JP3713359B2 - Level measuring instrument - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a satellite reception level measuring device that measures the absolute level of a received signal transmitted from an artificial satellite and received by a receiving antenna.
[0002]
[Prior art]
Conventionally, a level measuring device for measuring a signal level received by a receiving antenna has been used in order to measure the electric field strength of a terrestrial television broadcast radio wave or adjust the direction of the receiving antenna. In this type of level measuring device, in order to measure the reception level for each broadcast channel, a channel selection circuit (so-called tuner) is provided for extracting the reception signal of the desired channel from the reception signal from the reception antenna. The reception level obtained by the channel selection circuit is detected and the detection voltage is measured to measure the reception level.
[0003]
In addition, this type of level measuring instrument is used to calibrate the measured value for each measurable broadcast channel in advance so that the measured reception level is not affected by the frequency characteristics of the channel selection circuit or the like. It is also known that the calibration data of the channel is stored and when the reception level of a channel is measured from the detection voltage, the measured value is corrected using the calibration data of the channel (special (See Kaisho 57-157162). According to the level measuring device, the absolute value (absolute level) of the reception level can be accurately measured.
[0004]
[Problems to be solved by the invention]
Recently, satellite broadcasting using artificial satellites such as broadcasting satellites and communication satellites has been put into practical use. And also in the receiving antenna which receives the transmission wave of such an artificial satellite, it is necessary to measure the reception level for adjusting the antenna direction and the like.
[0005]
However, satellite broadcasting includes analog broadcasting and digital broadcasting, and the effective frequency bandwidth and signal waveform per transponder differ depending on the difference in transmission method and modulation method. This is because, in the case of analog broadcasting, frequency components of signals are concentrated at the center of the transmission band, whereas in the case of digital broadcasting, it is evenly distributed within the transmission band. Each transponder can be identified by a transponder number, and the transponder number may be referred to as a channel such as a OO channel. In digital broadcasting, the effective frequency bandwidth per transponder varies depending on the transmission speed such as the transmission bit rate. For this reason, the above conventional level measuring device cannot be used for accurate measurement of the reception level of satellite broadcasting, and measurement is performed using an expensive measuring device such as a spectrum analyzer (so-called spectrum analyzer). It was necessary to convert the measured value into a bandwidth.
[0006]
In other words, the channel selection circuit provided in the conventional level measuring device performs frequency conversion so that the reception signal from the transponder to be measured has a predetermined intermediate frequency among the reception signals from the reception antenna, and the intermediate signal after the frequency conversion. By passing the frequency signal through a bandpass filter, the received signal from the transponder to be measured is taken out, and the effective bandwidth does not take into account that the signal varies. It is impossible to accurately measure the reception level of satellite broadcasting.
[0007]
In the conventional level measuring device, if the bandwidth of the bandpass filter constituting the channel selection circuit is switched, the reception level of the satellite broadcast can be measured, but for the bandwidth switching of the bandpass filter. The circuit configuration becomes complicated. In addition, if the bandwidth of the bandpass filter is set for each transponder for level measurement in this way, the bandwidth switching of the bandpass filter can be performed when the transmission method of the transponder or the transmission speed of the digital broadcast signal is changed. The circuit for must be replaced.
[0008]
The present invention has been made in view of these problems, and the reception level of satellite broadcasting using artificial satellites is affected by differences in analog / digital transmission methods, data transmission speed differences in digital broadcasting, and the like. The purpose is to enable accurate measurement for each transponder.
