Classifications

• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
  • H03J1/00—Details of adjusting, driving, indicating, or mechanical control arrangements for resonant circuits in general
  • H03J1/0008—Details of adjusting, driving, indicating, or mechanical control arrangements for resonant circuits in general using a central processing unit, e.g. a microprocessor
  • H03J1/0058—Details of adjusting, driving, indicating, or mechanical control arrangements for resonant circuits in general using a central processing unit, e.g. a microprocessor provided with channel identification means
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N5/00—Details of television systems
  • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
  • H04N5/50—Tuning indicators; Automatic tuning control

Definitions

• the invention relates to a method for detecting a channel, on which a video signal receiver that can be set to a plurality of freely selectable channels is set, wherein
• the selectable channels are set successively with a reference tuner and the corresponding video signals are determined with a demodulator
• At least one reference signal component is extracted from each determined video signal and c) the at least one reference signal component is compared with a corresponding measurement signal component which has been derived from at least one signal tapped at the video signal receiver.
• the invention further relates to a device for carrying out the above.
• Systems for the virtual recording of ratings are known for the purposes of demoscopic TV viewer research.
• these systems comprise a large number of devices which monitor the home devices of television viewers on site and which are connected to the central computer via a telephone line.
• the devices are installed in consultation with the TV owner. As a rule, they require galvanic contacting of individual, selected television internal conduction paths. More recently, surveillance devices have been proposed which do not require intervention in the television set.
• a monitoring device is known from EP 0 064 847, which electrically compares a signal induced in a sensor with a second signal which has been determined by a controlled receiver. If the signals match, the channel is considered to be recognized and is stored in a memory. If there is no match, the controlled tuner is switched to other selectable channels. until coincidence occurs. In order to be able to compensate for phase shifts between the signal picked up on the television and the signal determined with the controlled tuner, a special circuit with a monostable flip-flop is used.
• a television monitoring device is known from US Pat. No. 4,764,808, which scans the horizontal beam deflection signal of the television tube by means of an inductive sensor and determines its frequency. This measurement signal is compared with stored frequencies for the purpose of assigning the signal displayed on the screen to a broadcaster.
• the basic idea of this known system is that the line signal in the broadcaster is derived from a highly stable quartz oscillator and that the inevitable, individual mutual deviations in the ppm range can be used to uniquely identify the broadcaster.
• the problem now is that the deviations are in a range of ⁇ 10 Hz in relation to approx. 3.57 MHz.
• EP 0 382 996 A1 discloses a method for recording the television habits of a test population.
• the carrier frequency of the channel switched on in the TV set is determined on site with a telecontrol device and passed on to a central computer.
• the carrier frequency is scanned on the video tuner with a sensor.
• a method is also described which is suitable for storing channel identification data in VHS and Betamax video recorders.
• the data is written with the CTL head or read, which is known to be necessary for the synchronization of the video images and reads synchronization pulses from the corresponding CTL track.
• the data are stored sequentially between the synchronization pulses.
• the object of the invention is to provide a method of the type mentioned at the outset which can identify any number of channels with great certainty and very quickly. - o -
• the solution is that all selectable reference signal components are buffer-stored in a memory and renewed there cyclically and repetitively, and that the measurement signal component is compared with all temporarily stored reference signal components for the purpose of identification.
• the essence of the invention therefore lies in the fact that the comparison of measurement and reference signal components no longer takes place in real time, but at least partially “decoupled” using a buffer memory. It is important that the memory content is not fixed once and for all, but is renewed cyclically.
• the flywheel principle is thus used: the temporarily stored signal components (“flywheels") are kept in cyclical “scanning" of the channels in “step” with the signal components transmitted in the channels (ie they are kept “as it were” ").
• An important advantage of the invention is that all reference signal components are always available for comparison.
• the settling time that the reference tuner requires per channel is largely decoupled from the other process steps. This makes it possible to accelerate the correlation steps.
