JP3207790B2 - In-vehicle radio - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of transmitting and receiving necessary information between a fixed station installed at a tollgate on a toll road and a vehicle-mounted radio device mounted on a vehicle, for example, while preserving a predetermined fee ( For example, the present invention relates to an on-vehicle wireless device used in a wireless toll collection system for collecting tolls on a toll road.

[0002]

2. Description of the Related Art Conventionally, in a toll collection system for a toll road, a toll collector collects cash directly from an occupant of a passing vehicle, or automatically transfers cash to an automatic machine by an occupant of a passing vehicle. Is adopted. Therefore, it is necessary to temporarily stop the vehicle at the tollgate. In addition, passengers of passing vehicles need to prepare cash.

[0003] On the other hand, as a toll collection system that does not transfer cash at a tollgate, wireless communication is performed between a fixed station installed at a tollgate on a toll road and a vehicle-mounted wireless device mounted on a passing vehicle. By sending and receiving necessary signals,
Wireless toll collection systems that collect tolls by postpaid or prepaid payments have been developed.

FIG. 2 is a perspective view showing an outline of such a wireless toll collection system. A fixed station (not shown) is provided at the tollgate on the toll road, and a fixed station antenna A of the fixed station is attached to a gantry G provided across the road W so as to correspond to each lane. . When the vehicle V equipped with the on-vehicle wireless device travels on the road W and enters the communication area of the fixed station antenna A, wireless communication is performed between the on-vehicle wireless device and the fixed station via the fixed station antenna A, The pass-through fee is subtracted from the money amount information recorded in the on-vehicle wireless device.

FIG. 3 is a functional block diagram showing a conventional configuration example of a vehicle-mounted radio. As shown in FIG. 1, the conventional in-vehicle wireless device includes a receiving antenna 1, a low noise amplifier 2, a power divider 3, a demodulator 4, a signal processing unit 5, an amplifier 6, a modulator 7, a power amplifier 8, and a transmitting antenna 9. are doing.

The radio wave transmitted from the fixed station antenna A is
It is received by the receiving antenna 1 and converted into an electric signal (received transmission signal). The received transmission signal obtained by the receiving antenna 1 is amplified by a low noise amplifier 2 and then supplied to a demodulator 4 via a power divider 3 and demodulated by the demodulator 4 to obtain a received digital signal. .

The signal processor 5 recognizes the content of the received digital signal obtained by the demodulator 4 and generates a transmission digital signal according to the content. On the other hand, in the power divider 3, an unmodulated wave is branched from the received transmission signal provided from the low noise amplifier 2. The split unmodulated wave (downlink carrier) is amplified by the amplifier 6 and then supplied to the modulator 7 as an uplink carrier.

[0008] In the modulator 7, the downlink carrier wave supplied from the amplifier 6 is modulated by a digital signal generated by the signal processing unit 5 to be a transmission transmission signal. 9 to the fixed station antenna A.

[0009]

As described above, the conventional in-vehicle wireless device uses the downlink carrier wave included in the transmission signal transmitted from the fixed station as the uplink carrier wave, so that an oscillator or the like is not required. The configuration can be simplified.

However, on the other hand, since the transmission signal of the downlink and the transmission signal of the uplink are in the same frequency band, leakage from the transmitting antenna of the fixed station antenna to the receiving antenna becomes an interference wave for the uplink communication and the sensitivity is reduced. There was a problem such as deterioration. In order to prevent this, the antenna must be enlarged in order to increase the isolation between the transmitting and receiving antennas, or a complicated structure such as attaching a radio wave absorber between the transmitting and receiving antennas has to be used.

The present invention has been made in view of such circumstances, and its purpose is to make a complicated structure such as enlarging an antenna or attaching a radio wave absorber between transmitting and receiving antennas. It is an object of the present invention to provide an in-vehicle wireless device capable of preventing deterioration in sensitivity due to interference between a downlink transmission signal and an uplink transmission signal and performing good communication.

[0012]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a receiving means for receiving a downlink transmission signal transmitted from a fixed station installed at a tollgate, for example, comprising a receiving antenna and a low noise amplifier. And extracting a carrier component from the downlink transmission signal received by the receiving means,
Regenerate the downlink carrier signal, for example, a downlink carrier regeneration means comprising a power divider and an amplifier, and multiply or divide the downlink carrier reproduced by the downlink carrier regeneration means to generate a predetermined uplink carrier, for example, a multiplier or Uplink carrier generation means comprising a frequency divider and a band pass filter, and a signal processing means comprising a demodulator and a signal processing unit, for example, which recognizes the downlink transmission signal and generates a predetermined transmission signal according to the content thereof, Uplink transmission signal generation means such as a modulator for generating an uplink transmission signal by modulating the uplink carrier generated by the uplink carrier generation means with the transmission signal generated by the signal processing means,
An in-vehicle wireless device comprising: a transmission unit configured to transmit the uplink transmission signal generated by the uplink transmission signal generation unit to the fixed station, for example, including a power amplifier and a transmission antenna.

