JP3745745B2 - Signal analyzer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a signal analysis apparatus for analyzing a signal of each slot in a signal under measurement in which a plurality of slots into which phase-modulated signals are incorporated are time-division multiplexed.
[0002]
[Prior art]
In PHS (Personal Handy phone System), a signal 3 transmitted and received between the base station 1 and each mobile station 2 shown in FIG. 6A includes a number of frames 4 as shown in FIG. included. Furthermore, in each frame 4, as shown in FIG. 7, four slots 5 in which signals to be individually transmitted from the base station 1 to, for example, four mobile stations 2 are incorporated, and four mobile stations 2. 4 slots 6 in which signals to be transmitted to the base station 1 are incorporated by a time division multiple access (TDMA) system.
[0003]
In the PHS currently in practical use, the time width of one frame 4 is 5 ms and the time width of one slot 5 and 6 is 625 μs. Various information is transmitted from the base station 1 to the four mobile stations 2 at intervals of 5 ms as burst signals incorporated in the slot 5 of 625 μs at the timing shown in FIG. Each mobile station 2 sets the transmission information of its own station in the frame 4 as a burst signal incorporated in the slot 6 of 625 μs after 2.5 ms from the time of receiving the burst signal incorporated in the slot 5 of 625 μs from the base station 1. And transmit to the base station 1.
[0004]
The frequency of each signal transmitted from the base station 1 to the four mobile stations 2 is equal to the frequency of each signal transmitted from the four mobile stations 2 to the base station 1.
[0005]
Further, in the PHS currently in practical use, information transmitted and received between the base station 1 and the four mobile stations 2 is a signal 3 in a state where it is phase-modulated by the modulation method of π / 4 shift QPSK. In each slot 5 of 625 μs.
[0006]
Various information transmitted / received between the base station 1 and each mobile station 2 is divided into a plurality of types of channels, and each channel is incorporated into each slot 5 and 6 of 625 μs and transmitted / received. The types of channels are roughly divided into a control channel incorporating control information exchanged between the base station 1 and each mobile station 2, and an information channel (TCH) incorporating information to be originally transmitted / received such as voice, text, and images. ) And.
[0007]
FIG. 8 is a diagram showing a configuration of slot 5 of each information channel (TCH) transmitted from base station 1 to each mobile station 2. When the symbol rate is 192 ksps when the phase modulation method is adopted, for example, when the modulation method of π / 4 shift QPSK is adopted, it corresponds to one symbol with 2 bits. Therefore, transmission of information (data) when phase modulation is performed The speed is 192 ksps × 2 = 386 kbps. In this case, the code length of each slot 5 of 625 μs is 386 kbps × 625 μs = 240 bits, and the symbol length of each slot 5 is 240/2 = 120 symbols.
[0008]
First, 2 symbols of ramp bits R are provided, then 1 symbol of status symbols SS, 3 symbols of preamble PR, 8 symbols of synchronization word UW, 2 symbols of channel information CI, and 8 symbols of low-speed ACCH are designated. The information to follow continues. Then, information (data) I to be transmitted of 80 symbols and an error check bit CRC of 8 symbols are set. Note that eight symbol guard bits are provided between the slots 5.
[0009]
FIG. 9 is a signal space diagram of the modulation signal shown on the IQ coordinate in π / 4 shift QPSK adopted in the phase modulation method of information transmitted from the base station 1 to each mobile station 2.
[0010]
The π / 4 shift QPSK is a quaternary transmission method in which information is transmitted by 2 bits at every symbol time as in QPSK. However, this π / 4 shift QPSK uses a carrier axis that rotates by π / 4 (45 °) phase every symbol time. Therefore, as shown in FIG. 9, each signal point 7 obtained by combining the symbol data I and Q on the IQ coordinate alternately takes white circles and black circles in the drawing in the even-numbered and odd-numbered symbols. By adopting π / 4 shift QPSK as the modulation method in this way, since the origin does not pass at the transition of the signal point 7, the nonlinear transmission path has a strong feature.
[0011]
The signals included in the slots 5 and 6 in the signal 3 transmitted / received between the base station 1 and each mobile station 2 adopting π / 4 shift QPSK as such a modulation method were in various standards for modulation. A signal analyzer for inspecting whether the signal is a signal has been put into practical use.
