JP2007013621A - Symbol discrimination apparatus for digital modulation signal, symbol discrimination method for digital modulation signal, symbol discrimination program for digital modulation signal, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a symbol discrimination apparatus for a digital modulation signal that does not erroneously detect a symbol value even when a state equivalent to variations in the frequency modulation sensitivity takes place in a received signal, and to provide a symbol discrimination method for the digital modulation signal, a symbol discrimination program for the digital modulation signal, and a recording medium. <P>SOLUTION: When receiving and detecting a signal modulated by a digital signal and discriminating a symbol data value by comparing the detection signal in a prescribed timing with a threshold value, the symbol discrimination apparatus detects a sampled value of detection outputs by which the symbol data value can be discriminated, for example, a signal comparatively easily detectable such as a synchronous word in an APCOP 25 system, obtains the average value of amplitude values, calculates variations in the frequency shift of the received signal on the basis of the obtained average, corrects the coefficient of the multiplier means and discriminates an information data symbol. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a digital modulation signal symbol determination apparatus, a digital modulation signal symbol determination method, a digital modulation signal symbol determination program, and a recording medium, which are suitable for a digital wireless communication device or the like.

In digital wireless communication, data to be transmitted is transmitted and received in units of frames, but a synchronization signal (Frame Sync Word) having a specific signal arrangement pattern at a predetermined position of each frame, for example, the beginning of the frame, on the transmitter side The receiver side detects the frame synchronization word in the detection output signal, establishes synchronization, and demodulates the information data following the FS word according to the synchronization timing. Thus, in digital wireless communication, ensuring synchronization on the receiving side is extremely important in demodulating data.
As a functional block configuration of a digital wireless communication device, one shown in FIG. 8 is known. The radio receiver 300 shown in FIG. 8 is used for frequency shift keying (FSK), and includes an antenna 51, a front end unit 52, an FM detection processing unit 53, an I & D filter 54, A symbol detection unit 55, a decoding processing unit 56, a speaker 57, and a frame synchronization device 58 are included.
The antenna 51 derives a radio wave in the transmitted space and supplies it to the front end unit 52. The front end unit 52 passes a desired frequency component from the received radio carrier signal and amplifies the signal to a required level. The FM detection processing unit 53 performs FM detection on the output of the front end unit 52 and demodulates it into a pulse train signal representing information. Note that the output of the FM detection processing unit 53 is ideally a rectangular wave, similar to the transmitted pulse train waveform, but actually has a waveform with a blunt and rounded edge. An I & D filter (Integrate and Dump Filter) 54 is an integral discharge filter that removes an intersymbol interference component of a signal, branches the output into two, and supplies one to the symbol detector 55 and the other to the frame synchronizer 58. The frame synchronizer 58 has a correlator function inside, and generates a known frame sync word (hereinafter referred to as “FS word”) or stores it in a memory and is supplied via the I & D filter 54. The required bit string extracted from the pulse string signal of the output signal of the FM detection processing unit 53 is compared with the previous FS word bit, and when both match, the maximum peak signal is output.
When the frame synchronizer 58 successfully detects the FS word and establishes synchronization, it supplies the symbol timing information to the symbol detector 55, detects the symbol value from the information bit signal transmitted following the FS word, Convert to symbol data representing information bits. The symbol data obtained in this manner is converted into the original information signal in the decoding process 56, and then output from the speaker 57 in the case of an audio signal.

As an example of the digital modulation method, APCOP25 will be specifically described as an example. APCO is a quaternary FSK modulation method, and one of four symbols, “00”, “10”, “01”, “11”, is a combination of two bits in one symbol of one frequency deviation (Devation) value. It is decided to represent one.
Examples of actual frequency deviation values include four values of +0.6 kHz, +1.8 kHz, −1.8 kHz, and −0.6 kHz, and the FM detection processing unit 53 has an amplitude corresponding to the frequency deviation. The pulse train signal of the value is output, and through the I & D filter 54, the symbol detector 55 detects which of the four frequency shift values corresponds. In this symbol detection, the reference 0 Hz is compared with a threshold value corresponding to an amplitude value when the frequency shift is ± 1.2 kHz. That is, in APCO, the symbol and the threshold value are spaced at 600 Hz.
Further, the FS word (synchronization word) of the APCOP25 method is 48 bits. However, as described above, the FS word (synchronization word) is 24 symbols because it is quaternary FM modulation in which 1 symbol represents 2 bits. The frame synchronizer 58 generates 48 bits from the 24 symbol data, obtains a correlation with a known sync word bit pattern, and performs synchronization supplement processing.

