DE19956933A1 - Receiver for analog and digital broadcast programs - Google Patents

Abstract

A receiver for analog and digitally transmitted radio programs is proposed, which serves to automatically switch to a radio program equivalent to a radio program that is currently set if a signal quality of the radio program currently set drops below a threshold value. Furthermore, the system automatically switches from an analog radio program that is currently set to a digitally transmitted radio program if the signal quality of the digitally transmitted radio program is above a first threshold value. The receiver according to the invention has an antenna (1), a high-frequency receiving part (2) and a processor (3) for receiving analog and digital radio signals. The measurement of radio programs equivalent to the radio program currently set is carried out for short periods of time, with no audible effects. Various parameters are used as the signal parameters of the radio signals to be examined (e.g. the signal field strength and the baseband energy). If different signal parameters are used to estimate the signal quality of a radio program, these different signal parameters are weighted, a sum is formed, and the sum is compared with threshold values. Alternatively, a majority vote can also be taken.

Description

State of the art

The invention is based on a receiver for analog and digitally broadcast programs according to the genus of independent claim.

It is already known from published patent application EP 086 517 5 A2 known that receivers for analog and digitally transmitted Broadcast programs are available, each separately Receiver for FM (ultra short wave) and for DAB (digital Audio broadcasting) is used. This makes it possible that if a receiving part is currently receiving a Broadcasting program is used at this time the other Receiving part equivalent radio programs on their Checked signal quality to see if the Signal quality of the current broadcast program to switch to this equivalent radio program. This equivalent broadcast program is either the same Broadcasting program, now instead of digitally transmitting analogue transmitted or vice versa, and / or it will be on one transmit another frequency, or it's a Broadcasting program that contains information and / or music transmits the current broadcast program  correspond. So this receiver has two in parallel working receiving parts on to analog and digital to receive broadcast radio programs.

Advantages of the invention

The receiver for analog and digital broadcast radio programs with the characteristics of In contrast, independent patent claims have the advantage that only one receiving part for receiving the analog and digitally broadcast programs are used and that in time slots during reception the quality of equivalents to the currently set broadcast program Broadcast programs is checked. These are time slots so short that this review is inaudible to one User is.

By using only one receiving part Components saved. This makes the receiver smaller and easier installation is possible, especially for installation in motor vehicles is advantageous. About that moreover, the use of fewer components leads to one cheaper price for the recipient. So it will be here enables a cost-effective service for the user who him using the receiver to broadcast programs with excellent quality received, very strong facilitated.

By those listed in the dependent claims Measures are advantageous training and Improvements in the independent claim specified recipient possible.

It is particularly advantageous that for the reception and the Processing of broadcast signals using an analog  and have been sent using a digital transmission method, only one antenna and / or one radio frequency receiving part and / or a processor are necessary. This will cost and size of the recipient is significantly reduced because Components that only exist once for the Processing of analog and digital broadcast signals be used.

Advantageously, the sections of a frame when receiving digitally transmitted broadcast signals used in which no information for the current set radio program are included, then in analog and / or digital equivalent to these sections Check radio programs for their signal quality. This ensures that the check is not audible Effects leads so that the user through this measurement is not irritated.

In a development of the invention, at least the Duration of a frame used to measure the Signal quality of equivalent analog and / or digital To carry out broadcasting programs. This has the advantage that the loss of a frame leads to hardly audible effects, because the audio information of a broadcast program is on many Frame is distributed and the loss of a frame means Error correction method can be compensated.

In addition, it is advantageous that in the Broadcasting programs contain data that is a list of have equivalent radio programs. That’s it a processor of the receiver is possible in a simple manner, from this list set frequencies to in short Periods the signal quality of equivalents Check broadcasting programs.  

It is also advantageous that the recipient of one analog broadcast program on a digital transmitted radio program switches if the analog broadcast radio program a low audio level having.

