EP0739550A1

EP0739550A1 - Radio broadcast reception process and circuitry

Info

Publication number: EP0739550A1
Application number: EP94915044A
Authority: EP
Inventors: Jens Hansen
Original assignee: HuC Elektronik GmbH
Current assignee: HuC Elektronik GmbH
Priority date: 1993-05-16
Filing date: 1994-05-16
Publication date: 1996-10-30
Also published as: WO1994027368A1; DE4316687A1

Abstract

A radio broadcast reception process is disclosed. The reception frequency of a reception part is tuned to different broadcasting frequencies and the equality between the programmes of a broadcasting station (reference station) to which the reception part is tuned and of another broadcasting station (potential alternative broadcasting station), i.e. the coincidence between the information broadcast by both stations is checked. For that purpose, the reception frequency of a single reception part is tuned to the reference broadcasting station, then is temporarily tuned several times at predetermined time intervals to the broadcasting frequency of the potential alternative broadcasting station. A signal sample characteristic of the low frequency modulation of the potential alternative broadcasting station is obtained and the thus obtained signal samples are compared with signal probes from the reference broadcasting station recorded at different moments in time within a predetermined time frame. The result from the comparison is processed and a signal is generated if the result of the comparison shows a coincidence between the modulations of the reference broadcasting station and of the alternative broadcasting station, thus a coincidence between the information transmitted by the reference broadcasting station and the alternative broadcasting station. Also disclosed is a circuitry for carrying out this process.

Description

Method and circuit arrangement for radio reception

Description

The invention relates to a method according to the preamble of claim 1 and a circuit arrangement for broadcast reception.

In particular with mobile radio reception - for example in a motor vehicle - it is a problem that In response to the reception of a set station which broadcasts a desired program, there is no information as to whether an alternative transmitter envisaged is really broadcasting a matching program information. For example, it is often the case with stations with nominal program correspondence that this is not adhered to in actual broadcasting operations, for example if a regional program is being broadcast or a regional program from another broadcaster is being taken over or regionally being split up the transmitter chain is necessary for other reasons.

This can also be the case if the station concerned has an RDS identifier which indicates an assumed program match. A corresponding case exists if a transmitter of an external transmitter chain with the same frequency as a remote transmitter of the transmitter chain with the set program is present on the edge of the transmission area of a transmitter chain. In this case, if an automatic station change after RDS is necessary, the station of the other station chain will be set with the wrong program, since it supposedly has the program just set. Such an incorrect switching would nevertheless lead to considerable confusion for the user of such a receiving part, since he must rely on the automatic selection of the transmitter and the user does not have any information and setting means for overcoming the faulty automatic switching. This would be a tuning of the transmitter scale by hand or by means of an electronic channel search, which provides the listener with the required information could in any case be associated with an undesired interruption of the pursuit of the originally set program.

The invention is based on the object of specifying a method and a circuit arrangement for radio reception in which - in particular without a noticeable interruption of the current program - information can be obtained as to whether at least one further receivable station has the same program as the set station , ie broadcasts the same program information (simultaneously) at the same time, so that switching can take place essentially imperceptibly.

This object is achieved by a method having the features of claim 1 and a circuit arrangement having the features of the corresponding subsequent claim.

Appropriate configurations result from the respective subclaims.

The method according to the invention for radio reception, in which the program equality of a radio transmitter with a comparison transmitter, ie the presence of a matched program information transmitted at the same time, is checked, includes the idea that during the reception of the comparison transmitter - in particular using one and the same Receiving part - directly the LF modulation - in particular an LF voltage value or simply the polarity - of this transmitter with that of the comparing the current transmitter briefly, so that, in particular, a reliable statistical statement can be obtained from a large number of comparisons. On the basis of the transmit signals arriving at different times at the receiver due to the spatial distribution of transmitters with a different delay time, a circuit is provided in the receiver which compensates for these delay times when evaluating the signal and thus program correspondence. Either temporary storage or a compensating delay in running time can be considered.

The method according to the invention is further distinguished, in accordance with a preferred development, in that after the comparison transmitter has been set at predetermined time intervals in the receiving part, the reception frequency is briefly adjusted to the transmission frequency of the transmitter to be tested and a signal sample characterizing its LF modulation obtained and the signal samples thus obtained are compared with signal samples of the comparative transmitter registered in essentially the same way (ie by means of a similar signal processing) at different points in time within a predetermined time frame and the comparison result is subjected to statistical processing, in its result result is obtained a statement on the agreement or non-agreement of the transmitted information, a corresponding signal being generated in the event of the agreement.

The influence of deviations in the technical transmission parameters and signal Counterfeiting and in particular runtime influences on the way from the transmitter to the receiver, which make it difficult to recognize two modulations as belonging to the same program, to a large extent on the security of the detection of a program match.

If, in an expedient embodiment of the method for obtaining a comparison result, a signal sample of the potential alternative transmitter is taken in a comparison step, but several signal samples of the comparison transmitter for the first are taken at different time intervals, the time is advantageously minimized which is to be switched over to the transmitter to be checked in order in this way to reduce the possible impairment when tracking the current program to an imperceptible level.

The comparison described is expediently carried out with intermediate storage of a number of signal samples from the comparison and / or the potential alternative transmitter, as a result of which the total time required for a comparison cycle is kept short.

The statistical processing will advantageously include a summation of the comparison results obtained with the same time intervals and the evaluation of the shape of a distribution curve resulting from the summation.

Another advantageous further development is based on the specified method, in which a transmitter that is recognized as having the same program as a program transmitter due to its modulation equality is stored as an alternative transmitter,

- The reception quality of the set transmitter and the alternative transmitter is subjected to a comparative evaluation and

in the case of better reception quality of the alternative transmitter than the originally set transmitter, the alternative transmitter is set.

Compared to the known RDS system, the solution according to the invention is advantageous in that - in contrast to the use of the RDS transmitter identification, only a relatively small reception field strength is ahead, so that high-quality receivers can be capable of receiving the program of a transmitter in a qualitatively acceptable manner without having to decrypt its RDS identifier.

In particular, the method according to claim 3 has the following advantages:

A transmitter with the same program as a set transmitter is recognized regardless of the assignment and transmission and receipt of a transmitter identifier.

