EP1241812A1 - Method for determining an RDS-code with a broadcast receiver - Google Patents

Abstract

The method involves looking for code in several cycles, statistically evaluating received data, fixing periodic time windows to receive TMC data at a first reception frequency with gaps, changing the frequency to tune the receiver outside the gaps at one frequency and inside at a second and determining the RDS code from the RDS data received in gaps at the second frequency so the RDS data received in several gaps is statistically evaluated.

Description

The invention relates to a method for determining an RDS code, in particular a program identification code Pl, from an RDS data stream with a radio receiver, a part contained in several cycles of the data stream is examined and a statistical evaluation of the received Data is performed. Such a method is known from the DE 44 41 789 C1 known.

With the introduction of the Radio Data System (RDS), the functionality of radio receivers, and in particular car radios increase. RDS is a standardized procedure for Transmission of data from the broadcasters to a radio receiver. The transmitted data include, for example, a program identification code (Pl), information about alternative frequencies (AF) and the name the broadcaster (PS), or the program type (PTY) and the label a traffic announcement (TA) or the transmission of a date and time coding (CT). The RDS standard is international IEC 62 106 standard.

Usually the RDS data stream is first in the radio receiver synchronized before the transmitted data is evaluated and used. A synchronization method is specified in IEC 62 106, in particular in Annexes A - C. From DE 44 41 789 C1 is a Known method that does not require synchronization. The procedure will used especially when the reception quality is poor and the received data are therefore faulty. Through statistical analysis of multiple received RDS data and comparison with an expected Sufficiently reliable information for the same radio station can thus be of value (same Pl code) can be obtained.

A further development of RDS is the so-called RDS-TMC (TMC: Traffic Message Channel) with the traffic reports in coded form from a Broadcasters can be transmitted to a radio receiver. The RDS-TMC standard is among others in the European pre-standard ENV 123 13-1. In the so-called RDS-TMC "enhanced mode", the time windows are described in more detail in the aforementioned RDS-TMC standard Ta in which the radio receiver to receive traffic reports is ready, and further time windows Tw are set, in which, for example, the Reception quality on alternative frequencies can be checked. Within the traffic window Ta is transmitted in coded form, with gaps between the individual traffic reports remain. The width of the gaps between the individual traffic reports is communicated to the radio receiver with the RDS-TMC data stream. It there is therefore basically the possibility, even within the gaps G Check the reception situation for further reception frequencies. The one here Occurring periods are sometimes very short, so that the required Steps of conventional methods can often not be carried out.

This is where the present invention comes in, the object of which is a method indicate with which even short gaps within the time window Ta still used to determine an RDS code on a second reception frequency can be.

• ein in mehreren Zyklen enthaltener Teil des Datenstroms untersucht wird,
• eine statistische Auswertung der empfangenen Daten durchgeführt wird und
• eine zeitliche Festlegung von periodischen Zeitfenstern Ta zum Empfang von TMC-Daten auf einer ersten Empfangsfrequenz erfolgt,
• innerhalb des Zeitfensters Ta zum Empfang von TMC-Daten Lücken vorgesehen sind,
• innerhalb des Zeitfensters Ta mehrfach die Empfangsfrequenz derart gewechselt wird, daß der Rundfunkempfänger im wesentlichen außerhalb der Lücken auf die erste Empfangsfrequenz und innerhalb der Lücken auf eine zweite Empfangsfrequenz abgestimmt ist,
• aus den innerhalb mehrerer Lücken auf der zweiten Empfangsfrequenz empfangenen RDS-Daten der RDS-Code derart bestimmt wird, daß die innerhalb mehrerer Lücken empfangenen RDS-Daten statistisch ausgewertet werden.