In addition, it is advantageous that as a signal parameter the signal field strength of equivalent radio programs is measured to decide whether to switch to a equivalent radio program is possible. The Signal field strength is a meaningful signal parameter, that can be measured easily.

Another advantage is that as additional signal parameters in the case of digitally transmitted radio programs Baseband energy, the results of one Attempting to synchronize, the signal field strength of Adjacent channels and the bit error rate are measured in order based on these different signal parameters meaningful picture about the quality of equivalents To win broadcasting programs.

In addition, it is advantageous that at analog broadcast radio programs a signal-to-noise ratio, a Frequency deviation, an estimate of the Multipath, a signal field strength of a Adjacent channel, a pilot tone detection, a frequency swing and an evaluation of a digital medium, preferably one RDS (Radio Data Signal), measured as signal parameters to make a decision on whether to equivalent analog broadcast program can be switched.

In a development of the invention it is provided that the different signal parameters for an equivalent  Broadcast program can be measured, weighted and summed up and then compared to thresholds to decide whether to switch to this equivalent Broadcasting program is possible. This avoids that a wrong one by measuring only one signal parameter Impression of the signal quality of an equivalent Broadcasting program arises.

It is also advantageous that the threshold values either loaded from memory, then it are specified and / or are processed by the processor of the Recipient calculated or at least recalculated to a situation such as B. generally bad Reception conditions to respond.

Furthermore, it is advantageous that when receiving analog broadcast radio programs in predetermined short Intervals the signal parameters of equivalent digital and / or analog radio programs can be measured without that there is an audible effect.

drawing

Embodiments of the invention are shown in the drawing and explained in more detail in the following description. In the drawings Fig. 1 shows a receiver according to the invention for analog and digital broadcast radio signals, Fig. 2 shows a DAB frame and Fig. 3 is an RDS group.

Description of the embodiments

Through the introduction of terrestrially transmitted digital Broadcasting programs that continue alongside that for the time being existing analog broadcast programs  to be broadcast, there is a need for Radio receivers, especially for those in Motor vehicles that are both transmitted analog Broadcast programs as well as digitally transmitted Can receive radio programs. Important criteria for Such a recipient are the lowest possible price and the smallest possible construction volume.

Since analogue broadcast programs and also digital broadcast radio programs coexist and in certain places with different qualities transferred, it is necessary in such Receiver to provide equivalent broadcast programs to be checked during reception to an automatic Switch to such equivalent radio programs a reduction in the signal quality of the currently set Broadcast program below a threshold. The key here is that a user of the recipient perceives no audible effects from this measurement. Various signal parameters of To consider broadcast signals of a broadcast program in order to a comprehensive picture of the reception quality of the To provide broadcasting program or at least to insure whether the measurement of a signal parameter at a correct result.

At DAB (Digital Audio Broadcasting), which is especially for suitable for terrestrial reception in moving vehicles is currently not a nationwide one Coverage area, all are still transmitted analog Broadcast programs broadcast using DAB. Therefore at Leaving a supply area by means of DAB broadcast radio program an automatic Switching to an equivalent radio program necessary  to the driver of a manual search for a new one To relieve broadcasting program.

The same applies to radio programs that use other digital transmission methods such as DVB (Digital Video Broadcasting), DRM (Digital Radio Mondial) or ATSC (Advanced Television Systems Committee) or at least it is planned to use radio programs to transmit this digital transmission method.

According to the invention this object is achieved in that a Receiver for digitally and analogue transmitted Broadcast programs in a short period of time a measurement of Signal parameters of equivalent radio programs performed without audible effects.

In Fig. 1, a receiver according to the invention is shown. An antenna 1 is connected to a radio frequency receiving part 2 . Digital and analog radio signals received by means of the antenna 1 are filtered, amplified and converted into an intermediate frequency by the high-frequency receiving part 2 .