It is thus in particular not limited to reception areas and transmitters in which or for which there is such an identifier, and it is also possible for transmitters which are relatively weak, but can still be received in good quality with a high-quality receiver. In addition, only transmitters that actually broadcast the same program at the relevant time are recognized as alternative transmitters for receiving the same program.

Switching to a likewise disturbed transmitter is avoided.

In addition, it is also possible to switch to an alternative transmitter with a higher reception quality as soon as one has been determined, without a clear interference with the originally set transmitter.

In an advantageous embodiment according to claim 7, the time intervals which are required for obtaining the test signal of the potential alternative transmitter are kept very short, and the entire test and setting cycle can be carried out in a short time.

However, it is also possible to get by with limited storage possibilities, for example by comparing each of the sample values of the election transmitter recorded at different times immediately (without intermediate storage in the transmitter signal value memory) with a trial value of the comparison transmitter and each such comparison. result is saved individually.

A voltage value of the low-frequency signal is advantageously recorded and used as the low-frequency signal value of the comparison transmitter (optional transmitter) or of the transmitter to be tested (potential alternative transmitter). The respective voltage value of the LF signal is expediently subjected to digitization using a predetermined sequence of quantization stages before use.

In the investigations of the inventors, it was found to be sufficient and advantageous in particular to use only the polarity of the voltage value of the LF signal as the signal value, i.e. digitize at the lowest level with only two possible levels (approximately "1" for positive and "0" for negative polarity).

It is particularly important for the practical acceptance of the method according to the invention that the step of obtaining an LF signal sample from the transmitter to be tested (potential alternative transmitter) is carried out in such a way that this step is not audible.

On the one hand, this is achieved in that the duration of the execution of the step is equal to or less than 50 μs.

As an alternative or in addition, the inaudibility of the switchover to the transmitter to be tested can be achieved in that the NF signal of the comparison or election transmitter during a period before the step of obtaining the NF signal sample of the transmitter to be tested (potential alternative transmitter) , which is equal to the time span of its execution, and this stored LF signal during the execution of the step as LF replacement signal is provided for audio processing.

This corresponds to the principle of "noise canceling" known for suppressing broadband reception interference.

For reliable detection of transmitters with the same program, even with a large temporal and / or transmission-related time-related modulation difference, it is important that the time range specified for the execution of the modulation match check is at least equal to the sum of the maximum expected negative and positive runtime Modulation difference of all transmitters receivable in the reception area is set.

It has proven to be expedient that step h) in the sequence of steps mentioned above comprises 10 to 50 repetitions of steps b) to g) that m.a.W. 10 to 50 comparative measurements can be carried out and evaluated.

A number of 40 cycles is particularly practical in terms of both the reliability of the information obtained and the limitation of the duration of a test procedure.

It is further expedient if the intervals of the times t1, t2, ..., tz for recording and storing the individual signal values in steps b), d) and f) are identical to one another.

However, it is also possible to have different ones, for example at the time of sampling of the alternative transmitter signal (t _n ) decreasing time intervals and increasing again from this point in time.

It is practically advantageous to carry out the method according to the invention immediately after setting a selection transmitter, in order to have the optimum transmitter with the same program or at least one alternative transmitter immediately available in the event of a sudden disturbance of the set transmitter.

After an alternative transmitter has been determined, the process can be terminated.

In most cases, however, it is more expedient that after finding an alternative transmitter, the other receivable transmitters are checked and, if there are additional alternative transmitters, these are also stored.

Advantageously, if a predetermined time duration and / or a predetermined level disturbance of the election transmitter occurs, steps b) to i) are repeated for the alternative transmitter or transmitters, the result of step i) according to predetermined criteria for characterizing the current reception quality of the alternative transmitter (s) is used, and preferably based on this characterization a decision is made to switch to one of the alternative transmitters.

Such or a similar procedure, in which the recognition of the program correspondence with the assessment of the reception quality in the same procedural steps is closely is a particularly advantageous realization of the method according to the invention.

As an alternative to this, it is possible for steps b) to i) to be repeated for the alternative transmitter or transmitters at regular intervals (as a background query) during reception of the election transmitter, the result of step i) in each case according to predetermined criteria Characterization of the current reception quality of the alternative transmitter (s) is used and, based on this characterization, a statement or a ranking of the susceptibility as a basis for a decision to switch to one or the alternative transmitter when compared to an alternative transmitter lower reception quality of the election transmitter is provided.

This is the case with mobile radio reception because of the Rapidly changing reception conditions are particularly useful for different stations.

In the investigations, it turned out to be expedient that after each step c), in the result of which an alternative transmitter signal is obtained below a predetermined minimum signal level, the subsequent steps are not carried out, ie the cycle here lacks one sufficiently meaningful comparison signal is terminated, and instead steps b) and c) are repeated until an alternative transmitter signal exceeding the minimum signal level is obtained, and that the subsequent steps are then carried out, one terminated according to c) ne sequence of steps in the sense of step h) does not count as a repetition, ie the test process is extended by the partial cycles which have been terminated without result.

With such a procedure, it is advantageous to count all steps c), in the result of which an alternative transmitter signal is obtained in a predetermined level range, during a repetition cycle of steps b) to g) and the counting result in order to obtain information about the To use modulation and / or the reception quality of the potential alternative transmitter - specifically to count those steps c) after which the sequence of steps is terminated and restarted.

In particular, the number of registrations of main transmitter signal values in step b) which are below the minimum signal level specified for the alternative transmitter can be recorded, and this number can be compared with the number of steps c) after which the sequence of steps was terminated and the comparison result according to predetermined criteria can be used as an auxiliary statement regarding the program identity of the election and potential alternative station.

This is particularly advantageous if there are slightly modulated program sections during the test and, in the alternative, also enables the relatively reliable detection of "program equality" in program breaks.

Furthermore, it is possible to use the number of steps c), after which the step sequence has been terminated and restarted, as (a) a measure of the reception quality of the / an alternative transmitter. As an alternative to this or in addition, it is possible to use the expression of a match maximum in step i) as a measure of the reception quality of the / an alternative transmitter - a pronounced maximum at least tends to speak for good reception quality.

Both variants thus open up the possibility of using the specified method not only for the detection of stations of the same program, but also for the additional use for determining the reception quality.

