JP3369700B2 - Burst wave rise / fall characteristics evaluation device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for displaying the correlation between a symbol determination point of a signal and a reference time when measuring the rising and falling characteristics of a burst wave signal.

[0002]

2. Description of the Related Art In recent years, portable radio telephones that are rapidly becoming popular use digitally modulated burst wave signals as communication signals. It is important that the rise / fall time characteristics of the burst wave signals are within the specified values so that these burst signals do not affect the burst wave signals of the adjacent channels. There are two methods for measuring the rise / fall time characteristics. One is a measurement method using a spectrum analyzer, and the other is a measurement method using a modulation accuracy measuring instrument.

First, the digitally modulated burst wave signal and the rise / fall time characteristics of the burst wave signal will be described with reference to FIG. The burst wave signal refers to a signal which is propagated by repeating a state in which a radio frequency signal exists for a certain period as shown in FIG. 8A and no signal exists for the next certain period. During the duration of this signal, the transmitted signal, that is, the digitally modulated radio frequency signal exists in the state as shown in FIG. 8 (B). For example, in the case of BPSK modulation, a digital signal "
A sine wave signal having a phase delay of 0 degrees exists in the 1 "state, and a phase delay of 1 degree exists in the digital signal" 0 "state.
There is an 80 degree sine wave signal, and this combination propagates the necessary information. From the phase of this modulated signal,
The time timing for determining the digital value is called a symbol determination point. Since the band of this digitally modulated signal is limited by the filter, not only the phase but also the amplitude fluctuates. In digital modulation such as BPSK, QPSK, or π / 4 shift QPSK, there is timing information at the symbol decision point even in this amplitude variation. Therefore, the symbol determination point serving as the reference time can be obtained from the modulated signal component in the received burst wave signal.

The burst wave signal uses the same frequency by a plurality of wireless stations. Therefore, when using in time division, each burst wave signal from each wireless station is
The lengths of the rising and falling edges are defined so as not to collide with each other in terms of time, and are standardized using the symbol determination point of the modulated signal as the reference time. Here, it is important that the signal rises within a few symbol decision points from the state where there is no signal to the modulation portion by the data to be transmitted. For example, if the rising edge is slow, the level of the portion to be transmitted is insufficient, and sufficient demodulation cannot be performed. Also, if the trailing edge is slow, it will collide with burst wave signals from other wireless stations assigned in the next time.

Next, a conventional technique example using a spectrum analyzer will be described with reference to FIG. The configuration is such that the burst wave signal input to the input terminal 11 and the local oscillator 1
A mixer 12 for mixing the output signal of 3 as an input signal, a bandpass filter 14, a logarithmic amplifier 15, a detector 16, an AD converter 17, and a display unit 19. The signal mixed by the mixer 12 and passed through the band-pass filter 14 is output as an intermediate frequency signal of several tens of kHz.
The level is further amplified by the logarithmic amplifier 15, and the detector 1
At 6, envelope detection is performed. That is, the signal of FIG. 8 (A) is output as a rectangular wave signal as shown in FIG. 8 (C).

Further, this signal is converted into a digital signal value by the AD converter 17, and the result is displayed on the display 19 as shown in FIG.
It is displayed like (C). Then, using the trigger function of the spectrum analyzer, the tester determines the trigger point to determine the symbol determination point. In this case, the dynamic range is large and the C / N ratio can be up to 90 dB, but the trigger point and the reference time of the symbol decision point cannot be correlated. Further, a tester may cause a difference in the setting of the trigger points, so that some error always occurs.

Next, an example using a modulation accuracy measuring instrument will be described with reference to FIG. The configuration is such that the burst wave signal input to the input terminal 11 and the mixer 12 that mixes the output signal of the local oscillator 13 as an input signal, the bandpass filter 14, the AD converter 17, the display 19, and the entire control. And a microprocessor 18 for performing. Since the measuring instrument does not have the detector 16, the intermediate frequency signal input to the AD converter 17 also includes the modulation signal component. Therefore, as shown in FIG. There is an advantage that the time relationship with the judgment point can be clearly displayed. However, on the other hand, the dynamic range can be only about 60 to 70 dB, and in order to obtain the C / N ratio of 90 dB, the AD converter 17 having a large number of effective bits is required, which is an expensive device.

[0008]

As described above, when the spectrum analyzer is used, the dynamic
Although the range can be sufficiently obtained, on the other hand, there is a problem that the symbol decision point and the reference time cannot be correlated. Further, when the modulation accuracy measuring instrument is used, the time relationship between the symbol decision point and the reference time can be displayed clearly, but on the other hand, there is a problem that the dynamic range is insufficient. The present invention has been made in view of these problems, and an object thereof is to provide an evaluation device capable of sufficiently obtaining a necessary dynamic range and displaying a clear time relationship between a symbol determination point and a reference time.