• the at least one reference signal component per channel comprises the phase and preferably additionally the frequency of the time lens synchronization signal.
• the phase or Frequency is measured against an internal, frequency and phase stable comparison signal. As a rule, monitoring of the phase is sufficient. However, it can happen that special frequencies have to be checked separately or that large frequency differences exist.
• the phase and preferably the frequency of the picture frame synchronization signal is additionally recorded as the reference signal component for each channel.
• the line synchronization signal can be determined relatively quickly on account of its relatively high frequency and enables a larger number of channels to be distinguished well on average. Distinctness is significantly increased if the image or Field frame synchronization signal is used. The probability that two channels coincide with their picture frame synchronization signals is extremely small. But the time to determine the phase position and / or the frequency is a lot longer.
• a time-defined section of a beam current signal tapped at the video signal receiver is correlated with a corresponding signal part of the reference tuner set to a selected channel.
• one or more picture lines of the video signal determined with the reference tuner and the picture signal picked up at the video signal receiver are correlated.
• the correlation process is relatively complex. However, since it is only carried out in the sense of an optional, second stage in the invention, the correlation is rarely and if so, only carried out against selected channels. The optional second step only slightly increases the time it takes to identify a channel.
• the picture frame synchronization signal is used in addition to the line synchronization signal, a three-stage procedure can be used. In such a case, the image signal correlation used as the last stage should be required very rarely.
• VPS signals present in the video signals are temporarily stored in the mentioned or another memory in order to assign the selectable channels to broadcasters in addition to the reference signal components.
• the stored data are queried from a central computer via a modem.
• the stored data include the times and identification codes of the active channels and the VPS signals mentioned. broadcasting station codes obtained therefrom. This has the advantage that the channel assignment can be easily determined and kept up to date. If television sets are monitored by a central computer, which are attached to different communal antenna systems with different channel assignments, then the channel information transmitted by the respective monitoring device must be matched by means of concordance lists. Will be in a Ge Community antenna system, the channel assignment changed, this must be in the central computer tracked the same time, 'otherwise might arise errors.
• the inventive Monitoring of the VPS signals enables automatic updating of the aforementioned concordance tables.
• the signals at the video signal receiver are preferably tapped without contact, in particular with capacitive or inductive sensors. An intervention in the circuit of the device is therefore unnecessary.
• a device for carrying out the method for recognizing the channel comprises a reference tuner that can be set to all available channels, a switching arrangement for deriving the at least one reference signal component from the respectively set channel, first means for tapping at least one signal at the video signal receiver and one Arithmetic circuit for determining the at least one measurement signal component from the at least one tapped signal and second means for comparing measurement and reference signal components.
• a characteristic of this facility is a Memory for temporarily storing the reference signal components.
• the control of the device is carried out by a computing processor which processes a stored program which contains the method steps according to the invention.
• VCR video recorders
• the video recorder emits the antenna signal at its input essentially unchanged (ie apart from any constant amplification) so that a television set can be connected in series. In this way it is possible to record or view different programs at the same time.
• the broadband RF signal to be supplied to the television set is preferably inversely modulated with respect to the modulation of the antenna signal (supplied to the video recorder) in order to avoid or avoid asynchronous interference in the non-recorded channels. to eliminate.
• the antenna signal is amplitude modulated in broadband, which means that the signal amplitudes change in all channels.
• the amplitude modulation which is synchronous with respect to a single channel thus simultaneously represents an asynchronous disturbance for the other channels.
• the current television standards CCIR, PAL, SECAM contain picture and synchronization content in the amplitude modulation and the sound content in the frequency modulation.
• the entire antenna signal is weakened over a broadband range (or raised). All channels are therefore simultaneously modulated in terms of amplitude. Since the amplitude modulation is synchronous with respect to what is to be recorded or recorded video signal resp. Channel, the data can be stored together with the video signal in a manner that does not interfere with the sound and image reproduction.
