JP2991361B2 - Digital modulation signal analyzer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital modulation signal analyzing apparatus which can be used to evaluate, for example, the quality of a digital modulation signal used in mobile communication or the like.

[0002]

2. Description of the Related Art In the field of mobile communication, a digital modulation system is frequently used because of a narrow band occupied by radio waves and little influence of fading. As one example of a digital modulation method, a π / 4DQPSK modulation method is used in mobile phones. In order to evaluate a signal of a modulation method in π / 4DQPS, conventionally, an IQ pattern (hereinafter, referred to as a constellation display or a constellation image) is drawn on a display as shown in FIG. and evaluated by observing the phase transition axis trajectory degree of concentration and the like at the point P _1, P ₂ ~P _8.

The constellation display can be displayed by a combination of devices as shown in FIG. In the figure, reference numeral 1 denotes a receiving device. This receiving device can be replaced by a device capable of selecting and receiving a digitally modulated carrier frequency. In general, a target digital modulation signal ( 800
(Carrier frequency of about MHz). The received signal taken into the spectrum analyzer is converted into an intermediate frequency signal of about 200 KHz through several stages of frequency converters and output. This output signal is AD-converted by the AD converter 2, and the AD-converted output is temporarily stored in the buffer memory 3.

The signals fetched into the buffer memory 3 are sequentially read out and demodulated by a demodulation processor 4. The demodulated output of the demodulation processing device 4 is taken into the data memory 5, converted into image data by the imaging processing device 6, the image data is taken into the image memory 7, and the image taken into the image memory 7 is used as the receiving device 1. Spectrum analyzer display 9
, The constellation display shown in FIG. 3 can be obtained.

On the other hand, by giving the demodulated data stored in the data memory 5 to the arithmetic unit 8, the in- phase components of the respective symbol points P ₁ , P ₂ ,.
I and the orthogonal component Q can be displayed as characters.

[0006]

The object of the invention is to be Solved by the conventional constellation display, same
Since the display of the phase component I and the quadrature component Q are displayed separately by switching the mode, the symbol points P ₁ , P ₂ , P
There is a disadvantage that it is not possible to judge the correspondence between the position of ₃ ... Conventionally, each symbol point P ₁ ,
Only the information of P ₂ ,... Could be displayed.

An object of the present invention is to provide a digital modulation signal analyzing apparatus capable of displaying information on a target symbol point and information on a locus in association with a position on a constellation display.

[0008]

According to the present invention, a digitally modulated signal is AD-converted, the AD-converted output is demodulated by a demodulation processing device, and the demodulated output is stored in a data memory and the demodulated data stored in the data memory. Data is converted into image data by an image processing device, the image data is stored in an image memory, and a phase change of a received signal is displayed on a display as a constellation image. Generator, a marker display means for giving an address generated by the address generator to an image memory, writing a marker at this address position, adding the marker to the constellation image and displaying the marker, The address generated by the generator is converted to the corresponding address in the data memory, and this address is Scan reads the data memory by and is characterized by being configured by adding an address decoder for displaying data corresponding to a portion to the marker position indicated by the indicator.

According to the configuration of the present invention, by appropriately setting the address generated from the address generator, any one of the constellation-displayed symbol points can be indicated by the marker. By pointing an arbitrary symbol point with a marker, the content of the data that changes with time at that symbol point can be displayed as characters in the data display column.

[0010]

FIG. 1 shows an embodiment of the present invention. Parts corresponding to those in FIG. 4 are denoted by the same reference numerals. The feature of the present invention is that the address generator 11 and the marker display means 12 are provided.
And an address decoder 13. The address generator 11 can generate an arbitrary address in the entire address area of the image memory 7 by a manual operation. Therefore, in this example, a case is shown in which it is constituted by a numeric key switch 11A and a rotary knob 11B. The approximate value in the address area is input by the numeric switch 11A. At the same time, when the rotary knob 11B is turned, for example, to the + side, an address counter (not particularly shown)
The count is started in the direction, and the address is set to +1 in correspondence with the clock speed. Further, when the user rotates in one direction, the address counter starts counting down and changes the address by -1. By increasing the rotation angle of the rotary knob 11B, the speed of the clock is increased, and accordingly, the speed at which the address counter changes by +1 or -1 also changes. In other words, when the rotary knob 11B is turned greatly, the clock speed increases and the address step speed also increases. When the rotary knob 11B is set to 0, the address increment stops.