The high-frequency receiving part 2 is connected to a processor 3 via an input / output. The processor 3 receives from the radio-frequency receiving part 2 the signals converted to an intermediate frequency in order to first digitize them, to decode them, to carry out the digital DAB / FM signal processing and then to transfer them to an audio processing 4 connected to the processor 3 via a first data output. The processor 3 sends the radio frequency receiving part 2 data as to which frequencies and thus which radio programs are to be filtered out of the spectrum. The audio processing 4 is connected to a loudspeaker 5 via a first output. The processor 3 is connected to a display 13 via a second data output.

The audio processing 4 prepares the digital data for the acoustic representation by means of the loudspeaker 5 . The processor 3 prepares the digital data for an optical display if the received data contains not only audio data but also data that is also to be displayed by means of the display 13 . The display 13 is a screen, but other projection techniques are also possible.

Both analog and digitally transmitted radio signals are received by means of the antenna 1 . The analog broadcast signals include in particular VHF (ultra-short wave) signals, which also have a digital carrier (RDS = Radio Data System). FM has the best signal quality from analogue broadcast programs. However, medium wave and short wave are also possible. RDS can have different data, e.g. B. Information about frequencies on which equivalent radio programs are transmitted.

Equivalent radio programs here either denote the same radio programs that are on different frequencies be transferred and / or by means of another Transmission process, i.e. digital instead of analog or analog instead of digital. The equivalent Broadcasting programs also refer to programs that a similar content to that currently set Show radio program. Here, for. B. a News broadcaster with another news broadcaster replaced. This program information, what kind of Information or music in a particular Broadcasting programs are broadcast at digital  broadcast radio programs in co-transmitted data included and RDS is also used for FM.

For digitally broadcast radio programs in particular the DAB (digital audio Broadcasting). DAB exhibits a complex Frame structure that allows it, in addition to audio data other data, such as B. to transmit multimedia data. Furthermore, at DAB the signal to be transmitted is used on many different frequencies distributed to the effects of a frequency-selective attenuation to the received signal minimize. Because by distributing the signal different frequencies will only make up a small percentage of the transmitted signal by a frequency selective Damping disturbed. This disorder can then be corrected Error detection and correction procedures corrected become. Processes related to DAB are DVB (Digital Video Broadcasting) and DRM (Digital Radio Mondial). This Methods differ from DAB in particular in the Transmission frequencies, the transmission rate and the exact Frame structure. However, these procedures are also for the Device according to the invention can be used. ATSC points out Signals only at one frequency.

The receiver according to the invention receives a digital broadcast radio program, the receiver performs for short Periods of measurement of signal parameters from Broadcast signals from equivalent broadcast programs. The time intervals between measurements can be considerable be longer.

If now the signal parameters of the currently received Broadcasting program that automatically with the received data are available, are above a first threshold, then at the currently received digital  Broadcast program remained, or it will be on equivalent digital broadcast program switched when the signal parameters of the current received radio program under this first Threshold value, be that currently received Broadcast radio program digital or analog. The prerequisite for this is that an equivalent digital broadcast radio program has signal parameters that are above the first threshold.

This is digitally transmitted according to the invention Broadcast programs always have priority over analogue broadcasts Broadcasting programs given as digitally transmitted Broadcast programs have a clearly better signal-to-noise ratio and still attractive opportunities for multimedia Applications that are used in analog transmitted Broadcast programs only to a very limited extent possible are. The procedure is such that if a change from the current broadcast program necessary due to deteriorating signal parameters is, initially according to the same radio program on a other frequency is sought, with digital and then analog broadcast programs are examined. If this search does not lead to success, then will Radio programs with equivalent content, again digital broadcast programs and then examined analog broadcast programs become.

When the audio level of a set analogue drops broadcast radio program is possibly on a digitally broadcast program switched over so that an interruption of a running program or a noticeable change in the signal-to-noise ratio as disruptive effects be minimized.  

