Mobile radio apparatus, such as a car radio or the like, in particular a VHF receiver.

The invention relates to a stationary variable radio, such as the radio or the like., In particular an FM tuner, the DEFINE th in the preamble of claim 1 genus.

In a known radio receiver of this type (DE-OS 32 14 155) is provided for checking the reception quality of the alternative transmitters s complete second receiving part with tuning control device, in which successively set parallel to the currently listened-to channel the alternative transmitters and its reception quality, here the reception field strength, with of comparing the currently heard radio station. Once this one Altemativsender a better reception quality, here a higher received field strength, than said currently owned stations, the latter will be replaced by this alternative transmitter which is then switched audibly and represents the new station you were listening.

Such Rundfunkemfpänger is and always find relatively expensive because of the required full second receiver train just as a car radio the upper price Kate gory. Although it has already been proposed in the DE-OS, to dispense with the second reception path and carry out the review of Altemativsender in the transmission pauses the currently heard radio station, but there this vote to be carried out in the relatively short pause times of Altemativsender and determining its field strength due possibly currently the faults occurred a little reliable information on the reception quality, so that it might be at times frequent changes of each included transmitter. Also pause recognition circuits are relatively expensive.

The invention has the object to improve a mobile broadcast receiver of the type mentioned, that in the presence of only one receiver train without disturbing the Höreindruckes the currently heard radio station a reliable testing of the reception quality of heard of, stations and alternative transmitters is achieved and switching only on the longer^fRistig better transmitter occurs.

This object is achieved according to the invention in a radio receiver of the type indicated in the preamble of claim 1 by the features in the characterizing part of claim 1.

The radio receiver according to the invention has the advantage that in the Bestauswahl the transmitter in addition to the current measured values ​​of the reception quality of a plurality into account individual, detected at different times measured values ​​of the reception quality, wherein the relevance of the individual values ​​for the test may still be taken into account additionally. The detection of the individual values ​​of the reception quality is carried out in extremely short silent periods of the currently heard radio station of about 20 ms, which are not perceived by the listener is not too great frequency. The currently played station - hereafter called G-transmitter -is so only by an alternative station -in the following short A-transmitter called -replaces when this long has the better reception quality.

An advantageous embodiment of the invention results from claim 2. This averaging of the sample or measured values ​​of the reception quality corresponding to the filtering by a digital recursive low-pass filter of the first order or in about the filtering by an analog RC lowpass filter, is an evaluation of the reception quality achieved, taking into account optimum listening. It is sufficient, the testing of the receiving quality, which is modulation dependent and has static character, only rarely, ie s to perform at intervals of 5 s -30 depending on the quality of the reception quality. Setting the link factor k is adjusted while the circumstances. For the first sample k is close to 0, since this measured value has high relevance, as he lies with a relatively stable, ie slightly fluctuating, or increasing the quality of reception area 1, which is strongly averaged. If the current reception quality significantly worse than the average, so k is again close to 0, so that the sampling or measurement strongly influenced the mean. The latter makes sense in as eg single strong and temporally brief disturbances are subjectively perceived much stronger than it according to their weight and thus seriously affect the hearing impression. This change in the linking factor k can easily after a predetermined definition function of the United same result, as the difference, effected from instantaneous sample or measured value and average value.

An advantageous embodiment of the invention also results from claim 4. By this measure unnecessary mutes are avoided. The reception quality of the G-station but is constantly monitored and the test result • continuously improved by averaging over an ever increasing number of samples.

An advantageous embodiment of the invention is also evident from claim 5. By these measures the reception quality test is optimized; because reception quality check by

Examination of the field strength alone is only sufficient if ideal, ie undisturbed reception conditions prevail. In this case, the reception quality is proportional to the received field strength. When mobile radio receiver, car radio, but paling effect also reduces the multipath or the so-called while driving occur, caused by reflections. The reception quality in spite of sufficient field strength considerably. The gewonne means of a circuit arrangement described in DE-OS 31 26 224 freedom from interference, denoted there by Qualitatsmaß, considered such a reception quality disturbing influences. The level of Störfreiheitsmaßes is a measure of the size and frequency of these disorders and this is inversely proportional.

An advantageous development of the invention also results from claim 6. Through this measure the field strength enjoys in Bestauswahl priority; because only sufficiently large field strength ensures an acceptable reception. But if this is present, the evaluation of the reception quality of the Störtreiheitsmaß is determined.

An advantageous embodiment of the invention is also evident from claim 7. This ensures that beiweniger satisfying current Empfangsfeidstärke both the G-transmitter and the revised A-station of the A-station is only switched audible if its field strength in the longer term and in relation to the auditory impression is better.