By adopting such means, the upstream carrier for wirelessly transmitting the transmission signal generated by the signal processing unit is based on the carrier component (downstream carrier) of the downstream transmission signal transmitted from the fixed station. Generated. However, since the uplink carrier is generated by multiplying or dividing the downlink carrier, it has a different frequency from the downlink carrier. Therefore, the uplink transmission signal generated by the uplink transmission signal generation unit and transmitted to the fixed station by the transmission unit has a different frequency band from the downlink transmission signal transmitted from the fixed station, and no interference occurs between the two signals. .

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a functional block diagram showing a configuration of a vehicle-mounted radio device according to the present embodiment. The same parts as those in FIG. 3 are denoted by the same reference numerals.

As shown in FIG. 1, the on-vehicle wireless device according to the present embodiment includes a receiving antenna 1, a low-noise antenna 2, a power divider 3, a demodulator 4, a signal processing unit 5, an amplifier 6, a modulator 7, a power amplifier 8, A transmission antenna 9, a multiplier 10 and a band-pass filter (BPF) 11 are provided.

The receiving antenna 1 receives the radio wave transmitted from the fixed station antenna of the fixed station, converts it into an electric signal (received transmission signal), and converts the received transmission signal into a low noise amplifier 2.
Give to.

The low-noise amplifier 2 amplifies the reception transmission signal supplied from the reception antenna 1 to a level sufficient for performing various processes at the subsequent stage, and supplies the amplified signal to the power divider 3. The power divider 3 supplies the received transmission signal supplied from the low-noise amplifier 2 to the demodulator 4, branches the unmodulated wave (downlink carrier) in the received transmission signal, and supplies it to the amplifier 6.

The demodulator 4 demodulates the received transmission signal supplied via the power divider 3 to obtain a received digital signal, and supplies the received digital signal to the signal processing unit 5.
The signal processing unit 5 recognizes the content of the received digital signal,
A transmission digital signal corresponding to the recognized content is generated. Then, the signal processing unit 5 gives the generated transmission digital signal to the modulator 7.

The amplifier 6 amplifies the downlink carrier split by the power divider 3 and supplies the same to the multiplier 10. The modulator 7 modulates the uplink carrier provided from the bandpass filter 11 with the transmission digital signal provided from the signal processing unit 5 to generate a transmission transmission signal.
This is given to the power amplifier 8.

The power amplifier 8 amplifies the transmission signal transmitted from the modulator 7 to a level sufficient for wireless transmission, and supplies the signal to the transmission antenna 9. The transmission antenna 9 converts the transmission signal supplied from the power amplifier 8 into a radio wave, and emits the radio wave toward the fixed station antenna. The multiplier 10 multiplies the downlink carrier supplied from the amplifier 6 by n times, An uplink carrier having n times the frequency of the carrier is generated. And the multiplier 10
Supplies the generated uplink carrier to the band-pass filter 11.

The band-pass filter 11 removes unnecessary frequency components from the uplink carrier supplied from the multiplier 10 and supplies the same to the modulator 7. Next, the operation of the on-vehicle wireless device configured as described above will be described.

First, when a vehicle equipped with the on-vehicle wireless device of the present embodiment enters a communication area of a fixed station antenna at a tollgate, a radio wave transmitted from the fixed station antenna reaches the receiving antenna 1. Then, the radio wave transmitted from the fixed station antenna is received by the receiving antenna 1 and converted into an electric signal (received transmission signal). The received transmission signal obtained by the receiving antenna 1 is amplified by a low noise amplifier 2 and then supplied to a demodulator 4 via a power divider 3 and demodulated by the demodulator 4 to obtain a received digital signal. .

The signal processing unit 5 recognizes the content of the received digital signal obtained by the demodulator 4 and generates a transmission digital signal according to the content. On the other hand, in the power divider 3, an unmodulated wave (downlink carrier) is branched from the received transmission signal provided from the low noise amplifier 2. The split downlink carrier is supplied to an amplifier 6
, And then multiplied by n in the multiplier 10,
An uplink carrier having n times the frequency of the downlink carrier. Then, the frequency component unnecessary for transmitting the uplink, that is, the component of the downlink carrier is removed by the band-pass filter 11 and then supplied to the modulator 7.

In the modulator 7, the downlink carrier supplied from the band-pass filter 11 is modulated by the digital signal generated by the signal processing unit 5 to be a transmission signal, and after being amplified by the power amplifier 8, The signal is transmitted from the transmitting antenna 9 to the fixed station antenna A.