If the signal parameters of all equivalent digitally transmitted radio programs and also the signal parameters of the currently received digital radio program are below this first threshold value, the system switches to an equivalent transmitted analogue radio program if the signal parameters of this analogue radio program are above a second threshold value. If the signal parameters of this analog broadcast program are below the second threshold, the display 13 indicates that reception is not possible.

The threshold values are loaded from a memory connected to the processor 3 , these threshold values then being determined in advance, specifically on the basis of experimental investigations into the audio quality of the radio programs received. In a further development of the invention it is provided that these threshold values are calculated by the processor 3 on the basis of the loaded threshold values in order to react to changed reception conditions so that there is an adaptation to these reception conditions.

Alternatively, it can be provided that the processor 3 continuously recalculates the threshold values on the basis of stored mathematical models and current reception conditions.

A DAB frame is shown in FIG . Field 6 of the DAB frame contains synchronization signals and information about the frame structure. Field 7 of the DAB frame contains data for a radio program A, field 8 contains data for a radio program B and field 9 contains data for a radio program C. The radio program B is currently set. This means that during sections 7 and 9 , which contain data that are not currently necessary for the set radio program, measurements of radio programs equivalent to the radio program B are carried out. This means that there are no audible effects for the user of the radio receiver, since the duration of sections 7 and 9 are irrelevant for the display of the radio program B anyway.

Alternatively it is provided that a measurement of Signal parameters of equivalent radio programs during at least one whole frame is carried out. This leads to no audible effects for the user, since the Data at DAB are scrambled over time, i.e. H. it is a so-called time interleaving. The Audio information distributed over sixteen DAB frames. Is missing now a frame of it, so a sixteenth of the Overall audio information, this can be done by already implemented error correction procedures are corrected.

FM signals are interrupted for a very short time of reception, which is used for the measurement of signal parameters of equivalent radio programs is necessary to none audible effects for the user of the receiver. Such a brief interruption has a duration of, for example 5 ms. In the case of FM, a list of the frequencies of equivalent broadcast programs. Instead of one List of equivalent radio programs is to be transmitted it is also possible to have a list of all broadcast programs, which can be received to transmit to the To let the recipient evaluate the nature of the respective radio programs are. At DAB there is one Program type identifier is provided and is at RDS Program information code. For radio programs that are transmitted analogously and which are not digital carriers  must be specified in a list, which type of music and information on this radio program be broadcast.

An RDS group is shown in FIG . A program identification is given in field 10 , an error detection in field 11 and further information is contained in field 12 . The program information in field 10 can be used to determine what type the broadcast program is.

As a signal parameter that is used to check the Broadcast signals from broadcast programs is suitable the signal field strength is particularly suitable. It indicates how strong a radio program is received. With digital Broadcast signals are the other signal parameters Baseband energy and / or results one Attempting to synchronize or the signal field strength of a Adjacent channel to use. The signal field strength of a Adjacent channel denotes another's crosstalk Transmitter that is not necessarily a radio broadcaster. Nevertheless, this transmitter can, if only a small one Has frequency distance to a radio program, a cause significant interference and thus the signal quality of the radio program decisively affect.

In the case of analog broadcast signals, there are more Signal parameters a signal-to-noise ratio and / or a deviation of the the frequency specified in the RDS or DAB signal is analog broadcast radio program or a channel estimate that indicates how the multipath propagation for this Broadcasting program presents itself and / or the Signal field strength of a neighboring signal and / or a Pilot tone detection and / or detection of a digital Carrier, which is preferably the RDS and / or the  Determination of the frequency swing. As an alternative to channel estimation the use of a symmetry detector is an advantage. If the symmetry detector detects an asymmetry, this is attributable to multipath propagation. This method is considerably less computationally intensive than a channel estimate. The symmetry detector determines, for example, from one Sum and difference signal for stereo transmissions balanced signal and recognizes whether there is an asymmetry is present.