Finally, it is advantageously possible to use the number of steps c), in which the alternative transmitter signal was in a certain level range, to obtain information about the program type of the potential alternative transmitter.

This also opens the way to a program type selection of stations - for example, according to the language program / music program.

According to the investigations of the inventors, in order to avoid uncertainties regarding the agreement or disagreement of the modulation in the case of abrupt changes in the transmitted frequency spectrum, the apparent jumps in the transit time of the LF signal may be advantageous if a total sequence of steps b ) to j) is subdivided into several partial sequences, step i) being carried out in each case after the completion of a partial sequence and the respective statements as to whether and under which / which address (es) are used for the partial sequence in this step Maximum agreement was determined, be subjected to logical processing, the result of which is the statement j1) or j2).

In this way, in particular, shifts in the maximum of the distribution curve during the overall test procedure, which are the result of the apparent jumps in transit time mentioned, can be recognized as such, while they may possibly be in the overall distribution curve. can only lead to smearing and thus give rise to a misinterpretation of the test result ("No alternative transmitter!").

To switch off interfering stereo noise and the likewise disturbing 38 kHz carrier and, if possible, also the 19 kHz carrier when comparing the modulation of two transmitters, it is advantageous if steps c) and d) are at least two times apart of a fraction of the 38 kHz carrier period and / or the 19 kHz carrier period having short sub-steps, which meanwhile switches back to the selection transmitter, and that the arithmetic from the at least two signal values obtained Formed means and this is fed as an alternative transmitter value for further processing in the subsequent steps.

In the simplest case, two partial steps can be carried out at intervals of half a 38 kHz carrier period.

The entire method can also be carried out as a “background query” during the listening reception of a third transmitter are, ie in short periods of time in which the listener hears the program of this third transmitter, the reception frequency of which is also derived from the same individual receiving part which also supplies the frequency for comparison and alternative transmitters.

This offers a wide range of possibilities for information provision and processing independently of the hearing process and with little effort.

For example, if the entire method is carried out in the "background" for the transmitters available in the frequency band, a constantly self-updating transmitter memory of the programs or transmitters best to be received can be implemented.

Separate oscillators can be used to generate the required reception frequencies, which contributes to the implementation of a very short test time interval as a result of the rapid switchover without transient processes.

To avoid in-band interference, it is advantageous if the oscillation frequency of the oscillator for receiving the alternative transmitters and possibly also that of the oscillator for receiving the third ("foreground") transmitter lie outside the transmission frequency band and the reception frequency is obtained from this by frequency conversion, in particular frequency division.

In another embodiment, at least two or even all reception frequencies are used to generate and uses the same oscillator that is switched between the respective reception frequencies.

Here, as in the entire description and the claims, the term “reception frequency” stands in the sense of the frequency corresponding to a specific transmission frequency to which the receiving part is tuned, or for the oscillator frequency required to generate this frequency in the HF mixing stage.

A circuit arrangement for checking a broadcast transmitter for program equality with a comparison transmitter, i.e. the presence of a concurrently transmitted matching program information has the elements specified in claim 27.

A circuit arrangement for optimizing the radio reception using this arrangement additionally has an evaluation device for evaluating the reception quality of the set transmitter and the alternative transmitter and for outputting a corresponding signal, for automatic operation of a control signal for switching the reception frequency of the transmitter with the better reception quality on the HF mixing stage.

Expediently, such an arrangement also has a frequency memory for storing the frequency of a transmitter identified as an alternative transmitter, which can thus be called up immediately if required.

In an expedient embodiment, the device for generating the second reception frequency is a second oscillator circuit. In an alternative embodiment, the device for generating the second reception frequency is a device for switching over the oscillation frequency of the (single) oscillator circuit, which has to ensure that the settling to the new frequency is very fast - preferably within one or a few Microseconds - follows.

Advantageously, the frequency memory is assigned a priority allocator, which is connected to the output of the evaluation device and which assigns stored frequencies a priority derived from the current reception quality, so that a switch is made to the transmitter with the best quality.

In accordance with an advantageous embodiment of the method according to the invention described above, the processing and identification device has an adding device for summing up a predetermined number of comparison results.

An advantageous combination of modulation test and reception quality check is achieved by connecting an input of the evaluation device to the output of the device for digitizing the LF signal and designing the evaluation device such that the signal values of the LF signal of the Comparison transmitter and the transmitter to be checked in the evaluation of the reception quality.

Alternatively or additionally, an input of the evaluation device can be connected to the output of the processing and Identification device connected and the evaluation device be designed so that the result of the evaluation of the comparison results is included in the evaluation of the reception quality.

The control device expediently comprises a program memory and a clock generator for specifying a program sequence for actuating the first in coordination with the second switching device and for controlling the comparison device and the processing and identification device for carrying out a modulation comparison checking station with the comparison station.

In an arrangement which is suitable for realizing a "background scan", means are provided for generating the third reception frequency, and the switching device must be designed to feed all three reception frequencies to the HF mixing stage.

To realize an advantageous suppression of an audible switching disturbance when switching from the choice to the potential alternative transmitter or from the third transmitter to one of the first two, a third LF signal memory connected via a third switching device to the output of the LF stage and one Fourth switching device arranged downstream of this and the NF stage, with which, upon a command from the control device, the LF signal of the transmitter provided for audio processing is stored for a predetermined period of time and later instead of after switching through the second (or also first) ) Receive frequency on the HF mixer at the output The LF signal of a transmitter not provided for audio processing of the LF stage, the stored LF signal of the third transmitter or of the selection transmitter can be switched through for further audio processing.

Further features and advantages of the invention result from the explanation of exemplary embodiments with reference to the figures.

From the figures show:

1 is a block diagram of a circuit arrangement for radio reception according to an embodiment of the invention,

2 shows a schematic basic illustration of the overall sequence of the method according to the invention for radio reception according to one embodiment,

3 shows a diagram of the step-by-step construction of a distribution curve of the comparison results of signal comparisons of signal samples from a comparison transmitter and a transmitter to be tested, which distribution curve is used to identify the program equality in the embodiment of the method according to FIG. 2,

4 (a) to (c) examples of distribution curves constructed according to FIG. 3 for transmitters with a mismatched program,

(d) to (f) examples of such distribution curves for transmitters with a matching program, 5 shows a diagram of the comparison and the summation of the comparison results of signal samples of a comparison transmitter and a transmitter to be tested in an embodiment modified from FIG. 3 and

6 (a) to (c) examples of distribution curves constructed according to FIG. 3 or FIG. 5 for transmitters with a mismatched program,

(d) to (f) Examples of such distribution curves for transmitters with a matching program, but during the test process the frequency distribution of the LF signal changed significantly.