• the data are advantageously modulated in synchronism with an intermediate picture line of the recorded video signal, the selected intermediate picture line should have a high blanking of black.
• the intermediate image line is a line that is not displayed on the screen.
• the antenna signal is for the purpose of modulation weakens ask ⁇ and amplifies the "output by the VCR RF signal equalization in order accordingly.
• the data recording does not interfere with the operation of the devices and is both invisible and inaudible. Neither the recording nor the reproduction of the signals are impaired in terms of quality. This also applies to the continuous video channels. Finally, the security of the data recording is not reduced by level differences in the antenna signal.
• the data can be easily extracted from the video signal output from the VCR during tape playback.
• a device for carrying out the data recording method is between the video recorder on the one hand and the antenna connection or. TV on the other hand switched. She points
• the method for recording digital data is preferably used in combination with the method for recognizing a channel, but in principle also on its own. can be used to record other types of digital data.
• FIG. 1 shows a block diagram of an advantageous channel recognition device according to the invention
• FIG. 2 shows a block diagram of a switching arrangement for recording digital data using a video recorder
• 3a-i are schematic time diagrams for explaining the modulation and equalization method according to the invention. Ways of Carrying Out the Invention
• the aim of a commercially available television set 1 is to identify the channel to which the device is set as far as possible without intervention.
• the television set 1 mentioned is one with a Braun tube.
• An electron beam is in a picture tube 2 by means of deflection magnets 3 and 4 for the horizontal and. vertical deflection controlled.
• a beam current generator 5 controls the current of the electron beam, as a result of which different pixels are generated on the screen.
• the deflection magnets 3 and 4 are controlled by a deflection magnet control 6.
• the RF signal present at the input 9 is filtered out with a TV tuner 8, a specific channel whose video signal is demodulated in a demodulator 7.
• the television set 1 is a well-known device and its detailed structure is of no further interest for the invention, the components mentioned above are only indicated schematically.
• the only thing of interest for the invention is the fact that the deflecting magnets 3 and 4 and the beam current of the beam current generator 5 generate electromagnetic stray fields which can be scanned on the outside of the housing with suitable sensors.
• a composite signal output 17 which is present in certain, but not all, television sets.
• the video signal of the channel to which the television set 1 is switched on is output on this.
• the television set 1 is - as is common today - connected to a video recorder 10 via a cable.
• the video recorder 10 includes, among other things, a signal recording device 11, a tuner 14 and a demodulator 13.
• the tuner 14 is connected to a signal input 15 which can be connected to an RF source 18 (television antenna, cable connection, satellite antenna, etc.).
• the video recorder 10 also has a signal output 16 for connecting the television set 1.
• Video recorders also have a composite output 17.
• television set 1 and video recorder 10 are monitored using the device described below.
• a reference tuner 20 is connected to a signal input 19 of the monitoring device, which in turn is connected to the RF source 18.
• the reference tuner 20 is controlled by a control computer 33.
• a demodulator 21 demodulates the channel to which the reference tuner 20 is set.
• the video signal is available in a standardized form known per se.
• Reference tuner 20 and demodulator 21 are designed in a conventional manner. The difference between the components mentioned and those in the television set. Corresponding circuits provided in the video recorder at best consist in the higher quality of the processed signals.
• the video signal of the demodulator 21 is fed to a signal processing circuit 22.
• This extracts on the one hand line and picture frame synchronization signals (horizontal and vertical deflection signals) and on the other hand a line-oriented picture signal (beam current signal).
• the phase position and preferably also the frequency of the line synchronization signal are determined using the reference signal.
• the reference signal has e.g. B. a frequency which corresponds to the mean expected frequency of the line synchronization signals belonging to different channels.
• the phase is e.g. B. determined by measuring the time that elapses between predefined edges or zero crossings with an internal, very fast counter.
• the phase and frequency are stored in a predefined manner in the form of digital characteristic values in a memory 23.
• the picture frame resp. Field frame synchronization signal is advantageously processed in the same way.