An advantageous embodiment of the invention results from claim 8. This ensures that the tested A-channels not to show audibly and its further examination will be canceled if its current reception field strength is already less than that of G-transmitter.

An advantageous embodiment of the invention also results from claim 9. This causes the A transmitter not switched audibly and its verification is already terminated when, unlike the G-station is its current reception field strength below the predetermined field strength minimum.

An advantageous embodiment of the invention also results from claim 10, in particular in conjunction with claim 11 By these measures it is ensured that with adequate reception field strength of the A-station this is only switched audible when not only his current freedom from interference is greater than the the G-station, but he already has a long-term to better listening experience mediating freedom from interference. on the other hand is its freedom from interference current sample is smaller than that of the G-channel, so its further examination will be canceled and fall back to the G-station.

An advantageous embodiment of the invention is also evident from claim 12. By these measures the frequency of required Bestauswahl depending on the reception quality of the G-station is controlled to require as few silent hours for transmitter verification. Sinks case of freedom from interference sample of the G-transmitter with a first threshold from what corresponds to about the field strength minimum value lying field strength sample an average reception quality, so is s output a trigger signal to initiate a new Bestauswahl by example 30th Sinks of freedom from interference sample contrast below a second threshold from which one - corresponds to poor reception quality, so a trip signal is issued after 5 s. Sinks of freedom from interference sample of the G-station under a third threshold, what a very - corresponds to poor reception quality, then after 0.5 s the output of the trigger signal. In all cases, repeated in this time frame the issue of further trigger signals, if not now an A transmitter has been switched audible with better reception quality. In the latter case the very - poor reception quality is limited to seven because of the noticeable over a longer time interval silent hours ei a switching cycle of 0.5 s, the trigger signal repetition. If you can still not alternative station with better reception quality found and connected audibly, is switched to a Abprüfrhythmus of 5 s.

An advantageous embodiment of the invention results from claim 13. By this measure it is ensured that in case of insufficient field strength in each case a Überprüfvorgang of available A transmitter is triggered to better reception quality.

An advantageous development of the invention results from claim 14. By this measure, the Abprüfmodus is accelerated, since the A-channel can be selected according to the probability of a better reception quality. The higher the field strength of an A-station, the more likely is that he has a good reception quality.

An advantageous embodiment of the invention results from claim 16. By this A transmitter update all A-stations are automatically determined such new O stations with poor reception quality, which are now be received as a result of the temporary movement of broadcast radio and may have better reception quality. Since this identification of new A transmitter requires a review of the entire main memory and the coordination of possible A transmitter, the speaker for an extended period (second range) to be muted.

An advantageous embodiment of the invention results from claim 17. This measure is a continuation and thus a mute unnecessarily, ie with low chance of success, carried out; because the more A-transmitters have already been determined, the less likely that there are more A-station and vice versa.

An advantageous embodiment of the invention is also evident from claim 18. This results in a further write circuit is realized not only in a simple manner but also the field strength and the freedom from interference are taken into account in the frequency of updating. Are both very good, need not updated at the polls. The down counter is not decremented. If the field strength as continuously very small, we find by running decrement the down counter an update early instead. Since the field strength at a site mostly for all channels is equally bad, it is advisable only to start the Fort Write attempt when again greater field strength occurs. The waiting time is thereby limited, zBauf 3 min, and then launched an update, even at very small field strength.

The invention is described in detail with reference to an embodiment shown in the drawing below. The drawing shows a block diagram of a conceived as a car stereo FM receiver.

The FM receiver has a receiving portion 10 which an FM tuning or tuner 11 comprises in a known manner with tuning control device 12 for tuning or preset station, an FM demodulator 13 and a low frequency amplifier 14th With 15, the antenna and designated 16 of the speaker. Between the FM demodulator 13 and the low-frequency amplifier 14 is still a mute turned 17, by means of which the tuned in the tuner 11 stations can be switched audibly or silently. With the transmission setting means 12, a control panel 18 is connected, by means of which selected the desired program a desired broadcaster or for the auto scan a scan of tuning control device 12 can be triggered by pressing the button SA.

