JPH01157131A - Antenna switching device - Google Patents

Abstract

PURPOSE:To receive a radio broadcasting wave signal by remaining receivers in a noiseless state when one receiver receives a TV broadcasting wave signal by preventing the radio broadcasting wave signal from being inputted to the receiver. CONSTITUTION:An antenna switching device 40 outputs the radio broadcasting wave signal SAM obtained via a distributor 8 in a first distribution circuit 3 to a selection circuit 10 via a switch circuit 41. The circuit 41 is constituted of a relay circuit, and at the time of receiving the TV broadcasting wave signal by a radio TV receiver 5, the circuit is controlled so as to be switched to an OFF state reacting to a control signal SD, and the signal SAM is prevented from being inputted from the distributor 8 to the receiver 5. Therefore, at the time of receiving the TV broadcasting wave signal by the receiver 5, the circuit 41 is turned OFF, and a noise component via a circuit 10, an HPF circuit 16, an amplifier circuit 14, a distributor 12, an HPF circuit 11, an LPF circuit 7, and the distributor 8 out of the noise components outputted from the receiver 5 and the circuit 10 is suppressed sufficiently by coupling loss at the circuit 14 and insertion loss at the circuits 11 and 15 and the distributor 12, then, it is inputted to a radio receiver 4.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of Application The present invention relates to an antenna switching device, and particularly to a device for simultaneously receiving a television broadcast wave signal and a radio broadcast wave signal by sharing one antenna with two receivers. This is suitable for application to an antenna switching device designed to do this.

B. Summary of the Invention The present invention provides an antenna switching device configured to share one antenna and simultaneously receive a television broadcast wave signal and a radio broadcast wave signal with two receivers. By preventing the radio broadcast signal from being input to the receiver while the receiver is receiving the television broadcast signal, the remaining receiver can receive the radio broadcast signal without noise. can be received.

C. Prior Art Conventionally, for example, in an on-vehicle antenna switching device, for receiving television broadcast wave signals and radio broadcast wave signals,
Some devices are designed to share one antenna.

That is, as shown in FIG. 4, reference numeral 1 designates an on-vehicle antenna switching device as a whole, which transmits a received signal S obtained from a rod antenna 2 to the front seat and rear seat of the vehicle, respectively, via a first distribution circuit 3. It is distributed to a radio receiver 4 and a radio television receiver 5 attached to the seats.

That is, in the first distribution circuit 3, the received signal S1 is applied to the low-pass filter circuit 7, and after extracting the radio broadcast wave signal S□ in the medium wave band, it is passed through the distributor 8 to the selection circuit 9 and the selection circuit 9 with high output impedance. Output to 10.

Further, the bypass filter 11 extracts from the received signal S, a radio broadcast wave signal SIFM in the FM broadcast band and a television broadcast wave signal SI? After extracting V, the distributor 12
and a selection circuit 9 through amplifier circuits 13 and 14 and bypass filter circuits 15 and 16, respectively.
and a medium wave band radio broadcast wave signal S□ outputted to 10
with low output impedance.

Therefore, in the radio receiver 4 and the radio television receiver 5, the rod antenna 2 is shared by switching the contacts of the selection circuits 9 and 10 to the output signals S and SIg output from the first distribution circuit. Radio broadcast wave signals SIAM and SIFM in the medium wave band and FM broadcast band, radio broadcast wave signals S□ and SIFM in the medium wave band and FM broadcast band, and television broadcast wave signal S+, respectively.
tV can be received.

In this way, the low-pass filter circuit 7 and the distributor 8 extract the radio broadcast wave signal S in the medium wave band from the received signal SI obtained through the antenna 2, and then divide the signal into two parts. A radio broadcast wave signal distribution circuit is configured to output to a radio receiver 4 and a radio television receiver 5, which are receivers.

On the other hand, bypass filter circuits 11 and 16,
The distributor 12 and the amplifier circuit 14 extract the television broadcast wave signal 5ITv from the received signal S along with the radio broadcast wave signal SIF in the FM broadcast band, and transmit the television broadcast wave signal 5ITv to the second receiver. Configure the circuit.

On the other hand, the second distribution circuit 20 receives the received signal S via the embedded antenna 21 embedded in the dream window of the car.
2 is obtained, and the received signal S2 is passed to the bypass filter circuit 22.
give to

The bypass filter circuit 22 receives the received signal S! From FM broadcast band radio broadcast wave signal S gFN and television broadcast wave signal S! After extracting the TV, the distributor 23
The signal is divided into two parts via amplifier circuits 24 and 25 and bypass filter circuits 26 and 27, and output to selection circuits 9 and 10 with low output impedance.

Therefore, in the radio receiver 4 and the radio television receiver (il15), the output signal S output from the first distribution circuit 3 connects the contacts of the selection circuits 9 and 10, respectively.

By switching to the output signals S□ and StZ of the second distribution circuit 20 instead of SIg and SIg, the radio broadcast wave signal S2□ of the FM broadcast band and the radio broadcast wave signal S2□ of the FM broadcast band are transmitted through the embedded antenna 21 instead of the rod antenna 2, respectively. Radio broadcast wave signal S gFN and television broadcast wave signal s z
yv can be received.

Therefore, when receiving radio broadcast wave signals in the medium wave band in the front and rear seats of a car, the contacts of the selection circuits 9 and 10 are connected to the output signals S and SI output from the first distribution circuit 3.
By switching to g, the radio broadcast signal SAM with high impedance output can be received via the rod antenna 2.

On the other hand, when receiving radio broadcast wave signals in the FM broadcast band in the front and rear seats of a car, the contacts of the selection circuits 9 and 10 are connected to the output signals S11 and SIg of the first distribution circuit 3 and the second distribution By switching between the output signals S□ and S:2 of the circuit 20, even when a car is running and the reception status is changing from time to time, the signal can be transmitted through the antenna 2 or 21 with a good reception status. It is possible to receive radio broadcast wave signals in the FM broadcast wave band.

Further, the selection circuit 10 sends received signals S and S obtained through embedded antennas 30 and 31 embedded in window glass on the right side and left side of the car to an amplifier circuit 3, respectively.
2 and 33 and bypass filter circuits 34 and 35.

Further, when the radio television receiver 5 is receiving a television broadcast wave signal, the selection circuit 10 sequentially switches the contacts during the vertical blanking period, and selects the rod antenna 2.
and embedded antennas 2i30 and 31, the antenna 2.21.30 that provides the highest signal level of the received signal
or 31 to receive the television broadcast wave signal.

Therefore, even when the car is running and the reception status changes from moment to moment, antenna 2.
21.30 or 31 can be automatically selected to receive the television broadcast wave signal, and display images with good image quality can be obtained.

D Problems to be Solved by the Invention However, in the antenna switching device 1 in which one antenna 2 is used in common for reception of radio broadcast wave signals and reception of television broadcast wave signals, the radio receiver 4 and When the radio television reception a5 receives a radio broadcast wave signal and a television broadcast wave signal in the medium wave band, respectively, there is a problem that noise is mixed into the radio receiver 4.

That is, when the radio receiver 4 receives a radio broadcast wave signal in the medium wave band, the selection circuit 9 selects the output signal S11 of the first distribution circuit 3 obtained via the antenna 2.

On the other hand, when the radio television receiver 5 receives a television broadcast wave signal, during the vertical blanking period,
Since the selection circuit 10 sequentially switches the contacts, the harmonic signal of the drive signal used to drive the selection circuit 10 is transmitted from the selection circuit 10 to the radio receiver 4 via the distributor 8 of the first distribution circuit 3. is input.

In fact, as shown in FIG. 5, the drive signal for switching the contacts of the selection circuit 10 has a pulse width of 10
Since a pulse signal of the order of c) is used, the curve S
As shown in 1, a harmonic signal with a large signal level is generated in the medium wave band, and the drive signal is output every vertical blanking period. (Hz)), it will be output repeatedly.

Therefore, in the radio receiver 4, the repetition of the harmonic signal causes a so-called buzz sound to be output, which is similar to when a signal component of a commercial power source is mixed into an audio signal.

Furthermore, in a period other than the vertical planning half period, the selection circuit 11 selects the output signal SI obtained from the rod antenna 2.
! is selected, the horizontal output signal etc. radiated from the radio television receiver 5 is input to the radio receiver 4 via the distributor 8, and noise different from the buzz sound is output. It becomes like this.

The present invention has been made in consideration of the above points, and is designed to prevent noise from being mixed into the radio broadcast wave signal even if a television broadcast is received while receiving a radio broadcast wave signal in the medium wave band. This paper attempts to propose an antenna switching device.

Means for Solving Problem E To solve this problem, in the present invention, from the antenna 2 and the received signal SI obtained through the antenna 2,
A radio broadcast wave signal distribution circuit 7.8 distributes and outputs the extracted radio broadcast wave signal S0, and a television broadcast wave signal extraction circuit 11 extracts a television broadcast wave signal, 5ITV, from the received signal S. .12.14.16 and
The first receiver 4 receives the radio broadcast wave signal S distributed by the radio broadcast wave signal distribution circuit 7.8, and the radio broadcast wave signal S distributed by the radio broadcast wave signal distribution circuit 7.8.
A second receiver 5 receives the AD signal via the switch circuit 41 and also receives the television broadcast wave signals S, A, obtained through the television broadcast wave signal extraction circuits 11, 12, 14, and 16. , in the second receiver 5,
When receiving the television broadcast wave signal s+yv, the switch circuit 41 is controlled to be in an OFF state.