[0009]

[Means for Solving the Problems]

(Claim 1) A burst wave signal, which is a signal under measurement, is input to the input terminal 11. The mixer 12 having the burst wave signal and the output signal of the local oscillator 13 as input signals, the band filter 14, the logarithmic amplifier 15, the detector 16, the AD converter 17, the display 19, and the microprocessor 18 are included. To do. An inverse logarithmic conversion operation is performed based on the digital signal value obtained by the conversion by the AD converter 17 to obtain an amplitude component of the modulation signal of A (t) = (I ² + Q ² ) ^1/2 . Here, I and Q are I = In phase in FIG.
Component, Q = Quadrature phase component. From the amplitude component data of the same modulation signal, θx = arc tan {ΣA ² (t) ・ Sin (ω
₀ t) / ΣA ² (t) · Cos (ω ₀ t)}, the phase difference θx 32 from the reference time is obtained. Next, in order to match the time of the symbol determination point with the displayed time axis, the display data is time difference tx corresponding to the phase difference θx 32 on the time axis. The parallel movement of 31 minutes for display makes it possible to clarify the relationship between the symbol determination point and the reference time. Further, the dynamic range can be sufficiently obtained by using the logarithmic amplifier 15.

(Claim 2) A burst wave signal which is a signal under measurement is input to the input terminal 11. The burst wave signal and the output signal of the local oscillator 13 are used as input signals, a mixer 12, a bandpass filter 14, a logarithmic amplifier 15, an AD converter 17, a display 19, and a microprocessor 18. Since the data converted into the digital signal value by the AD converter 17 also includes the modulation signal component, the reference time is extracted from this by the processing of the microprocessor 18, and the envelope detection is further performed by the microprocessor. A rectangular wave signal is extracted by the processing of 18, and both data are sent from the microprocessor 18 to the display 19 for display.

(Claim 3) A burst wave signal which is a signal under measurement is input to the input terminal 11. A mixer 12 that receives the burst wave signal and the output signal of the local oscillator 13 as input signals, and a bandpass filter 14 are provided. The intermediate frequency signal output from the bandpass filter 14 passes through the logarithmic amplifier 15 and the detector 16, is converted into a digital signal value by the AD converter A17a, and is displayed on the display 19 as a rectangular wave signal. The intermediate frequency signal is also AD
It is also input to the converter B17b, converted into a digital signal value, and input to the microprocessor 18. Since the data input to the microprocessor 18 also includes the modulation signal component, the reference time is extracted from this and displayed on the display 19 as the reference time.

(Claim 4) A burst wave signal, which is a signal under measurement, is input to the input terminal 11. A mixer 12 that receives the burst wave signal and the output signal of the local oscillator 13 as input signals, and a bandpass filter 14 are provided. The intermediate frequency signal output from the band-pass filter 14 passes through the logarithmic amplifier 15 and the detector 16, is converted into a digital signal value by the AD converter 17, and is displayed on the display 19 as its rectangular wave signal. The intermediate frequency signal is also input to the timing extraction circuit to detect the reference time signal.
The detected reference time signal is input to and displayed on the display unit 19, and is also input to the AD converter 17 and used as a conversion start signal to obtain a digital signal value according to the reference time. Then, it is sent to the display device 19 and displayed as a rectangular wave signal.

[0013]

[Action]

(Claim 1) The logarithmic amplifier 15 enables a large dynamic range. The detector 16 has a function of performing envelope detection and outputting a rectangular wave signal.
The D converter 17 samples the rectangular wave signal and converts it into a digital signal value. The microprocessor 18 calculates the inverse logarithmic conversion based on the digital signal value and the phase difference θx =
arc tan {ΣA ² (t) ・ Sin (ω ₀ t) ／ ΣA ² (t) ・ Cos (ω
₀ t)}. And the phase difference θx 3
2 is the time difference tx The reference time can be displayed on the display 19 by converting into 31. Therefore, the time relationship between the symbol determination point and the reference time is clearly displayed on the display 19.

(Claim 2) The AD converter 17 receives the logarithmically amplified intermediate frequency signal including the modulation signal component and converts it into a digital signal value. The microprocessor 18 performs inverse logarithmic conversion to restore the actual signal, extracts the reference time from the modulated signal component, and performs envelope detection of the burst wave signal by arithmetic processing. The display 1 shows the time relationship between the symbol determination point and the reference time.
9 acts as a clear expression.