FIG. 9 is an eye pattern diagram for explaining the relationship between the frequency shift value and the threshold value in a radio receiver employing the APCOP25 method. The eye pattern is a digital signal waveform superimposed for a considerable period of time and observed with an oscilloscope. The original signal superimposed on the transmitted wave is a rectangular wave, but the waveform is rounded and rounded. It is called an eye pattern. The better the communication line is, the better the electric field strength is, and the better the SN (signal-to-noise ratio), the more a single curve is assembled as shown in FIG. 9, but the actual eye pattern is noise. 9 is not necessarily as shown in FIG. 9 and the touch of the locus is included to some extent.
In order to determine which of the above four symbols each symbol value corresponds to the frequency shifts of 0 kHz, −1.2 kHz, and +1.2 kHz as shown in FIG. A threshold is set and compared with each symbol. As shown in FIG. 9, ideally, each symbol passes through a point corresponding to each of the four frequency shifts at the Nyquist point, and the timing is determined as symbol timing information by establishing frame synchronization from the frame synchronizer. Supplied. Here, the term “sampling means” used here refers to sampling including detection of symbol data from the output signal of the FM detection processing unit 53 based on symbol timing information generated from the frame synchronization signal. Means for reading an analog signal as a digital value, in addition to those described above, means for sampling a pulse signal included in a baseband signal output from an FM detection processing unit at symbol timing, and means for sampling a detection signal by oversampling or the like It means the broadest concept.
JP 2004-040583 A

However, when the frequency deviation value is actually modulated by the transmitter and the frequency deviation value is detected from the frequency modulated signal by the receiver to restore the original signal waveform, the frequency deviation value fluctuates due to various reasons. Often to do. The cause is, for example, a change in modulation sensitivity due to aging or temperature change of a VCO (Voltage Controlled Oscillator) or a VCXO (Voltage Controlled Crystal Oscillator) used in a modulator of a transmitter, or A variation in the detection output level due to a variation in sensitivity of the FM detector of the receiver can be considered.
In this way, when the modulation sensitivity is increased as a result in the transmitter or the receiver, for example, as shown in FIG. 10, the eye pattern has a shape stretched in the vertical axis direction as a whole. The amplitude value of the signal that was ± 0.6 kHz in FIG. 9 is comparable to 1 kHz in FIG. On the other hand, since the threshold value corresponding to the threshold value of 1.2 kHz is fixed, there is no sufficient margin between the symbol value that should be ± 0.6 kHz and the symbol value expanded to ± 1 kHz. When the absolute value of the value level fluctuates in a larger direction, there is a problem that it is determined that the data value exceeds the threshold value and is incorrect. On the contrary, the same problem also occurs when the frequency shift amount of the received signal contracts smaller than actual. FIG. 11 shows this state, and illustrates the state where the overall frequency shift is reduced to about half. When the overall modulation sensitivity is reduced in this way, the detection output level of the symbol value that was originally ± 1.8 kHz becomes a level comparable to ± 1.5 kHz, and the fixed threshold value ± 1.2 kHz is obtained. If the difference becomes small and the level becomes even small due to fluctuations in noise or the like, the symbol value is erroneously detected as one lower level. If such fluctuations occur, symbol detection cannot be performed accurately.
The present invention has been made in order to solve such a problem in the conventional digital modulation signal symbol determination apparatus, and is a case where a state corresponding to a variation in frequency modulation sensitivity occurs in a received signal. Another object of the present invention is to provide a digital modulation signal symbol determination apparatus, a digital modulation signal symbol determination method, a digital modulation signal symbol determination program, and a recording medium that prevent erroneous detection of symbol values. .