As described above, while the vehicle-mounted radio transmits and receives predetermined digital information to and from the fixed station, the toll is subtracted from the amount data stored in the signal processing unit 5 to collect the toll. Do.

As described above, according to the present embodiment, the uplink carrier has n times the frequency of the downlink carrier, so that the downlink transmission signal and the uplink transmission signal are in different frequency bands. .

As a result, even if the fixed station antenna leaks from the transmitting antenna to the receiving antenna, it does not become an interference wave for the uplink communication and the sensitivity does not deteriorate. Therefore, it is possible to perform favorable communication with the fixed station without increasing the size of the antenna or attaching a radio wave absorber between the transmitting and receiving antennas.

The present invention is not limited to the above embodiment. For example, the multiplier 10 in the above embodiment
, A frequency divider may be provided, and an uplink carrier having a frequency of 1 / m of the downlink carrier may be generated and used.

In the above embodiment, the on-vehicle wireless device of the present invention is used in a wireless toll collection system for collecting tolls on toll roads. The present invention can be applied to a wireless toll collection system for performing the above. In addition, various modifications can be made without departing from the spirit of the present invention.

[0030]

According to the present invention, receiving means for receiving a downlink transmission signal transmitted from a fixed station installed at a tollgate, extracting a carrier component from the downlink transmission signal received by the receiving means, Downlink carrier regeneration means for regenerating a down carrier signal, an up carrier generation means for multiplying or dividing the down carrier reproduced by the down carrier regeneration means and generating a predetermined up carrier, and recognizing the down transmission signal A signal processing unit for generating a predetermined transmission signal according to the content thereof, and generating an uplink transmission signal by modulating an uplink carrier generated by the uplink carrier generation unit with the transmission signal generated by the signal processing unit. The transmission means for transmitting the uplink transmission signal generated by the uplink transmission signal generation means to the fixed station. Prevents deterioration of sensitivity due to interference between downlink transmission signal and uplink transmission signal without taking a complicated structure such as increasing the antenna or attaching a radio wave absorber between transmitting and receiving antennas. An in-vehicle wireless device that can perform good communication.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a configuration of an in-vehicle wireless device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing an outline of a wireless toll collection system.

FIG. 3 is a functional block diagram showing a conventional configuration example of an in-vehicle wireless device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Receiving antenna 2 ... Low noise antenna 3 ... Power divider 4 ... Demodulator 5 ... Signal processing part 6 ... Amplifier 7 ... Modulator 8 ... Power amplifier 9 ... Transmitting antenna 10 ... Multiplier 11 ... Bandpass filter

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-73350 (JP, A) JP-A-57-100587 (JP, A) JP-A-8-223103 (JP, A) (58) Field (Int. Cl. ⁷ , DB name) G07B 11/00-17/04

Claims (2)

(57) [Claims] The present invention is used in a wireless toll collection system for transmitting and receiving necessary information between a fixed station installed at a tollgate and an in-vehicle wireless device mounted on a vehicle and collecting a predetermined fee for the vehicle. Receiving means for receiving a downlink transmission signal transmitted from the fixed station; and extracting a carrier component from the downlink transmission signal received by the receiving means and reproducing the downlink carrier signal. And an uplink carrier generating means for multiplying the downlink carrier reproduced by the downlink carrier reproducing means to generate a predetermined uplink carrier; and recognizing the downlink transmission signal and generating a predetermined transmission signal according to the content thereof. A signal processing means, and modulating an uplink carrier generated by the uplink carrier generation means with the transmission signal generated by the signal processing means to generate an uplink transmission signal. Vehicle radio to the upward transmission signal generation means, characterized in that the uplink transmission signal generated by the uplink transmission signal generating means is a transmitting means for transmitting towards said fixed station that. 2. A wireless toll collection system for collecting and receiving a predetermined fee for a vehicle while transmitting and receiving necessary information between a fixed station installed at a tollgate and an in-vehicle wireless device mounted on the vehicle. Receiving means for receiving a downlink transmission signal transmitted from the fixed station; and extracting a carrier component from the downlink transmission signal received by the receiving means and reproducing the downlink carrier signal. And an upstream carrier generating unit for dividing the downstream carrier reproduced by the downstream carrier reproducing unit to generate a predetermined upstream carrier, and recognizing the downstream transmission signal and generating a predetermined transmission signal according to the content thereof. Signal processing means for modulating an uplink carrier generated by the uplink carrier generation means with the transmission signal generated by the signal processing means to generate an uplink transmission signal. Vehicle radio to the upward transmission signal generation means, characterized in that the uplink transmission signal generated by the uplink transmission signal generating means is a transmitting means for transmitting towards said fixed station that.