The address generated by the address generator 11 is provided to a marker display 12. The marker display means 12 writes, for example, a character code serving as a marker into the image memory 7 at the address. By writing a marker in the image memory 7, a marker M is displayed at a position corresponding to the write address as shown in FIG. The marker M is adjusted to a desired symbol point by operating the numeric key switch 11A and the rotary knob 11B.

When the marker M indicates a target symbol point, the address signal is converted into a corresponding address in the data memory 5 by the address decoder 13 in that state. By receiving an address representing a marker position from the address decoder 13, the data memory 5
Reads out the demodulated data at the symbol point indicated by the marker M, supplies the demodulated data to the arithmetic unit 8 for arithmetic processing, and performs an in- phase component I and a quadrature component at the symbol point .
The minute Q is calculated and supplied to the display 9. For example, as shown in FIG. 2, the display 9 has a data display column 9A at the upper left of the constellation display screen. The data display column 9A has the symbol point number, the in- phase component I and the quadrature component of each symbol point.
Display Q. The in-phase component I and the quadrature component Q sequentially change over time. Each time the content changes, the in- phase component I
The content of the intersecting component Q indicates a state in which the data is sequentially moved upward (scroll) in the data display column 9A and sequentially changed. By changing the position of the marker M, the contents of the demodulated data at an arbitrary symbol point can be displayed. Since there are several sampling points between the symbol points, the received data of each sample point is also stored in the data memory 5. Accordingly, by moving the marker M along a locus connecting the symbol points to each other, when the marker M matches the sample point, the in- phase component I and the quadrature component Q of the sample point can be displayed.

[0013]

As described above, according to the present invention, in addition to the constellation display of the digital modulation signal, the position of each symbol point and the in- phase component I and the quadrature component Q can be observed in association with each other. Therefore, there is obtained an advantage that the quality of the digital modulation signal can be accurately evaluated.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a front view for explaining an example of a constellation display obtained by the present invention.

FIG. 3 is a front view for explaining an example of a constellation display obtained by a conventional technique.

FIG. 4 is a block diagram for explaining a conventional technique.

FIG. 5 is a front view for explaining a data display mode according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Receiving device 2 AD converter 3 Buffer memory 4 Demodulation processing device 5 Data memory 6 Imaging processing device 7 Image memory 8 Arithmetic device 9 Display 9 A Data display column 11 Address generator 12 Marker display means 13 Address decoder

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04L 27/00-27/38 G01R 29/06

Claims (1)

(57) [Claims] 1. A. First Embodiment The digital phase modulation signal is A / D converted, the A / D converted output is demodulated by a demodulation processor, and the demodulated data is stored in a data memory.
The demodulated data stored in the data memory is converted into image data by an image processing apparatus, stores the image data stored in the image memory, the display on the display device as the phase transition constellation image of the received signal, the upper Symbol data memory Performs arithmetic processing on the demodulated data and converts the in- phase and quadrature components to characters.
A digital modulation signal analyzer capable of displaying on a part of the display, B. an address generator capable of manually generating an arbitrary address in the address area of the image memory; D. a marker display means for giving an address generated by the address generator to the image memory and displaying a marker at the address position; The address generated by the address generator is converted into a corresponding address in the data memory, the data memory is read out by the converted address, and an in- phase component on the constellation display indicated by the marker indicated by a part of the display , quadrature,
A digital modulation signal analyzer, comprising: an address decoder for displaying a component ;