EP0652654B1 - Method for detecting data in an RDS bitstream - Google Patents

Abstract

An apparatus for the detection of information expected to be present in a defined data block of a RDS data flow transmitted as a predetermined number of groups which periodically follow one another, with a radio receiver tuned-in one after the other to a number of senders to be tested and whose RDS decoder is synchronized with the RDS data flow of the respective tuned-in sender. A running counter is provided having the frequency of the RDS data cycle and which is respectively reset upon reaching a count status corresponding to the period of a number of groups.

Description

The invention relates to a method for the detection of information contained in a certain block of data in a predetermined number of periodically successive groups of transmitted RDS data stream are expected, In the case of a radio receiver, the consecutively on several transmitters to be tested is set and its RDS decoder with the RDS data stream of each set station is synchronized.

Radio receivers with particularly powerful station selection functions, in particular Car radios have a separate receiver, which is constantly in the Background searches for channels worth receiving or freely definable if necessary Traffic radio stations regularly checked for traffic announcements. In the Verification of the receivable stations are increasingly being carried out by the Broadcasters evaluated RDS information sent. The one in the background working receiver must permanently set many different RDS transmitters and evaluate the received RDS data. Often there is only certain RDS information of concern, for example an announcement identifier at a traffic information station or an alternative frequency. Because this information is in certain Data blocks of the RDS data stream must be transferred after each setting on a transmitter and after synchronization of the RDS decoder on the received one RDS data stream are waited until the relevant data block is received.

A method for recovering the RDS data stream and an RDS demodulator for Implementation of this method is known from DE 35 10 562 C2. The RDS demodulator does indeed A high level of interference immunity, however the downstream RDS decoder is required due to the fact that information about the phase position of the RDS data stream is neither with demodulation is still available during decoding, a considerable time to Snap into the RDS data stream. The more often the frequency has to be changed to Identifying or checking different stations, the more time is available for each necessary synchronization of the RDS decoder to the RDS data stream is lost. The for the synchronization required time, at which a period of time until the occurrence of the expected information added in a certain data block stands for others Features not available. For example, if a traffic information station is on the If an announcement code (TA) appears, only a single bit in the B block is required of the RDS data stream can be evaluated. From attitudes to those concerned Traffic radio station via the synchronization of the RDS decoder until the appearance of the B blocks searched, whose location in the received RDS data stream is not in advance is known, a period of more than 100 milliseconds may elapse. For the Evaluation of the B block alone would take a little longer than 20 Milliseconds are enough.

The invention has for its object a method for the targeted detection of To create information in the RDS data stream, in which the majority of those for the Synchronization and waiting for the data block you are looking for so far saved and made available for other functions.

a) ein durch den RDS-Datenakt inkrementierter Zähler, dessen Zählerstand in einer zufälligen Relation zu der Blockfolge des RDS-Datenstromes steht, jeweils bei Erreichen eines der Anzahl von Bits einer Gruppe entsprechenden Zählerstandes zurückgesetzt;

b) bei erfolgter Synchronisation des RDS-Decoders mit dem RDS-Datenstrom des jeweils eingestellten Senders der Zählerstand des Zählers in Relation zu der Blockfolge des empfangenen RDS-Datenstromes gesetzt und eine diese Relation kennzeichnende Referenzgröße mit Kenndaten des eingestellten Senders in einer Sendertabelle gespeichert;

c) bei erneuter Einstellung auf einen Sender, dessen Kenndaten mit der zugehörigen Referenzgröße bereits in der Sendertabelle aufgenommen sind, keine Synchronisation des RDS-Decoders vorgenommen und die zeitliche Lage des Datenblocks, in dem die Informationen erwartet werden, aus dem aktuellen Zählerstand und der aus der Sendertabelle ausgelesenen Referenzgröße des eingestellten Senders errechnet.

In the method according to the invention for the targeted detection of information in the RDS data stream

a) a counter incremented by the RDS data act, the counter reading of which is in a random relation to the block sequence of the RDS data stream, is reset in each case when a counter reading corresponding to the number of bits in a group is reached;

b) when the RDS decoder has been synchronized with the RDS data stream of the currently set transmitter, the counter reading of the counter is set in relation to the block sequence of the received RDS data stream and a reference variable characterizing this relation is stored in a transmitter table with characteristic data of the set transmitter;

c) when re-tuning to a transmitter, the characteristics of which are already included in the transmitter table with the associated reference size, the RDS decoder is not synchronized and the temporal position of the data block in which the information is expected from the current meter reading and from the reference size of the set transmitter read out from the transmitter table.

With this method, the synchronization of the RDS decoder to one received station made only once; when voting again the same transmitter, for example to check a traffic information station the appearance of an announcement identifier, the time of appearance of the data blocks searched in advance based on the data stored in the station table Reference size can be determined. It is only at this point that the Alignment of the receiver working in the background with the one to be checked Channel.

