JPH0416975B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a channel determination method for measuring audience ratings of satellite broadcasting. (Background technology) Satellite broadcasting began in Japan in 1982, ahead of the rest of the world, and it became possible for each home to directly receive radio waves sent from broadcasting satellites. Currently, there are two channels in total, BS-11 channel and BS-15 channel, but the number of channels is expected to increase in the future.
As a aspect of television viewing, it cannot be ignored in accurately understanding audience ratings. Figure 7 shows the units necessary for receiving satellite broadcasting. 2 is a BS antenna (offset type parabolic antenna) that focuses the radio waves arriving from the broadcasting satellite 1, and 3 is the unit that is reflected by BS antenna 2. receives the focused radio waves and amplifies and converts the frequency for easy transmission.
BS converter, 4 is the coaxial cable for connection,
5 is a BS tuner that demodulates video signals and audio signals. In other words, broadcast radio waves in the 12 GHz band are sent from the broadcasting satellite 1, but if the received signal is simply transmitted via the coaxial cable, the loss will increase, so high frequency amplification is performed in the BS converter 3 and the 1 GHz band is transmitted. Frequency conversion is performed on the band signal, and the signal is transmitted to the BS tuner 5 via the coaxial cable 4. Then, the BS tuner 5 performs conversion to an even lower intermediate frequency and demodulates video and audio. The demodulated video and audio signals are sent to AV (Audio Video) type televisions, video tape recorders, etc. as video signals S _V ,
In addition to being able to directly supply the audio signal S _A , the modulated output signal S _UHF remodulated into 13 channels of UHF can also be extracted so that it can be applied to conventional televisions. Figure 8 shows a connection example when actually viewing using the above-mentioned satellite broadcast receiving unit. This is the case when the video signal and audio signal are directly received via the AV terminal, such as on an AV type television. However, in order to be able to share regular VHF and UHF television signals, the signal from BS tuner 5 is
VHF, UHF antenna with BS/UV coupler 6
The signal from the BS tuner _{5 is mixed with the signal coming from the ANT and input to the antenna terminal T ANT of the} TV _TV . The signal is now input directly. In addition,
Since the audio signal is a stereo signal, there are two sets. By the way, in the current audience rating measurement of VHF and UHF television broadcasting, various signals generated inside the television receiver, such as local oscillation signals, video intermediate frequency signals, audio intermediate frequency signals, etc., are detected and received. However, since the satellite broadcasting receiving system described above includes units other than the television receiver (BS antenna, BS converter, BS tuner, etc.), it is difficult to judge the channel using conventional audience rating measurement equipment. There is a problem that data cannot be detected. In addition, satellite broadcasting uses microwaves in the 12 GHz band, and the signals handled are extremely weak, so there are various technical problems with the configuration of audience rating measurement equipment, such as unstable operation. However, the equipment has become more complex, larger, and more expensive. On the other hand, when used by connecting to a conventional TV as shown in Figure 8A, satellite broadcasting is remodulated and, for example, TV TV is broadcast on 13 channels of UHF.
Therefore, after the viewing of 13 channels of UHF is detected by conventional audience rating measurement equipment, BS is sent to
Channel determination of Channel 5 (satellite broadcasting channel determination) may be performed, but as shown in Figure 8 (b), when using an AV type television, normally,
There may be multiple sets of AV terminals, so
Since it may be used as a monitor for a video tape recorder or a personal computer, it is necessary to detect what is actually being watched, i.e. which AV terminal is being used. Therefore, a new function called AV terminal detection has become necessary. (Objective of the Invention) The present invention has been proposed against the above background, and its purpose is not only to be able to judge channels of satellite broadcasting, but also to satisfy the characteristics imposed as an audience rating measurement device, such as home use. The purpose of the present invention is to provide a channel determination method for measuring audience ratings of satellite broadcasting that satisfies the following requirements: making as little modification to the internal equipment as possible, being able to perform stable measurements, being simple and compact, and being low cost. . (Structure of the Invention) The present invention will be described in detail below with reference to the drawings showing examples. Note that the symbols attached to the signal terminals in the drawings refer to the terminals themselves, and also represent the signals generated at the terminals. FIG. 1 is a block diagram showing an embodiment of a satellite broadcasting channel determination circuit embodying the present invention. To explain the configuration in the figure, a BS converter 3 is provided at the focal position of the BS antenna 2,
The output b of this BS converter 3 is the coaxial cable 4
It is connected to a BS tuner 5 via a power on/off detector 7 and a distributor 8, and a television TV is connected to the BS tuner 5. Here, the distributor 8 is provided to detect the local oscillation signal generated inside the BS tuner 5, and the local oscillation signal has a larger amplitude than the received signal of satellite broadcasting and is difficult to use in general circuits. BS because the frequency is higher than that
Leakage from inside the tuner 5 inevitably occurs, and can be easily detected by distributing a portion of the signal from the coaxial cable 4 connecting the BS converter 3 and the BS tuner 5. On the other hand, there are two ways to connect the BS tuner 5 and the TV, as shown in Figure 8 (a) and (b). In addition, the power on/off detector 7 detects the operating state of the receiving system, and the BS
By detecting the DC power supply voltage for circuit operation that is applied from the tuner 5 to the BS converter 3 via the coaxial cable 4, it is possible to determine whether the power is on or off. Next, the other output terminal d of the distributor 8 is inputted to an image reorganization mixer 10 via a low noise amplifier 9.