In order to solve such a problem, the present invention provides a digital modulation signal symbol determination apparatus according to claim 1 for receiving and detecting a signal modulated with a digital signal and demodulating the signal into a transmitted original information signal. Symbol determination device for determining a symbol data value by comparing a pulse amplitude value at a Nyquist point of a received and detected signal with a predetermined threshold in a symbol determination device for a digital modulation signal, and a symbol data value can be determined Pulse amplitude value averaging means for obtaining an average value of the plurality of pulse amplitude values, and threshold value complementing means for correcting the threshold value based on the obtained average value of the pulse amplitudes.
The digital modulation signal symbol determination apparatus according to claim 2, wherein the digital modulation signal symbol determination apparatus receives and detects a signal modulated by the digital signal and demodulates the signal to a transmitted original information signal. Detecting means for detecting a signal; sampling means for sampling a pulse signal output from the detecting means; symbol data value determining means for determining a symbol data value by comparing a sampling value with a predetermined threshold; and a symbol data value A pulse amplitude value averaging means for obtaining a pulse amplitude average value of a plurality of symbol data that can be determined, and a threshold value complementing means for correcting the threshold value based on the obtained average value of the pulse amplitudes. .
The digital modulation signal symbol determination apparatus according to claim 3, wherein the digital modulation signal symbol determination apparatus receives and detects a signal modulated by the digital signal and demodulates the signal to the original transmitted information signal. Detecting means for detecting a signal; sampling means for sampling a pulse signal output from the detecting means; symbol data value judging means for judging a symbol data value by comparing a sampling value with a predetermined threshold; and the symbol data Based on the specific word detecting means for detecting a known specific word from the output of the value judging means, the pulse amplitude average means for obtaining the pulse amplitude average value of the specific code, and the pulse amplitude average value obtained by the pulse amplitude average means And threshold correction means for correcting the threshold.
5. The symbol determination method for a digital modulation signal according to claim 4, wherein the signal modulated by the digital signal is received and detected and demodulated into the transmitted original information signal. A symbol data value determining process for determining a symbol data value by comparing a pulse amplitude value at a Nyquist point of the received signal with a predetermined threshold, and an average value of a plurality of the pulse amplitude values from which the symbol data value can be determined. A pulse amplitude value averaging process to be obtained; and a threshold value complement process for correcting the threshold value based on the obtained average value of the pulse amplitudes.

6. The symbol determination method for a digital modulation signal according to claim 5, wherein the signal to be transmitted is detected by receiving a signal modulated by the digital signal and demodulating it to the original information signal transmitted. In the method, a sampling process for sampling the detected pulse signal at a predetermined period, a symbol data value determination process for determining a symbol data value by comparing a sampling value obtained by the sampling process with a predetermined threshold value, and a symbol A pulse amplitude average value process for obtaining a pulse amplitude average value of a plurality of symbols whose data values can be determined, and a threshold value correction process for correcting the threshold value based on the obtained pulse amplitude average value. .
7. The digital modulation signal symbol determination method according to claim 6, wherein a signal modulated with a digital signal representing information to be transmitted is received and detected and demodulated into a transmitted original information signal. In the determination method, a sampling process for sampling the detected pulse signal at a predetermined period, a symbol data value determination process for determining a symbol data value by comparing a sampling value obtained by the sampling process with a predetermined threshold value, Specific word detection processing for detecting a known specific word from the symbol data subjected to the symbol data value determination processing; and pulse amplitude average processing for obtaining a pulse amplitude average value of a symbol of the specific code when the specific word is detected; Threshold correction processing for correcting the threshold based on the obtained pulse amplitude average value; Characterized in that it comprises a.
According to a seventh aspect of the present invention, there is provided a digital modulation signal symbol determination method according to any one of the fourth to sixth aspects, wherein the digital modulation signal symbol determination method is programmed to be controlled by a computer.
A recording medium according to an eighth aspect is characterized in that the digital modulation signal symbol determination method program according to the seventh aspect is recorded in a computer-readable format.
In the present invention described above, “sampling” refers to detecting symbol data based on the timing signal supplied from the frame synchronizer, as already described. It means a broad concept including what is sampled.