1 schematically shows a circuit arrangement for carrying out the method according to the invention in a first embodiment. The operation of the arrangement is explained below.

The RF sum reception signal U _jj p received via an antenna 1 passes via an antenna coupling stage 2 and an RF preamplifier 3 to an RF mixing stage 4, which also via a switch S1 either directly with a first tunable oscillator circuit 01 or via a frequency divider F can be connected to a second tunable oscillator circuit 02 which oscillates outside the VHF frequency band.

The output of the HF mixer stage 4 is connected to an IF decoupling stage 5, the output of which is connected to a IF stage 6 shown as a block is connected, its output is connected to a demodulator 7 and its output is connected to an NF stage 8, which is also shown in highly schematic form as a block.

The antenna coupling stage 2, the HF pre-stage 3, the HF mixing stage 4, the two oscillator circuits 01 and 02, the frequency divider F, the switch S1 and the IF coupling-out stage 5 form an FM-FM tuner T.

The LF signal U _{NF present} at the output of the LF stage 8 is on the one hand, via a switch S2, optionally the input of a FIFO signal memory 9 and, on the other hand, an evaluation to be described below and on the other hand via a switch S3 optionally for further processing in ( not shown) audio stages supplied.

The LF signal intended for further evaluation within the scope of the method according to the invention passes via a node K upstream of the switch S3 to a serial A / D converter 10 with threshold characteristics, which in the present example is designed in such a way that LF signal components positive polarity above a predetermined voltage value the output value "1" of the A / D converter and LF signal components of negative polarity above a certain voltage value are assigned the output value "0", while signal components with a value between the predetermined positive and the predetermined one Negative voltage value level are not subjected to digitization, ie no value is output for such signal components. The output of the A / D converter 10 is connected to a first evaluation unit 11 and, via a switch S4, optionally to the input of a serial memory 12a - the selection transmitter signal memory - or the input of a one-bit memory 12b - the alternative transmitter -Signalspei¬ chers - connectable.

The output of the first evaluation unit 11 is connected to a signal input of a microprocessor MP which controls the entire arrangement and whose individual functions will be described below.

The outputs of the selection transmitter signal memory 12a and of the alternative transmitter signal memory 12b are connected to the signal inputs of a comparator 13 which has a control input (via a control line (not shown for reasons of clarity) connected to a control output of the microprocessor MP) and its output with a combined adder / serial memory 14 - the comparison result memory - is connected.

The output of the comparison result memory 14 is connected to the input of a second evaluation unit 15 and the output thereof is connected on the one hand to a control input of the microprocessor MP and on the other hand to a control input of a direct access memory (RAM) 16 - the transmission frequency memory.

The data input and the data output of the transmission frequency memory 16 are connected to the second one via a switch S5

Oscillator circuit 02 connected while a control input of the transmission frequency memory 16 is connected (via a control line, again not shown) to a control output of the microprocessor MP.

A priority assignor (pointer) 17 is assigned to the transmit frequency memory 16, the data input of which is connected to the output of the first evaluation unit 11, the address input of which is connected to the output of the evaluation unit 11 in parallel with the address input of the transmit frequency memory and which is also connected to has a control output connected to a control output of the microprocessor.

A clock 18, a program memory (ROM) 19, a data memory with direct access (RAM) 20 and an input and control unit 21 are assigned to the microprocessor MP in the usual way. These components, together with the microprocessor MP as the core, form the control computer MC of the arrangement shown.

The circuit arrangement also includes a digital display unit 22 for displaying the reception frequencies, control commands, operating states, etc., the inputs of which are connected to the outputs of the oscillator circuits 01 and 02 and the microprocessor MP.

When a transmitter is tuned - or more precisely: when a program is selected that is transmitted by a specific transmitter ("optional transmitter") - by the user of the arrangement, the first oscillator 01 is set to the transmission frequency of this transmitter when the switch S1 is in the upper position and the switch Sl the HF mixer stage 4 is supplied and the received signal is subjected to the usual processing by the VHF tuner T, the IF stage 6 and the LF stage 8, which ends with the provision of an LF signal at the output of the LF stage 8. (The processing of the LF or audio signal in subsequent filter, tone control and amplifier stages is disregarded here.)

Examples of such LF signals are prepared in the form of amplitude-tudenfU _jj) time-charts in Fig. 4 (a) to (f) darge, will be returned to hereinafter.

The LF signal tapped at node K is - as illustrated schematically in FIG. 2 (a) - under control by the microprocessor MP over a time range of approximately 6.5 ms at uniform time intervals at the times t _j , t ₂ , ..-, t _{n- 1} initially 16 select transmitter signal samples WS, each of about 50 μs in duration, and digitized in the serial A / D converter 10 in the manner described above.

The sampling program is stored in the ROM 19 of the control computer unit MC, while the time range, the time intervals and the duration of the registration of the signal samples can be stored in the RAM 20 and are matched to typical - for example country-specific - reception conditions. The selected time range of 6.5 ms is based on a maximum transit time modulation difference of +/- 5 ms under Central European FM reception conditions.

The digitized signal values are switched via the switch S4 in the upper position in this phase successively transmitted to the serial selection transmitter signal memory 12a and stored there.

After obtaining the LF signal value of the election transmitter at the time tn-1, the switch S2, which connects the output of the LF stage 8 with the LF, is closed 50μs before the start of the next scanning process (at the time tn) for a period of likewise 50 μs Signal latch 9 connects, and a portion of the LF signal is stored in it.

Immediately thereafter, the second oscillator circuit 02 is set to the frequency of the transmitter closest to the selected transmitter ("potential alternative transmitter") and the second oscillator circuit by switching the switch S1 to the lower position for a time span of approximately 50 μs connected to the HF mixer 4.

The received signal of the potential alternative transmitter is now fed to the further processing in the tuner T, the IF stage 6 and the NF stage 8 instead of the originally set optional transmitter, and a corresponding LF signal of the potential alternative transmitter ¬ reaches node K.