Insbesondere erfolgt die Festlegung der Zeitfenster gemäß dem genormten RDS-TMC "enhanced mode", der in der Vornorm ENV 123 13-1 näher beschrieben ist.The object is achieved by a method for determining an RDS code, in particular a program identification code P1, from an RDS data stream with a radio receiver, wherein

• a part of the data stream contained in several cycles is examined,
• a statistical evaluation of the received data is carried out and
• a periodic time window Ta for receiving TMC data is determined at a first reception frequency,
• gaps are provided within the time window Ta for receiving TMC data,
• the reception frequency is changed several times within the time window Ta such that the radio receiver is tuned to the first reception frequency substantially outside the gaps and to a second reception frequency within the gaps,
• the RDS code is determined from the RDS data received within several gaps on the second reception frequency in such a way that the RDS data received within several gaps are statistically evaluated.

In particular, the time window is determined in accordance with the standardized RDS-TMC "enhanced mode", which is described in more detail in the pre-standard ENV 123 13-1.

The within a time window Ta, which is actually used to transmit traffic information It is intended to provide existing gaps between each Traffic reports are with the inventive method Testing of further reception frequencies used. The width of these gaps is transmitted to the radio receiver together with the RDS-TMC data. The RDS-TMC data is received at a first reception frequency. According to the RDS-TMC pre-standard are for the gaps in particular 3, 5, 8, 11 or 8 - 14 groups are provided. A group contains 104 bits that are transmitted within about 87 milliseconds. Especially when there are only very small gaps of, for example, only three Groups therefore only have one between the individual traffic reports short period of time to check further reception frequencies.

In a synchronized RDS procedure this would be within this period Tuning the receiver to the second reception frequency, regeneration of RDS bits on this second reception frequency, the RDS synchronization, the recovery of RDS information on the second Reception frequency, a reset of the radio receiver to the first Receive frequency, the regeneration of RDS bits on the first receive frequency and the RDS synchronization on the first reception frequency to carry out the following on the first reception frequency transmitted traffic information can be received. Often needed but the RDS synchronization alone takes so much time that within the short No relevant RDS information is missing on the second reception frequency can be obtained.

With the method according to the invention, the RDS data stream is synchronized waived on the second reception frequency. The one that occurs Uncertainty regarding the received RDS data is inventively eliminated that within several gaps on the second RDS data received statistically evaluated become. This can result in a similarly high level of reliability with regard to received data can be reached as in the synchronized state. With the The inventive method, the radio receiver is thus multiple to a second within different gaps in the RDS-TMC data stream Receiving frequency tuned, and those obtained within the multiple gaps RDS information on the second reception frequency is interlinked combined.

In particular, a PI code can also be used with the method according to the invention can be reliably detected on the second reception frequency by the PI code deviates from the first reception frequency. Thus, with the invention The procedure also identified radio stations that are not compatible with the Broadcast transmitters match the first reception frequency.

The criteria according to which the RDS codes determined within various gaps can be recognized as correct with sufficient probability be determined differently in individual cases. As a sufficient criterion can be viewed, for example, that an RDS code is recognized as applies if RDS data is detected within at least three gaps and the RDS codes determined match in at least half of all cases. In the special case, this means that with one within three Gaps detected program identification code Pl this is considered correct if it has been identified identically at least twice. To one Achieving higher reliability can be the limit for those to be evaluated Gaps can of course also be set significantly higher than three.

In a special embodiment of the method it is provided that the Number of groups within a gap compared to a default value and the procedure is only carried out when the number of groups is not greater than the default value. As already mentioned, the number of the groups within a gap G with the RDS data. This Value can therefore easily be compared with a default value. The unsynchronized procedure is then only carried out if the number of groups is not greater than the default value. this means in other words, if there are large gaps where sufficient time to carry out a synchronization also on the second Receiving frequency remains, such a synchronization also carried out and a statistical evaluation of the RDS data from several gaps is unnecessary. In special embodiments it is provided that the default value is not greater than eight or five or three.

Figur 1:

ein Blockschaltbild eines Rundfunkempfängers

Figur 2:

die Zeitfenster im RDS-TMC "enhanced mode"

Figur 3:

einen Ausschnitt aus dem Zeitfenster Ta mit den Lücken zwischen den Verkehrsinformationen.