If one uses several such signal parameters to get one Image of the signal quality of a radio program can make the different signal parameters depending on Importance are weighted and you form a sum that is then compared with the corresponding threshold: Das is the first threshold for digital broadcast signals and the second for analog broadcast signals Threshold. Alternatively, by identifying multiple Majority of the signal parameters. The results of the evaluation of the signal parameters with Threshold values are signaled, and the Signaling results are then shared compared, for example with a logical link. The individual signal parameters can also be weighted to be using the same thresholds too to compare.

Instead of only one high frequency receiving part and one It is also possible to use only one processor to use these components for FM and DAB, and the other to have twice. This can have advantages in the Bring processing in.

Claims (12)

1. Receiver for analog and digital broadcast programs, there are also analog and digital broadcast programs for a digital broadcast program at other frequencies, the receiver receiving the digital broadcast programs in frames, characterized in that the receiver when receiving the digital or analog broadcast programs in short time periods measures signal parameters of each analog and / or digital broadcast signals from equivalent broadcast programs and that if the signal parameters of the digital broadcast signals remain above a first threshold when a digital broadcast program is received or when a digital broadcast program is received switches or that when the signal parameters of the digital broadcast signals are below the first threshold, switched to an equivalent analog broadcast program whose Signal parameters lie above a second threshold value or that if no signal parameters of radio signals of a radio program lie above the second threshold value, then the receiver indicates that reception is not possible. 2. Receiver according to claim 1, characterized in that an antenna ( 1 ) and / or a radio frequency receiving part ( 2 ) serve to receive the digital and analog radio signals and / or that a processor ( 3 ) of the receiver decodes the received digital and analog radio signals . 3. Receiver according to claim 1, characterized in that the receiver when receiving digital broadcast signals of a radio program during part of a Frame duration for the signal parameters of analog and digital radio signals of equivalent radio programs performs a measurement without the measurement becoming a leads audible effect. 4. Receiver according to claim 1, characterized in that the receiver when receiving digital broadcast signals of a radio program during a framework for the Signal parameters of analog and digital broadcast signals equivalent radio programs perform a measurement without that the measurement leads to an audible effect. 5. Receiver according to claim 3 or 4, characterized in that the radio signals contain data that indicate on which frequencies equivalents Radio programs can be found. 6. Receiver according to claim 5, characterized in that the receiver switches from an analog one Broadcasting program on a digitally broadcast equivalent Broadcasting program at a low audio level of the current Broadcasting program. 7. Receiver according to one of the preceding claims, characterized in that the recipient as Signal parameters a signal field strength with a threshold compares.   8. Receiver according to claim 7, characterized in that the receiver for digital broadcast signals as another Signal parameters the baseband energy and / or results a synchronization attempt, a bit error rate and / or a signal field strength of an adjacent channel is used. 9. Receiver according to claim 7, characterized in that the receiver for analogue radio signals as another Signal parameters a signal-to-noise ratio and / or a deviation of the frequency specified in the data with the actual frequency for the equivalent digital broadcast radio program and / or an estimate of the Multipath propagation and / or a signal field strength of a Adjacent channel and / or a pilot tone detection and / or a Detection of a digital carrier, preferably an RDS, and / or a frequency swing is used. 10. Receiver according to one of claims 7, 8 or 9, characterized characterized in that the recipient is different Signal parameters for digitally transmitted and analog broadcast radio signals weighted differently, summed and the sum for the digital broadcast signals with a first threshold and the sum for the analog Broadcast signals compared with a second threshold. 11. Receiver according to one of the preceding claims, characterized in that the recipient the first and loads the second threshold value from a memory and / or by means of of the processor. 12. Receiver according to one of the preceding claims, characterized in that when receiving analog Broadcast signals of a broadcast program in time segments predefined duration for the signal parameters of equivalents  digital and / or analog radio programs a measurement performed without the measurement leading to audible effects.