[0012]
[Problems to be solved by the invention]
However, the signal analysis apparatus described above still has the following problems to be solved.
[0013]
In recent years, also in PHS, there is an increasing need to transmit and receive a large amount of information (data) such as images and moving images between the base station 1 and each mobile station 2 in a short time. As a method for increasing the transmission rate (bps) of information (data) without changing the frequency of the carrier wave, it is conceivable to modulate the phase modulation method to the multi-level modulation method. Specifically, for example, the π / 4 shift QPSK may be changed to 16QAM.
[0014]
FIG. 11 is a signal space diagram of the modulation signal shown on the IQ coordinate in the 16QAM phase modulation system. This 16QAM is a 16-value transmission system in which information is transmitted by 4 bits every symbol time. Therefore, as shown in FIG. 11, the signal points 8 obtained by synthesizing the symbol data I and G on the IQ coordinates appear at 16 locations.
[0015]
In this case, when the symbol rate when the phase modulation method is adopted is 192 ksps, when the 16QAM modulation method is adopted, it corresponds to one symbol with 4 bits. Therefore, the transmission rate of information (data) in the case of phase modulation is 192 ksps × 4 = 768 kbps. In this case, the code length of each slot 5 of 625 μs is 768 kbps × 625 μs = 480 bits, and the symbol length of each slot 5 is 480/4 = 120 symbols.
[0016]
As described above, by adopting 16QAM as the phase modulation method, information (data) can be transmitted at a speed twice the conventional speed.
[0017]
However, the portion that needs to transmit information (data) at high speed in one slot 5 and 6 is information (data) I to be transmitted of 80 symbols in the information channel (TCH) of FIG. Data) Only the part related to I. Control information such as other ramp bits R, status symbols SS, and synchronization words UW need not be transmitted at high speed. Note that information (data) transmitted from each mobile station 2 to the base station 1 is not required to be so fast.
[0018]
Therefore, as shown in FIG. 10, among 625 μs and 120 symbol information channels (TCH), 625 μs of signals 3 transmitted and received between the base station 1 and each mobile station 2 are incorporated in each frame 4 of 5 ms. In each slot 9, a total of 23 symbols of 2 symbols of ramp bits R, a total of 13 status symbols SS and a preamble PR, and 8 symbols of synchronization word UW are defined as the first half region 10. Further, a total of 89 symbols including 1-symbol channel information CI, 8-symbol low-speed ACCH information, 80-symbol transmission information (data) I, and 4-symbol error check bit CRC are defined as the second half region 11. To do. Note that eight symbols of guard bits are provided after the second half region 11.
[0019]
Then, it is conceivable that the first half region 10 is phase-modulated with the conventional π / 4 shift QPSK and the second half region 11 is phase-modulated with the new 16QAM.
[0020]
Therefore, in the signal 3 transmitted from the base station 1 to each mobile station 2 in which each slot 9 having a different phase modulation method in the first half region 10 and the second half region 11 is time-division multiplexed, each slot 9 includes It is necessary to check whether each signal included in the areas 10 and 11 is a signal that meets various standards regarding modulation.
[0021]
The present invention has been made in view of such circumstances, and a signal analysis apparatus capable of separating and evaluating each signal even if a signal using a different phase modulation method is included in one slot. The purpose is to provide.
[0022]
[Means for Solving the Problems]
The present invention provides a signal for analyzing a signal in each slot in a signal under measurement in which a plurality of slots into which signals modulated by first and second phase modulation schemes different from each other in the time axis direction are incorporated are time-division multiplexed. It is an analysis device.