(Claim 3) AD converter A17a
The above is the same as the description of the "operation regarding claim 1". AD converter B17b and microprocessor 18
Extracts the reference time from the modulated signal component and sends the data to the display 19 to display the reference time. Since the role of the microprocessor 18 in this example is only to extract the reference time, there is an advantage that the burden on the microprocessor 18 is light and the display speed is correspondingly high.

(Claim 4) Up to the AD converter 17, the operation is the same as that described in "Operation of Claim 1". The timing extraction circuit serves to extract the reference time by hard means.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in the case of claim 1 is shown in FIG. A burst wave signal, which is a signal under measurement, is input to the input terminal 11. This burst wave signal and local oscillator 1
It comprises a mixer 12 having the output signal of 3 as an input signal, a bandpass filter 14, a logarithmic amplifier 15, a detector 16, an AD converter 17, a display 19, and a microprocessor 18. Although not specifically mentioned here,
It is assumed that the processor 18 also includes a memory circuit. The intermediate frequency signal S (t), which is the output of the band-pass filter 14, is logarithmically amplified by the logarithmic amplifier 15, that is, data of log S (t) is input to the detector 16. The logarithmically amplified signal is envelope-detected by the detector 16 and output as a rectangular wave signal of log (I ² + Q ² ) ^1/2 . This signal is converted into a digital signal value by the AD converter 17, and once
It is stored in a memory circuit in the processor 18.

The microprocessor 18 uses its own arithmetic function to perform an inverse logarithmic conversion operation on the basis of the digital signal value obtained by the conversion by the AD converter 17, and A (t) = (I ² + Q ² ) ^1/2 of the amplitude component of the modulated signal is obtained. From the amplitude component data of the modulation signal, θx = ar
c tan {ΣA ² (t) ・ Sin (ω ₀ t) / ΣA ² (t) ・ Cos (ω ₀ t)}
By performing the following calculation, the phase difference θx 32 from the frequency signal which becomes the reference time can be obtained. Next, on the display screen of the display 19, the displayed rectangular wave signal is aligned with the time of the symbol determination point and the displayed time axis, and the time difference tx corresponding to the phase difference θx32 on the time axis is displayed. Move in parallel for 31 minutes. From the above, the symbol determination point could be adjusted to the reference time. Furthermore, the dynamic range is sufficiently obtained.

An embodiment in the case of claim 2 will be described with reference to FIG. A burst wave signal, which is a signal under measurement, is input to the input terminal 11. The burst wave signal and the output signal of the local oscillator 13 are used as input signals, a mixer 12, a bandpass filter 14, a logarithmic amplifier 15, an AD converter 17, a display 19, and a microprocessor 18. In this case, since the detector 16 is not provided, the data converted into the digital signal value by the AD converter 17 includes the modulation signal component and is stored in the storage circuit. Therefore, micro
The processor 18 extracts the reference time from this by arithmetic processing, and further extracts the envelope of the burst wave. By sending both data from the microprocessor 18 to the display unit 19 for display, a sufficient dynamic range can be obtained.
Moreover, the time relationship between the symbol determination point and the reference time could be displayed clearly.

An embodiment in the case of claim 3 will be described with reference to FIG. A burst wave signal, which is a signal under measurement, is input to the input terminal 11. A mixer 12 that receives the burst wave signal and the output signal of the local oscillator 13 as input signals, and a bandpass filter 14 are provided. The intermediate frequency signal output from the band-pass filter 14 passes through the logarithmic amplifier 15 and the detector 16, is converted into a digital signal value by the AD converter A17a, and the rectangular wave signal is displayed on the display device 19. On the other hand, the intermediate frequency signal that still contains the modulation signal component is AD
It is also input to the converter B17b, converted into a digital signal value, and input to the microprocessor 18. The microprocessor 18 extracts the reference time from the input data and displays it on the display 19 as the reference time.

An embodiment in the case of claim 4 will be described with reference to FIG. A burst wave signal, which is a signal under measurement, is input to the input terminal 11. A mixer 12 that receives the burst wave signal and the output signal of the local oscillator 13 as input signals, and a bandpass filter 14 are provided. The intermediate frequency signal output from the band-pass filter 14 passes through the logarithmic amplifier 15 and the detector 16, is converted into a digital signal value by the AD converter 17, and the rectangular wave signal is displayed on the display unit 19. On the other hand, the intermediate frequency signal still including the modulation signal component is also input to the timing extraction circuit. And by hard means,
A reference time signal is detected. The detected reference time signal is input to and displayed on the display unit 19, and is also input to the AD converter 17 and used as a conversion start signal to obtain a digital signal value according to the reference time. And display 19
And displayed as a rectangular wave signal. Further, the reference time signal is also sent to the display device 19 and displayed.