[0009]
[Means for Solving the Problems and Effects of the Invention]
In the level measuring device of the present invention made to achieve the above object, first, the satellite selecting means is the artificial satellite designated from the outside among the received signals from the receiving antenna for receiving the transmission radio wave of the artificial satellite. The frequency conversion is performed so that the received signal from the transponder becomes an intermediate frequency signal in a predetermined frequency band, and the intermediate frequency signal after the frequency conversion is used, for example, by using a band filter suitable for reception of a standard analog broadcast. A part corresponding to the bandwidth is taken out, and the detecting means detects the picked up intermediate frequency signal. Then, the calculation means corrects the detected voltage based on calibration data set in advance according to the frequency characteristic of the channel selection means, and calculates a reference absolute level. Further, the conversion data for converting the reference absolute level to the display absolute level according to the transmission method of the received signal selected by the channel selection means represents at least the artificial satellite and the transponder that transmit the signal. Storage means for storing together with the identification information is provided. Then, by searching the channel selection conditions such as the satellite name and transponder number given to the channel selection means, the selected reception signal is a digital broadcast signal from the artificial satellite / transponder stored as identification information in the storage means. When it is found, the calculation means reads the conversion data corresponding to the signal from the storage means, further corrects the reference absolute level with the read conversion data, and for the display obtained by the correction The absolute level is displayed on the display means as the reception level, and if the selected received signal is not a digital broadcast signal, the reference absolute level is displayed on the display means as it is.
[0010]
Therefore, according to the present invention, the reception level (absolute level) of the received signal from the desired analog broadcast transponder is not affected by the frequency characteristics of the channel selection means, like the level measuring device described in the prior art page. It can also be measured. Also, even when the bandwidth of the received signal taken out by the channel selection means does not match the transmission bandwidth of the digital broadcast signal to be selected, the reception level (absolute level) of the digital broadcast signal should be accurately measured. Is possible. In addition, when the absolute level for display is displayed together with the conversion data, the measurer has already converted the characteristics such as the transmission method for the received reception level, and needs to convert it further using a calibration table or the like. It is possible to know that there is not, and it is possible to prevent unnecessary error work.
[0011]
Still further, when the display control means receives the conversion data display command from the outside, the level measuring device of the present invention reads the conversion data of the satellite / transponder corresponding to the command from the storage means together with the identification information, and the display means. To display. When the conversion data rewrite command is input, the conversion data update unit changes the conversion data stored in the storage unit to conversion data based on the rewrite command.
[0012]
Therefore, even if the transmission method of the specific transponder of the artificial satellite is changed from analog broadcasting to digital broadcasting, or the data transmission speed in digital broadcasting is changed, the user can convert the converted data according to the change of the broadcasting contents. Can be rewritten. Also, by inputting only the conversion data rewrite command without giving a display command from the outside, the conversion data to be stored in the storage means can be set at the time of shipment.
[0013]
As a result of setting or changing the conversion data, according to the level measuring device of the present invention, it is possible to receive a signal from a desired satellite transponder without being affected by a transmission method from an artificial satellite or a difference in data transmission speed. The level can always be accurately measured and displayed as an absolute level.
[0014]
In digital broadcasting, information data such as a transmission method is usually transmitted in a time-sharing manner together with video / audio data for digital broadcasting for each transponder. If the conversion data calculation means for obtaining the bandwidth of the received signal corresponding to the transponder number and calculating the conversion data is separately provided, the conversion data stored in the storage means without bothering the user. Can always be automatically updated to the latest conversion data.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of a level measuring device 10 according to an embodiment to which the present invention is applied.
[0016]
The level measuring device 10 of the present embodiment receives a radio wave transmitted from a satellite, converts it into a received signal in a predetermined frequency band (for example, 950 to 1880 MHz), and outputs it from a satellite radio wave receiving parabolic antenna (receiving antenna). The reception level (absolute level) of the received signal is measured.
[0017]
The level measuring device 10 amplifies the received signal from the receiving antenna inputted to the input terminal 12, and the variable attenuator 16 that attenuates the amplified received signal to a predetermined level capable of measuring the level. For example, the variable oscillation circuit 18 capable of changing the oscillation frequency between 1350 to 2280 MHz, the output signal from the variable oscillation circuit 18 and the reception signal from the variable attenuator 16 are mixed, and a predetermined transponder in the reception signal is mixed. A mixer 20 that converts a broadcast signal into an intermediate frequency signal in the 400 MHz band (center frequency 402.78 MHz), an amplification circuit 22 that amplifies the reception signal converted into the intermediate frequency signal by the mixer 20, and amplification by the amplification circuit 22 Only received signals with a predetermined bandwidth (for example, center frequency 402.78 MHz, bandwidth ± 5 MHz) are allowed to pass through the received signals. It includes a band-pass filter 24, the tuning circuit 26 as a tuning means comprising a. In addition to the above-described channel selection circuit 26, the level measuring device 10 includes a detection circuit 28 as detection means for detecting an output signal from the channel selection circuit 26, and a detection voltage output from the detection circuit 28 is converted into a digital signal. A / D converter 30 that performs operation, an operation unit 32 for designating a satellite name and a transponder number at the time of level measurement, a level measurement start command, a display unit 34 including a liquid crystal display panel, and a display for driving the display unit 34 A control circuit 40 composed of a well-known microcomputer centering on a CPU 40a, a ROM 40b, and a non-volatile RAM 40c, which executes various processes such as a well-known level measurement routine according to an input signal from the circuit 36 and the operation unit 32; And the external terminal 38 for connecting with an external apparatus is provided.