Here, image rejiexion mixer 10
mixes the oscillation signal l given from the variable frequency oscillation circuit 21 , which will be described later, and the input signal i to convert it into an intermediate frequency signal for measurement. This circuit has the characteristic of extracting only the desired side and greatly attenuating the image signal. Its configuration is that an input signal is given to one input terminal i,
A 90° hybrid coupler 11 whose other input terminal is grounded via a resistor R, a power divider 14 that divides the oscillation signal l from the variable frequency oscillation circuit 21 by in-phase and same amplitude, and a 90° hybrid coupler 11. mixers 12 and 13 that mix the two outputs j and k of the power divider 14 and the two outputs m and n of the power divider 14, respectively, and input the outputs o and p of these mixers 12 and 13 to two input terminals, respectively. 90° hybrid coupler 15, and an intermediate frequency signal is obtained from one output terminal r of this 90° hybrid coupler 15. Note that an image signal is obtained from the other terminal q of the 90° hybrid coupler 15. Next, image rejiexion mixer 1
The output of 0 is passed through a narrow band intermediate frequency amplification circuit 16 consisting of a band pass filter 17, an amplifier 18, and a gain controller 19, and then sent to a detection circuit 2.
0 and is converted into a direct current signal according to the amplitude of the output signal of the intermediate frequency amplification circuit 16 . In addition, image rejiexion mixer 10
The variable frequency oscillation circuit 21 provides an oscillation signal l for frequency conversion to the output signal u of the detection circuit 20.
a counter 22 whose step start or stop is controlled by the output of the counter 22; a tuning voltage generator 23 which generates a tuning voltage corresponding to a predetermined broadcasting channel by the output of the counter 22; A voltage controlled oscillator 24 generates a signal of a corresponding frequency, and the binary output of the counter 22 is the channel data.
It is now being extracted as D _CH . Further, the counter 22 is supplied with a signal v from the power on/off detector 7, so that channel determination is not performed when the satellite broadcast receiving system is not operating. FIG. 2 shows how the distributor 8 detects the local oscillation signal in the BS tuner 5, and the same parts as in FIG. 1 are given the same reference numerals. However, the front stage of BS tuner 5 is preamplifier 5.
a, the mixer 5b and local oscillator 5c convert the frequency to the second intermediate frequency, but the oscillation output (local oscillation signal) of the local oscillator 5c is sent from the BS converter 3. Since the received signal is larger than that of the received signal and has a higher frequency of about 1 GHz than that of a general circuit, it leaks back through the mixer 5b, preamplifier 5a, and distributor 8, and the output b of the distributor 8. contains a considerable amount of local oscillation signal g. In addition,
The actual frequency relationship between the signals of each part is shown in the table below. [Table] [Table] In the table, CHANNEL is the broadcasting channel number, CENTER FREQ is the center frequency of each channel of radio wave a transmitted from broadcasting satellite 1,
FREQ, BAND is the frequency band, BS-IF is BS
The center frequency of the intermediate frequency signal b after frequency conversion by the converter 3 (it is lower than the broadcast radio wave by a certain frequency and differs for each channel),
2nd-IF is the frequency of the second intermediate frequency signal h after frequency conversion inside the BS tuner 5 (currently, two frequencies have been tentatively decided, and it varies depending on the manufacturer or model), and LOCAL is the frequency shown above. This is the frequency of the local oscillation signal g that must be oscillated by the local oscillator 5c to obtain the second intermediate frequency. To explain the operation, returning to FIG. 1, the signal d containing the local oscillation signal g inside the BS tuner 5, which is extracted by the distributor 8, is amplified by the low noise amplifier 9, and then subjected to image reorganization. - Variable frequency oscillation circuit 21 in mixer 10
is mixed with the oscillation output signal l and converted into an intermediate frequency for measurement. Although the intermediate frequency is not particularly limited, it is set to 20MHz in the actual circuit, so the variable frequency oscillation circuit 21
It outputs an oscillation signal in the range of 1.20374~1.74078GHz. Figure 3 shows image rejiexion mixer 1 .