F action When the second receiver 5 receives the television broadcast signal S+tV, if the switch circuit 41 is controlled to be in the OFF state,
The signal level of noise components that enter the first receiver 4 from the second receiver 5 via the radio broadcast wave signal distribution circuit 7.8 can be reduced, and the mixing of noise can be reduced accordingly. can.

G example An embodiment of the present invention will be described in detail below with reference to the drawings.

(G1) First Embodiment In FIG. 1, in which parts corresponding to those in FIG.
A radio broadcast wave signal SAW obtained via the distributor 8 of the distribution circuit 3 is outputted to the selection circuit 10 via the switch circuit 41.

The switch circuit 41 is constituted by a relay circuit, and is configured to switch to an OFF state in response to a control signal SD when the radio television receiver 5 receives a television broadcast wave signal. The radio broadcast wave signal SAW is not input to the television receiver 5.

Therefore, when the radio television receiver 5 receives a television broadcast wave signal, the switch circuit 41 is switched to the OFF state, so that the signal is transmitted from the radio television receiver 5 and the selection circuit 10 to the radio receiver via the distributor 8. The signal level of the noise component input to 4 can be reduced,
Accordingly, the mixing of noise can be reduced.

Incidentally, among the noise components output from the radio television receiver 5 and the selection circuit 10, one of the noise components from the selection circuit 10--the low-pass filter circuit 16--the amplifier circuit 14--the distributor 12--the bypass filter circuit 11--the low-pass filter circuit 7--the distributor The noise component input to the radio receiver 4 via
The signal is input to the radio receiver 4 after being suppressed to a practically sufficient signal level due to the insertion loss of the distributor 12 and the like.

Actually, as shown in FIG. 2, if the signal level of the noise component represented by the curve CI in FIG. As shown by curve C5, the signal level of radio receiver 4 can be reduced by about -80 [dB] to -100 (dB) in the medium wave band, which is a practically sufficient range.
It was possible to suppress the noise components mixed in.

Thus, in the radio receiver 4, even when the radio television receiver 5 is receiving the television broadcast wave signal, it is possible to receive the radio broadcast wave signal in the medium wave band with noise suppressed sufficiently for practical purposes. Can be done.

In the above configuration, among the input signals S input from the antenna 2, the radio broadcast wave signal SAW in the medium wave band is input to the radio receiver 4 via the distributor 8.

On the other hand, in the radio television receiver 5, when receiving the radio broadcast wave signal S in the medium wave band, the switch circuit 41 is turned on, and the radio broadcast wave signal S in the medium wave band is transmitted to the distributor. 8 to the radio television receiver 5.

On the other hand, when the radio television receiver 5 receives a television broadcast wave signal, the switch circuit 41 is controlled to be in an OFF state, and the signal level of the noise component mixed into the radio receiver 4 is within a practically sufficient range. The television broadcast wave signal 31τV which is suppressed by the distributor 12 and the received signals St, Ss and S of the antennas 21, 30 and 31 are
4, the signal with the highest signal level is selected, and thus the television broadcast wave signal can be received in the best reception condition, and the radio broadcast wave signal can be received in a noise-free condition.

According to the above configuration, when the radio television receiver 5 receives a television broadcast wave signal, the radio television receiver 5
By preventing radio broadcast wave signals in the medium wave band from being input to the receiver, the noise components that enter the radio receiver can be suppressed sufficiently for practical use, and the radio broadcast wave signals can be received in a noise-free state. .

(G2) Second Embodiment In FIG. 3, 50 indicates a first distribution circuit as a whole, and a diode 51 is used as a switch circuit.

That is, a received signal S obtained through the antenna 2 is received by a low-pass filter circuit composed of a coil 53 and a capacitor 54 to extract a radio broadcast wave signal S□ in the medium wave band. Furthermore, the radio broadcast wave signal SAW is sent to the coil 5.
After being received and distributed by a divider composed of 5, 56 and 57, the signal is output to the selection circuit 9 (FIG. 1) and is also output to the diode 51 via the capacitor 66.

The diode 51 has a coil 62 and a resistor 63 at its anode.
At the same time, a control signal SD is applied to the U-sode via resistors 64 and 65.
When I is applied and the control signal SDI falls, the diode 51 is turned on.