At this point in time, the microprocessor control has opened the switch S2 again and brought the switch S3 into the upper position connecting the LF signal memory 9 with the subsequent stages (not shown), so that instead of the LF currently present at node K Signal of the potential alternative transmitter of the previously stored signal section of the selection transmitter NF signal is fed to the further audio signal processing and a possibly occurring interference is minimized ("noise canceling").

For the listener, this arises on the one hand because of the very short switchover time to the potential alternative transmitter and, in addition, by bridging this short period in which the current LF signal of the election transmitter is not available, with the immediately preceding section of the NF signal the impression of an uninterrupted reproduction of the election program; in other words: the switchover is inaudible.

The NF signal of the potential alternative transmitter (alternative transmitter signal sample AS in FIG. 2 (a) now comes from the node K to the A / D converter 10, where, if it is above a signal threshold or minimum amplitude, a one bit thereof Signal is obtained, which is fed to the alternative transmitter signal memory 12b via the switch S4 which has now been switched to the lower position, and at the same time the digitized signal reaches the evaluation unit 11, the input of which is released by the microprocessor at this point in time, and is there under one the address currently assigned to the potential alternative transmitter present.

If the recorded signal of the potential alternative transmitter is below the predetermined signal threshold, it cannot be digitized in the A / D converter and no output signal can be emitted by it. This is due to the tax Purity MC registered, which then aborts the current cycle, deletes the content of the election transmitter signal memory 12a and starts a new cycle: however, if a usable alternative transmitter signal was registered and stored, the entire arrangement is switched back to further reception of the election transmitter , ie the first oscillator circuit 01 is switched back to the HF mixing stage 4 via the switch S1, the output of the LF stage is connected again to the subsequent audio stages via the switch S3 and the A / D converter 10 becomes reconnected to the selection transmitter signal memory 12a via the switch S4.

During a further time period of approximately 6.5 ms, another 16 signal samples of the selection transmitter NF signal are then taken at the same time intervals and corresponding to the first extraction cycle and are stored in serial form in the selection transmitter signal memory 12a in the manner described for the first cycle in digitized form .

The input of the A / D converter is then temporarily blocked by the microprocessor, the comparator 13 is activated and the data in the signal memories 12a and 12b are fed to the comparator, the individual sample value of the signal of the potential alternative transmitter stored in the memory 12b is constantly applied to one input of the comparator and the individual bits of the 32-bit word in the memory 12a are fed serially to the other input.

In the comparator, the agreement or disagreement with is determined for each bit of the signal sample of the election transmitter the signal sample of the potential alternative transmitter is checked and each result (“1” for agreement, “0” for non-agreement) is stored individually in the adder / comparison value memory 14 under the address corresponding to the time at which the signal sample was taken.

This completes the cycle of sampling outlined in FIG. 2 (a). FIG. 2 (b) shows how the sampling cycle AZ of 13.5 ms resulting from FIG. 2 (a) fits into a scheme of 14 repetitions. If, after averaging over these sampling cycles, an accumulation of the matches for a specific time offset is found, a program match can be assumed. Since a signal sample is only taken for a short time from the alternative transmitter while the majority is being removed from the current program, interruptions are hardly disturbing.

The overall cycle GZ of a modulation test with respect to a signal sample shown in FIG. 2 (b) takes about 600 ms in the example shown. 2 (c) shows how several total cycles can be combined to form a measurement sequence, which, for example, concern several alternative transmitters transmitting on different frequencies. The total cycles for different frequencies follow at intervals, so that the process takes a few seconds.

In Fig. 3 for better understanding of the method is shown in detail, as can be seen from two as well builds an evaluable result for further assumed sampling cycles.

First of all, reference is made here to FIG. 3 (a), in which the amplitude profile of two identical, but phase-shifted LF signals as a function of time is outlined together with the information present in the result of the first sampling cycle described above.

The election transmitter signal is drawn with a solid line, while the alternative transmitter signal is drawn with dash-dotted lines. The black bars directly below the LF signal curves denote areas in which the voltage values of the election transmitter signal have positive polarity.

Below the amplitude-time diagram there is shown a time bar of the sampling times and below that the output of the comparator as a sequence of bit values. In the first partial cycle, the polarity of the selection transmitter LF signal is recorded and stored for the times t ± to t _n _ ₁ .

Then, at time t _n, the polarity of the alternative transmitter LF signal is detected and stored, which is positive in Fig. 3 (a).

Then, at times t _{n + 1} to t _z in the second partial cycle, the polarities of the election transmitter signal are again recorded and stored.

Finally, the polarities of all optional transmitter signal samples are individually compared with the polarity of the alternative transmitter Signal sample compared at time t _n , and the result (the bit sequence in the lower part of FIG. 3 (a) representing a first cycle) is stored in the adder / comparison result memory.

The procedure is completely analogous, as described above, in a second cycle (cf. FIG. 3 (b)) and a number of subsequent sampling cycles, with the comparison result being added to the memory content of the adder and comparison value memory after each cycle.

The overall result of the modulation test - of which 13 cycles are indicated in FIG. 2 (b) - is shown in FIG. 3 (c) above after n cycles in the form of a distribution curve and in the lower part in the form of the memory content of the comparison result memory Summation of all comparison results of the cycles is shown.

In the example, the distribution curve has a clear maximum, with which the potential alternative transmitter, which has been checked for modulation and thus program equality, can be recognized as a transmitter that actually broadcasts the same program, that is to say, literally, as an "alternative transmitter".

This evaluation takes place in the second evaluation unit 15 connected downstream of the adder / comparison result memory and, in the case of a positive evaluation result - as in the example - transmits a control signal to the transmission frequency memory 16, which then stores the frequency set on the second oscillator circuit 02 at a first address. This is thus on call - for example in the event of a disruption or deterioration in reception of the election transmitter - as a second reception frequency for the set program.

If - unlike in the example shown - there is no distribution curve with a sufficiently pronounced maximum in the result of the summation of the comparison results of the individual cycles, it can be concluded that the potential alternative transmitter tested does not have the same program information at the same time as the election transmitter broadcasts, ie is not an alternative transmitter.

4 (a) to (f) are three examples of distribution curves of transmitters based on 40 sampling cycles each with the same program information (FIG. 4 (d) to (f)) and different program information (FIG. 4 (a) to (c) juxtaposed.