0, the signals input to one end i of the 90° hybrid coupler 11 appear at the output terminal j with the same phase, and appear at the output terminal k with a phase difference of 90°. Further, the signal l applied to the power divider 14 appears at the terminals m and n with the same phase and amplitude, and the mixers 12 and 13 output the signals j and
Mixing is performed with k. Therefore, the phase relationship of the signals o and p applied to the input terminal of the 90° hybrid coupler 15 on the output side changes depending on the magnitude of the frequency of the input signal i and the oscillation signal l. An intermediate frequency signal corresponding to the desired signal, which is lower than the signal l by the frequency difference, always appears at the output terminal q, and a higher image signal appears at the output terminal q. Figure 4 shows the above relationship, and in A, the local oscillation signal L _p (signal l)
Two signals separated by an intermediate frequency above and below
After RF ₁ and RF ₂ , RF ₁ is the desired signal, and RF ₂ is an image, but as shown in (b), the respective intermediate frequency signals IF ₁ and IF ₂ appear as a difference of 20 dB or more at the terminal r. Generally, to remove an image to this extent requires a configuration such as a three-stage heterodyne, which results in a very complicated circuit, but by using an image redirection mixer, sufficient image removal can be achieved with a simple configuration. This can be achieved with small size and low cost. Next, image rejiexion mixer 1
The output of 0 is given to a narrow band intermediate frequency amplifier circuit 16 set to the intermediate frequency for measurement, and when the signal frequency-converted by the image reorganization mixer 10 falls within that band, the signal is output to the output terminal t. appears, and the output of the detection circuit 20 becomes high level. On the other hand, the counter 22 of the variable frequency oscillation circuit 21 receiving the output signal u of the detection circuit 20 continues to step while the signal u is at a low level and sequentially changes its binary output in a binary manner. When becomes high level, it stops advancing and maintains that state. Then, the tuning voltage generator 23 is connected to the counter 22.
The voltage controlled oscillator 24 generates a predetermined voltage signal for each channel according to the binary output given from the oscillator 24, and outputs a signal of a predetermined frequency. Therefore, the frequency of the output signal of the voltage controlled oscillator 24 is set to have a certain difference (passage frequency of the intermediate frequency amplifier circuit 16 ) from the local oscillation signal generated when the BS tuner 5 captures each channel. Therefore, when the output of the counter 22 scans all channels and the channel actually received by the BS tuner 5 matches the channel selected by the output of the counter 22, a signal is output to the output of the intermediate frequency amplification circuit 16 . Then, the output signal u of the detection circuit 20 becomes high level, and the counter 22 stops advancing. Therefore, the binary output when the counter 22 stops advancing represents the receiving channel of the BS tuner 5, and is taken out as channel data D _CH . Next, FIG. 5 shows an example of a specific configuration of the variable frequency oscillation circuit 21. In FIG. In the figure, the oscillation output of the voltage controlled oscillator VCO is sent to the power divider 14 side as a signal l, and
Via the frequency divider DIV consisting of elements such as ECL
PLL synthesizer (IC such as TC9125BP)
is used. ) is now input to SYN. Note that the reason for providing the frequency divider DIV is to match the signal frequency to the reference frequency of the PLL synthesizer, and because the oscillation frequency is extremely high at around 1 GHz.