According to a first aspect of the present invention, there is provided a digital modulation signal symbol determination apparatus that receives and detects a signal modulated with a digital signal and compares a pulse amplitude value at a Nyquist point with a threshold value to determine a symbol data value. The average value of the plurality of pulse amplitude values with which the symbol data value can be discriminated is obtained, the fluctuation amount of the frequency shift of the received signal is calculated based on the obtained average value of the pulse amplitudes, and the threshold value is corrected. Since the determination of the information data symbol is performed as described above, it is possible to accurately detect the symbol value even if the frequency shift amount of the received signal (considered as the modulation degree conversion amount) fluctuates. Even if a DC offset is included in the detection output, the threshold value can be corrected if the synchronization word can be detected, so that the effect of the present invention can be obtained.
Claims 2, 3, and 5 are also based on the same technical idea, and the same effect can be obtained.
Note that examples of the plurality of pulse amplitude values from which the symbol data values can be distinguished include signals that are relatively easy to detect, such as a synchronization word in the APCOP25 system as described later, but are not limited thereto. There is no need to do.
According to a fourth aspect of the present invention, there is provided a method for determining a symbol of a digital modulation signal, a process for obtaining an average value of a plurality of sampling values from which the respective symbol data can be distinguished from a sampling value of a detected pulse train; Since the processing includes detecting the relationship between the amplitude value of the pulse obtained as described above and its ideal value and correcting the threshold value for determining the symbol data value, or includes similar means and step processing. It is characterized by comprising so that the method of implementing invention of thru | or 3 can be provided.
According to the seventh aspect of the present invention, the method of the present invention can be implemented by a computer that can process the OS by programming the digital modulation signal symbol determination method of the present invention according to an OS that can be controlled by the computer.
According to another aspect of the present invention, a program for determining a symbol of a digital modulation signal is recorded on a recording medium in a computer-readable format, and the program can be operated anywhere by carrying the recording medium.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .
FIG. 1 is a functional block configuration diagram of a wireless receiver according to an embodiment of the present invention. The radio receiver 100 shown in the figure is used for frequency shift keying (FSK) as in the case shown in FIG. 8, and includes an antenna 1, a front end unit 2, and an FM. The detection processing unit 3, the I & D filter 4, the symbol detection unit 6, the decoding processing unit 7, the speaker 8, and the frame synchronization device 9 are included. (Threshold portion) 5 and symbol average value calculation portion 10. If the portion corresponding to the symbol determination device for digital modulation signals according to the present invention is shown, the portion surrounded by a broken line in FIG. However, since it is often realized by software, it is not limited to this example.
The antenna 1 derives a radio wave in the transmitted space and supplies it to the front end unit 2. The front end unit 2 passes a desired frequency component from the received radio carrier signal and amplifies the signal to a required level. Then, the FM detection processing unit 3 performs FM detection on the output of the front end unit 2 and demodulates it into a pulse train signal representing analog information, and an I & D filter (Integrate and Dump Filter) 4 generates an intersymbol interference component of the signal. The integral discharge filter for sampling removes the output at two chip time intervals, and the output is branched into two, one being supplied to the symbol detector 6 and the other to the frame synchronizer 9 as in FIG. However, the symbol detection unit 6 is supplied with a signal for comparison with the symbol from the threshold unit 5. The threshold value unit (threshold value unit) 5 is supplied with a signal for correcting the threshold value from the symbol average calculation unit 10 or the threshold value itself.

