JPH0313636B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vehicle-mounted receiving device that receives traffic information such as traffic congestion on a road.

In order to listen to traffic information contained in radio broadcasts and traffic information transmitted by radio waves in predetermined areas of roads, conventional car radios etc. installed in moving objects such as cars are used. When installing another receiver in addition to the receiver to receive traffic information, if signals are supplied from a single antenna to the two receivers via a branching circuit, the sensitivity and S/N ratio will decrease. The problem arises.

Therefore, it is conceivable to install an antenna for a receiving device that receives traffic information separately from the antenna of a conventional car radio, but if a new whip antenna is installed on the vehicle for receiving traffic information, the structure of the antenna itself will be large. Therefore, it is not desirable in terms of appearance, and it is also difficult to install, which poses a problem in that it becomes a major factor in increasing costs.

The present invention has been made in view of these conventional problems, and is an in-vehicle traffic information system that can be miniaturized and cost-effective, and does not adversely affect the existing in-vehicle radio tuner. The purpose is a receiving device for

In order to achieve the above object, the present invention provides separate antennas for a tuner for traffic information reception and an antenna for an existing tuner for receiving general broadcasting, and also provides an antenna for a tuner for traffic information reception in the longitudinal direction of a vehicle. It is configured as a bar antenna with parallel longitudinal directions.

Although bar antennas have slightly lower sensitivity and are more directional, traffic information is transmitted from antennas installed parallel to the road in predetermined areas of the road, so it is difficult for vehicles to receive traffic information. The electric field arrives from the side, that is, perpendicular to the front-rear direction of the vehicle, and the direction of arrival is constant and the electric field strength is also constant. Therefore, by arranging the bar antenna with its longitudinal direction parallel to the front-rear direction of the vehicle, , the bar antenna can receive traffic information without any problem.

The present invention includes a start identification signal indicating the start of broadcasting of traffic information, traffic information, and an end identification signal indicating the end of broadcasting of the traffic information, from an antenna installed parallel to the road in a predetermined area of the road. Traffic information is transmitted, and when transmitting traffic information,
An in-vehicle receiver that receives traffic information broadcast transmitted in the order of the start identification signal, traffic information, and end identification signal, the receiver comprising: a tuner 17 that demodulates the start identification signal, traffic information, and end identification signal; , another tuner 14, a changeover switch 16 that selectively outputs the output signal of the tuner 17 or the other tuner 14 to the speaker 22, and a switch 16 that is connected to the tuner 17 and detects the start identification signal and the end identification signal. , and an identification circuit 33 that switches and controls the connection state of the changeover switch 16 based on the detection of each identification signal, and the antenna 23 for the tuner 17 and the antenna for the other tuner 14 are each provided separately. The antenna 23 for the tuner 17 is a vehicle-mounted traffic information receiving device characterized in that it is configured as a bar antenna having a longitudinal direction parallel to the longitudinal direction of the vehicle.

FIG. 1 is a plan view of a road according to an embodiment of the present invention. Antennas 5 and 6 are buried in roadside strips in predetermined traffic information receiving areas 3 and 4 on the up and down lines 1 and 2, respectively.
To these antennas 5 and 6, carrier waves modulated by signals containing traffic information are derived from transmitters 7 and 8 as radio waves. This traffic information receiving area 3,
The carrier frequencies c1 and c2 in 4 are different from each other, thereby preventing interference.

Referring to FIG. 2, in traffic information receiving areas 3 and 4, a start identification signal 9, traffic information 10, and end identification signal 11 are repeatedly transmitted in this order by modulating carrier waves. Up line 1 and down line 2
An automobile 12 as a moving body that is traveling includes a receiving device 13 . The receiving device 13 is configured to detect the start identification signal 9, interrupt the traffic information 10 and convert it into audible sound, and return to the original state upon detection of the end identification signal 11.

FIG. 3 is a block diagram showing a specific configuration of the receiving device 13. As shown in FIG. A signal from an antenna 15 is given to a tuner 14 of a conventional receiving device such as a car radio. The thus demodulated audio frequency signal shown in FIG. 2 is applied to the individual contact 18 of the changeover switch 16. The demodulated signal from another tuner 17 according to the invention is applied to the other individual contact 19 of the changeover switch 16. Common contact 20 of changeover switch 16
The signal from is amplified by the amplifier circuit 21,
The sound is made into sound by the speaker 22.

