JPH08107368A - Multiplex fm broadcast receiver - Google Patents

Abstract

PURPOSE: To obtain a multiplex FM broadcast receiver mounted on a vehicle such as an automobile by allowing the receiver to receive effectively multiplexed data such as traffic information and meteorological information so as to build up a data group efficiently. CONSTITUTION: An FM receiver searches an FM band to provide a receptible multiplex station list and to discriminate a network of each multiplex station. In the case of selecting a succeeding reception station depending on deterioration electric field strength, the prefecture of a current station location is identified in the step 201; whether or not a selected broadcast station belongs the same station as that of the current reception station is discriminated in the step 202; whether or not the selected broadcast station belongs to the same prefecture is discriminated in the step 203; and the new station is selected in the step 204 when the new station belongs to the same network and the same prefecture. In this case, the storage content of a memory storing multiplexed data is continued and the built-up data group is used continuously as it is.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio with a built-in FM multiplex mounted on a moving vehicle, and in particular receives and manages various data such as traffic information by digital data multiplexed on an FM signal. The present invention relates to an FM multiplex broadcast receiving device.

[0002]

2. Description of the Related Art FM multiplex broadcasting in which digital data is multiplexed with an audio signal is considered, but as a precedent to such FM multiplex broadcasting in Japan, RDS (Radio Radio) is used in Europe. Data System) has been put to practical use. Similar to FM multiplex in Japan (hereinafter simply referred to as FM multiplex), this RDS multiplexes data with respect to a voice signal and is served as FM broadcast, but the data transmission rate is about 1 kbps. It is a low-speed one, and the application is mainly voice, and the multiplex data is in an auxiliary position to enhance this voice service.

For example, the best five functions often used in this RDS are PI (country, program code) and PS.
(Station name), AF (alternative frequency), TP (traffic information station flag), and TA (traffic information providing flag),
Even with the maximum data length of this multiplexed data, the frequency list for up to 25 stations in AF and PS is at most 8 characters, and the size of several bytes to 1 bit in other functions.

On the other hand, FM multiplexing, which has been tried in Japan, has a transmission capacity of about 16 times that of 16 kbps and RDS, so that the application in which the multiplexed data itself is the main is possible. . Such FM multiplexing can of course be used as in RDS, but it is possible to transmit a large amount of data compared to RDS. Visual applications such as traffic information and weather information such as weather maps are expected. Such visual application information requires 3 to 4 kilobytes of data per piece of information.

FM mounted on a moving body such as an automobile
Different FM when receiving FM multiplex broadcasts by radio, especially when traveling on a highway.
Pass through the broadcasting service area one after another. Then, the channel selection is switched every time the broadcast service area is passed, and the reception frequency is also changed each time. In the case of RDS, since the data size of each unit is small and the amount of data is small, there is no problem even if the memory for data processing is cleared and the stored data is updated every time the channel selection is switched.

However, in the case of FM multiplexing, a meaningful data block (data group: DG) is RD.
It handles data of a much larger size than S. Therefore, the larger the size of a data group due to the effects of fading and multi-pulses, the smaller the rate of successful completion of this data group. In order to deal with such a problem, the broadcasting station is designed to periodically retransmit the same data, and the sending side should be controlled so that the data group is normally constructed on the receiver side. There is. In the operational restrictions, the transmission cycle of this transmission control is 2.5 minutes at maximum in the traffic information, and the number of times of retransmission is specified to be 2 or more.

In FM multiplexing carried out in such a situation, if the memory storing the data group is cleared every time the receiving side switches the receiving station, it is necessary to construct one data group. Since the data processing memory is cleared before all such packets are normally received, it is difficult to completely complete the data group. Therefore, in the case where this FM multiplex broadcast receiver is installed in the traveling vehicle,
Drivers can't get in touch with new information quickly.

For example, assuming that the service area of one broadcasting station installed on a certain route is 10 km, it is assumed that the vehicle is traveling at 100 km / h. It will pass through the area. That is, it becomes necessary to perform selective switching of the transmitting station in units of 8 minutes, and the number of times of re-reception of the data group decreases as the traveling speed of the vehicle increases, so that the rate of normally completing the data group deteriorates.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and is multiplexed, for example, when it is mounted on a traveling vehicle and passes through the service areas of a plurality of broadcasting stations. Data is efficiently received and the driver can be serviced. In particular, when multiple data is received multiple times to construct one data group, it passes through the service area of one broadcasting station. Then, even when you enter the service area of the next broadcasting station, the data group is easily completed,
For example, the present invention intends to provide an FM multiplex broadcast receiving apparatus that allows a driver to properly perform services such as traffic information.