  FIG. 2 is a symbol pattern diagram showing a frame synchronization word in APCOP25. As described above, the APCOP 25 is a four-value FSK modulation method, and a combination of two bits “00”, “10”, “01”, “11” with one symbol of one frequency deviation (Deviation) value. It is determined to represent any one of the four values, and the actual frequency deviation value is four values of +0.6 kHz, +1.8 kHz, −1.8 kHz, and −0.6 kHz. The FM detection processing unit 3 outputs a pulse train signal having an amplitude value corresponding to the frequency shift, and the symbol detector 6 detects which of the four frequency shift values corresponds. In this symbol detection, the reference 0 Hz is compared with a threshold value corresponding to an amplitude value when the frequency shift is ± 1.2 kHz. In APCO, the symbol and the threshold value are at an interval of 600 Hz. This is as shown in FIG. Further, the FS word (synchronization word) of the APCOP25 method is 48 bits. However, as described above, since it is 4-level FM modulation in which 1 symbol represents 2 bits, it becomes 24 symbols. The frame synchronizer 9 generates 48 bits from the 24 symbol data, obtains a correlation with a known sync word bit pattern, and performs synchronization supplement processing. Since the operation of the frame synchronizer 9 has already been described, a description thereof will be omitted, but the frame synchronization word in the APCOP 25 is a quaternary FSK modulation system as shown in FIG. There are a total of 24 deviations representing 11 deviations representing “01” at +1800 Hz and 13 deviations representing the symbol “11” at −1800 Hz. Accordingly, it can be said that detection is relatively easier than symbols of information frames in which quaternary symbols appear randomly. Therefore, in the exemplary embodiment shown here, a case where a variation in the received signal is detected using a synchronization word and the threshold value is corrected is illustrated.

FIG. 3 is a flowchart illustrating an example of a digital modulation signal symbol determination method according to the present invention. The digital modulation signal symbol determination apparatus and method according to the present invention will be described in detail with reference to FIGS.
In FIG. 3, first, detection data from the FM detection processing unit 3 is acquired in order to detect a synchronization word (step S1), and a buffer memory (not shown) is reserved for the purpose of calculation (for example, And stored in the memory in the frame synchronizer 9 (step S2). At the same time, in order to confirm whether or not the stored detection data includes a frame synchronization signal, the frame synchronization device 9 executes a synchronization timing acquisition algorithm, detects a synchronization word (step S3), and performs synchronization. It is determined whether or not it has been removed (step S4). If synchronization is established in this determination (step S4 Yes), symbol data corresponding to the synchronization word is extracted from the detection data stored in the buffer memory (step S5). Note that the detection data stored in the buffer memory may have the same number of symbols as the synchronization word, and a method of detecting the synchronization word by executing the synchronization timing acquisition algorithm while storing the data for one symbol while shifting. When the synchronization word is detected in this way, the symbol average value calculation unit 10 calculates the average of the amplitude value of the symbol data (the amplitude value of the detection pulse) (step S6). At this time, as shown in FIG. 2, in the APCOP 25, the deviation representing the symbol “01” is composed of 11 pieces of +1800 Hz and the deviation representing the symbol “11” is composed of 24 pieces of 13 pieces of −1800 Hz. Therefore, the average of 11 symbols of “01” and the average of 13 symbols of “11” are calculated, and the absolute value of the average value of both is further averaged. Here, the purpose of obtaining the average of the amplitude values is to detect a variation in the deviation of the received signal, so it is necessary to average the + side and the − side separately, but the detection signal must have a DC offset. For example, an average of absolute values of all symbol values may be calculated. Further, if the average is obtained for symbols of all patterns of the synchronization word, the variation tendency of the deviation can be detected more correctly than the average is obtained for some symbols. However, the present invention is not necessarily limited to this. Since the calculation processing speed is faster when the number of symbols is smaller, obtaining the average value of either 11 “01” symbols or 13 “11” symbols is also effective in increasing the processing speed. There is.

When the average value of the symbol data is obtained in this way, since the deviation of the symbol at that time is larger or smaller than the specified value and the ratio can be calculated, the threshold value is corrected according to the ratio. A correction signal is supplied from the symbol average value calculator 10 to the threshold unit 5. Alternatively, the threshold value corrected by the symbol average value calculation unit 10 may be generated, and the signal may be supplied to the threshold value unit 5 (step S7). When the new threshold value is set in the threshold value unit 5 (step S8), this threshold value is supplied to the symbol detection unit 6 to detect symbols of information data received following the frame synchronization signal.
In addition, in the said step S4, when synchronization is not taken (step S4 No), a processing flow is complete | finished. Such a process may be executed for each synchronization frame detection process, but may be executed intermittently at a predetermined cycle when deviations in the deviation do not tend to occur so frequently. It is also conceivable to execute this process when the received electric field strength is sufficient but the error correction rate is reduced, or when other information suspected of variation in the deviation is obtained.