[0023]
The signal analyzing apparatus converts the signal under measurement into symbol data I and Q and outputs the converted signal, and the symbol data I and Q output from the input processing unit are used to calculate each slot in the signal under measurement. A slot detection unit for detecting a range; and a range of each detected slot in a first analysis region in which the first phase modulation method is employed and a second analysis region in which the second phase modulation method is employed. At least modulation analysis of a signal modulated by the first phase modulation method in the first analysis region in each slot based on the analysis region partitioning section to be classified and the symbol data I and Q included in the first analysis region a first signal analyzing unit for performing symbol data I contained in the second analysis region, the second phase modulation system signal modulated by the second analysis region of each slot based on Q A second signal analyzing unit for performing modulation analysis even without, the second analysis region obtained by modulation analysis result and the second signal analyzer of the first analysis region obtained by the first signal analysis unit An analysis result combining unit that combines the modulation analysis results, an analysis result memory that stores the modulation analysis results combined by the analysis result combining unit, a modulation analysis result in the first analysis region, and a second analysis result on the same IQ coordinate A display output unit configured to display and output the modulation analysis result synthesized so as to be distinguishable from the modulation analysis result in the analysis region on the display;
[0024]
In the signal analyzing apparatus configured as described above, the input signal under measurement is converted into symbol data I and Q by the input processing unit. Next, the slot detector detects the range of each slot in the signal under measurement based on the values of the symbol data I and Q. Specifically, the rising positions of the values of the symbol data I and Q are detected. The range of each slot is divided into a first analysis region in which the first phase modulation method is adopted and a second analysis region in which the second phase modulation method is adopted. The positions (bit positions, symbol positions) in the slots of the first analysis area and the second analysis area are given in advance.
[0025]
Then, in the first and second signal analysis units, the first and second analysis regions in the first and second analysis regions in each slot based on the symbol data I and Q included in the first and second analysis regions, respectively. Each signal modulated by the phase modulation method 2 is subjected to modulation analysis. The first and second modulation analysis results are combined, and the combined modulation analysis results are displayed and output on the display so that the first and second modulation analysis results can be distinguished.
[0026]
Another invention is the signal analyzing apparatus according to the invention described above, wherein the first phase modulation method is π / 4 shift QPSK and the second phase modulation method is 16QAM.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a signal analyzing apparatus according to an embodiment of the present invention. The PHS system to be measured by the signal analyzing apparatus according to this embodiment and the slot configuration diagram of the signal under measurement are the same as the PHS system and slot configuration diagrams shown in FIGS.
[0029]
The signal analyzing apparatus according to this embodiment receives a signal under measurement a into which the slot 9 shown in FIG. 10 output from the base station 1 is incorporated, and receives symbol data I and Q from the input signal under measurement a. Input processing unit 12 to be output, and data for analyzing each signal in the first half region 10 and the second half region 11 of each slot 9 in the signal under measurement a using the symbol data I and Q output from the input processing unit 12 The processing unit 13 and a display 14 for displaying the analysis result of each signal in the first half region 10 and the second half region 11 in the signal a to be measured a obtained by the data processing unit 13.
[0030]
As shown in FIG. 10, 23 symbols in each slot 9 of 625 μs incorporated in each frame 4 of 5 ms in the signal to be measured a which is the signal 3 transmitted and received between the base station 1 and each mobile station 2. The first half region 10 is phase-modulated with π / 4 shift QPSK, and the second half region 11 for 89 symbols is phase-modulated with 16 QAM.
[0031]
A high-frequency signal to be measured a is input into the input processing unit 12 via the input terminal 15, and after the signal level is adjusted by the attenuator 16, the frequency converter 17 converts the signal to a frequency signal from the local oscillator (LOOSC) 7. After the frequency conversion to an intermediate frequency of, for example, 16 MHz, unnecessary frequency components are removed by the band pass filter 19 and A / D conversion is performed by the A / D converter 20 at a sampling frequency of, for example, 64 MHz.
[0032]
The A / D converted digital measured signal a is input to a pair of DBMs (Double Balance Mixers) 21 and 22. One DBM 21 receives sine wave data from the oscillator 23, and the other DBM 22 receives cosine wave data from the oscillator 23 via the 90 ° phase shifter 24. Therefore, the digital signal under measurement a is quadrature demodulated into I (in-phase component) data and Q (quadrature component) data, and simultaneously baseband converted.
[0033]
Unnecessary frequency components are removed from the I data and Q data by the low-pass filters 25 and 26, and the frequency conversion units 27 and 28 convert the data to 198 kHz I data and Q data, that is, symbol data I and Q having a symbol transmission rate of 198 ksps The The symbol data I and Q having a symbol transmission rate of 198 ksps are written into the I and Q data memory 29 for N frames, for example. The symbol data I and Q written in the I and Q data memory 29 are sequentially read and input to the next data processing unit 13.