[0010]

An FM multiplex broadcast receiving apparatus according to the present invention discriminates its reception intensity based on an FM reception signal, and selects an optimum next reception station upon detection of deterioration of a reception state. It is provided with a function for switching the received data, and multiplex data multiplexed on the received FM signal is decoded and stored in the data storage means. Further, the multi-station list forming means searches the reception frequencies to create a receivable FM multiplex transmission station list, and the area identification means is currently receiving based on the multiplex data contained in the signal currently received. This is for determining the area to which the FM multiplex broadcasting station belongs,
Further, a first discriminating means for discriminating whether or not the next receiving station to be switched and selected by the FM receiving means belongs to the belonging area identified by the area identifying means, and the next receiving station to be switched and selected by the FM receiving means. Has a second discriminating means for discriminating whether or not the receiving stations belong to the same network, and if the next receiving station belongs to the same belonging area and belongs to the same network by the first and second discriminating means. In the discriminated state, when the transmitting station is switched by the FM multiplex receiving means, the deletion of the multiplex data stored in the storage means is prohibited, and when the receiving station of the same area and the same network is switched and selected, Storage means Reconstruction of stored multiplex data is not required.

[0011]

According to the FM multiplex broadcast receiving apparatus configured as described above, when the vehicle running on the highway is receiving the FM multiplex broadcast, the FM multiplex broadcast receiving apparatus leaves the service area of the currently receiving broadcast station. In such a situation, the broadcasting station to be received next is searched for, and the selection of the receiving station is automatically switched. In this case, the receiving station of the data multiplexed in the FM broadcast is also switched, but at the time of this switching, it belongs to the same area as the area to which the broadcasting station that has been receiving so far (in units such as prefectures) belongs. It is determined whether the broadcasting station is selected or the network relationship is the same. If the area and the network are the same, the multiplexed data is also recognized as the same. The stored data in the storage means that stores is not updated. Therefore, even if the receiving broadcasting station is switched, the repeated reception of the multiplex data can be continuously performed, and the normal construction of the data group can be reliably performed. Meteorological information such as weather maps can be accurately transmitted.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, FIG. 1 shows the configuration of an FM multiplex broadcast receiver 10 mounted on a vehicle or the like, and a radio wave received from an antenna 11 is input to a front end 12. The front end 12 is tuned to a predetermined radio frequency and is at the intermediate frequency (I
F), and the signal converted to this intermediate frequency is amplified by the IF amplifier 13. The amplified intermediate frequency signal is converted into a baseband signal by the detection circuit 14, and the bandpass filter (BPF) 15 performs MSK.
The modulated subcarrier having a center frequency of 76 kHz is passed.

Then, in the multiplex data decoding circuit 16,
Error correction and error detection are performed while synchronizing, and the multiplex data is decoded. This decoded multiplexed data is supplied to the microcomputer 17, and this microcomputer 17
The front end 12 is controlled so as to be tuned to the reception frequency notified to the PLL synthesizer 18 from. Decoded multiplexed data is output from the microcomputer 17, and this multiplexed data is stored in the memory 19 and output as, for example, navigation data.

The station detector 20 determines that there is a receivable station when the intermediate frequency being received is within the frequency deviation and the intensity of the intermediate frequency is equal to or higher than a preset value. Further, the signal meter 21 outputs a voltage corresponding to the signal strength of the intermediate frequency signal output from the IF amplifier 13. The outputs from the station detector 20 and the signal meter 21 are input to the microcomputer 17. Further, the subcarrier detector 22 detects the strength of the signal after passing through the predetermined bandpass filter 15, and when the detected strength is higher than a predetermined value, multiplex broadcasting is broadcast. And the determination result is input to the microcomputer 17.

In the FM broadcast receiver 10 thus constructed, the value of the signal meter 21 is regularly measured, and when the measured value is less than a predetermined value. Can judge that the reception condition has deteriorated,
The multiple receiving station itself starts the operation of switching the broadcasting station to be received to the optimum broadcasting station. When such a switching request of the receiving station is generated, it is considered that the multiple receiving station itself determines and performs the request, or the request is made by a device other than the multiplex receiver by an operation of a driver or the like.

As a precondition for dealing with the case where such a switching request of the receiving station is generated, in the FM broadcasting receiver, the FM band is searched and the currently receiving FM broadcasting multi-station is periodically. Since it is updated and created, the network of each multiplex broadcasting station is also determined based on the broadcasting station identification code of the additional information of the multiplex data.