[0018]
In the level measuring device 10 configured as described above, when a coaxial cable from a receiving antenna (not shown) is connected to the input terminal 12 and the operation unit 32 is operated to designate the satellite name and the transponder number, the control circuit 40 is known. A channel selection routine is executed, the oscillation frequency of the variable oscillation circuit 18 is adjusted according to the transponder number of the satellite, and the designated broadcast signal is selected by the channel selection circuit 26.
[0019]
Here, there are cases where the transponder number of the designated satellite is performing an analog broadcast or a digital broadcast. When the analog broadcast transponder number is designated, the control circuit 40 executes a well-known level measurement routine to measure the detection voltage after operating the operation unit 32 and inputting a level measurement start command. Further, the detected voltage is corrected using the calibration data stored in the RAM 40c so as not to be affected by the frequency characteristics of the tuning circuit. Then, the obtained absolute level of the reference is directly displayed on the display unit 34 as a reception level (absolute level).
[0020]
On the other hand, when a transponder number for digital broadcasting is designated, the control circuit 40 executes a level measurement routine, and corrects the detection voltage using calibration data to obtain a reference absolute level. Further, the control circuit 40 executes a level conversion routine and searches for a channel selection condition such as a satellite name and a transponder number given to the channel selection circuit 26, so that the selected digital broadcast signal is identified in the RAM 40c. If you know that it is a digital broadcast signal from an artificial satellite or transponder stored as information, add the conversion value of the conversion data corresponding to the identification information to the absolute level of the reference to make the absolute level for display, The absolute level for display, that is, the reception level (absolute level) is displayed on the display unit 34 together with the conversion code of the conversion data.
[0021]
The above conversion data is a map provided with conversion values and conversion codes corresponding to identification information such as transmission methods (analog and digital) and transmission bit rates (transmission speeds) for each transponder of an artificial satellite (communication satellite) performing digital broadcasting. It is. An example of this conversion data map is shown in FIG. The identification information is for identifying the transponder of each satellite, and includes parameters indicating the satellite name, the transponder number of each satellite, the transmission method and the transmission bit rate of each transponder. In FIG. 2, for the sake of convenience, the satellite names are alphabetized as A, B, etc., and the transponder number of each satellite is No. 1, no. Numbers such as 2 are shown. As for the transmission method, when the broadcast signal of the transponder number (hereinafter simply referred to as the broadcast signal) is analog, analog is used as it is, and when it is digital, the transmission method is called QPSK (¼ phase shift keying) method. Is stored. The transmission bit rate stores Nil (blank) when the broadcast signal is analog, and stores the bit rate value when the broadcast signal is digital. The conversion value is for converting the signal level obtained by the level measurement routine into an absolute level. When the broadcast signal is analog, 0 is used, and when the broadcast signal is digital, a value created by a method described later is used. Stored. For example, in the case of a digital broadcast signal, the conversion code is a code in which D representing digital is added to the converted value rather than displaying the converted value as a dB value when measuring the absolute level of the digital broadcast signal. In the case of an analog broadcast signal, the display unit 34 displays, for example, a code with 0 indicating A as analog, which makes it easy to understand that the displayed numerical value is a converted value. Among the many transponders, there is a transponder that is not broadcasting. In such a case, the conversion data map includes, for example, the transponder number No. of the satellite name B. As shown in FIG. 3, all information is stored as Nil.