[0034]
For example, the symbol data I and Q input to the data processing unit 12 configured with a DSP (Digital Signal Processor) are input to the slot detection unit 30. The slot detecting unit 30 detects the ramp bit R following the no-signal 8-symbol guard bits provided between the slots 9, thereby starting the start position of each slot 9 in the symbol data I and Q sequentially input. And the end position is detected, and the symbol data I and Q that are sequentially input are stored in the slot waveform memory 31 in units of 9 slots.
[0035]
Accordingly, in the slot waveform memory 31, 120 symbol data I and Q of the slot 9 each having a length of 120 symbols are stored, including the guard bits of 8 symbols which are no signals between the slots 9.
[0036]
The analysis area sorting unit 32 includes a first half area 10 as a first analysis area in which a phase modulation scheme of π / 4 shift QPSK in the slot 9 of 120 symbol length stored in the slot waveform memory 31 is used, and 16QAM The second analysis area 11 is divided into the second analysis area in which the phase modulation method is adopted. Specifically, 23 symbols from the beginning of slot 9 to the 23rd symbol are set as the first half area 10, and 89 symbols from the 24th symbol to the 112th symbol are set as the second half area 11. The analysis area sorting unit 32 writes the sorted first half area 10 to the first half area memory 33 and writes the sorted second half area 11 to the second half area memory 3 4.
[0037]
The first signal analyzer 35 is modulated by the phase modulation method of π / 4 shift QPSK in the first half area 10 in the slot 9 based on the symbol data I and Q for 23 symbols written in the first half area memory 33. Analyzing the received signal.
[0038]
The second signal analysis unit 36 also modulates the signal modulated by the 16 AM phase modulation method in the second half region 11 in the slot 9 based on the symbol data I and Q for 89 symbols written in the second half region memory 34. Is analyzed.
[0039]
The first and second signal analyzers 35 and 36 use the symbol data I and Q to perform modulation analysis (constellation) corresponding to each phase modulation method, modulation error, amplitude error, phase error, origin offset, Perform signal analysis such as modulation accuracy. Each of these signal analysis methods will be described with reference to FIG. 2 using a 16QAM phase modulation method as an example.
[0040]
In the modulation analysis (constellation), as shown in FIG. 2A, 16 signal points 8 obtained by synthesizing 89 sets of symbol data I and Q on IQ coordinates are obtained. As shown in FIG. 2B, the modulation error (EVM error vector magnitude) is the error vector magnitude between the theoretical signal point 41 on the IQ coordinate and the actually measured signal point 8. It is an absolute value.
[0041]
As shown in FIG. 2B, the amplitude error (ME) includes the absolute value of the theoretical vector up to the origin and the theoretical signal point 41 on the IQ coordinate, and the measured vector up to the origin and the measured signal point 8. It is indicated by the difference from the absolute value of. As shown in FIG. 2B, the phase error (deg) is an angle between the origin on the IQ coordinate and the theoretical vector up to the theoretical signal point 41 and the origin and the measured vector up to the actually measured signal point 8. Indicated by φ.
[0042]
As shown in FIG. 2D, the origin offset indicates how much the measurement origin obtained from the 16 signal points 8 measured on the IQ coordinate is deviated from the theoretical origin. . As shown in FIG. 2C, the modulation accuracy is obtained by statistically calculating the degree of variation of each signal point 8 synthesized on the IQ coordinate.
[0043]
The signal analysis for the signal modulated by the π / 4 shift QPSK phase modulation method is almost the same as the signal analysis for the signal modulated by the 16QAM phase modulation method.
[0044]
The above-described analysis results in the first half region 10 and the second half region 11 obtained by the first and second signal analysis units 35 and 36 are individually written into the analysis result memory 38 and sent to the analysis result synthesis unit 37. The The analysis result synthesis unit 37 synthesizes or averages the above-described analysis results in the first half region 10 and the second half region 11 to create an analysis result for each slot 9 and writes it in the analysis result memory 38. As a result, the analysis result memory 38 stores the analysis result of the first half area 10, the analysis result of the second half area 11, and the analysis result of the unit of slot 9 in which these are synthesized.