In FM receiver a known sender identification device 19 is also available, which identifies a set via search or by key dialing stations to broadcaster, program, transmission frequency, transmitter location and transmitter range. The transmitter identification device 19 takes this to a main memory 20, in which all receivable in the possible range of the FM receiver stations are stored with their transmission frequencies, transmitter locations, radiated programs, their associated broadcasting companies and their transmission ranges. One possible structure of the transmitter identification device 19 is described in the DE-OS. In addition to the functions set out therein, the transmitter identification device 19 determines called to a received and identified stations alternative station -in the following briefly called A transmitter -., Ie those available stations, which emit the same program the same broadcaster as the station being received. This A stations are put in a Altemativsenderspeicher which is combined with the main memory 20th Appropriately, only the A-station identifying marks are therefor placed in the main memory. A possible expansion of the transmitter identification device 19 to achieve this operation is described in DE-OS 32 14 155th After a tuned in the tuner 11 station identification so are all the receivable at the current location of the FM receiver channels with the same broadcasting program as the station being received for selection in the main memory 20 or in the built-in this Altemativsenderspeicher available. Identifying the sender device 19 and its cooperation with the control panel 18 and the tuning control apparatus 12 is controlled by a control device 21, executes the additional control functions described below.

The FM receiver further includes a test apparatus 22 which -and- -in the following shortly called the reception of the current audible transmitter G transmitter that of the A-sender checks and the transmitter indicating with the respectively better reception quality of the control device 21, which then the tuning control device 12 causes the setting of Bestsenders. In this inspection apparatus 22, the reception quality check is performed according to two criteria: firstly, by examining and comparing the received field strengths and secondly by examining and comparing a so-called Störfreiheitsmaßes, considered the interference to radio communications.. To determine the Störfreiheitsmaßes of a transmitter, an S circuit 23 connected to the demodulator 13 at whose output an output voltage proportional to the freedom from interference is removable. The letter S S circuit 23 is hereinafter for freedom from interference. Design and operation of the S-circuit is described in DE-OS 31 26 224th In the S-23 circuit to interference of reception, as are formed by multipath reception or by the so-called. Paling effect as detected. The freedom from interference S is inversely proportional to the frequency and magnitude of the disturbances occurring.

The reception field strength F and the freedom from interference S of G-transmitter be taken out as analog samples by means of a sample-and-hold circuit 24 or 25 from the tuner 11 or the output of the S-circuit 23rd After analog / digital conversion in the A / D transducers 26,27 are digital F respectively. S samples available, which F-or the current. form S-values ​​of the G-station. The reception field strength F and the freedom from interference S of A-channels are in turn taken in extremely short silent times of 20 ms by the sample-and-hold circuits 24,25. In this short silent periods of G-transmitter is turned off by the muting circuit 17 and the tuner 11 is tuned to a predetermined A transmitter. The 24,25 removed from the sample and hold circuits or analog-F. S-samples form the digital current F and S values ​​of the A-station after conversion in the A / D converters 26,27. The scanning sequence of the sample and hold circuits 24,25, as well as activating the muting circuit 17 is controlled by the control device 21st

For every service, ie for the G channel and for each of the available A station, the F-values ​​on the one hand and the S values ​​on the other hand in an arithmetic circuit 28 and 29, an averaging undergo. The arithmetic circuit 28 and 29 calculates the n-th sample at the Mitteiwert<o>A</o>_naccording to the following equation: Ä _n = <o>A</o>_n-1 • k + (1 -k) to

A stands for the respective F-or S-value. <o>A</o>_n-1 is the mean value that has been formed from n-1 sampled values. The linkage factor k, according to the relevance of the respective to the averaging relied F-respectively. S-value is between the end values ​​"0" and "1 is set. In relation to the mean Ä_n-1 At a larger sample is in this case the factor to "1" and compared with the average value A n_-1 smaller value to the factor to be moved "0" out. In addition, the factor "0" is the first to be considered in the averaging sample A close because this first sample A, plays a great relevance. This adjustment of the linking factor k, for example, carried out by a differentiator 30 and 31 respectively, of the current sample A_n and the average value A _n-1 and comparing a size of the difference value is corresponding to the calculation circuit 28 and 29 respectively. The mean values ​​F and 5 are stored for each transmitter in a -Speicher F 32 and a S -Speicher 33 at the same address. This address corresponds to in each case equal to the address at which the G-transmitter or the individual A transmitter can be called up in the main memory 20th

Die_aktuellen_F and S values ​​and the values ​​F and 3 of the G-station and a selected A-station are now compared in a comparison circuit 34 according to certain criteria for comparison with each other and the station with the best reception quality - (Bestauswahl) indicated the controller 21st Only the reception field strength F is taken into account when the current, ie the just sampled and digitized R-value of the A-station at a predetermined field strength minimum value F_min lies, and only the freedom from interference S considered when the current F-value of the A-station above the field strength minimum value F_min lies.