A certain counter reading is preferably stored as the reference variable. This can be the beginning of a reference data block in the RDS data stream of each set station, for example the first data block in a Group, i.e. the A block, or the meter reading that corresponds to the start of the specific, searched data blocks in the RDS data stream of the currently set Transmitter corresponds, for example the B block when checking for announcement identification. The former method offers greater flexibility and offers itself when more than one data block is to be evaluated. The The temporal position of the desired data block can then be based on the as The stored counter reading can be calculated. The second method is useful if only one data block is evaluated at a time, as the The stored counter value directly as a criterion for the Setting on the transmitter to be checked can be used. The setting on the transmitter to be checked takes place if the Counter reading of the free running counter with the as reference value stored counter reading.

It is particularly useful to use a counter that is analogous to the sequence the data in the RDS data stream from a block phase counter and a group phase counter is built up, the counting range of the block phase counter by the number of bits in a block and the counting range of the group phase counter, which is incremented when the block phase counter overflows the number of blocks in a group is determined. The reference size will be then saved as a combination of block phase and group phase.

As is known, the RDS data are divided into periodic groups Transfer group type. Relevant information is often only in Groups of a certain type. In such cases, the preferred embodiment the procedure to tune to a station to be checked first at the time of the occurrence of the searched data block in a group of the desired one Type made. Since the group types are periodic, can be calculated in advance using the stored reference size what time the desired data block in a group of the desired Type appears.

Figur 1 ein schematisches Blockschaltbild eines Empfängers zur Durchführung des Verfahrens;

Figur 2 ein Funktionsdiagramm, in dem die wesentlichen Schritte des Verfahrens veranschaulicht sind;

Figur 3 ein Flußdiagramm, das die Tätigkeit eines Hintergrund-Empfängers bei der Überwachung von Verkehrsfunksendern auf Durchsagekennungen zeigt;

Figur 4 eine schematische Gegenüberstellung des herkömmlichen und des erfindungsgemäßen Verfahrens zur Dekodierung bestimmter Informationen im RDS-Datenstrom;

Figur 5 ein Anwendungsbeispiel für das Verfahren; und

Figur 6 ein weiteres Anwendungsbeispiel des Verfahrens.

To further explain the method according to the invention, reference is now made to the drawing. The drawing shows:

Figure 1 is a schematic block diagram of a receiver for performing the method;

Figure 2 is a functional diagram illustrating the essential steps of the method;

FIG. 3 is a flow chart which shows the activity of a background receiver in the monitoring of traffic radio transmitters for announcement identifiers;

Figure 4 is a schematic comparison of the conventional and the inventive method for decoding certain information in the RDS data stream;

Figure 5 shows an application example for the method; and

Figure 6 shows another application example of the method.

In the following description, a car radio is used as a radio receiver assumed that an additional receiving part working in the background whose task is to identify receivable stations, Check alternative frequencies, evaluate the RDS data stream and if desired, certain traffic radio stations on the appearance of announcement identifiers to monitor. With such a radio receiver it is possible the main recipient working in the foreground to any desired Set stations and the traffic announcements recognized in background mode to switch through at will or to store for later retrieval. In Figure 1 shows only the receiving part working in the background. He contains an RF receiving part 10, the tuning stage by a frequency synthesis circuit 12 is controlled, a subsequent RDS demodulator 14, whose output controls an RDS decoder 16, two cascaded counters 18, 20, which are incremented by the data clock obtained from the RDS decoder, a microcontroller 22 and a memory 24. The counter 20 is a Block phase counter incremented by the RDS data clock from the RDS decoder 16 and counts from 0 to 25 and the counter 18 is a group phase counter, which counts from 0 to 3 and by overflow of the block phase counter 20 is incremented. The frequency of the RDS data clock is 1187.5 Hz Stores 24 store information for each station found and checked, which will now be explained in more detail with reference to FIG. 2.

When setting the RF receiver 10 to a transmitter that has not yet been checked , the RDS decoder is first synchronized with the received data stream. This synchronization, according to conventional methods takes at least about 110 milliseconds. As soon as the synchronization has taken place, the one just received will be Data block in relation to the random number of counters 18, 20 set. In the application example considered here, traffic radio stations are intended be checked for the appearance of announcement identifiers. To do this a bit in the B block can be checked. The meter reading now becomes the meter 18, 20 determined at the beginning of the received B data block and together with the most important characteristics of the received transmitter stored in the memory 24. The counter reading is a combination of the counter readings of the block phase counter 20 and the group phase counter 18 recorded in the one shown in FIG For example, the information 14/2. Accordingly, is received for everyone and checked transmitter, so that a memory table in the memory 24 is formed, the reference variable for each recorded transmitter contains a counter reading which is assigned to the beginning of a B data block.

If a station already included in the station table is checked again is to be, the associated meter reading becomes from the transmitter table removed, when reached then the setting is made to this transmitter. There is a renewed synchronization to the RDS data stream of this transmitter superfluous, which saves the time otherwise required for this.