4, 5, and 6 are diagrams for explaining the effects when the threshold is corrected based on the present invention as described above. First, FIG. 4 is a diagram showing the relationship between the eye pattern and the threshold when the deviation of the received detection output signal is equivalently enlarged. The deviation of the received detection output signal is about 1.67 times. The threshold value is corrected by the averaged result of the synchronized word symbols, and the threshold value corresponding to 1.2 kHz is corrected to 2.0 kHz. As a result, there is a margin between each symbol, and no erroneous detection occurs due to some level fluctuation.
FIG. 5 is a diagram showing the relationship between the eye pattern and the threshold when the deviation of the received detection output signal is equivalently reduced, and the deviation of the received detection output signal is about 0.83 times. However, the threshold value is corrected by the averaged result of the synchronized word symbols, and the threshold value corresponding to 1.2 kHz is corrected to 1.0 kHz. Even in this result, there is a margin between each symbol, so that erroneous detection is not caused by a slight level fluctuation.
FIG. 6 shows a difference between a conventional fixed threshold value and a threshold value corrected according to the present invention. The vertical axis represents the bit error rate (BER), and the horizontal axis represents the equivalent deviation of the received detection output signal. The center value is 1800 kHz. A broken line in the figure indicates a case where the threshold value is a fixed value of ± 1.2 kHz as in the conventional case, and a solid line indicates a case where the threshold value is corrected according to the present invention. As is apparent from the figure, even if the equivalent deviation of the received detection output signal changes greatly to the + side and the − side, the bit error rate (BER) does not change, so that the effect of the present invention is extremely large. .

  In addition, as disclosed in Patent Document 1, the same applicant eliminates the influence of fluctuations in the received detection output signal at the time of frame synchronization detection, and accurately detects a synchronization word. However, if this method is used in combination with the present invention, the realization of the present invention can be more effective. That is, in the invention disclosed in Patent Document 1, when a correlator is used for synchronous word detection, if the deviation of the signal fluctuates, the peak value of the correlator output becomes smaller than the threshold value, and the detection may not be possible. Therefore, the level value of the signal for detecting the peak by the correlator is corrected so that a sufficient peak value can be obtained. However, on the other hand, only the corrected level value reduces the correlation detection accuracy. To compensate for this, the correlation detection is performed even on the uncorrected signal, and the synchronization detection is performed based on the AND output of both. Is what you do. As an apparatus for that purpose, an apparatus disclosed in the publication is shown in FIG. The FS detector 20 shown in FIG. 7 branches the detection output supplied via the I & D filter 4 into three branches, one directly to the data acquisition unit 17 and the other branch signal to the symbol determination unit 11 and the first determination unit. The other branch signals are supplied to the AND circuit 16 via the second correlator 14 and the peak detector 15 through the correlator 12 and the discriminator 13, and to the AND circuit 16. By supplying the output of the AND circuit 16 to the data acquisition unit 17, even if there is a deviation variation in the received detection output signal, the synchronization word is accurately detected. Since the present invention is disclosed in detail in the publication, description thereof will be omitted. However, if this method is used, synchronization detection is further ensured, which is suitable for the implementation of the present invention. That is, as described above, according to the present invention, first, it is necessary to extract the relationship (coefficient) between the signal waveform level of a symbol whose data value can be determined and a specified deviation. It is. As shown in FIG. 2, the FS word (synchronization word) of the APCOP25 method includes only “01” and “11” of ± 1800, and is easier to detect than other information data. Therefore, it is not always necessary to use Patent Document 1 together, but it is particularly useful when it is difficult to detect the synchronization word in other methods.