The method according to the invention is described in more detail below using an exemplary embodiment and the drawing. Show it:

Figure 1 :

a block diagram of a radio receiver

Figure 2 :

the time slots in RDS-TMC "enhanced mode"

Figure 3 :

a section of the time window Ta with the gaps between the traffic information.

Figure 1 shows a simplified block diagram of a radio receiver, in particular a car radio, with two tuners, namely an audio tuner 1 and a data tuner 2. The designation of the tuner as audio tuner 1 or Data tuner 2 is primarily used for easier differentiation. A strict one It is not necessary to separate the functions. For example, the Data tuner 2 at least temporarily take over audio functions.

The tuners 1, 2 receive their input signals from an antenna 3. Alternatively can the tuners 1, 2 of different antennas or over several Antennas, for example by means of a so-called "antenna diversity" system, be supplied.

Both tuners 1, 2 each generate a multiplex signal MPX. The MPX signal of the data tuner 2 is fed to an RDS decoder 5. The one here as an RDS decoder 5 designated module can in particular a known RDS preprocessor, for example of the type SAA 6588, the other tasks takes over. The output signal of the audio tuner 1 becomes a sound processor 6 fed, which also inputs signals from other audio sources, such as a CD player, a cassette player, or one Receives phone. The audio signals generated by the sound processor 6 are fed to an amplifier 7, which passes them on to loudspeaker 8, via which the audio signals are output.

The output signals of the RDS decoder 5 are a central control unit 9 fed, which takes over the preparation of the RDS information. The Control unit 9 is also with input / output units, not shown (e.g. keyboard, display) connected. Such a Broadcast receiver is known per se and the individual components can with Standard components are built.

The data tuner 2 can also be accommodated in a separate additional device be, for example, acquired as a retrofit device and with the actual Car radio (for audio operation), which itself has the audio tuner 1, connected becomes.

The data tuner 2 works in the RDS-TMC "enhanced mode". In the RDS-TMC "enhanced mode "different time windows are defined, the one with the RDS data stream transmitted time coding CT used as a basis for determination becomes. In "enhanced mode" the time between the reception of two CT signals CT1 or CT2, which corresponds to one minute, in divided into equally long periods of time.

In the example shown in FIG. 2a there are six time segments A, B, C, D, E and F provided. Each of these time segments is again in time window Ta and Tw divided, which are preceded once by a delay section Td can (Figure 2b). All traffic information transmitted according to the TMC standard should start within a period of Ta. However, you can be ended outside the time period Ta. Are at the beginning of the period Tw no traffic data before, or was the transmission of traffic data within the time period Tw ended, so then until the beginning of the new period Ta in period B alternative transmission frequencies are checked without the risk of Miss traffic data. Other functions performed within Tw are in particular a search run across the whole FM frequency band, a search for not restricted to a station chain Traffic information or the like.

In the "enhanced mode", however, remain within the time window Ta is itself reserved for receiving traffic information, gaps between the individual traffic information. The size of these gaps will increase with the RDS signal. Thus, the data tuner can also be used within this Gaps, for example, to check the reception situation on other reception frequencies be used. Because of the often very short duration of this Gaps is the usual synchronized RDS reception on a second reception frequency however often not possible. With the method according to the invention, which statistically evaluates RDS data from several gaps but now also very short gaps for the reception of RDS information, in particular a program identification code Pl, on others Receiving frequencies can be used.

Figure 3 shows a section of a time window Ta in the RDS-TMC "enhanced mode ". In the example shown it is assumed that the RDS-TMC data received on a frequency of 93.0 MHz. This corresponds thus the first reception frequency. With the RDS data on this the first reception frequency also contains information about alternative frequencies, on which the same program can be received. The radio receiver can now check whether it is on a transmitted Alternative frequency actually transmit the same program and how the reception quality is on this alternative frequency. In the event of deterioration the reception situation on the first reception frequency can then be switched to such an alternative frequency if necessary. However, since the same frequency in different spatial areas different transmitters can be used, it is necessary to use the alternative frequency to check whether the same program is actually broadcast there becomes. This is done based on the evaluation of the program identification code Pl of the RDS data stream on the alternative frequency. In addition, you can with the method according to the invention in particular also other radio transmitters can be identified that have a different PI code than that Radio stations received on the first reception frequency. It will so no information about an expected PI code is required.