First, the procedure for creating this multi-station list is shown in FIG.
This will be described below. In FIG. 2, in step 101, the reception frequency is the lowest frequency of the FM frequency band, 76.1 MH.
Set to z. In step 102, it is determined based on the signal from the subcarrier detector 22 whether or not the received signal contains a subcarrier. If it is determined that there is a subcarrier, the process proceeds to step 103. In this step 103, the value of the signal (S) meter 21 is read, and the value of this signal meter 21 is set to A every 0.5 milliseconds.
It is recorded after being converted to / D, and the average value is obtained after, for example, measuring 5 times. This is the average value A.

At step 104, an interval of time Δt (about 50 milliseconds) specified in consideration of mobile reception is set, and the routine proceeds to step 105. In this step 105, the process in step 103 is repeated, and the average value of the values of the digital meter 21 obtained here is B. Then, in step 106, steps 103 and 105
The average values A and B obtained respectively in step 1 are compared, and the higher value is adopted as the value of the signal meter 21.

When the processing in step 106 is completed,
If it is determined in step 102 that there are no subcarriers, the process proceeds to step 107, in which 0.1 MHz is added to the reception frequency f to set a new reception frequency. In step 108, it is judged whether or not the received frequency has reached 90 MHz, which is the upper limit frequency of the FM band, and the process returns to step 102 in a state where it is still judged to be 90 MHz or less. When it is determined that the reception frequency has reached 90 MHz, it is determined that the entire FM radio band has been searched. In step 109, the value of the signal meter 21 is arranged in this order from the highest value, for example, 6 stations. Select and arrange them in descending order. In step 110, the broadcasting station determined in step 109 is selected to complete the multi-station list. This multi-station list is expressed by the relationship between frequency and network (NHK, JFN, ...).

Under such a premise, the processing for the switching request of the receiving station is performed, and FIG. 3 shows the flow of the processing. First, in step 201, it is determined whether the prefecture (affiliation area) of the broadcasting station currently being received has been identified. Programs such as traffic information to be multiplexed are shown in FIG.
As shown in, each program is composed of program management data relating to the entire program and a plurality of page data. Headers are set for the program management data and each page data, which are referred to as program data header data B and page header data B, respectively.

Originally, these program data header data B
The prefecture identification code of the page data header data B is given as a code of 0 to 47 (0 is unspecified) according to JISX 0401-1973 in the prefecture associated with the information of the program or each page. Since the information is basically provided by prefecture, it can be used as the prefecture where the broadcasting station is located.

As another means for identifying the prefecture of the broadcasting station, when the broadcasting station identification data as shown in FIG. 5 transmitted from the broadcasting station can be received, this is used.
This broadcasting station identification data consists of 3 bytes of an extended country identification code, a country identification code, a cover area code, and a broadcasting company number.

In the multiple receiver, if the correspondence table of broadcasting station identification and prefecture identification is recorded in advance, the prefecture where the receiving station is located can be easily identified. If it does not match the prefecture identification code, the broadcasting station identification is adopted.

If the prefecture of the current receiving station can be identified in step 201, the process proceeds to step 202. In this step 202, the present receiving station and the receiving station to be switched next belong to the same network. It is determined using the multi-station list. If it is determined that the current receiving station and the next receiving station belong to the same network, the process proceeds to step 203. In this case, the receiving station to be selected next has both a case where it is requested by the driver and a case where the multiple receiver itself judges, but in both cases, it is performed based on the multiple station list. Networks of stations to be switched from are known.

In step 203, it is determined whether or not the station to be switched to belongs to the same prefecture as the receiving station so far. For FM broadcast receivers, the frequencies of FM broadcast stations nationwide are recorded in advance as a database of the frequencies of each broadcast station for each prefecture and for each network. Please refer to these records. Thus, it can be determined whether or not the current receiving station and the switched station belong to the same prefecture. And this step 203
If it is determined in step 1 that they belong to the same prefecture, step 20
Proceed to step 4 and execute tuning operation. Here, when the receiver itself selects the next receiving station, the same network as the current receiving station in the multiplex list and the signal meter 21
Match the value with the highest frequency.

As shown in FIG. 6, the multiplexed data is classified into packets and is broadcast. One meaningful data (data group) is usually composed of a plurality of packets. This figure particularly shows the structure of the program data head data.

