality of reception signals from each antenna conductor are provided on a window glass surface, the diversity reception circuit as described above; includes a tuner circuit that converts a received RF signal into an IF signal; a switching control circuit that forms a switching control signal based on the IF signal; A diversity receiving device for an automobile, comprising a changeover switch for selecting one channel and outputting it to a receiver, wherein the tuner circuit receives channel selection information from the receiver. 2. The automotive diversity receiving device according to claim 1, wherein the changeover switch selects one of the plurality of received RF signals from the antenna conductor based on the changeover control signal. 3. Claim 1, wherein the tuner circuit is provided corresponding to each antenna conductor, and the switching control circuit forms the switching control signal based on a mutual comparison of IF signals output from each tuner. diversity receiver for automobiles. 4. The tuner circuit is provided in correspondence with one received RF signal selected by the changeover switch, and the changeover control circuit is configured to perform an IF signal output from the tuner based on a comparison between the IF signal output from the tuner and a preset reference value. 2. The automobile diversity receiving apparatus according to claim 1, wherein said switching control signal is formed. 5. The tuner circuit is provided corresponding to each antenna conductor, and the changeover switch selects one of the plurality of received IF signals from the tuner circuit according to the changeover control signal. The automobile diversity receiving device according to claim 1. 6. The tuner circuit is provided corresponding to each antenna conductor, and further includes a detection circuit that converts the output of each tuner circuit into a detection output signal, and the changeover switch switches between the detection circuits and the detection circuits according to the switching control signal. Claim 1, characterized in that one of the detected output signals from the detector is selected.
diversity receiver for automobiles.