As described above, according to the present invention, when a signal modulated by a digital signal is received and detected, and a symbol data value is determined by comparing a detection signal at a predetermined timing with a threshold value, a plurality of symbol data values can be determined. For example, in the APCOP25 system, a signal that is relatively easy to detect, such as a synchronization word, is detected, and an average value of the amplitude values is obtained. Based on the obtained average, Since the fluctuation amount of the frequency shift is calculated and the information data symbol is determined after correcting the threshold value, the symbol value can be accurately detected even if the frequency shift amount of the received signal fluctuates. It becomes possible. Even if a DC offset is included, if the synchronization word can be detected, the functions of the present invention can be used as long as the deviation can be calculated.
In addition, since various concrete implementation methods of the apparatus described above can be considered, a modified block configuration can be selected as appropriate.
In addition, since such an apparatus is suitable for digital signal processing, each functional block sharing process may be programmed so that it can be processed by a computer.
Further, by programming the digital modulation signal symbol determination method of the present invention according to an OS that can be controlled by a computer, any computer equipped with the OS can be controlled by the same processing method.
In addition, by recording a digital modulation signal symbol determination program on a recording medium in a computer-readable format, the program can be operated anywhere by carrying the recording medium.

The present invention is not limited only to the above-described embodiments. Each function constituting the digital modulation signal symbol determination apparatus of the above-described embodiment is programmed, written in a recording medium such as a CD-ROM in advance, and a medium driving apparatus such as a CD-ROM drive mounted on a computer It goes without saying that the object of the present invention is achieved by mounting the CD-ROM or the like, storing these programs in a memory or storage device of a computer, and executing them.
In this case, the program itself read from the recording medium realizes the functions of the above-described embodiment, and the program and the recording medium recording the program also constitute the present invention.
As a recording medium for storing the program, a semiconductor medium (for example, ROM, nonvolatile memory card, etc.), an optical medium (for example, DVD, MO, MD, CD, etc.), a magnetic medium (for example, magnetic tape, flexible disk, etc.) ) Or the like.
Further, not only the functions of the above-described embodiment are realized by executing the loaded program, but also the above-described implementation by cooperating with the operating system or other application programs based on the instructions of the program. The case where the function of the form is realized is also included.
When distributing to the market, store the program in a portable recording medium for distribution, or store the program in a storage device of a server computer connected via the Internet, etc. Can also be transferred to. In this case, the storage device of this server computer is also included in the recording medium of the present invention.
In the computer, the functions of the above-described embodiments are realized by installing a program on a portable recording medium or a transferred program on a recording medium connected to the computer and executing the installed program. Is done.

It is a principal part block diagram of the symbol determination apparatus of the digital modulation signal concerning one Embodiment of this invention. It is a figure which shows the example of the synchronous word used in one Embodiment of this invention. It is a flowchart explaining the symbol determination apparatus and method of the digital modulation signal concerning one Embodiment of this invention. It is a figure which is a case where this invention is applied, Comprising: When the equivalent deviation of a detection output signal fluctuates to the larger one, it is a figure which shows the relationship between an eye pattern and a threshold value. It is a figure which is a case where this invention is applied, Comprising: It is a figure which shows the relationship between an eye pattern and a threshold value when the equivalent deviation of a detection output signal changes to the smaller one. It is a figure which shows the relationship between the fluctuation | variation of the deviation for demonstrating the effect concerning one Embodiment of this invention, and a bit error rate (BER). It is a block diagram of the FS detection circuit used for the example of another embodiment of this invention. It is a block block diagram which shows an example of the conventional digital receiver. It is a figure which shows the relationship between an eye pattern and a threshold value when the equivalent deviation of a detection output signal is a regulation value. It is a figure which shows the relationship between an eye pattern and a threshold value when the equivalent deviation of a detection output signal is large. It is a figure which shows the relationship between an eye pattern and a threshold value when the equivalent deviation of a detection output signal is small.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Antenna, 2 Front end, 3 FM detection process part, 4 I & D filter, 5 Threshold part (threshold part), 6 Symbol detection part, 7 Decoding process part, 8 Speaker, 9 Frame synchronizer, 10 Symbol average value calculation Part, 11 symbol determiner, 12 first correlator, 13 discriminator, 14 second correlator, 15 peak detector, 16 AND circuit, 17 data acquirer, 20 FS detector.