In this case, the frequency set on the oscillator circuit 02 is not stored, but the next station worthy of reception is set as a potential alternative station and the entire procedure is repeated for this, etc., until a station with the same program information is found or the FM band is fully scanned. This procedure is outlined schematically in FIG. 2 (c).

As soon as an alternative transmitter has been found, the process can be terminated or continued until the frequency band has been scanned completely, in order to find further transmitter stations with the same program, if necessary. This are then stored under a different address in the frequency memory 16.

With the arrangement according to FIG. 1, it is then also possible with the aid of the first evaluation unit 11 to determine, among these transmitters, the one with the currently best reception quality and the addresses in the frequency memory 16 via the pointer 17 a priority or ranking of the reception quality assign, after which a switchover from the frequency of the election transmitter to the frequency of the alternative transmitter with the highest reception quality then becomes necessary.

Of course, it is also possible to store the originally set optional transmitter in the frequency table and, like the alternative transmitters, to subject it to an evaluation of the reception quality, so that even after a particular transmitter with better reception quality has been detected, this transmitter can be switched to without any particular interference with this transmitter can be.

The reception quality can be assessed using the data recorded during the modulation test.

On the one hand, as shown in FIG. 1, it is possible to use the output data of the A / D converter directly, in particular the portion from within the "threshold" of the A / D converter, ie below a certain voltage value. tes lying signal samples for the number of signal samples lying above this threshold enables a prediction of the expected reception quality. For this purpose, the control unit MC transmits a signal to the evaluation unit 11 at every sampling time t _n , regardless of whether it has also received an output value from the A / D converter 10 or not.

The total number of signals in a cycle is counted. In addition, the number of output values of the A / D converter temporarily stored in the first evaluation unit in each sampling cycle is determined, and the ratio of the two numerical values is the quantity sought.

Advantageously, further variables indicating the reception quality can be processed in the evaluation unit; however, this is not part of the invention and is therefore not discussed further.

As an alternative or in addition to the evaluation described, such can also take place on the basis of the shape of the distribution curve of the comparison values within a modulation test.

The more pronounced the maximum of a distribution curve, the higher - at least tends to be - the quality of reception. In the example of FIG. 4, the transmitter according to FIG. 4 (e) would therefore be rated the highest with regard to the reception quality on the basis of this criterion.

In a modification of the exemplary embodiment described, an A / D converter is used which not only converts the recorded LF signal values into values according to their polarity

"1" or "0" converts, but according to a corresponding one Quantization specification in fine steps, so that only nearly identical LF amplitude values are classified as corresponding.

This modified principle is outlined in Fig. 5, which is constructed similarly to Fig. 3, but in Fig. 5 (a) to

(d) four sampling cycles of 19 samples each and in FIG. 5

(e) shows the memory content of the adder / comparison result memory after the fourth cycle. The arrows pointing downward in each partial illustration designate points of agreement of the amplitude values of the selection and alternative transmitter signal on the time scale. A value "1" is written into the addresses corresponding to these times in the comparison result memory, while all others Time grid points each have the value "0". When adding up over the cycles, the bit sequence according to FIG. 5 (e) results with a maximum at the time t _n _ ₂ , which speaks for modulation and thus program identity.

A further modification of the exemplary embodiment is characterized in that, instead of adding up the comparison results of the individual scanning cycles in one go over the entire time interval of the test, a separate addition of the comparison results for four partial time intervals t to t _zl , t _{2l + 1} to t _z2 , t _{z2 +} ι to t _z3 and t _{z3 + 2} to t _{z4 is} carried out, where about t _z2 = t _n , and then the four partial sums are subjected to a separate evaluation with which, for example, a directed one _{Migration of} a distribution maximum _j _ _nner _ half of the test period of a total of approx. 13.5 ms as a result a rapid change in the signal modulation can be recognized.

Such wandering would appear in an overall distribution as an indication of several maxima - for example as shown in FIGS. 6 (d) to (f) in comparison with three distributions without a maximum in FIGS. 6 (a) to (c) - or in In the worst-case scenario, the complete "smearing" of the distribution can have the effect that it can give the incorrect impression that the program content of the selected and potential alternative station is different, and thus make it impossible to recognize the latter as a genuine alternative station.

The evaluation of the partial sums in their chronological sequence prevents this and thus enables the alternative transmitter to be recognized even in the event of abrupt modulation changes during the test period.

The modification mentioned does not require any change to the arrangement shown schematically in FIG. 1, but only a modification of the evaluation unit 15 and the control program of the microprocessor.

A further modification of the exemplary embodiment consists in that the signal values of the alternative transmitter are not determined in one sampling interval (of approximately 50 μs), but rather at two successive sampling "times" (periods of a few μs) which are spaced apart by half a period of the 38th -kHz stereo carrier, ie of about 26 μs, from each other, and that the arithmetic mean is formed from the two values and this is used as a basis for further processing. On the one hand, this shortens the blanking period of the electoral broadcaster and additionally divides it into two short intervals, which are easier to bridge than a longer period of time by means of the "noise canceling" described above.

On the other hand, this eliminates the disturbing (L-R) stereo difference signal and largely also high-frequency noise components during the modulation test and thus increases the reliability of the test result.

This modification is expediently implemented by inserting a latch ("latch") and an assembly for averaging between the node K and the A / D converter 10 in FIG. 1.

A further modification provides for the adder / comparison value memory to be queried after about 10 to 15 sampling cycles in order to determine whether there are any signs of a maximum being formed in the distribution curve and to abort the test process if no formation of a maximum is recognizable.

The investigations of the inventors have shown that in such a case there is no maximum even after the full test cycle.

On the other hand, if there is a recognizable formation of a maximum after said 10 to 15 cycles, the test process must be carried out completely in order to ensure that a transmitter with the same program has actually been found. This modification also does not require any significant change to the circuit arrangement according to FIG. 1.

Instead of the two oscillators 01 and 02 (which are, moreover, preferably designed as PLL circuits) and the switch S1 in FIG. 1, a single oscillator circuit that can be quickly switched in frequency can be provided, which in particular saves a voltage-controlled oscillator in a cost-saving manner (VCO) of a conventional receiver.

This design also has the advantage that commercially available receiving parts can be used without significant changes.