In Figure 3 are the essential processes for the assumed application shown. In step 30, the RF receiver is set for the first time 10 on a traffic radio station found. This is done in step 32 the synchronization of the RDS decoder 16 on the received RDS data stream. At the same time, the count of the counters 18, 20 for the start of the B data block in the memory 24 with the most important characteristics of the received transmitter stored in memory. In the following endless loop, the RF receiving part successively set to other receivable transmitters in step 34, to be checked. If it is determined in step 36 that a certain amount of time has passed, after which the review of a certain traffic information station on the appearance of an announcement identifier is attached, it is checked in step 38 whether the current count of the Counter 18, 20 matches the entry in memory 24 for the transmitter in question. If there is a match, the setting is made in step 40 to traffic radio station concerned, whose B data block is then specifically evaluated becomes. Step 34 then checks other transmitters continued.

Figure 4 illustrates this method compared to the prior art. According to the conventional method, each time you tune to a transmitter received a randomly dependent data block, in the example shown the B data block. The RDS decoder can only be synchronized after Reception of a complete group of 4 data blocks has been reached at the earliest after 110 milliseconds. Only then can the evaluation of the next one B data blocks occur. In the method according to the invention that in FIG is referred to as "with synchronization", the setting is made to the on the other hand, the traffic radio station checking at the very beginning of the reception of a B data block, then targeted within a little more than its duration can be evaluated.

Figure 5 illustrates the incoming RDS data stream shown in the drawing passes from right to left. If the B data block is checked in each case there should be a period of time between two successive B data blocks of around 65 milliseconds available, which is sufficient to, for example in the channel search the reception worthiness of a channel (stop signal) or an alternative frequency to the station currently in the foreground check.

An even longer period of time for other activities in the background working receiving part is available if the circumstance is exploited is that the information relevant for certain purposes is usually not in all groups, but only in groups of a certain group type be transmitted. So traffic information from the broadcasters usually only transmitted in every third group. If this is known or during the check of the tuned station is determined, according to the in Figure 6 example shown the check of the B data block for the groups of applicable group type. The one shown in Figure 6 State was determined by checking a B data block that this belongs to a group of group type "6" that contains no traffic information. Since it is known that at least one further irrelevant group follows, the in the example shown is also of the type "6", the evaluation of the next B data blocks are omitted. Only the following B data block is evaluated so that a period of about 150 milliseconds Is available that is sufficient to check another station on which The example shown shows the PI code of the transmitter contained in the A block.

The examples described relate to the permanent monitoring of traffic information stations on announcements. But the invention is just as well targeted Detection of other types of information applicable in the RDS data stream. A Another application for a car radio is the targeted collection of information via alternative frequencies to already found transmitters. Generally can with the described method specifically and without constant resynchronization of the RDS decoder on information of any intended type and in any for the expected information applicable group type can be accessed. At all Applications is not only the time saved by the elimination of the constant resynchronization beneficial to already tested channels, but it will too the security of the RDS decoding is increased since a synchronization has taken place once preserved.

Claims (6)

1. Method for detecting information which is expected in a particular data block of the RDS data stream transmitted in a predetermined number of periodically successive groups, in a broadcast receiver which is successively set to a plurality of transmitters to be checked and the RDS decoder (16) of which is synchronized (32) with the RDS data stream of the respectively set transmitter, characterized in that

   a) a counter (18, 20), which is incremented by the RDS data clock signal and whose counter reading is in a random relationship with the block sequence of the RDS data stream, is reset each time a counter reading corresponding to the number of bits of a group is reached;

   b) when the RDS decoder is synchronized with the RDS data stream of the respectively set transmitter, the counter reading of the counter is placed in a relationship with the block sequence of the received RDS data stream and a reference quantity identifying this relationship is stored (32) with characteristic data of the set transmitter in a transmitter table (24);

   c) when a transmitter whose characteristic data have already been recorded together with the associated reference quantity in the transmitter table (24) is set again, the RDS decoder is not synchronized and the position in time of the data block in which the information is expected is calculated (38) from the current counter reading and the reference quantity of the set transmitter read from the transmitter table (24).
2. Method according to Claim 1, characterized in that a counter reading which corresponds to the beginning of a reference data block in the RDS data stream of the respectively set transmitter is stored as the reference quantity.
3. Method according to Claim 1, characterized in that a counter reading which corresponds to the beginning of the particular data block in the RDS data stream of the respectively set transmitter is stored as the reference quantity.
4. Method according to one of the preceding claims, characterized in that the counter comprises a block phase counter (20) and a group phase counter (18), in that the counting range of the block base counter (20) is determined by the number of bits in a block of the RDS data stream, and in that the group phase counter (18) is incremented upon overflowing of the block phase counter (20) and has a counting range which is given by the number of blocks in a group of the RDS data stream.
5. Method according to one of the preceding claims, characterized in that a transmitter whose characteristic data have already been recorded together with the associated reference quantity in the transmitter table (24) is set at the instant of the next appearance of the particular data block in the RDS data stream of this transmitter.
6. Method according to one of Claims 1 to 4, characterized in that a transmitter whose characteristic data have already been recorded together with the associated reference quantity in the transmitter table (24) is set at the instant of the next appearance of the particular data block within a group of a particular group type in the RDS data stream of this transmitter.

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