Therefore, when the control signal 5i11 falls, the radio broadcast wave signal SAH is obtained from the cathode of the diode 51 via the capacitor 66, and the radio broadcast wave signal SAW is output to the selection circuit 10 (FIG. 1). On the other hand, when the control signal 5l11 rises, the diode 51 is controlled to be in the OFF state, and the radio broadcast wave signal S□ is controlled not to be input to the radio television receiver 5 (FIG. 1). The signal level of the noise component that enters the radio receiver 4 via the radio receiver 4 is suppressed sufficiently for practical purposes.

Furthermore, the first distribution circuit 50 receives the received signal S.

is applied to a divider made up of a capacitor 70, coils 71 and 72, and a resistor 73 to be divided into two, and then passed through a bypass filter circuit made up of a capacitor 75, 76 and a coil 77, and a capacitor 78 to the amplifier circuit 13. and 16, thus outputting a radio broadcast signal in the FM broadcast band and a television broadcast signal SFMI, 5vnz.
and syvz are extracted, respectively.

Furthermore, the first distribution circuit 50 receives the signal SFMI%SFM
By outputting Z and syvt to the selection circuits 9 and 10 through two bypass filter circuits constituted by coils 80 and 81 and capacitors 82, 83, 84 and 85, respectively, the radio receiver 4 receives the FM signal. The radio television receiver 5 receives the radio broadcast wave signal SFMI in the broadcast band and generates the radio broadcast wave signal S in the FM broadcast band.

and television broadcast wave signals SYVZ.

According to the configuration shown in FIG. 3, even if the switch circuit is configured using a diode instead of a relay circuit, the signal level of the noise component entering the radio receiver 4 can be suppressed within a practically sufficient range. Thus, it is possible to receive radio broadcast wave signals without noise with an overall simple configuration.

In addition, in the above-mentioned embodiment, the medium wave band and F
Although a case has been described in which a radio broadcast wave signal in the M broadcast band and a television broadcast wave signal are received, the present invention is not limited to this, and only a radio broadcast wave signal and a television broadcast wave signal in the medium wave band are received. It can also be applied in cases.

Furthermore, in the above embodiment, when receiving a television broadcast wave signal and a radio broadcast wave signal in the FM broadcast band, the antenna is switched and the antenna with the highest reception sensitivity is selected. The invention is not limited to this, but can be broadly applied to cases where one antenna is used in common for receiving radio broadcast wave signals and television broadcast wave signals.

Further, in the above-described embodiment, a case was described in which a radio receiver was used as the first receiver, but the present invention is not limited to this. For example, a radio receiver having the same configuration as the second receiver may be used as the first receiver. A television receiver may also be used.

Furthermore, in the above embodiment, a case was described in which one antenna is shared by two receivers, but the present invention is not limited to two receivers, and in short, the present invention is applicable to receiving television broadcast wave signals and radio broadcast wave signals. Widely applicable when multiple receivers share an antenna.

Further, in the above-described embodiments, the antenna switching device for vehicle use was described, but the present invention can be widely applied not only to vehicle-mounted antenna switching devices.

Effects of the Invention H As described above, according to the present invention, when a television broadcast wave signal is being received by one receiver, a radio broadcast wave signal is not input to the receiver, so that Other receivers that share the antenna can receive radio broadcast wave signals without noise.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
The figure is a characteristic curve diagram for explaining its operation, FIG. 3 is a connection diagram showing a second embodiment of the present invention, FIG. 4 is a block diagram showing a conventional antenna switching device, and FIG. 5 is a problem thereof. It is a characteristic curve diagram provided for explanation. 1.40...Antenna switching device, 2.21.3
0.31...Antenna, 3.50...
First distribution circuit, 20...Second distribution circuit, 41.
...Switch circuit, 51...Diode.

Claims (1)

[Claims] An antenna; a radio broadcast wave signal distribution circuit that extracts a radio broadcast wave signal from a received signal obtained through the antenna, distributes and outputs the extracted radio broadcast wave signal; a television broadcast wave signal extraction circuit that extracts the radio broadcast wave signal; a first receiver that receives the radio broadcast wave signal distributed by the radio broadcast wave signal distribution circuit; and a first receiver that receives the radio broadcast wave signal distributed by the radio broadcast wave signal distribution circuit; a second receiver that receives a radio broadcast wave signal via a switch circuit and receives a television broadcast wave signal obtained via the television broadcast wave signal extraction circuit; An antenna switching device characterized in that the switch circuit is controlled to be in an OFF state when receiving a television broadcast wave signal.