[0045]
The display output unit 39 reads out each analysis result stored in the analysis result memory 38 based on an instruction from an operator using the operation unit 40 such as an operation panel, and outputs the display result to the display unit 14.
[0046]
FIG. 3 is a diagram illustrating an example of the display screen 42 of the display 14 on which each analysis result is displayed and output. In this example, a π / 4 shift QPSK modulation analysis (constellation) 43 in the first half region 10 and a 16QAM modulation analysis (constellation) 44 in the second half region 11 are displayed in the upper part of the display screen 42. .
[0047]
In the lower part of the display screen 42, analysis results of modulation error, amplitude error, phase error, origin offset, etc. of π / 4 shift QPSK in the first half area 10, analysis results of 16QAM in the second half area 11, and the first half area 10 and the second half area 11 and the analysis result list 45 with the analysis results of the entire area of the slot 9 combined with the data 11 are displayed.
[0048]
FIG. 4 is a diagram illustrating another example of the display screen 42 of the display 14 on which each analysis result is displayed and output. In this example, in the upper part of the display screen 42, the entire slot 9, in which the modulation analysis (constellation) 43 of π / 4 shift QPSK in the first half region 10 and the modulation analysis (constellation) 44 of 16 QAM in the second half region 11 are combined. A region modulation analysis (constellation) 46 is displayed.
[0049]
In this case, in the modulation analysis (constellation) 46 of the entire region, the signal point 7 of the π / 4 shift QPSK is such that the observer can distinguish the signal point 7 of the π / 4 shift QPSK and the signal point 8 of 16QAM. Are indicated by white circles, and signal points 8 of 16QAM are indicated by black circles.
An analysis result list 45 is displayed at the bottom of the display screen 42 as in FIG.
[0050]
FIG. 5 is a diagram showing still another example of the display screen 42 of the display 14 on which each analysis result is displayed and output. In this example, a π / 4 shift QPSK modulation analysis (constellation) 43 in the first half region 10 and a 16QAM modulation analysis (constellation) 44 in the second half region 11 are displayed in the upper part of the display screen 42. . An analysis result list 45 is displayed at the bottom of the display screen 42 as in FIG.
[0051]
In this case, a template 47 indicating 16 regions centered on the above-described theoretical signal point 41 on the IQ coordinate is displayed in the modulation analysis (constellation) 44 of 16QAM. In this way, by displaying the template 47 together with the signal point 8 on the display screen 42, the error (modulation accuracy) of the measured signal point 8 from the theoretical signal point 41 can be visually confirmed. Further, when the measured signal points 8 vary, the degree of variation can be visually confirmed.
[0052]
In the signal analyzing apparatus configured as described above, the input first half region 10 employing the π / 4 shift QPSK modulation method shown in FIG. 10 and the latter half region 11 employing the 16 QAM modulation method are incorporated. The signal under measurement a in which the plurality of slots 9 are time-division multiplexed is converted by the input processing unit 12 into symbol data I and Q having a symbol transmission rate of 192 ksps.
[0053]
The slot detection unit 30 of the data processing unit 13 detects the range of each slot 9 of 120 symbols in the signal under measurement a based on the values of the symbol data I and Q. The range of the slot 9 is divided into a first half area 10 of 23 symbols in which the π / 4 shift QPSK phase modulation scheme is adopted and a latter half area 11 in which the phase modulation scheme of 16 QAM is adopted.
[0054]
Then, in the first and second signal analysis units 35 and 36, π / 4 of the first half region 10 and the second half region 11 in the slot 9 based on the symbol data I and Q included in the first half region 10 and the second half region 11, respectively. Each signal modulated by shift QPSK and 16QAM is analyzed.
[0055]
Each signal analysis for each modulation method, such as modulation analysis (constellation), modulation error, amplitude error, phase error, origin offset, and modulation accuracy, is based on an instruction from the operator using the operation unit 40 such as an operation panel, for example. 3, 4, and 5, the display unit 14 displays and outputs the signals separately for each modulation method.
[0056]
In this way, even if a signal using a different phase modulation method is included in one slot 9, each signal can be separated and evaluated.
