EP0469341B1 - Broadcast receiver with a radio data signal decoder - Google Patents

Abstract

A novel broadcast receiver with a radio data signal decoder and memory for the alternative frequency information in the radio data signal is described in which, when alternative frequencies are set, individual hopping frequencies determined in a learning phase are preferred.

Description

The object of the property right is a new radio receiver with a radio data signal decoder and memory for the alternative frequency information in the radio data signal.

The area of application of the new radio receiver is primarily intended for the motor vehicle. In the older patent DE 39 17 236 a radio receiver is described with a memory in which, in addition to the PI code characterizing a specific program, the alternative frequencies assigned to this program are stored. An evaluation memory is also assigned to each memory location for a frequency. The frequency with which the individual alternative frequencies have been set recently is noted in this memory.

If one of the rarer alternative frequencies of the desired program has been set by the automatic transmitter selection when the radio receiver is in operation while driving and the reception deteriorates, the older invention offers the possibility of switching the receiver to the alternative frequency with the greatest number of frequencies since this probably guarantees the best reception.

For the solution of this task, to switch directly to the transmitter with probably the best reception, the invention characterized by the features of claim 1 shows another way.

• in Figur 1 dargestellten Blockshaltbildes und einer
• in Figur 2 dargestellten Speicheraufteilung
  näher erläutert.

The invention is based on a

• block diagram shown in Figure 1 and one
• memory allocation shown in Figure 2
  explained in more detail.

The radio receiver according to the invention is connected to an antenna 1 for receiving the carrier frequency of the transmitter to which the tuner 2 is set by an automatic transmitter selection 3. At the output of tuner 2, the MPX signal, the modulation of the received carrier frequency, is acceptable. On the one hand, this signal is heard by the loudspeaker 6 via the stereo decoder 4 and the LF amplifier 5 and, on the other hand, is routed to the RDS decoder 9 via a 57 kHz filter 7 and an RDS demodulator 8. An output of the RDS decoder 9 is connected to a control input of the automatic transmitter selection 3.

The automatic transmitter selection 3 is also connected to an output of the tuner 2, to which a signal about the quality of the received carrier frequency, for. B. about field strength, multi-path reception and the like, is removable.

The tuner 2 and the automatic transmitter selection 3 thus represent a type of control loop. This serves to select the best received carrier frequency of a program that has been set once and is identified by the assigned PI code in the radio data signal.

As is known, the radio data signal has so far been broadcast in the FM range of radio. FM carrier frequencies have a limited range. On the other hand, only a limited number of carrier frequencies are available in the FM range. VHF carrier frequencies at a certain spatial distance are therefore used to transmit different programs. A car radio tuned to a certain frequency would, for. B. Listen to different programs on a longer travel route. In between there would be a travel section on which the quality of the received transmitter signal leaves a lot to be desired, if it does not completely disappear.

The alternative frequencies communicated to the radio receiver via the radio data signal for the currently set radio program now offers the possibility of switching to one of the alternative frequencies in the event of poor reception of the currently set carrier frequency, in the hope that reception on the newly selected carrier frequency will be better. Before the program is listened to in this newly selected alternative frequency, it must be checked whether the frequency at the receiving location actually transmits the desired program or whether another program with a different PI code is already being received at the receiving location at this frequency. It must therefore be checked whether the PI code has been preserved. The car radio remains muted during the review period. In order to keep the duration of the program interruption as short as possible, additional learning circles are provided in the new radio receiver, which work together with the memory shown in FIG. 2 as follows.

Each automatic transmitter selection 3 includes a plurality of station buttons 10 with which the driver can set certain carrier frequencies in the tuner 2. In a programming step that is not explained in more detail, these carrier frequencies are previously assigned to the respective station buttons. This frequency specification has been stored in a frequency memory 11.

With the definition of the frequency, the station key 10 is also assigned a specific program. Each station button 10 thus also has a very specific PI code which can be stored in a PI code memory 12. The alternative frequency information belonging to this PI code is also transmitted in the radio data signal, and an AF memory 13 is provided for the storage thereof.

The above-mentioned memories are mostly integrated in the microprocessor modules of the automatic transmitter selection 3.

If the reception quality on the carrier frequency set with the station key falls below a predetermined threshold while traveling, the microprocessor in the automatic transmitter selection 3 receives a start command from the tuner for a program for setting a well-received alternative frequency of the same program.

In the AF memory 13, these alternative frequencies are arranged purely by chance. Therefore, the program starts tuning any of the alternative frequencies.

In order to give this setting a direction, the automatic transmitter setting 3 according to the invention has learning memories 14 for each stored alternative frequency, of which there is of course also the frequency set using the station key.

These learning memories 14 are initially empty. If the reception quality falls below the predefined threshold for the first time after the station key has been reassigned, then the learning memory 14, which belongs to the previously set frequency, is activated. If, after the aforementioned random access to one of the other alternative frequencies, one with good reception quality has been found and the tuner has been finally adjusted to it, then this hop frequency is entered in the learning memory 14.

This process is repeated on a longer journey or more frequently in the mountainous area on shorter journeys. With such a change in the setting of the tuner 2, the frequency which is stored in the frequency memory 11 is also set again at some point. If the reception quality again becomes too weak after it has been set again, information about a frequency is now available in the learning memory 14, which should preferably be set because the change to this hopping frequency has already been successful. A check of the PI code on this reset hop frequency can thus be omitted. The newly set transmitter can thus be switched through immediately.

If the hop frequency stored in the learning memory 14 cannot be set at the current reception location because of poor quality, then the program returns to the selection of any other alternative frequency.

In mountainous areas it is more often to be expected that the hopping frequency stored in the learning memory 14 cannot be received. It is therefore possible to assign several learning memories to each alternative frequency. In this case, a counter 15 is expediently connected to each of the learning memories 14, which counts the frequency with which the hopping frequency read in the learning memory has been successfully set. At the next frequency jump, the learning memory with the highest counter reading is preferred for the new setting.

As can be seen from the illustration, it is irrelevant to the invention whether the content of the frequency memory 11 was determined when a station key was programmed or was read in by another manual tuning of the radio receiver.

If there is sufficient storage space, the radio receiver has a matrix after a long period of operation, in which the alternative frequencies and the jump frequencies assigned to each PI code are listed.

If the driver moves in an area in which another program can already be received on one of the alternative frequencies supplied by the RDS decoder, searching for this frequency is largely avoided because this frequency is not entered as the hopping frequency. This is because the jump frequency is only read into the learning memory 14 when the match of the PI code has also been established when an alternative frequency is sought for the first time.

Claims (3)

1. Broadcast receiver with a radio data signal decoder, with a memory for the alternative frequency information in the radio data signal and with a microprocessor with a program for changing to an alternative frequency, characterized in that a learning memory (14) is assigned to each memory for an alternative item of frequency information (13), in that a previously identified jump frequency is stored, with good reception quality, in the learning memory (14), and in that the broadcast receiver is designed in such a way that after a change the said broadcast receiver sets itself to the jump frequency of the learning memory (14) which is associated with the previously set frequency.
2. Broadcast receiver according to Claim 1, characterized in that a plurality of learning memories (14) are assigned to each memory (13) for an alternative item of frequency information.
3. Broadcast receiver according to Claim 2, characterized in that each learning memory is connected to a counter (15) in which the number of changes to the jump frequency entered is counted.

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