This is to facilitate handling and to be compatible with commercially available parts. Then PLL synthesizer
The output signal of the SYN phase comparison is applied to a low-pass filter LPF, which
Voltage controlled oscillator VCO with LPF output as control voltage
It is beginning to be given to On the other hand, ROM is a memory that provides data for setting the frequency to PLL synthesizer SYN,
Data output terminals D ₁ to _{D 4} are PLL synthesizer SYN
is connected to the input terminal of the programmable divider. Also, the memory ROM address pin
A ₁ to _{A 4} are the output terminals Q ₁ to _{Q 4} of the counter (decimal counter) CNT ₁ , and address terminals A ₅ to _{A 8} are the output terminals Q 5 to Q ₄ of the counter (hexadecimal counter) CNT ₂ .
Q ₈ are connected respectively. Furthermore, at present
There are two intermediate frequencies in the BS tuner 5, so
A switch SW is provided at the address terminal _A9 so that it can handle either case, and the setting data can be changed by turning the switch SW on or off. In addition, counter CNT ₁ is for sending data for one channel, and is used as a counter.
CNT ₂ is for channel data output. In other words, since the frequency setting data given to the PLL synthesizer SYN consists of a set of 10 characters, for example, the lower address of the memory ROM
A ₁ to _{A 4} are sequentially changed by a decimal counter CNT ₁ , and after one set of data has been taken in, the counter for channel data output is changed by a carrier.
I am trying to give a clock to CNT ₂ . Furthermore, the NAND gate G is for controlling the clock signal given to the counter _CNT1 .
A clock signal CLOCK from an oscillation circuit (not shown), an output signal v from the power on/off detector 7, and an output signal from the detection circuit 20 (inverted to match the logic) are applied to its input terminals. There is. Note that TIM is a PLL synthesizer
This is a timing signal generator for timing SYN operations. Since the signal applied from the detection circuit 20 is at a high level while the channel is not determined, the clock signal CLOCK appears at the output of the NAND gate G, and the counter _CNT1 increments. Then, 10 pulses are received and the counter
During one cycle of CNT ₁ , frequency setting data for one channel is given from the memory ROM to the PLL synthesizer SYN, and according to this setting data, the voltage controlled oscillator VCO is controlled to oscillate at an appropriate frequency. Then counter CNT ₁
The carry when the count is full is given to the counter CNT ₂ as a clock, and it ups one channel. After that, the same operation is performed until the signal from the detection circuit 20 becomes low level.
That is, all channels are periodically scanned until the channels match. Next, FIG. 6 shows an example of an AV terminal detection circuit when an AV type television is used for receiving satellite broadcasting. The figure shows the case where three sets of AV terminals are provided.
Type TV TV _AV 1st to 3rd AV terminal AV ₁
~ AV ₃ is equipped with BS tuner 5, video tape recorder VTR, and personal computer.
Assume that the PC is connected. Note that the number of AV terminals and the devices to be connected are not limited to these. Now, block 25 indicated by a dashed line is an AV terminal detection circuit, and is an input terminal for audio signals.
T _IN1 , T _IN2 , T _IN3 and output terminals T _OUT1 , T _OUT2 , T _OUT3
have. One of the audio signal output terminals of the BS tuner 5, video tape recorder VTR, and personal computer PC, for example, the left signal terminal, is connected to the input terminals T _IN1 , T IN2, and T IN3, and the output terminal T _OUT1 is connected to the input terminal T IN1, T _IN2 , and T _IN3 . , T _OUT2 , and T _OUT3 to the audio input terminals T _AL1 , T _AL2 , and T _AL3 on the left side of the AV terminal. The AV terminal detection circuit 25 is provided with audio mixers MIX ₁ , MIX ₂ , and MIX ₃ corresponding to the number of AV terminals, and input terminals T _IN1 , T _IN2 , and T _IN3 are connected to one of the input terminals. The output terminals are connected to output terminals T _OUT1 , T _OUT2 , and T _OUT3 , respectively. In addition, audio mixers MIX ₁ , MIX ₂ ,
The other input terminal of MIX ₃ is an analog switch.
The oscillator is connected to the output terminals X ₁ , X ₂ , and X ₃ of ASW, respectively, and is applied to the input terminal
OSC oscillation signals are given in order. Also, the output of the oscillator OSC is the frequency divider DIV _L
The frequency is divided by and given as the clock signal of the counter CNT. On the other hand, the left speaker SP _L of the AV type TV TV _AV
A microphone M is installed close to the microphone M, and the signal detected by the microphone M is passed through a bandpass filter.
