Method for tuning a mobile broadcast receiver

The invention relates to a method according to the Oberbe handle of the claim. Such a method is known from "Rundfunktechnische Mitteilungen", Jg. 28 (1984) H. 2, pages 69 to 73.

In traffic radio receivers it is known (DE-OS 31 20 690) to use the classification of the Federal Republic of Germany in five so-called traffic information areas for automatic search as soon as the user selects a traffic information area by pressing a correspondingly assigned button on the receiver. Since each traffic information area A to F is more than just one state or Transmission area of ​​a state broadcaster includes, after the manual range selection based on the number of receivable traffic stations an automatic country selection, d. H. a statement in which state or Broadcasting area of ​​which state broadcaster is the current receiver location. The traffic radio stations present in each federal state are permanently stored in the receiver list-wise with their transmission frequencies. The individual transmission frequencies of the first stored list associated with the selected traffic information area are successively addressed and read out, whereby the car radio receiver is correspondingly tuned one after the other. The transmitter received with sufficient signal strength "remembers" the receiver, so that he can determine from the receivable transmitter, whether the receiver is in the transmission range of the first list associated state broadcaster. If the receiver rejects this, then the transmission frequencies of the second list are read out, etc. If the input of the traffic information area has been carried out correctly, the result of these checking steps is the selection of a single list and the setting to the respective transmission frequency of the selected list which is best receivable. This procedure is time-consuming and requires a high memory overhead for all traffic radio frequencies in the Federal Republic of Germany. When traveling abroad, where also Verkehrsrundfunksender are present, the known method fails. Finally, on the part of the user the correct input of the traffic information area is assumed. Since the user often does not know which traffic information area is currently being driven through, the practical benefit of the known method remains low.

In contrast, to allow a fully automatic vote without the involvement of the user on those traffic stations, which is the best receivable at the current recipient site, it is from "Rundfunktechnische Mitteilungen", Jg. 28 (1984), H. 2, p. 69 to 73 are known to transmit a list of alternative frequencies (AF) as the content of a data signal modulated onto a 57 kHz subcarrier. This information indicates on which frequencies a particular program from the same broadcasting chain (e.g. B. BR 3) is broadcast. This allows suitably trained receivers with memory to store this list and thus set the time for setting the receiver to the respective optimum frequency of this list (eg after optimal reception conditions). The list is limited to a maximum of 25 frequencies or channel numbers as agreed. In the case of transmitter networks with more than 25 transmitters, as is the case for example for the transmitter network Bayern 3, can not send out a common list for all stations of the transmitter network; rather, each transmitter or group of spatially adjacent transmitters must send out their own list, which may contain a maximum of 25 frequencies. The difficulty lies in the fact that due to the large number of ball routes in the network of broadcasting stations within the public service broadcasters of the Federal Republic of Germany, the list sent out by the parent station u. U. not fit; it must be filtered out after the ball receiver and replaced by the list applicable to the respective subsidiary sender. This filtering and re-feeding is associated with increased effort. In addition, the quality of the program signal is also degraded by the filtering. Although transmitter chains with fewer than 25 transmitters would be able to record all the transmitter frequencies in a common list, this would lead to correspondingly long receiver response times for very many transmitter frequencies.

The object of the invention is to provide a method of the type mentioned, in which a filtering and re-feeding the list of alternative frequencies are avoided and the receiver-side vote can be done with a relatively short response time.

This object is achieved by the characterizing features of the claim.

In the method according to the invention, each transmitter broadcasts not only its own list but also sequentially the lists of all other transmitters of the same transmitter chain, the operating frequencies of the individual transmitters each being at the beginning of the individual lists. The receiver, upon receipt of all the lists, may, on the basis of its current tuning frequency, select the list associated with the currently tuned station by comparing the tuning frequency with the first frequency of each list within the list sequence. Filtering and re-feeding is thereby unnecessary during ball reception. Furthermore, the receiver also recognizes the alternative frequencies at which it can continue to receive the same program upon leaving the coverage area of ​​the currently tuned station without having to check the alternative frequencies of the remaining lists. Switching to another transmitter of the same transmitter chain can be carried out very quickly in this way in the rule.

The invention will be explained in more detail with reference to the drawing which shows a schematic representation of the sequence of lists of alternative frequencies radiated by each transmitter of a transmitter chain. In the example considered, it is assumed that a broadcast signal in which a subcarrier of 57 kHz is inserted. The subcarrier may include an amplitude modulation, which has a traffic information to the content. As modulation or as a further modulation, the subcarrier is impressed with a data signal which is coded in a specific manner, which is of no further interest here. This data signal is transmitted in a consistent form from all transmitters of a transmitter chain, for example, from all 29 stations of the transmitter chain "Bayern 3" in the supply area of ​​the Bavarian Radio. The coincidentally transmitted data signal contains a sequence of lists of alternative frequencies for all transmitters of the transmitter chain, in the illustrated example the list of transmitter no. 1, the list of the station no. 2, the list of the station no. 3 up to the list of the station no. 29 in the case of a transmitter chain with 29 transmitters. Each list is tailored to each broadcaster and, according to the agreement within the European Broadcasting Union, contains a maximum of 25 frequencies, but as a rule much less. According to the invention is at the beginning of each list, the operating frequency of the associated transmitter, d. h., in the list of the station no. 1 is the beginning of the operating frequency of the transmitter no. 1, z. B. 98.5 MHz. As mentioned, the illustrated sequence of 29 lists is transmitted by each transmitter of the transmitter chain as a data signal.

The receiver receives and decodes the transmitted data signal, i. h., the sequence of lists of alternative frequencies. In order to select the list for the currently tuned station from the received list sequence, the receiver only needs to compare the first frequency of each list with the current tuning frequency, which is feasible even in 29 lists in an extremely short time. This selection can be done either in on-line mode or in off-line mode, ie. h., without or with caching of the received sequence of lists. In any case, the selected list is saved. When processing the received and possibly cached sequence of lists, the receiver selects that list whose first frequency (equal to operating frequency of the associated transmitter) coincides with the current tuning frequency. If the first frequency of several lists matches the set operating frequency, all these lists must be selected. Only the selected list (s) will be used for the subsequent tuning of the vote. This tuning is done either by a corresponding command of the listener or automatically, for example, if the currently received station is no longer receptive. In the tuning process, the receiver automatically tunes to the alternative frequencies listed in the selected list (s) and selects the alternative frequency that offers the best possible reception.

With the aid of the data signal transmitted according to the invention, a rapid optimization of the tuning of mobile receivers can be carried out even with transmitter chains having more than the specified maximum number of frequencies without filtering out and re-feeding frequency lists at the location of child transmitters.