Claims (8)

  In a symbol determination apparatus for a digital modulation signal when a signal modulated with a digital signal is received and detected and demodulated to the original transmitted information signal, a pulse amplitude value at a Nyquist point of the received signal is predetermined. Symbol data value determining means for determining a symbol data value by comparing with a threshold value, pulse amplitude value averaging means for obtaining an average value of a plurality of pulse amplitude values from which the symbol data value can be determined, and the obtained pulse And a threshold value complementing means for correcting the threshold value based on an average value of amplitudes.   In a symbol determination device for a digital modulation signal when receiving and detecting a signal modulated with a digital signal and demodulating it to the transmitted original information signal, a detection means for detecting the received signal, and a pulse signal output from the detection means Sampling means for sampling the symbol, symbol data value judging means for judging the symbol data value by comparing the sampling value with a predetermined threshold value, and obtaining the pulse amplitude average value of a plurality of symbols from which the symbol data value can be judged A symbol determination device for a digital modulation signal, comprising: pulse amplitude value averaging means; and threshold value complementing means for correcting the threshold value based on the obtained average value of the pulse amplitudes.   In a symbol determination device for a digital modulation signal when a signal modulated with a digital signal is received and detected and demodulated into the transmitted original information signal, a detection means for detecting the received signal, and a pulse signal output from the detection means Sampling means for sampling the symbol data value judging means for judging the symbol data value by comparing the sampling value with a predetermined threshold value, and a specific word for detecting a known specific word from the output of the symbol data value judging means Detecting means; pulse amplitude averaging means for obtaining a pulse amplitude average value of the specific word; and threshold correction means for correcting the threshold based on the pulse amplitude average value obtained by the pulse amplitude averaging means. A symbol determination apparatus for a digital modulation signal.   In a symbol determination method of a digital modulation signal when a signal modulated with a digital signal is received and detected and demodulated to an original transmitted information signal, a pulse amplitude value at a Nyquist point of the received signal is predetermined. Symbol data value determination processing for determining a symbol data value by comparing with a threshold value, pulse amplitude value averaging processing for obtaining an average value of a plurality of the pulse amplitude values from which the symbol data value can be determined, and the obtained pulse amplitude And a threshold value complementing process for correcting the threshold value based on an average value of the digital modulation signal.   In a symbol determination method of a digital modulation signal when a signal modulated with a digital signal representing information to be transmitted is received and demodulated to the original transmitted information signal, the detected pulse signal is sampled at a predetermined period. Sampling processing, symbol data value determination processing for determining a symbol data value by comparing a sampling value obtained by the sampling processing with a predetermined threshold, and pulse amplitude averaging of a plurality of symbols from which the symbol data value can be determined A symbol determination method for a digital modulation signal, comprising: pulse amplitude average value processing for obtaining a value; and threshold correction processing for correcting the threshold based on the obtained average value of the pulse amplitude values.   In a symbol determination method of a digital modulation signal when a signal modulated with a digital signal representing information to be transmitted is received and demodulated to a transmitted original information signal, the detected pulse signal is sampled at a predetermined period. A sampling process, a symbol data value determination process for determining a symbol data value by comparing a sampling value obtained by the sampling process with a predetermined threshold value, and a known identification from the symbol data subjected to the symbol data value determination process A specific word detection process for detecting a word, a pulse amplitude average value process for obtaining an average value of symbol pulse amplitudes of the specific word when the specific word is detected, and the threshold based on the obtained pulse amplitude average value Threshold correction processing for correcting Method.   7. A digital modulation signal symbol determination method program, wherein the digital modulation signal symbol determination method according to claim 4 is programmed to be controlled by a computer.   A recording medium, wherein the digital modulation signal symbol determination method program according to claim 7 is recorded in a computer-readable format.

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