• the phase and frequency of this signal are also preferably buffered.
• the memory 23 has a sufficient number of memory cells 23.1, ..., 23.N.
• the memory 23, like the signal conditioning circuit 22, is controlled by the control computer 33, the relevant process steps being described below.
• An inductive sensor 34 which is attached to the outside of the housing of the television 1 at a suitable location, detects the scatter signals of the deflection magnets 3 and 4.
• Another capacitive sensor 35 also attached to the housing of the television 1 at an appropriate location, detects the beam current.
• a sensor 36 for inductively tapping the erase coil signal is also attached to the video recorder 10. The signals from the sensors 34, 35 and 36 are amplified by 25, 26 and. 28 reinforced.
• An amplifier 27 respectively. 29 amplifies the composite signal output 17 and. 12 of the TV 1 respectively.
• Video recorders 10 tapped video signal on a plug. The gain factors can be regulated by means of the control computer 33 in order to adjust the levels of the signals.
• the amplified sensor signals of the sensor 34 (horizontal and vertical deflection) and the sensor 35 (beam current signal) are fed to a signal processing circuit 24 together with the composite video signals that may be available. This reconstructs from the measured signals measurement signal components, which the on the television 1 or.
• Video recorder 10 set video signal.
• the phase and additional frequency of the line and frame synchronization signal of the video signal to be determined are determined.
• the quench coil signal obtained by means of the sensor 36 is displayed to the control computer 33. It is sufficient to state its presence.
• the amplifier 28 therefore preferably comprises a discriminator which only responds to the erase coil signal and thereby performs the desired function.
• a correlator 31 is provided.
• Another correlator 30 is used for "the all réelle required comparison of the image, respectively. Beam current signals.
• the er ⁇ with the correlators 30 and 31 mediated results are supplied to the control computer 33.
• This has a memory 37 (RAM, Magnet Eat ⁇ plate, tape, etc. '), in which the desired data (e.g. the active channels registered at certain times, the VPS code, the recording by video recorder etc.) are stored until they are transmitted to a central computer via modem 39 and telephone line.
• a VPS decoder 32 determines and decodes a VPS signal that may be present in the video signal. This or an identification code derived therefrom is fed to the control computer 33. It is particularly advantageous to also temporarily store the identification code in the memory 23 and to keep it up to date.
• All parts of the monitoring device are clocked by a high-precision clock signal generator 38.
• the RF source 18 provides a larger number of channels that are in a predefined frequency range. With the device according to the invention, these channels are scanned systematically and cyclically. Starting e.g. B. at the bottom of the frequency range, the tuner is successively adjusted to the existing channels. Circuits that enable such a so-called scanning are well known.
• the video signal is demodulated in each channel and the corresponding reference signal components are extracted with the signal conditioning circuit 22.
• a memory area (memory cell 23.1,..., 23.) is assigned to each channel for the intermediate storage of the determined phases and frequency values.
• the reference tuner 20 is switched to the next channel.
• the upper limit of the frequency range has been reached, all the existing channels are scanned once and the associated frequency and phase values (of the picture frame and / or line synchronization signals) have been stored.
• the scanning of the channels is now not ended. Rather, the reference tuner 20 is reset to the lower limit of the frequency range and a new run is carried out.
• the phase and frequency values determined in the second and each subsequent run are again buffered in the memory 23.
• the old values are overwritten. As a result, the values are updated cyclically and repetitively and kept up to date.
• the age of the data results from the time required to scan the entire frequency range. With a small number of selectable channels, this may e.g. B. be in the range of a few seconds. The greater the number of available (i.e. receivable) channels, the greater the time required for a run.
• the stray fields of the deflection magnets 3 and 4 are measured with the sensor 34. These contain the information required according to the invention about the line and picture frame synchronization signal. That is, their frequency and phase.
• the latter characteristic values are extracted with the signal conditioning circuit 24.