[0057]
In addition, this invention is not limited to embodiment mentioned above. The combination of the phase modulation schemes employed in the first half region 10 and the second half region 11 of each slot 9 of the signal to be measured a to be analyzed by the signal analyzing apparatus in the embodiment is set to π / 4 shift QPSK and 16QAM. A combination of other phase modulation methods may be used. For example, a combination of QPSK and 16QAM or a combination of QPSK and 12QAM may be used.
[0058]
Furthermore, it goes without saying that the present invention can also be applied to a phase-modulated signal employed in other communication systems other than PHS.
[0059]
【The invention's effect】
As described above, in the signal analyzing apparatus of the present invention, each signal can be separated and evaluated even if a signal using a different phase modulation method is included in the slot.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of a signal analysis apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing a signal analysis method in the signal analysis apparatus of the embodiment. FIG. 4 is a diagram showing a signal analysis result displayed on a display in the apparatus. FIG. 4 is a diagram showing a signal analysis result displayed on a display in the signal analysis apparatus of the same embodiment. FIG. 5 is a signal analysis of the same embodiment. FIG. 6 is a schematic diagram showing a basic configuration of PHS. FIG. 7 shows a configuration of each frame in a signal transmitted and received between the base station and the mobile station. FIG. 8 is a diagram showing a slot configuration in each frame in a signal transmitted and received between a base station and a mobile station. FIG. 9 is a diagram showing signal points on IQ coordinates in π / 4 shift QPSK. ] With base station [EXPLANATION OF SYMBOLS] shows signal point on the IQ coordinates in FIG. 11 is a 16QAM showing a slot configuration within each frame in signals transmitted and received between the Dokyoku
DESCRIPTION OF SYMBOLS 1 ... Base station, 2 ... Mobile station, 3 ... Signal, 4 ... Frame, 7, 8, 41 ... Signal point, 9 ... Slot, 10 ... First half area, 11 ... Second half area, 12 ... Input processing part, 13 ... Data Processing unit, 14 ... Display, 17, 27, 28 ... Frequency conversion unit, 29 ... I, Q data memory, 30 ... Slot detection unit, 32 ... Analysis region division unit, 35 ... First signal analysis unit, 36 ... Second signal analysis unit, 37 ... analysis result synthesis unit, 38 ... analysis result memory, 39 ... display output unit, 40 ... operation unit, 43, 44, 46 ... modulation analysis (constellation), 45 ... analysis result list

Claims (2)

Analyzes the signal of each slot in the signal under measurement (a) in which a plurality of slots (9) in which signals modulated by the first and second phase modulation methods different from each other in the time axis direction are incorporated are time-division multiplexed. A signal analyzing device for
An input processing unit (12) for converting the signal under measurement into symbol data I and Q and outputting them;
A slot detector (30) for detecting a range of each slot in the signal under measurement from the values of the symbol data I and Q output from the input processor;
The range of each detected slot is divided into a first analysis region (10) in which the first phase modulation method is adopted and a second analysis region (11) in which the second phase modulation method is adopted. An analysis area dividing section (32) to be divided;
A first signal that performs at least modulation analysis of a signal modulated by the first phase modulation method in the first analysis region in each slot based on the symbol data I and Q included in the first analysis region An analysis unit (35);
A second signal for performing at least modulation analysis of the signal modulated by the second phase modulation method in the second analysis region in each slot based on the symbol data I and Q included in the second analysis region. An analysis unit (36);
An analysis result synthesizing unit that synthesizes the modulation analysis result of the first analysis region obtained by the first signal analysis unit and the modulation analysis result of the second analysis region obtained by the second signal analysis unit ( 37)
An analysis result memory (38) for storing the modulation analysis result synthesized by the analysis result synthesis unit;
Display output for displaying the synthesized modulation analysis result on the display (14) so that the modulation analysis result of the first analysis region and the modulation analysis result of the second analysis region can be distinguished on the same IQ coordinate. And a signal analysis device comprising a unit (39).   2. The signal analyzing apparatus according to claim 1, wherein the first phase modulation scheme is π / 4 shift QPSK and the second phase modulation scheme is 16QAM.

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