The comparison circuit 34 includes a plurality of comparators and a check logic 35, which is suitably a part of the control device 21st A first comparator 36 are successively fed to the current F-values ​​of the G-transmitter and one to be compared A transmitter via a switch controlled by the check logic 35 switches 39, including the two F values ​​are buffered in a 2 bit shift register 37th The comparator 36 compares the two F values ​​sequentially with a field strength minimum value F_min, In a second comparator 38 the two F values ​​are compared with each other. In a third comparator 40, the F values ​​of the G-transmitter and A transmitter are compared, including the from the F -Speicher 32 sequentially read F values ​​the comparator 40 again directly (F value of the A-channel) be and once supplied via a 1-bit shift register 41 (F value of G-transmitter). The outputs of the three comparators 36,38 and 40 are connected to the test logic 35th

In a fourth comparator 42, the current S-values ​​of the G-transmitter and A transmitter are compared, for which they are stored in a 2 bit shift register 43rd In a fifth comparator 44 the averages S of A-channels and gas stations are compared. These S values ​​by appropriate addressing of 9 - read memory 33 successively from this, the F value of G-station is temporarily stored in a 1 bit shift register 45th The outputs of the two comparators 42 and 44 are also connected to the check logic 35th

The taking place in the comparators 36, 38, 40, 42, 44 compared to the determination of the Bestsenders is performed by the check logic 35 in the following manner: First, the current F-value of the A-station with the field strength minimum value F_min compared. If this is below the predetermined threshold, the F value of G-station is compared to the field strength minimum value by switching the switch. 39 If it is greater than the predetermined threshold, outputs the check logic 35 of the control device 21 the G channel as a best receiving at. If the F value of G-transmitter also below this threshold F_min, Then the second comparator 38 is enabled, and compared the two F values ​​of A-G of the transmitter and the transmitter with each other. Is the F-value of the G-channel is greater than the F-value of the A transmitter, as is the test logic 35 of the control device 21 the G channel as a best receiving at. If the F value of the A-channel is greater than that of the G-station, the third comparator 40 is activated, which compares the field strength averages of the two channels together and identifies the station with the largest f value as the best receiving. This is communicated by the check logic 35 of the control device 21st

If the comparison in the comparator 36 that the F-value of the A-channel is greater than the predetermined field strength minimum value, so the fourth comparator 42 is activated, which compares the current S-values ​​of G and A channels together. If the S-value of the A transmitter smaller than that of the G-channel, it is communicated by the check logic of the G channel as a best receiving the control device 21st If the S-value of the A-channel is greater than that of the G-station, so by the check logic 35 of the fifth comparator 44 is activated, the now compares the averages 3 of the two channels with each other and the transmitter with the larger a value of the check logic 35 indicates as a best receiving, in turn, communicates this to the control device 21st

To initiate the above-described testing procedure, an alternative transmitter, on the one hand umfaß the comparison process described above, and the other part determining the time required for comparison values, the tester 22 a Abprüf start circuit 46 that a time-delayed triggering signal for reading out an A-channel from the main memory 20 and tuning the read A station in the tuner 11 outputs. The time delay of the output of the trigger signal is set depending on the size of the current S-value of the G-station, specifically here in stages. If the S-value below a lintel S_MaxBut in the vicinity thereof, so every 30 s issued a trip signal. If the S-value close to a lower threshold S_minSo the output of a trigger signal is carried out after 5 seconds. If the S-value below the lower threshold S,_in, A trigger signal is given s already after 0.5 to the control device 21st Such Abprüf-start circuit 46 may be for example of a presettable down counter (down counter) formed 47 whose setting is performed by a comparator 48 having a plurality of threshold levels and is given the current S-value. The down counter 47 is decremented at a predetermined clock frequency, and upon reaching a zero position, it outputs a trigger signal to the control device 21st

With the Abprüf-start circuit 46 is still a comparison unit 49, in which the current F value of G-transmitter with the field strength minimum value F_{m; "} is compared. If this is below this minimum value F_{mi "}, The Abprüf-start circuit 46 is activated, which in turn outputs a trigger signal to the control device 21st Again, this can be effected in that the comparison unit 49 to down counter 47 immediately sets to zero.