A bar antenna 23 is provided in association with the tuner 17. This bar antenna 23 is constructed by winding a coil 25 around the outer periphery of a core 24 made of a ferromagnetic material. A signal from the bar antenna 23 is given to a primary coil 28 of a matching transformer 27 via a coaxial cable 26. The primary coil 28 is matched with the bar antenna 23 with low input impedance. This primary coil 2
The signal applied to 8 is boosted by the secondary coil 29 and applied to the field effect transistor 30 with high output impedance. A resistor 31 is connected in connection with the field effect transistor 30. The output from this field effect transistor 30 is applied to the tuner 17 via a coupling capacitor 32. Considering that the capacitance of a conventional general antenna is 80 pF, the capacitance of this coupling capacitor 32 is selected to be the same value, 80 pF.
The demodulated signal from the tuner 17 is applied to the individual contact 19 of the changeover switch 16 as described above, and is further applied to the identification circuit 33. The identification circuit 33 switches the common contact 20 of the changeover switch 16 to the individual contact 19 to conduct when the start identification signal 9 is included in the output from the tuner 17, and switches the common contact 20 to the individual contact 19 when the end identification signal 11 is detected. The individual contact 18 is switched to conduction and returned to the original state.

FIG. 4 is a simplified perspective view of a portion of the interior of the automobile 12. The bar antenna 23 is attached to a pillar 36 between a windshield 34 and a door 35.

FIG. 5 is a simplified plan view of the automobile 12. The longitudinal direction of the core 24 of the bar antenna 23 is
It is parallel to the traveling direction of the automobile 12. The directivity of the bar antenna 23 extends in the width direction of the vehicle 12, as indicated by reference numeral 37. The car 12 is in the traffic information receiving area 3 of the up line 1 or the down line 2,
Assume that you are driving on 4. Receiving device 13
The tuning frequency of the tuner 17 is the carrier frequency
Matches c1 and c2. Therefore, the identification circuit 33
detects the start identification signal 9 with high sensitivity. As a result, the common contact 20 of the changeover switch 16 is electrically connected to the individual contact 19, so that the tuner 14 can interrupt the reception of radio broadcasts to receive traffic information.

A road 40 that enters the up line 1 and the down line 2,
41 is provided with preparation areas 42 and 43 such as toll booths. The preparation areas 42 and 43 are covered with grounded metal or the like, and are shielded from radio waves such as radio broadcasts from the outside. This preparation area 42,4
3, a signal having a carrier frequency identical to that of the radio broadcast is emitted. The carrier frequencies include the carrier frequencies of all the plurality of radio broadcasts that can be heard outside the preparation area 42,43. In the preparation areas 42 and 43, the preparation area 4 receives audio signals obtained by converting the carrier frequencies c1 and c2 used in the reception areas 3 and 4 into acoustic signals.
The carrier wave frequency at 2 and 43 is modulated and transmitted as a radio wave. The audio signal is, for example, "Uplink traffic information can be heard on frequency c1." In this way, when radio broadcasts are being received on the approach roads 40, 41, the preparation areas 42, 4
3, carrier wave frequencies c1 and c2 in the traffic information receiving areas 3 and 4 can be heard. Passengers such as the driver of the automobile 12 are in the preparation area 4.
The carrier frequency c1 indicated in 2.43,
Adjust the tuning frequency of tuner 17 to c2. In this way, reception of traffic information in the traffic information receiving areas 3 and 4 is ensured.

The specific configuration of the identification circuit 33 is shown in FIG. The output from tuner 17 is passed through filter 1
30, 131 and level setting circuit 153. Filters 30 and 31 select and derive identification signals having frequencies 1 and 2, respectively. The outputs from the filters 130 and 131 are sent to the detection circuit 13.
2,133. Detection circuit 132 includes a coupling capacitor 151, a detection diode 152, and an integrating capacitor 136. The detection circuit 133 has the same structure as the detection circuit 132. Outputs from the detection circuits 132 and 133 are given to one input of comparison circuits 134 and 135. The other input of the comparison circuits 134 and 135 has
A signal is provided from the level setting circuit 153 via the detection circuit 154 . The detection circuit 154 has the same structure as the detection circuits 132 and 133. The outputs from the comparison circuits 134 and 135 are sent to the time judgment circuit 13.
7,138 respectively.