In the example shown in Figure 3, the data tuner at time t0 within the time window Ta to the first reception frequency on which the traffic information received, tuned. Within the time interval First traffic information is now received. To one The first traffic information is followed by a gap G according to the standard, which in Figure 3 is designated as the time interval Δt12. There will be none within this gap new traffic information transmitted. The width of such a gap can, for example, three groups of about 87 milliseconds each, so total about 261 milliseconds. According to the invention The data tuner is opened at the beginning of the gap, ie at time t1 a second reception frequency, here 98.0 MHz, tuned.

Because of the short period of time .DELTA.t12 the gap is synchronized Data stream waived on the second reception frequency. To carry out a synchronization should in particular after receiving a block A the receipt of the next block B is awaited and checked whether the Blocks A and B have the standard distance. In the embodiment within the time period Δt12 of the first gap, only block A in RDS data stream detected. Within block A is a PI code of, for example "8201" detected. The gap ends at time t2, at which the Data tuner tuned again to the first reception frequency of 93.0 MHz becomes.

New traffic information can be generated within the subsequent period Δt23 be received. A gap closes again at the period Δt23 in the period Δt34. At the beginning of the period Δt34, therefore, becomes the point in time t3 the data tuner in turn to the second reception frequency of 98.0 MHz tuned. In the period Δt34, block A becomes again on the second Reception frequency detected, but again no synchronization he follows. The PI code within block A is again determined to be "8201". At the end of the second gap at time t4, the data tuner is opened again the first reception frequency of 93.0 MHz is tuned and is then in Period Δt45 again for receiving traffic information on the first Receive frequency ready. The next gap begins at time t5, and the Data tuner is tuned again to the second reception frequency of 98.0 MHz.

The process continues in this order until the end of the time window Ta. In several gaps, data blocks became unsynchronized detected, but from which, for example, the PI code can be determined could. Through a statistical evaluation of the different gaps Pl codes received can now be decided whether this Pl code is to be regarded as reliable. This can be done, for example, that the PI code detected within three gaps is evaluated. Becomes If the same PI code is detected twice within three gaps, then this is considered correct. The radio receiver is thus aware that on the second receiving frequency of 93.0 MHz, a transmitter with the PI code "8201" Will be received.

With the method according to the invention it is thus possible, even in short Gaps G within the time window Ta of the RDS-TMC "enhanced mode" still Gain RDS information on a second receive frequency, where in particular, no specifications about an expected PI code are required.

Claims (8)

Method for determining an RDS code, in particular a program identification code P1, from an RDS data stream with a radio receiver, wherein a part of the data stream contained in several cycles is examined, a statistical evaluation of the received data is carried out and a periodic time window Ta for receiving TMC data is determined at a first reception frequency, gaps are provided within the time window Ta for receiving TMC data, the reception frequency is changed several times within the time window Ta such that the radio receiver is tuned to the first reception frequency substantially outside the gaps and to a second reception frequency within the gaps, the RDS code is determined from the RDS data received within several gaps on the second reception frequency in such a way that the RDS data received within several gaps are statistically evaluated. A method according to claim 1, characterized in that the time window is determined in accordance with the standardized RDS-TMC enhanced mode. Method according to one of the preceding claims, characterized in that the RDS code is regarded as recognized if RDS data are detected within at least three gaps and the RDS codes determined in this case match in at least half of all cases. Method according to one of the preceding claims, characterized in that the number of groups within a gap is compared with a default value and the method is only carried out if the number of groups is not greater than the default value. A method according to claim 4, characterized in that the default value is not greater than eight. A method according to claim 5, characterized in that the default value is not greater than five. A method according to claim 6, characterized in that the default value is not greater than three. Method according to one of the preceding claims, characterized in that different radio transmitters are received on the first and the second reception frequency, to which different PI codes are also assigned.

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