• the image signal can be obtained in the signal conditioning circuit 24 (with the aid of the sensor 35 and the amplifier 26) from the stray field of the beam current.
• the image signal can also be processed in the preferred line-oriented manner, since the line synchronization pulses (via sensor 34) are available. If the video signal can be tapped at an existing composite signal output 17, then the relevant measurement signal components are extracted in the same manner as in the signal conditioning circuit 22.
• the sensor signals (sensors 34 and 35) can then be dispensed with. In any case, a video signal is supplied by the video recorder 10.
• the identification of the unknown channel is as follows.
• Image frame synchronization signals are determined with respect to the same reference signal that is also used in the signal conditioning circuit 22.
• the above-mentioned characteristic values are now compared step by step with the corresponding characteristic values of the various channels scanned by the reference tuner 20 and stored in the memory 23.
• the step-by-step comparison is carried out by correlator 31. Whenever a ausrei ⁇ -reaching About 'conformity is found, this is the Steuer ⁇ computer 33 signals.
• the synchronization signals of the channel set on the television 1 can be uniquely and exclusively assigned to one of the channels sampled by the reference tuner 20 and temporarily stored in the memory 23.
• the control computer 33 takes the name of the selected channel from the memory 23 and stores it together with the measurement time in the memory 37. If available, the VPS signal or an identification code derived therefrom is also stored. The channel detection is thus successfully completed and can be repeated at a predetermined point in time.
• the correlator 31 finds two or more significant matches. This means that the channel cannot be identified because two or more channels happen to have the same synchronization signals.
• an optional second step ie a correlation of the picture signals or. the beam current signals are carried out.
• This correlation is carried out with the correlator 30.
• the reference tuner 20 is set on the first of the selected, indistinguishable channels in order to use the corresponding image signal with the signal obtained by means of the sensor 35 or picked up at the composite signal output 17. to be able to compare the extracted image signal.
• Whole lines are preferably correlated. Typically fewer than 20 lines, in particular 10-15 lines, are correlated. Depending on the algorithms used to perform the correlation, a single line may suffice.
• the reference tuner 20 is set to the next selected channel. This continues until a significant match is found. Since the probability that two different ones of the selected channels are indistinguishable on the basis of their image signals is negligibly small, it can be dispensed with, if there is a significant match, also the remaining selected ones, but not yet checked Correlate channels.
• the channel identified in the second step is stored in the memory 37 as already described.
• The. Identification has been successfully completed here too.
• no identity can be ascertained either in the first or in the subsequent second step.
• This case can be intercepted in advance in a simple manner. For this purpose, it is determined whether the line jitter characteristic of the playback of video tapes is present. This information can be supplied from the signal conditioning circuit 24 to the control computer 33.
• the channel detection is repeated in a predetermined time rhythm.
• a suitable rhythm would be e.g. B. the second rhythm, which can be realized with the invention without problems.
• the content of the memory 37 can be queried from a central computer via telephone line and modem 39.
• the switching arrangement described is preferably implemented by means of a programmable microcomputer.
• the described embodiment can be modified in various aspects.
• the invention is limited to: B. not on the scanning by means of inductive sensors. Rather, the desired measurement signal components can also be tapped by conventional galvanic contacting.
• Other sensors in particular optical sensors (glass fiber sensors etc.) can also be used.
• Decoding the VPS signal is of course optional.
• codes which have not yet been standardized can be evaluated for the purposes of the invention. Coding is used to identify the manufacturer of a shipment.
• the invention enables a very fast 'channel detection on television receivers and video recorders. Since the 'selectable channels are constantly monitored by the reference tuner, the precipitation of a particular channel may also so ⁇ equal found even if the TV resp. the VCR is not tuned to this disturbed channel. The reliability of a communal antenna system or a cable network can thereby be checked in a simple manner.
• FIG. 2 shows a block diagram of a corresponding switching arrangement.
• An intermediate device 41 with its input 45 is connected to an antenna 40.