[0022]
As described above, the conversion data is a map that stores conversion values of transponders that are currently being broadcast among many transponders on the satellite broadcast frequency band, and is written to the RAM 40c through the external terminal 38 at the time of shipment. . The map of the conversion data is created as follows.
[0023]
First, a carrier waveform equivalent to a signal transmitted from an arbitrarily selected satellite transponder is generated by a signal generator, and its level (referred to as level A) is measured by a level measuring instrument 10. Next, the level of the waveform obtained by multiplying the same carrier waveform by the modulation performed by the transponder (referred to as level B) is measured. A level value obtained by subtracting level B from level A is used as a converted value. Furthermore, the same measurement is performed for each transponder of each satellite, and the converted value obtained is written in a map together with other parameters to create conversion data.
[0024]
In addition, after the shipment, the transmission method and transmission bit rate of the digital broadcast signal are changed, and the converted value written at the time of shipment makes it impossible to convert the signal level to an absolute level. There are cases where digital broadcasting is opened and its absolute level is measured. Even in such a case, when the measurer inputs a conversion data change command to the operation unit 32, the control circuit 40 executes the conversion data change routine shown in FIG. 3, and stores the conversion data stored in the storage means at the time of shipment. By updating to the changed conversion data, the absolute level of the corresponding broadcast signal can be measured.
[0025]
The conversion data change routine will be described below.
First, at s10 (s represents a step), a list of satellite names of converted data written at the time of shipment as shown in FIG. For example, the horizontally written satellite names may be displayed on the display unit 34 in columns. Next, in s20, when the operator operates the operation unit 32 from the displayed satellite names and selects a satellite name that requires the conversion value to be changed, the process proceeds to s30. As a configuration of the operation unit 32 for selecting a satellite name, for example, the operation unit 32 has a well-known UP (or ↑) button for selecting an upper satellite name, and a lower satellite name. A DOWN (or ↓) button for selecting a button and an OK (or confirmation) button for confirming a selection state are provided, and an arbitrary satellite name can be selected from a list of satellite names displayed on the display unit 34. Select with, and confirm with OK button. Next, a list of transponder numbers corresponding to the satellite name selected in s20 is displayed on the display unit 34 (s30). For example, the horizontally written transponder numbers may be displayed in the vertical direction on the display unit 34. When the transponder number is displayed, a value other than 0 or Nil in the column of the conversion value [dB] may be urged to be alerted by changing the conversion value. Next, when the operator operates the operation unit 32 from the displayed transponder numbers at s40 and selects a transponder number that requires a conversion value change, the process proceeds to s50. For example, an arbitrary transponder number may be selected as in the case of selecting a satellite name. Next, all the parameters of the conversion data corresponding to the transponder number selected in s40 are displayed on the display unit 34 (s50).
[0026]
Next, a dialog for prompting whether or not to change the conversion value of the displayed conversion data is displayed, and when YES indicating a change request is input via the operation unit 32, the process proceeds to s70. If NO indicating no change request is input, the process proceeds to s90 (s60). Next, when there is a conversion data change request, an input to change conversion data is accepted (s70). Specifically, the change value can be input via the operation unit 32 instead of the conversion data transmission method, transmission bit rate, digital conversion value, and digital conversion code present value displayed on the display unit 34. As a configuration of the operation unit 32 for inputting the change value, for example, a well-known numeric keypad may be provided so that the change value can be input via the numeric keypad. Also, when inputting characters such as a transmission method, the above-mentioned UP and DOWN buttons can be selected on the operation unit 32 and selected from a large number of transmission method candidates displayed on the display unit 34, and further confirmed with the above-mentioned OK button. What should I do? Further, when a new digital broadcast is opened, Nil is stored in the transponder frame of the conversion data corresponding to the digital broadcast. When measuring the absolute level of this digital broadcast, Similarly, predetermined data may be input to the Nil portion. Next, the conversion data stored in the RAM 40c at the time of shipment is updated to the conversion data after the change and rewriting (s80). Next, a dialog for prompting whether or not the conversion data needs to be further changed is displayed on the display unit 34, and when YES indicating that it is necessary is input, s10 is executed again, If NO, which means that it is not necessary, is entered, the process proceeds to s100 (s90). Next, a dialog prompting whether or not to end the conversion value change routine is displayed on the display unit 34, and when YES is input to end the conversion value change routine, the conversion value change routine is ended and not ended. If NO is input, s50 is executed again.