The time determination circuit 137 includes a resistor 139, an integrating capacitor 140, a comparison circuit 141, and a resistor 13.
The comparator circuit 141 includes a diode 142 connected in parallel to the comparator circuit 141, and one input of the comparator circuit 141 receives the output from the integrating capacitor 140. Comparison circuit 1
A signal at a predetermined level is applied from a terminal 143 to the other input of 41. Another time determination circuit 138 has a similar structure to time determination circuit 137.

The output from the time determination circuit 137 is given to one input of an AND gate 145 via a monostable circuit 144 and directly to the AND gate 14.
6 is applied to one input. Time judgment circuit 13
The output from 8 is passed through monostable circuit 147.
It is applied to the other input of AND gate 146 and directly to the other input of AND gate 145. The output of AND gate 145 sets flip-flop 148 and the output from AND gate 146 resets flip-flop 148. Transistor 115 is rendered conductive by the set output from flip-flop 148.
Therefore, the relay coil 116 is energized, so that the common contact 20 of the changeover switch 16 conducts to the individual contact 19 only during this energization period.

For example, as shown in FIG. 7, the monostable circuit 144 includes a diode 110 and an integrating capacitor 111.
, a resistor 112 that forms a time constant circuit together with an integrating capacitor 111, and a transistor 113 that forcibly and instantaneously discharges the integrating capacitor 111, and the output of the integrating capacitor 111 is level-discriminated by the threshold of an AND gate 145. be done.

Referring to FIG. 8, when the tuner 17 is receiving the signal, the signal shown in FIG.
Assume a case derived from 7. Filter 13
0 selects only the identification signal having the audio frequency 1 and supplies it to the detection circuit 132. As a result, the output of the integrating capacitor 136, that is, the detection circuit 1
The output of 32 is as shown in FIG. 82. The identification signal having an audible frequency of 1 is sent to the level setting circuit 153.
is applied to the detection circuit 154 from the comparator circuit 134.
determine the discrimination level. When only the identification signal having the audible frequency 1 is being received, the output from the detection circuit 154 and therefore the discrimination level of the comparison circuit 134 is low. Therefore, when an identification signal of audio frequency 1 exceeding this discrimination level is given from the detection circuit 132, the comparison circuit 134 derives the waveform shown in FIG. 83. The output from this comparison circuit 134 is integrated by an integrating capacitor 140 via a resistor 139. The output waveform of the integrating capacitor 140 is shown in FIG. Integrating capacitor 1
When the output of the comparator circuit 14 exceeds the discrimination level given to the terminal 143 after the elapse of time T1, the output of the comparator circuit 14
1 derives a signal having the waveform shown in FIG. In this manner, the comparator circuit 141 derives an output only when the identification signal of the audio frequency 1 is continuously received for a time T1 or more. monostable circuit 144
is the predetermined pulse width W7 as shown in FIG.
Derive a pulse with . During the period of this pulse width W7, as described below, the audible frequency 2
An identification signal having the following information will be received and detected.

An identification signal having an audible frequency of 2 is sent to the tuner 17.
When the identification signal is output from the filter 13, the identification signal is output from the filter 13.
1 and detected by the detection circuit 133. The output from the detection circuit 133 is shown in FIG. The output from the comparison circuit 135 is the sixth
7, and the output from time determination circuit 138 is shown in FIG. 6. Time judgment circuit 138
The output from is derived when the identification signal having audio frequency 2 lasts for a time T2 or more. In this way, from the AND gate 145,
A waveform shown at 0 is obtained. Therefore, the flip-flop 148 is set and the traffic information from the tuner 17 is outputted from the speaker 22 via the changeover switch 16, the amplifier circuit 21, and the like.