• An output 47 of the intermediate device 41 is connected to an RF input 57 of a video recorder 42.
• An RF output 58 which emits the essentially unchanged input signal of the RF input 57 (except for any constant gain), is connected to a second input 50 of the intermediate device 41.
• a television 43 is connected to a second output 48 of the intermediate device 41.
• a channel detection device 44 is connected to a data port 56 of the intermediate device 41 and outputs the data to be recorded.
• the antenna signal (a) is a superimposition of all channels received. It is modulated in a broadband pulse modulator 46 with the data to be recorded. For this purpose, the broadband antenna signal is amplified in accordance with the data. moderately weakened (see signal b). The weakening takes place synchronized with respect to the recorded video signal, which is filtered out, demodulated and recorded with a tuner 60 in the video recorder and simultaneously output as a composite signal at the output 59. This contains both the synchronization signals and the entire image content including intermediate image information such as teletext, VPS and standard test signals.
• the intermediate device 41 comprises according to the invention, a Sehaltan Aunt with a video splitter '52, ⁇ which is Nals synchronized to a predetermined intermediate image row (row pulse Z,) of the Aus ⁇ gear 59 and delivered at the input 51 Videosig ⁇ .
• this synchronization can be carried out according to methods which are known per se and are customary in television sets.
• the relevant synchronization pulse (i) is delivered to a control module 53. On the one hand, this reads the data to be modulated (h) and on the other hand controls the broadband pulse modulator 46 and the broadband equalizer 49 with control signals (c) and. (f) via lines 54 and 55.
• the weakened antenna signal in the broadband pulse modulator 46 passes essentially unchanged through the video recorder 42 (via HF input 57 and HF output 58) and reaches the broadband equalizer 49, which is controlled in such a way that the amplitude reduction caused by the amplitude modulation is completely undone. This is illustrated in FIG. 3 on the basis of signals (d) to (f).
• equalization is not necessary if only the video recorder is running (ie the television set is not used) or if the program recorded by the video recorder is also viewed simultaneously on the television 43.
• intermediate image information is clearly separated from the visible television image, which is why the data modulation according to the invention does not impair the quality of the recorded video signal.
• the amplitude modulation with the broadband pulse modulator 46 results in asynchronous interference.
• the channels are in no way correlated with one another.
• the broadband attenuation therefore has an undesirable change in the image or Synchronization content of those channels to which the amplitude modulation is not synchronized.
• an annoying white line will appear in the picture on an a priori unknown line. This disturbance is caused by equalization.
• inverse modulation of the RF signal emitted from the video recorder 42 to the television set 43 is canceled.
• the weakening resp. Equalization is preferably on the order of 10 dB.
• the data pulse which is preferably introduced into an intermediate picture line with high black blanking, is stored together with the video signal on tape.
• it is sufficient to save one bit per picture.
• larger data rates can also be implemented without problems.
• the content of the data pulses preferably contains the information determined using the channel recognition method and relevant for viewer research.
• the recovered data information is stored by the acquisition system for evaluation.
• the channel detection and storage method are preferably used simultaneously.
• the intermediate device contains all the necessary circuits and is also equipped with the sensors and a modem. Of course, the two methods can also be used independently of one another.
• the preferred data recording method according to the invention allows data to be recorded together with a video signal on tape, neither the picture nor the sound quality of the original signal being impaired. It is also applicable without any intervention in a video recorder.

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• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Television Signal Processing For Recording (AREA)
• Testing, Inspecting, Measuring Of Stereoscopic Televisions And Televisions (AREA)

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• 1993
  • 1993-05-18 WO PCT/CH1993/000126 patent/WO1993023953A1/de not_active Application Discontinuation
  • 1993-05-18 JP JP5519747A patent/JPH06508738A/ja active Pending
  • 1993-05-18 EP EP93911724A patent/EP0596086A1/de not_active Withdrawn

Non-Patent Citations (1)

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