BPF _L , the detection circuit DET after passing through the amplifier AMP
A direct current signal indicating the presence or absence of the detection signal is extracted. Note that the sides to which the microphones are attached correspond to the left and right sides of the audio signals connected to terminals T _IN1 , T _IN2 , T _IN3 , T _OUT1 , T _OUT2 , and T _OUT3 .
Then, the output signal of the detection circuit DET is sent to the counter.
It is given to the reset circuit of the counter CNT as a control signal for starting and stopping the step of the CNT. Therefore, while the signal given from the counter CNT detection circuit DET is low level, the frequency divider
It continues to advance with the clock given from DIV _L , and changes the select terminals A and B of the analog switch ASW in binary. This allows the analog switch ASW to be fed from the oscillator OSC.
An oscillation signal of about 20KHz that cannot be heard by the human ear is applied to audio mixers MIX ₁ , MIX ₂ , and MIX ₃ in a time-sharing manner. Now, if AV type TV TV _AV Tatsuchi Channel SW ₁ is selected and BS Channel 5
Assuming that satellite broadcasting is being watched by
Analog switch for audio mixer MIX ₁
The oscillation signal will be detected from the speaker _SPL only when the oscillation signal is applied from the ASW. In addition, the signal detected by the microphone M is configured so that only signals around 20KHz can pass through the bandpass filter BPF _L , and when an oscillation signal is detected, the output of the detection circuit DET becomes high level, and the counter CNT outputs a high level. Progress is stopped.
Therefore, it is possible to detect which AV terminal is being used based on the output state when the counter CNT stops. (Effects of the Invention) As described above, in the present invention, in a satellite broadcast receiving system comprising a BS antenna, a BS converter, a BS tuner, and a television receiver, the BS converter and the BS tuner are connected. By installing a distributor in the middle of the cable, the BS
The oscillation signal leaking from the local oscillator inside the tuner is extracted, amplified and frequency converted, and then added to a narrowband amplifier, where the frequency of the local oscillation signal used for frequency conversion is increased until the output of this narrowband amplifier appears. It changes periodically in response to the broadcast channel, and the reception channel is determined by the tuning point when the output appears, so it can be used not only to determine the channel of satellite broadcasting, but also as an audience rating measurement device. A channel for satellite broadcast audience rating measurement that satisfies the required characteristics, such as minimal modification to household equipment, stable measurement, simple and compact configuration, and low cost. A determination method can be provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a channel determination circuit embodying the present invention, FIGS. 2 to 4 are diagrams explaining its operation, and FIG. 5 is a concrete diagram of the variable frequency oscillation circuit shown in FIG. 1. FIG. 6 is a circuit example of an AV terminal detection circuit, and FIGS. 7 and 8 are explanatory diagrams of a satellite broadcast receiving system. 1...Broadcasting satellite, 2...BS antenna, 3...
BS converter, 4...Coaxial cable, 5...BS
Tuner, 6...BS/UV mixer, 7...Power on/off detector, 8...Distributor, 9...Low/
Noise amplifier, 10 ...Image reflexion mixer, 11, 15...90° hybrid coupler, 12, 13...Mixer, 14...Power divider, 16...Intermediate frequency amplification circuit, 1
7...Bandpass filter, 18...Amplifier,
19...gain controller, 20...detection circuit, 21 ...variable frequency oscillation circuit, 22...counter, 23...tuning voltage generator, 24...voltage controlled oscillator, 25 ...AV terminal detection circuit, ANT …
…VHF, UHF antenna, TV…TV, TV _AV
...AV type TV.

Claims (1)

[Claims] 1. In a satellite broadcast receiving system comprising a BS antenna, a BS converter, a BS tuner, and a television receiver, a distributor is provided in the middle of a cable connecting the BS converter and the BS tuner. The oscillation signal leaking from the local oscillator inside the BS tuner is extracted, amplified and frequency converted, and then added to a narrowband amplifier, where the frequency of the local oscillation signal used for the frequency conversion is increased until the output of this narrowband amplifier appears. A channel determination method for measuring audience ratings of satellite broadcasting, characterized in that the channel is sequentially and periodically changed in accordance with the broadcast channel, and the receiving channel is determined based on the tuning point when the output appears. 2. A channel determination method for measuring audience ratings for satellite broadcasting as claimed in claim 1, wherein frequency conversion is performed by an image reorganization mixer using a 90° hybrid coupler.