When the radio broadcast of traffic information ends, identification signals having audible frequencies 2 and 1 are derived from the tuner 17 in this order. audible frequency 2
When an identification signal having a predetermined pulse width W8 is detected, a signal having a predetermined pulse width W8 is derived from the monostable circuit 147. Pulse width W8 may be equal to pulse width W7. During the period when the output is derived from this monostable circuit 147, the audio frequency 1
When an identification signal having ? is detected, the output from AND gate 146 causes flip-flop 148 to be reset. Therefore, the changeover switch 16 directs the signal from the tuner 14 to the amplifier circuit 21, and the radio broadcast being received by the tuner 14 can be heard again from the speaker 22.

In the above embodiment, when a signal having a frequency spectrum covering a wide frequency band including audio frequencies 1 and 2 is derived from the tuner 17, the level of the signal from the level setting circuit 132 via the detection circuit 154, that is, the comparison circuit 134 , 135 have a high discrimination level. Therefore, the comparison circuit 134,1
The output of 35 remains at a low level. In this manner, only when the identification signal having only the frequency spectrum of audible frequencies 1 and 2 is received by the tuner 17, high level outputs are obtained from the comparison circuits 134 and 135 as described above. This prevents erroneous detection of traffic information. In addition, the time determination circuits 137 and 138 use the audible frequency 1,
2 is greater than or equal to time T1 (see Figure 8, Figure 5) and time T
Outputs are obtained from the time determination circuits 137 and 138 only when each of them lasts for 2 (see FIG. 8) or more. Therefore, it is possible to more reliably prevent erroneous detection of traffic information. Furthermore, by the action of monostable circuits 144 and 147, the audible frequencies 1 and 2 are
Flip-flop 148 operates only when the identification signal having . This also further reliably prevents erroneous detection of traffic information.

Diode 14 included in time determination circuit 137
2 functions to discharge the charge in the capacitor 140 immediately when the output of the comparator circuit 134 becomes low level. Therefore, the comparison circuit 134 that is input next
can be reliably integrated by the capacitor 140 via the resistor 139. Accurate time T1 can be obtained.

The audible frequencies 1 and 2 of the identification signal may be selected to have a chord relationship that satisfies the first equation to obtain good hearing.

2=1.5・1…(1) For example, 1 is 900Hz and 2 is 1350Hz.

In order to detect that there is a pause period 2 between the signals of durations W1 and W3 in the start identification signal and thereby more reliably avoid false detection, the following configuration is provided. The output from the detection circuit 154 is given to one input of the comparison circuit 156. The other input of this comparison circuit 156 is given a voltage Vr1 that determines a predetermined discrimination level. The comparison circuit 156 is configured so that the output from the detection circuit 154 is a voltage Vr.
When the discrimination level corresponding to 1 is exceeded, a high level signal is given to the AND gate 157. The output from time determination circuit 137 is given to differentiation circuit 158. The output of the differentiator circuit 158 is the output of the comparator circuit 1.
59 is applied to one input. Comparison circuit 159
The other input is the voltage Vr that determines the discrimination level.
2 is given. Comparison circuit 159 is differentiator circuit 1
When the output from 58 is equal to or higher than the discrimination level corresponding to voltage Vr2, the high level signal is ANDed.
The signal is led out to gate 157. The aforementioned differentiation circuit 158
derives high-level and low-level differential pulses at the rise and fall of the time determination circuit 137, respectively. In this way, a high level pulse is derived from the comparison circuit 159 at the time of the fall of the time determination circuit 137. AND
The output of the gate 157 is given to a pulse shaping circuit 160, where the pulse width is shaped to a predetermined value, and the output is sent to the transistor 113 (the fifth transistor) of the monostable circuit 144.
(see figure). The monostable circuit 144 is reset in response to the output from the pulse shaping circuit 160, and its output is set to a low level.