For example, when one data group is composed of 10 packets, a normal data group cannot be constructed if even one of the 10 packets has an error. By repeatedly resending the same data, the multi-broadcasting station replaces the error packet with the correct packet and constructs a data group if it can receive the correct packet even if there is an error packet on the receiving side. You can

In step 201, the prefecture of the current receiving station is not identified, in step 202, the current receiving station and the next receiving station do not belong to the same network, and it is determined in step 203 that the switching station belongs to another prefecture. If so, the process proceeds to step 204 to reset the DG (data group) construction and clear the memory 19 storing the multiplex data. That is, when it is determined that the contents of the multiplexed data are different between the switched broadcasting station and the current receiving station, the memory area for constructing the data group is cleared, and the multiplexed data from the next receiving station is restarted. memory
Stored in 19, so that a new data group based on multiplex data from a new broadcasting station is constructed.

FIG. 7 shows the states of service areas of broadcasting stations along the Tomei Expressway running from Aichi Prefecture to Shizuoka Prefecture, for example, from one service area to the next service area. In the case of shifting to, the broadcasting stations to be received are sequentially switched and selected. In this case, for example, there are two networks, NHK system and JFN system, and since it spans two prefectures, Aichi prefecture and Shizuoka prefecture, basically, broadcasting stations of the same network are sequentially switched and selected, When changing, the multiplex data stored in the memory is updated and a new data group is constructed.

[0030]

When the FM multiplex receiver is installed in the automobile, the service area of the broadcasting station is continuously set along the traveling route, and the broadcasting station of the same net is selected by the automatic tracking and tuning. In the case where there is a high probability that the multiplexed data such as traffic information and weather information will be the same even when the broadcasting station is switched, the multiplexed data stored in the receiver does not change. In such a case, the same multiplexed data can be repeatedly received and processed without clearing the data stored in the memory (storage means), so that the data group can be constructed very efficiently. As a result, various services for the driver will be properly performed.

[Brief description of drawings]

FIG. 1 is a configuration diagram illustrating an example of an FM receiver that constitutes an FM multiplex broadcast receiving apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a procedure for creating a multi-station list which is premised on performing automatic tracking and channel selection.

FIG. 3 is a flowchart for explaining a basic process for a switching request from a receiving station.

FIG. 4 is a diagram illustrating a data structure of multiple information.

FIG. 5 is a diagram for explaining broadcast station identification data.

FIG. 6 is a view for explaining program data head data in the above data structure.

FIG. 7 is a diagram showing an arrangement example of broadcasting stations.

[Explanation of symbols]

10 ... FM broadcast receiver, 11 ... Antenna, 12 ... Front end, 13 ... IF amplifier, 14 ... Detection circuit, 15 ... Band pass filter, 16 ... Multiplex data decoding circuit, 17 ... Microcomputer, 18 ... PLL synthesizer, 19 … Memory, 20… Station detector, 21… Signal meter, 22… Subcarrier detector.

Claims (3)

[Claims] 1. An FM multiplex reception means having a function of determining the reception strength of the FM reception signal based on the FM reception signal and selecting and switching an optimum next station to be received in accordance with the detection of deterioration of the reception state. A data storage means included in the FM multiplex reception means and configured to decode the multiplex data multiplexed in the FM signal and store the same; and a list of FM multiplex transmission stations receivable by searching the reception frequency. Multi-station list forming means to be created, and area identifying means for discriminating an area to which the currently receiving receiving station belongs, based on multiplex data included in a signal from the currently receiving receiving station by the FM multiplex receiving means. And first discriminating means for discriminating whether or not the next receiving station to be switched and selected by the FM receiving means belongs to the belonging area identified by the area identifying means. Second to the next receiving station to be selectively switched in serial FM receiving means determines whether or not belonging to the same network
And the first and second determining means determine that the next receiving station belongs to the same belonging area and belongs to the same network when the transmitting station is switched by the FM multiplex receiving means. A storage data holding unit for prohibiting deletion of the multiplex data stored in the storage unit, and when the receiving station of the same area and the same network is switched and selected, the multiplex data stored in the storage unit is selected. An FM multiplex broadcast receiver characterized in that reconstruction is not required. 2. The multiplex data is configured to include a prefecture code, and the area identification means stores code correspondence data for each prefecture, and the belonging area for each prefecture is based on the received multiplex data. The FM multiplex broadcast receiving apparatus according to claim 1, wherein is recognized. 3. The FM multiplex broadcast receiver according to claim 1, wherein the multiplex data is configured to include traffic information for each prefecture.