[0027]
According to the level measuring device 10 described above, the following effects can be obtained.
According to the level measuring instrument 10, since the detection voltage is corrected with the calibration data when the level measurement routine is executed, the reception level of the received signal from the desired analog broadcast transponder is not affected by the frequency characteristics of the channel selection circuit 26. (Absolute level) can be measured. Further, even when the reception signal selected by the channel selection circuit 26 is a digital broadcast signal and the bandwidth of the reception signal extracted by the channel selection circuit 26 does not match the bandwidth of the digital broadcast signal, the level conversion routine Since the reference absolute level is corrected with the conversion data when executing the above, it is possible to accurately measure the reception level (absolute level) of the digital broadcast signal. Even if the transmission method of a specific transponder transmitted from an artificial satellite is changed from analog broadcasting to digital broadcasting, or the data transmission speed in digital broadcasting is changed, the user must follow the change of the broadcasting content. The conversion data can be rewritten.
[0028]
As a result, according to the level measuring device 10, the reception level of the signal from the desired transponder is always accurately set as the absolute level without being affected by the transmission method from the satellite or the difference in the data transmission rate. It can be measured.
In digital broadcasting, information data such as a transmission method is usually transmitted in a time-sharing manner together with video / audio data for digital broadcasting for each transponder. Therefore, the information data is demodulated to obtain the information data. If the conversion data calculation means for obtaining the bandwidth of the received signal corresponding to the transponder number and calculating the conversion data is separately provided, the conversion data stored in the storage means without bothering the user. Can always be automatically updated to the latest conversion data.
[0029]
Summarizing the correspondence between the embodiment and the claims, the level measurement routine and the level conversion routine are the calculation means, the ROM 40b and RAM 40c are the storage means, the conversion data change routines s10 to s50 are the display control means, and the conversion data change The routines s60 to s90 correspond to the conversion data update means.
[0030]
As mentioned above, although the Example of this invention was described, this invention is not limited to the said Example, Of course, you may implement in a various aspect.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a level measuring device 10 according to an embodiment.
FIG. 2 is a map of conversion data of an example.
FIG. 3 is a flowchart showing a conversion data change routine of the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Level measuring device, 26 ... Channel selection circuit, 28 ... Detection circuit, 32 ... Operation part, 34 ... Display part, 40 ... Control circuit

Claims (1)

Of the received signal from the receiving antenna that receives the transmission wave of the artificial satellite, the frequency conversion is performed so that the received signal from the transponder of the artificial satellite designated from the outside becomes an intermediate frequency signal in a predetermined frequency band, and the frequency conversion A channel selection means for selecting a received signal from the transponder by taking out a later intermediate frequency signal by a predetermined bandwidth, and
Detecting means for detecting the intermediate frequency signal obtained by the tuning means;
An arithmetic means for correcting the detection voltage from the detection means based on calibration data set in advance according to the frequency characteristic of the channel selection means, and calculating a reference absolute level;
In a level measuring instrument with
Depending on the transmission method of the received signal selected by the channel selection means, conversion data for converting the absolute level of the reference into an absolute level for display, at least an artificial satellite and a transponder that transmit the signal Storage means for storing together with identification information to represent;
When receiving a display command for the conversion data from the outside, the display control means for reading the conversion data of the artificial satellite / transponder corresponding to the command from the storage means together with the identification information, and displaying on the display means;
When the conversion data rewrite command is input, conversion data update means for changing the conversion data stored in the storage means to conversion data based on the rewrite command;
Further, the calculating means includes
When the received signal selected by the channel selection means is found to be a digital broadcast signal from an artificial satellite / transponder stored as identification information in the storage means, conversion data corresponding to the signal is sent from the storage means. Reading, further correcting the reference absolute level with the converted data, displaying the display absolute level obtained by the correction as a reception level on the display means, and the selected received signal is not a digital broadcast signal In this case, the level measuring device is configured to display the reference absolute level as the reception level on the display means as it is.

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