The embodiment of the invention is not limited to the preferred exemplary embodiments specified above. Rather, a number of variants are conceivable which make use of the solution shown, even in the case of fundamentally different types. With regard to the disclosure of the invention, reference is made to additional applications of the same applicant filed simultaneously.

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Claims

Expectations

1. A method for the wireless reception of broadcasts, which are broadcast simultaneously on different frequencies, in particular for the mobile reception of FM-modulated broadcasts in the VHF (VHF) range, with a receiving part which can be set to these frequencies,

characterized ,

that the correspondence of the currently transmitted program information transmitted to the user of a selected transmitter received by means of the receiving part on a first reception frequency with that of a further one received on a second frequency - one, in particular in the event of a disturbance of the on the the first reception frequency of the received transmitter, the potential alternative transmitter-forming transmitter is determined by taking at least one signal sample, which is characteristic of the NF modulation, from both transmitters in a corresponding manner, with points in time being distinguished by different time differences the range of the selected time differences is adapted to the range of the relevant time differences of the transmitters that can be received with matching program information, and at least the signal that appears earlier appears at least for the period of the respective time difference stores and / or is delayed, and

that an output signal indicating the match is output when, when performing a comparison, the for the LF modulation characteristic signal samples received on the two frequencies deviate from one another by less than a predetermined amount for one of the selected time differences.

2. The method according to claim 1, dadurchge ¬ indicates that when receiving with a ei¬ NEN signal processing path for the RF signal having receiving part each only a brief - kei¬ ne noticeable interruption of the program information passed on to the user for the User-causing - switching of the receiving part to the second frequency takes place.

3. The method according to claim 2, so that a signal sample of the potential alternative transmitter is compared with a plurality of signal samples of the selective transmitter received on the first frequency, recorded at different time intervals relative to this.

4. The method according to any one of the preceding claims, characterized in that the processing includes a plurality of processing cycles which essentially coincide with one another, the information indicating the agreement of the signal samples being recorded and added up in each case in association with the respective time difference, and that Display match The output signal is then output when the summed information for one of the time differences exceeds the other by a predetermined amount or a statistical accumulation is determined in some other way.

5. The method according to any one of the preceding claims, characterized in that the test is carried out successively for several alternative transmitters having different transmission frequencies until a program-identical transmitter is found and / or all receivable transmitters of a predetermined frequency range have been checked for program equality .

6. The method according to any one of claims 1 to 5, d a ¬ d u r c h g e k e n n z e i c h n e t that

the reception frequency or another identifier of a transmitter recognized as the same as a program due to its modulation equality is stored as an alternative transmitter,

the reception quality of the set transmitter and of the alternative transmitter is subjected to a comparative evaluation and

7. The method according to claim 6 with the steps:

a) adjusting the receiving part to the transmission frequency of the comparison transmitter (optional transmitter) and processing the received signal to obtain an optional transmitter signal that characterizes the low frequency modulation,

b) storing in each case at least one election transmitter signal value obtained from the received signal of the election transmitter at a plurality of times (t _j , t ₂ ,... t _n-1 ) in a election transmitter signal value memory,

c) briefly switching the receiving part to the transmission frequency of the potential alternative transmitter and processing the received signal in essentially the same way as with the selective transmitter for obtaining an alternative transmitter signal characterizing its NF modulation,

d) storing at least one alternative transmitter signal value obtained at a point in time (t _n ) in an alternative transmitter signal value memory,

e) readjusting the receiving part to the transmission frequency of the election transmitter and continuing to obtain the

Polling station signal,

f) storing at least one election transmitter signal value obtained over a predetermined time range in a plurality of further times (t _{n + 1} , t _{n + 2} , ..., t _z ) in the election transmitter signal value memory, g) supplying the values stored in the selection transmitter signal value memory on the one hand and the value stored in the alternative transmitter signal value memory on the other hand to a comparison circuit, carrying out a test of the alternative transmitter value for correspondence with each of the selection transmitter values and storing the comparison results in a comparison result memory ,

h) the optional execution of a number of repetitions of steps b) to g) while maintaining the intervals of the times for obtaining the signal values and adding the respective comparison results to the values stored under the corresponding addresses in the comparison result memory,

i) reading out the comparison result memory, checking the memory content for the presence of one or some neighboring address (s) with a number of agreement values (an agreement maximum) exceeding the other addresses,

k) characterization and display and / or storage of information associated with the potential alternative transmitter tested in this way in association with information associated with the optional transmitter,

1) the optional setting of the receiver to the stored transmission frequency of the alternative transmitter in the case of better reception quality of the alternative transmitter.

8. The method according to any one of the preceding claims, that a voltage value of the LF signal is used as the LF signal value of the comparison transmitter (optional transmitter) or of the transmitter to be tested (potential alternative transmitter).

9. The method of claim 8, d a d u r c h g e - k e n n z e i c h n e t that the respective voltage value of the LF signal is subjected to digitization by means of predetermined quantization levels.

10. The method according to claim 8 or 9, so that the polarity of the voltage value of the LF signal is used as the signal value.

11. The method according to any one of the preceding claims, that the execution of the step of obtaining an LF signal sample from the transmitter to be tested (potential alternative transmitter) is carried out in such a way that it is not audibly perceptible.

12. The method according to claim 11, dadurchge ¬ indicates that the duration of the execution of the step of obtaining an LF signal sample is equal to or less than 50 μs.

13. The method according to claim 11 or 12, characterized in that the NF signal of the comparison or election transmitter during a period before execution of the step of obtaining the NF signal sample of the transmitter to be tested (potential alternative transmitter), which is equal to the period of its execution is stored and this stored LF signal is provided as LF replacement signal for audio processing during the execution of the step.

14. The method according to any one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that the time frame specified for the execution of the modulation match check is set at least equal to the sum of the maximum expected negative and positive runtime modulation difference of all transmitters receivable in the reception area.

15. The method according to any one of claims 7 to 14, that the step h) comprises 10 to 50 repetitions of the steps b) to g).

16. The method according to any one of claims 7 to 15, since ¬ characterized in that the distances of the times (t- _{j ^} t ₂ , ..., t _z ) for recording and storing the individual signal values in steps b), d) and f) are identical to each other.