The operation of the radio equipment as described previously is summarized below by way of example:<ul><li>Pressing the SA button on the control panel 18, a channel scan with muting of the speaker 16 is performed in the tuning control device 12th The first FM station found is identified by its broadcast frequency in the transmitter identification device 19 and selects all A transmitter for this identified stations in memory 20th After the mute 17 is put out of function and the station will be heard as G-transmitter. By sample and hold circuits 24,25 which receive field strength F and the freedom from interference S are at the G-transmitter continuously sampled, digitized, the mean values ​​and the values ​​of the address at which the G-station can be accessed in the main memory 20, in the averaging memories 32 and 33 enrolled. As long as the current F value of G-transmitter on the field strength minimum value F_min (Comparative unit 49) and the current value of S-G-transmitter is not below the predetermined upper threshold S_Max drops (comparator 48) only this ongoing review of the G-station is performed.</li></ul>

Deteriorates now the reception quality of the G-station in such a way that the current S-value slightly below the upper threshold S_Max decreases, so a triggering signal is given to the control device 21 after a time delay of 30 s from the start circuit Abprüf 46th This searches in the main memory 20 an alternative station, and in the order of falling reception field strength, enables Mute 17 for 20 ms, and causes the tuning control device 12 to tune the tuner 11 to the new transmission frequency of the A station. Of the sample and hold circuits 24,25 now the reception field strength F and the freedom from interference S of the narrow set A transmitter is scanned, digitized the sample and the mean values, the. At the same address in which the A channel can be called in the main memory 20, are stored in the two Mittelwertspeichem 32.33. The check logic 35 of the comparator 34 performs now by comparing the above-described F, S, F -and- S values ​​of the A-channel and the G-station. If the G-station is detected as best receiving, so causing the control device 21, the transmission setting means 12 to tune the tuner 11 to the transmission frequency of the G-station. Activating the mute 17 is repealed. This test carried out in a silent phase of 20 ms operation is not perceived by the listener. As before, he will hear the G-transmitter during this process described.

After another 30 s -or- if the S value of the G-station now located to the lower threshold S_min has toward deteriorated after only 5 s -Is the Abprüf-start circuit 46, a new trigger signal 21 to the control device, this enables Mute 17 and calls from the main memory 20, the transmission frequency of a new A-transmitter from causing the transmission setting means 12 the tuner 11 tune to this transmission frequency. Again, the reception field strength F and the freedom from interference S of the new A-station are scanned, ie samples digitized, the mean values ​​and the values ​​of the next address where also the new A transmitter in the main memory 20 can be accessed, in the mean-Save 32.33 stored. Again, the comparison operation described is carried out. While the G-station is output as best receiving, the Abprüfmodus described with one another A-stations repeatedly. However, if the checked-A transmitter as identified, a best, then raises the control device 21 only the activation of the Stummschaitung 17 and the tuned in the tuner 11 A transmitter is switched into place. He now forms the new G-sender.

If the reception quality of the G-station and all available A transmitter continuously bad, which means that either the F-value of all stations under the field strength minimum value F_min is or the S value of all channels continuously below a predetermined minimum value S _min the average value of Störfreiheitsmaßes lies or both occur, then an update of the A transmitter, ie it is an attempt to identify receivable at the current receiving point of the radio device new alternative transmitters and insert into the table of A-channels. To this end, a A transmitter-Fort write circuit 50 is provided, which then generates a re-determination of A-chemi- by the transmitter identification device 19 triggering start signal when the F value and the 3 value of the G-transmitter continuously below the respective minimum value F_min or S _min lies. The frequency of the starting signal generation is the number of standing in Table A-station, so the number is marked in the main memory 20. A transmitter, inversely dependent.

Such an Fort write circuit 50 may (down counter) 51 are implemented in conjunction with two comparators 52 and 53 by a presettable down counter. The F-comparator 52 compares the current F-value with the predetermined field strength minimum value F_min and the 3 - Comparator 53 compares the average S of the G-station with the predetermined StörfreiheitsmaßMinimalwert S _min, The outputs of the two comparators 52,53 are connected to the counting input of the down-counter 51st Via the control device 21 of the counter 51 Runter- is preset to a number which is inversely proportional to the number of labeled in the main memory 20. A transmitter. Each output of the comparator 52.53 Now the Runter- counter 51 is decremented until he gives a start signal to the controller 21 when the counter reaches zero. In this start signal activates the control device 21 mute 17 and the transmitter identification device 19. The latter determines a new table received at the current location of the radio device A transmitter or complements the existing A-Channel table to newly added A transmitter. Mute will be doing for a long time - activated (seconds).

The invention is not limited to the embodiment described above. Advantageously, the control device 21, the transmitter identification device 19 and the test circuit 22 with the comparison circuit 34 and the Abprüf start circuit 46 as well as the alternative Fort write circuit 50 can be realized by a microprocessor.