Assume that a start identification signal having a normal waveform shown in FIG. 9 is derived from the tuner 17 on the line 14. In this case, the detection circuit 154
The comparator circuit 156 is supplied with the signal shown in FIG. 92. The output of the comparator circuit 156 is shown in FIG.
As shown in The time determination circuit 137 derives the signal shown in FIG.
44 and also to the differentiating circuit 158. The output of the differentiator circuit 158 is shown in FIG. Due to the functions of the differentiating circuit 158 and the comparing circuit 159, a pulse is derived from the comparing circuit 159 to the AND gate 157 at the falling edge of the pulse shown in FIG. AND gate 15
7 remains at a low level, so that the output from the pulse shaping circuit 160 is the pulse shown in FIG. 9. Therefore, monostable circuit 1
The transistor 113 of 44 is cut off, and its output is at a high level for a period W7 as shown in FIG. The output of time determination circuit 138 is shown in FIG. Therefore, the pulse shown in FIG. 9 is derived from the AND gate 145, and the flip-flop 148 is set.

Assume that a signal is mixed in the pause period W2 included in the start identification signal as shown in FIG. 10. The output of the detection circuit 154 is the 10th
2, the output of the comparator circuit 134 is shown in FIG.
It is as follows. The output of the time determination circuit 137 is as shown in FIG. 10. The output of the differentiating circuit 158 is as shown in FIG. AND gate 157 derives a high level pulse in response to the signal from comparison circuit 156 that remains high and the pulse from comparison circuit 159. The pulse shaping circuit 160 derives the pulse shown in FIG. 10 to cause the transistor 113 of the monostable circuit 144 to conduct. Therefore, capacitor 11
1 is discharged, and the output of the monostable circuit 144 is the eighth
It goes high for a very short time as shown in FIG. 8, and then is forced to a low level. The output of time determination circuit 138 is shown in FIG. The output of AND gate 145 remains low as shown in FIG. 10, and flip-flop 148 is not set. In this manner, the flip-flop 148 is not set when there is a frequency signal during the pause period W2, and erroneous detection of the start identification signal is prevented.

Since the tuner for receiving traffic information and the antenna of the existing tuner for receiving general broadcasting are provided separately, and the antenna of the tuner for traffic information receiving is configured as a bar antenna having a longitudinal direction parallel to the longitudinal direction of the vehicle, The configuration can be made smaller, the cost can be reduced, and there is no adverse effect on the existing in-vehicle radio tuner.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a road according to an embodiment of the present invention, FIG. 2 is a waveform diagram of signals sent in the traffic information receiving areas 3 and 4, FIG. 3 is a block diagram of the receiving device 13, and FIG. The figure is a perspective view showing a part of the interior of the automobile 12, FIG. 5 is a plan view of the automobile 122, and FIG.
The figure is a block diagram showing the specific configuration of the identification circuit 33, FIG. 7 is an electric circuit diagram of the monostable circuit 144, and FIGS. 8 to 10 are the identification circuit 33 shown in FIG.
FIG. 2 is a waveform diagram for explaining the operation of FIG. 1... Up line, 2... Down line, 3, 4... Traffic information receiving area, 12... Car, 13... Receiving device, 14, 17... Tuner, 16... Changeover switch, 21... Amplification Circuit, 22...Speaker,
23...Bar antenna, 27...Matching transformer, 33...Identification circuit.

Claims (1)

[Scope of Claims] 1. The vehicle includes a start identification signal indicating the start of broadcasting of traffic information, traffic information, and an end identification signal indicating the end of broadcasting of the traffic information, and is provided parallel to the road in a predetermined area of the road. An in-vehicle receiving device that receives traffic information broadcasting in which traffic information is transmitted from an antenna, and when the traffic information is transmitted, the start identification signal, the traffic information, and the end identification signal are transmitted in this order, the in-vehicle receiving device comprising: A tuner 17 that demodulates signals, traffic information, and termination identification signals; Another tuner 14; A changeover switch 16 that selectively outputs the output signal of the tuner 17 or the other tuner 14 to the speaker 22; The tuner 17 an identification circuit 33 connected to the antenna 15 for the tuner 17 to detect the start identification signal and the end identification signal and to switch and control the connection state of the changeover switch 16 based on the detection of each identification signal; The antennas for the other tuners 14 are provided separately, and the antenna 23 for the tuner 17 is configured as a bar antenna having a longitudinal direction parallel to the longitudinal direction of the vehicle. Receiving device.