17. The method according to any one of claims 7 to 16, since ¬ characterized in that in the event of a disturbance of the comparison transmitter (optional transmitter) exceeding a predetermined time period and / or a predetermined level, steps b) to i) for the or Alternative transmitters are repeated, the result of step i) is used according to predefined criteria to characterize the current reception quality of the alternative transmitter (s) and, based on this characterization, a decision is made to switch to one or the alternative transmitters.

18. The method according to any one of claims 7 to 17, characterized in that steps b) to i) are repeated for the alternative transmitter or transmitters at regular intervals during reception of the election transmitter, the result of step i) according to vorge¬ The given criteria are used in each case to characterize the current reception quality of the alternative transmitter (s) and, on the basis of this characterization, a statement or a ranking of the worthiness of reception as the basis for a decision to switch to one of the alternative transmitters in comparison to an alternative transmitter lower reception quality of the election transmitter is provided.

19. The method according to any one of claims 7 to 18, d a - d u r c h g e k e n n z e i c h n e t that in each case

Execution of a step c), in the result of which Alternative transmitter signal is obtained below a predetermined minimum signal level, the subsequent steps are not carried out and steps b) and c) are repeated instead until an alternative transmitter signal exceeding the minimum signal level is obtained and the subsequent steps are subsequently carried out, whereby a sequence of steps terminated according to c) in the sense of step h) does not count as a repetition.

20. The method according to any one of claims 7 to 19, - characterized in that all steps c), as a result of which an alternative transmitter signal is obtained in a predetermined level range, are counted during a repetition cycle of steps b) to g) and the counting result is used to obtain information about the modulation and / or the reception quality of the potential alternative transmitter.

21. The method of claim 20, d a d u r c h g e ¬ k e n n z e i c h n e t that the steps c) are counted, after which the sequence of steps is terminated and restarted.

22. The method according to claim 21, dadurchge ¬ indicates that the number of registrations of election transmitter signal values in step b), which are below the minimum signal level specified for the alternative transmitter, detects this number with the number of Steps c), after which the sequence of steps has been terminated, are compared and the comparison result is used according to predetermined criteria as an auxiliary statement regarding the program identity of the election and potential alternative station.

23. The method according to claim 20, so that the number of steps c) in which the alternative transmitter signal was in a certain level range is used to obtain a statement about the program type of the potential alternative transmitter.

24. The method according to any one of claims 7 to 23, - characterized in that a total sequence of steps b) to j) is divided into several partial sequences, step i) being carried out after the completion of a partial sequence and the respective Statements as to whether and under which address (s) a maximum of agreement was found for the partial sequence in this step are subjected to a logical processing, as a result of which the statement j1) or j2) is obtained.

25. The method according to any one of claims 7 to 24, since ¬ characterized in that the steps c) and d) at least two at a time interval of a fraction of the 38 kHz carrier period and / or the 19 MHz carrier period showing sub-steps ten are carried out, in the meantime switching back to the selection transmitter, and that the arithmetic mean is formed from the at least two signal values obtained and this is fed as an alternative transmitter value to the further processing in the subsequent steps.

26. The method of claim 25, d a d u r c h g e - k e n n z e i c h n e t that two substeps are carried out at a distance of half a 38 kHz carrier period.

27. Circuit arrangement for radio reception, comprising:

a receiving part (T) with at least one tunable oscillator circuit (01) for generating a first receiving frequency for receiving a comparison transmitter (optional transmitter) and an HF mixer stage (4),

a device (02) for generating a second reception frequency for receiving a transmitter to be tested (potential alternative transmitter),

a control device (MC),

a first switching device (S1) for selectively switching through the first or the second receiving frequency to the HF mixing stage (4) on command from the control device (MC), a device (10) for obtaining a signal sample which characterizes the LF modulation of the LF signal present at the output of an LF stage (8) of the receiving part,

a comparator and evaluation device (13, 14, 15, MP) for comparing signal samples obtained by the device (10) when the first or second reception frequency is switched through and for evaluating the comparison results and

a device downstream of the comparator and evaluation device (13, 14, 15, MP) for outputting a signal if, as a result of the comparison and evaluation process, identical programs of the comparison transmitter and the potential alternative transmitter were found.

28 Circuit arrangement according to claim 27, g e k e n n ¬ z e i c h n e t d u r c h

a device (10) for digitizing an LF signal present at the output of an LF stage (8) of the radio receiver,

- a first LF signal memory (12a),

a second LF signal memory (12b),

a second switching device (S4) for selectively connecting the device (10) for digitizing the LF signal to the first or the second LF signal memory (12a, 12b) as a function of the setting of the first switching device (Sl),

the comparator and evaluation device (13, 14, 15, MP) having:

a comparator device (13) connected to an output of the first LF signal memory (12a) and the output of the second LF signal memory (12b) for comparing the memory contents of the two LF signal memories (12a, 12b) with one another and for outputting a comparison result to one Command of the control device (MC),

a memory device (14) connected to the output of the comparator device for storing several comparison results,

a processing and identification device (14, 15, MP) for processing the several comparison results with one another and for evaluating the processing result upon a command from the control device (MC) to output a statement regarding the agreement or mismatch of the modulations of the comparison transmitter and of the transmitter to be checked and to characterize the latter as an alternative transmitter to the election transmitter if a match is found.

29. A circuit arrangement according to claim 27, an evaluation device

(11) to evaluate the reception quality of the set Transmitter and the alternative transmitter and for outputting a signal identifying them.

30. Circuit arrangement according to claim 27, characterized in that the control device (MC) has a program memory (19) and a clock generator (18) for specifying a program sequence for actuating the first (S1) in coordination with the second switching device (S4) and Control of the comparator device (13) and the processing and identification device (14, 15, MP) for performing a modulation comparison of the transmitter to be tested with the comparison transmitter.

31. Circuit arrangement according to claim 27, characterized in that a third LF signal memory (9) connected via a third switching device (S2) to the output of the LF stage and a fourth one downstream of this as well as the LF stage (8) Switching devices (S3) are provided, with which, upon a command from the control device (MC), the LF signal of the comparison transmitter (optional transmitter) is stored for a predetermined period of time and later instead of after switching through the second reception frequency to the HF mixing stage (4) at the output of the LF stage (8) LF signal of the potential alternative transmitter, the stored LF signal of the election transmitter can be switched through for further audio processing.

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