[0022]

Since the present invention is configured as described above, it has the following effects. It has been possible to provide an evaluation device that can obtain a necessary dynamic range sufficiently with one device and can display the time relationship between a symbol decision point and a reference time clearly. Since it can be realized without using expensive parts, it can be offered at a low price, and since the user does not have to set the trigger point, the same measurement result can be obtained regardless of who makes it reliable as measurement data. Greatly improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment.

FIG. 2 is a vector diagram of a frequency signal serving as a reference time.

FIG. 3 is a diagram illustrating a phase difference θx and a time difference tx.

FIG. 4 is a block diagram showing a second embodiment.

FIG. 5 is a block diagram showing a third embodiment.

FIG. 6 is a block diagram showing a fourth embodiment.

FIG. 7 is a block diagram showing a conventional method using a spectrum analyzer.

FIG. 8 is a waveform diagram and timing chart of a signal for explaining a signal under measurement and a symbol decision point.

FIG. 9 is a block diagram showing a conventional method using a modulation accuracy measuring device.

FIG. 10 is a diagram illustrating a signal under measurement by a modulation accuracy measuring device.

[Explanation of symbols]

11 input terminals 12 mixers 13 Local oscillator 14 band filter 15 logarithmic amplifier 16 detector 17, 17a, 17b AD converter 18 microprocessors 19 Display 31 time difference tx 32 Phase difference θx

Claims (4)

(57) [Claims] 1. A mixer (12) for mixing the output signal of the local oscillator (13) and the burst wave signal applied to the input terminal (11), and an output of the mixer (12) are input. Band filter (1
4), a logarithmic amplifier (15) that receives the output signal of the bandpass filter (14), and a detector (1 that receives the output signal of the logarithmic amplifier (15).
6), an AD converter (17) that receives the rectangular wave signal that is the output of the detector (16), and a digital signal value that is the output signal of the AD converter (17) as an input, and the phase difference θx ( 32) by calculation to extract the reference time, and a display () for displaying both by inputting the digital signal value of the rectangular wave signal output from the microprocessor (18) and the reference time data. 19), and a burst wave rising / falling characteristic evaluation device comprising: 2. A mixer (12) provided with a local oscillator (13) for receiving an output signal thereof and a burst wave signal applied to an input terminal (11) as inputs, and an output of the mixer (12) as an input. Band filter (1
4), a logarithmic amplifier (15) that receives the output signal of the bandpass filter (14), an AD converter (17) that receives the output signal of the logarithmic amplifier (15), and an AD converter (17). A microprocessor (18) that inputs a digital signal value that is an output signal and extracts a reference time and a rectangular wave signal by calculation, and a digital signal value and a reference time data of the rectangular wave signal that is output from the microprocessor (18). And a display device (19) for displaying both of them as inputs, and a burst wave rising / falling characteristic evaluation device. 3. A mixer (12) which is provided with a local oscillator (13) and which receives an output signal thereof and a burst wave signal applied to an input terminal (11) as inputs, and an output of the mixer (12) as an input. Band filter (1
4), a logarithmic amplifier (15) that receives the output signal of the bandpass filter (14), and a detector (1 that receives the output signal of the logarithmic amplifier (15).
6), an AD converter A (17a) that receives the rectangular wave signal that is the output of the detector (16), and an AD converter B (17b) that receives the output signal of the bandpass filter (14), A digital signal value of a rectangular wave signal output from a microprocessor (18) that receives a digital signal value that is an output signal of the AD converter B (17b) and extracts a reference time, and an output of the AD converter A (17a) And a display device (19) for displaying both of the reference time data output from the microprocessor (18) as an input, and a burst wave rising / falling characteristic evaluation device. 4. A mixer (12) provided with a local oscillator (13) and receiving the output signal of the local oscillator (13) and the burst wave signal applied to the input terminal (11) as input, and the output of the mixer (12) as input. Band filter (1
4), a logarithmic amplifier (15) that receives the output signal of the bandpass filter (14), and a detector (1 that receives the output signal of the logarithmic amplifier (15).
6) and the rectangular wave signal which is the output of the detector (16),
An AD converter (17) that uses the reference time signal output from the timing extraction circuit as a measurement start signal, and a timing extraction circuit that inputs the output signal of the bandpass filter (14) and outputs the reference time signal, and an AD converter A display device (19) for displaying both by inputting the digital signal value of the rectangular wave signal which is the output of (17) and the reference time data which is the output of the timing extraction circuit.
A burst wave rising / falling characteristic evaluation device comprising: