JP4007978B2 - Signal generator and signal generator level adjustment method - Google Patents

Description

  The present invention relates to a signal generation apparatus that supplies a signal for measuring the electrical performance of a measurement target terminal and a level adjustment method for the signal generation apparatus. For example, a mobile terminal whose characteristics with respect to the signal are represented by, for example, a mobile phone The present invention relates to a signal generation device that generates a signal for testing transmission / reception performance of a (measurement target terminal), and a level adjustment method that corrects a signal level transmitted to a mobile terminal of a measurement target terminal in the signal generation device.

For example, a mobile terminal test system for testing transmission / reception performance of a mobile terminal (measurement target terminal) such as a mobile phone is configured as shown in FIG. 11, for example. That is, in this mobile terminal test system 10, a signal generator 20 in which a signal generator 20b and an attenuator 20a are incorporated, a transmitter tester 30 in which a spectrum analyzer 30a and a power meter 30b are incorporated, an interface unit ( Connecting means) 40 is provided.

  A measurement target terminal 50 is connected to the interface unit (connection means) 40. Further, an error measurement device 60 is connected to the measurement target terminal 50. The interface unit (connecting means) 40 guides the test modulation signal output from the signal generator 20 to the measurement target terminal 50 and guides the modulation signal transmitted from the measurement target terminal 50 to the transmitter tester 30. It is composed of a network incorporating a plurality of changeover switches.

  In such a mobile terminal test system 10, the signal generator 20 b of the signal generator 20 outputs a modulated signal having a constant signal level for testing, for example, a W-CDMA system employed in the measurement target terminal 50. . The modulation signal having the constant signal level is input to the interface unit (connection means) 40 via the attenuator 20a. The test modulation signal that has passed through the interface unit (connection means) 40 is sent to the measurement target terminal 50. The measurement target terminal 50 demodulates the received test modulation signal, obtains original digital test data, and sends it to the error measurement device 60. The error measurement device 60 measures the error rate of the digital test data demodulated by the measurement target terminal 50.

  Then, the attenuation setting amount (dB) of the attenuator 20a is sequentially increased, and the signal level of the test modulation signal output from the signal generator 20 is sequentially decreased. Then, when the modulated signal of each signal level is received, the error measurement device 60 measures the error rate of each demodulated test data output from the measurement target terminal 50.

  Then, the relationship between the signal level of the modulation signal and the error rate is output as an error rate characteristic. That is, the lower limit signal level at the time of the allowable error rate (limit error rate) as the measurement target terminal 50 is obtained. That is, the reception sensitivity of the measurement target terminal 50 is obtained.

JP 2003-18104 A

  However, the signal generator 20 shown in FIG. 11 still has the following problems to be improved.

  In the signal generator 20 of FIG. 11, an interface unit (connection) including a connection cable or a circuit network such as a filter, an amplifier, and an attenuator is provided between the output terminal of the attenuator 20a and the measurement target terminal 50. Means) 40 exists. The signal level drop caused by resistance loss due to the modulation signal passing through the interface unit (connecting means) 40 is also a value that cannot be ignored with respect to the lower limit signal level. Furthermore, when the circuit network of the interface unit (connection means) 40 has frequency characteristics, the contribution of the frequency in the signal level cannot be ignored.

Furthermore, the signal generator 20b in the signal generator 20 has an output between the output at the time of shipment of the mobile terminal test system 10 and the output at the time of measurement at the system installation location, due to environmental conditions such as temperature and changes over time. Errors occur between the output at the time of regular calibration after shipment and the output at the time of measurement, and the output immediately after the start of system operation and the output when operated for a long period of time. This error level is also a value that cannot be ignored with respect to the above-described lower limit signal level.

    In the invention of Patent Document 1, the interface unit (connecting means) 40 is calibrated by the calibration power meter 70. The signal generator 20 and the calibration power meter 70 are controlled by an external control device 80 or the like. I need. Further, an algorithm for determining a correction parameter or the like from the impedance needs to be determined by the operator each time.

  The present invention has been made in view of such circumstances, and the calibration of the measurement system using the signal generator is determined without external control, and the calibration is performed by the measurement system and the power meter. I do. The signal level of the signal that is actually input to the measurement target terminal can be determined by obtaining in advance a calibration value due to loss caused by the interface unit (connecting means) that is the path from the signal generation device to the measurement target terminal. Provided is a signal generation device that can be set to a specified signal level with high accuracy and can greatly improve test accuracy for a measurement target terminal, and a level adjustment method for correcting the signal level output to the measurement target terminal in this signal generation device The purpose is to do.

  The present invention determines a correction parameter such as a measurement point from parameters such as a set frequency range, a signal level of a measurement system, and a type of connection means, and transmits the measurement parameter to the measurement target terminal via the connection means. A signal transmitted from the terminal is received and the signal level is measured with a power meter to obtain a calibration value. At this time, the number of measurement points is increased in the frequency band where the impedance change is large compared to the frequency band where the impedance change is small.

Specifically, the signal generator according to claim 1 of the present invention includes:
A signal generator for supplying a signal to a measurement object in order to measure the electrical performance of the measurement object,
A signal generator having a signal generator and a level adjusting means for adjusting a signal level in response to a signal from the signal generator; and an output terminal of a connection means connected between the signal generator and the measurement object. In a signal generator comprising a correction value table having a value for adjusting the level adjusting means so that the signal level becomes a predetermined value,
A level measuring device for connecting to the output end of the connecting means and measuring the signal level at the output end;
An impedance table for storing impedance characteristics of the connection means;
A measurement parameter table for storing measurement conditions;
Based on the impedance characteristic, first means (measuring point determining means) for determining a measurement point is the frequency to be measured, the level measuring means signal level through said connection means at the determined measurement point in with second means to measure, and a control means including a third means (correction table correction means) for correcting the correction table based on the measurement result of the second means.

Furthermore, the signal generator according to claim 2 of the present invention includes, in addition to claim 1,
Wherein, in addition to the prior SL impedance characteristics based on the measurement conditions stored in the measurement parameter table, first means for determining the measurement point is the frequency to be measured (measurement point determination means), the second means to measure the signal level through the connection means at the determined measurement point by the level measuring means, and the third modifying said correction table based on the measurement result of the second means Means (correction table correction means).

Furthermore, the signal generating device according to claim 3 of the present invention, in addition to claims 1 and 2,
The measurement parameter table stores parameters of frequency range, signal level, and modulation method.

Furthermore, the signal generator of Claim 4 of this invention is added to Claims 1-3,
The impedance table stores a Smith chart rotation locus.

Furthermore, the signal generator of claim 5 of the present invention includes, in addition to claims 1 to 3,
The impedance table stores S parameters obtained by measuring the connection means with a network analyzer in advance.

Furthermore, the signal generator of claim 6 of the present invention includes, in addition to claims 1 to 5,
Display means for displaying the measurement points;
Setting means for correcting the displayed measurement point.

Furthermore, the signal generator according to claim 7 of the present invention includes, in addition to claim 6,
The display means displays the measurement result of the second means;
The control means detects a new measurement point from the display result.

Furthermore, the signal generator of claim 8 of the present invention includes, in addition to claims 1 to 7,
The measurement parameter table stores determination criteria for determining pass / fail of the connection means,
The control means determines the measurement result of the second means based on the determination criterion.

Furthermore, the level adjustment method of the signal generation device according to claim 9 of the present invention includes:
In order to measure the electrical performance of a measurement object, a signal generator level adjustment method for supplying a signal to the measurement object,
The signal level at the output end of the connection means connected to the measurement object so as to have a predetermined value, based on the previously obtained correction value, level adjustment of a signal generator for adjusting the level of the signal from the signal generator In the method
Obtaining impedance characteristics of the connecting means;
Obtaining measurement conditions for the measurement object;
Connecting an output end of the connecting means to a level measuring means;
Determining a frequency to be measured based on the impedance characteristics and measurement conditions;
Measuring a signal level through the connection means at the determined frequency to be measured;
And correcting the correction value based on the measured measurement result.

  Since it is not necessary to control the processing procedure with an external personal computer or the like, the operator does not have to create a personal computer control program or consider an interpolation method. In addition, since parameters such as measurement points are automatically determined, the operator does not need to consider measurement points.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(Description of signal generator)
FIG. 1 is a block diagram illustrating an embodiment. The measurement system 1 includes a signal generator 2 and connection means 9 such as a cable. The control means 4 registers the measurement parameters in the storage means 3 according to the operator settings. The storage means 3 is a measurement parameter table 3b (FIG. 4) for storing the measurement parameters, a correction value table 3a (FIG. 9) for storing correction values described later, and an impedance table 3c (FIG. 9) for storing impedance characteristics of the connection means 9. 5).

  The control means 4 determines a measurement point from the measurement parameters stored in the measurement parameter table 3b and the impedance characteristics of the corresponding connection means 9 stored in the impedance table 3c, and controls the signal generation means 7 and the level measurement means 8. To do. The signal generating means 7 changes the frequency and the signal level, and the level measuring means 8 measures each signal level at the output terminal of the connecting means 9. The control means 4 determines whether or not the connection means is normal from the measurement result, and if it is normal, determines a correction value so that a desired signal level is obtained at the output terminal of the connection means 9, and corrects the correction value. Store in the value table 3a.

  As an example of use, when the signal level accuracy at the output end of the connection means (cable) 9 is required in the measurement system 1 using the signal generator 2, the measurement system 1 including the connection means (cable) 9 is described above. Accuracy can be guaranteed if calibrated by means.

(Description of signal generator level adjustment method)
The impedance characteristic of the connection means 9 is obtained, the measurement condition (measurement parameter) of the measurement target terminal 50 is obtained, the output terminal of the connection means 9 is connected to the level measurement means, and the measurement should be performed based on the impedance characteristic and the measurement condition. Ru determined Teisu the frequency (measurement points). Next, the signal level through the connection unit 9 at the determined measurement point is measured, a correction value is obtained based on the measured result, and the output level of the connection unit 9 connected to the measurement target terminal 50 is determined. The signal level from the signal generating means 7 is adjusted based on a correction value obtained in advance so that the signal level becomes a predetermined value.

  FIG. 2 illustrates a flowchart for creating the correction value table 3a of the signal generator 2. First, the connection means 9 used by the operator is registered (S1). The operator determines and sets the measurement range of the frequency, signal level, and modulation method (S2). A measurement point to be measured is determined from each parameter for which the measurement range has been determined (S3). Similarly, the type and the like of the power sensor 8b are determined from each parameter that has determined the measurement range (S4). The power at the output end of the connecting means 9 is measured by the level measuring means 8 (S5). It is determined whether the measurement result satisfies the standard (S6). In the case of YES (Good), a correction value table is created based on the measurement result (S7). In the case of NO (NG), it is determined that the connection means is defective (S8), and the operator is notified of the result.

Here, the detailed procedure of determining the measurement point (S3) will be described with reference to FIG.
Allocate measurement points evenly (P1). The impedance of the connection means 9 is read from the impedance table 3c (P2). Whether to compare with a reference value or to obtain frequency characteristics is selected (P3). When comparing with the reference value, the impedance of the connecting means 9 is compared with the reference value, and the frequency that is shifted is detected (P4). A measurement point is added to the detected shifted frequency range (P5). When obtaining the frequency characteristic, the loss due to the impedance mismatch of the connecting means 9 is calculated, and the frequency characteristic curve is estimated (P6). As shown in FIG. 7, a measurement point is added to a frequency range in which the estimated amount of change in frequency characteristics is large (P7). As a procedure for estimating the curve of the frequency characteristic, for example, the insertion loss change from the rotation trajectory like the Smith chart shown in FIG. 6 is a severe frequency determines the measurement point to finely measure. As shown in FIG. 8, the addition of the measurement point is determined by the control means 4, and the operator can also specify the measurement point. The measurement points including these added measurement points are displayed on the display means 5 (P8). Here, the frequency range in which the amount of change in frequency characteristics is large is a frequency range in which the difference in measurement level at a predetermined frequency interval is greater than a predetermined value, or when the number of measurement points is limited in advance, measurement at a predetermined frequency interval. The frequency range is determined in descending order of level difference.

Next, the procedure for selecting a power sensor (S4) will be described.
The modulation method is identified from the measurement parameter table 3b. For example, the diode type is selected for only the continuous wave, and the thermal type is selected for the modulated wave. The signal level is identified from the measurement parameter table 3b. For example, a threshold value serving as a reference for selection is set. When the threshold value is 30 dBm or less, the low power type is selected, and when the threshold value is exceeded 30 dBm, the normal type is selected. The frequency range is identified from the measurement parameter table 3b. Select the type that matches the frequency range. The type of the power sensor that satisfies these conditions is selected from the table in which the power sensor parameters are registered.

A detailed procedure for determining whether the measurement result satisfies the standard (S6, S8) will be described.
After the measurement by the power meter, the measurement result graph is displayed on the screen, and the operator determines pass / fail. At that time, from the measurement result graph, it is possible to measure again by changing the point within a certain range. Quality determination, for example, determines that the measurement result of the power meter also raised from the signal generator a signal level to limit case where the target or less, there is a problem in the connection means (amplifier).

  As shown in FIG. 10, an S parameter can be obtained using a network analyzer, and an impedance table can be created from the value.

The measurement flow will be described using the correction value table 3a obtained by calibration.
(1) Specify measurement parameters such as frequency, signal level, and modulation method.
(2) Refer to the area corresponding to the measurement parameter from the correction value table 3a.
(3) Interpolation is performed so that the required signal level is obtained at the output terminal of the connecting means 9.
(4) The signal generating means 7 is set.
(5) Measure with each measurement parameter.

  Although the embodiment has been described with respect to a mobile terminal test system that tests transmission / reception performance of a mobile terminal such as a mobile phone, the signal generator of the present invention can also be used in other test systems.

Block diagram showing schematic configuration of signal generator Flowchart for creating a correction table for a signal generator Flow chart for determining measurement points based on measurement parameters and impedance Diagram showing the contents stored in the measurement parameter table The figure which shows the memory contents of the impedance table Smith chart example Measurement point display example Display example to explain the selection of new measurement points from measurement points and measurement results The figure which shows the memory content of the correction value table Block diagram showing an example of a signal generator using a network analyzer The block diagram of the mobile terminal test system using the conventional signal generator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Mobile terminal test system, 2 ... Signal generator, 3 ... Memory | storage means, 4 ... Control means, 5 ... Display means, 6 ... Setting means, 7 ... Signal Generation means, 8... Level measurement means, 9... Connection means, 10.

Claims (9)

A signal generator for supplying a signal to a measurement object in order to measure the electrical performance of the measurement object,
A signal generator ( 7a ) and level adjusting means ( 7b, 7c ) for receiving the signal from the signal generator and adjusting the signal level, the signal generating means and the measurement object And a correction value table (3a) having a value for adjusting the level adjusting means so that the signal level at the output terminal of the connecting means (9) connected between the two is set to a predetermined value. In
Level measuring means (8) for connecting to the output end of the connecting means and measuring the signal level at the output end;
An impedance table (3c) for storing impedance characteristics of the connection means;
A measurement parameter table (3b) for storing measurement conditions;
Based on the impedance characteristic, first means for determining the measurement point is the frequency to be measured, a second for measuring the signal level through the connection means at the determined measurement point by the level measuring means And a control means (4) including a third means for correcting the correction value table based on a measurement result of the second means.
Wherein, in addition to the prior SL impedance characteristics, the measurement parameters based on the measurement conditions stored in the table, first means for determining the measurement point is the frequency to be measured, at the determined measurement point A second means for measuring the signal level via the connecting means by the level measuring means , and a third means for correcting the correction value table based on a measurement result of the second means. The signal generator according to claim 1.
3. The signal generation apparatus according to claim 1, wherein the measurement parameter table stores parameters of a frequency range, a signal level, and a modulation method.
The signal generator according to claim 1, wherein the impedance table stores a rotation trajectory of a Smith chart.
4. The signal generator according to claim 1, wherein the impedance table stores S parameters obtained by measuring the connection means with a network analyzer in advance.
And Viewing means (5) that displays the measurement points,
Signal generating apparatus according to any one of claims 1 to 5 you, characterized in that a setting means (6) to modify the displayed measurement point was.
The display means displays the measurement result of the second means;
7. The signal generator according to claim 6 , wherein the control means detects a new measurement point from the display result.
The measurement parameter table stores determination criteria for determining pass / fail of the connection means,
The control means, the signal generating apparatus according to the measurement results of the second means to one of claims 1 to 7, wherein the determining based on the criteria.
In order to measure the electrical performance of a measurement object, a signal generator level adjustment method for supplying a signal to the measurement object,
Level adjustment of the signal generator for adjusting the signal level from the signal generator based on a correction value obtained in advance so that the signal level at the output terminal of the connection means connected to the measurement object becomes a predetermined value In the method
Obtaining impedance characteristics of the connecting means;
Obtaining measurement conditions for the measurement object;
Connecting an output end of the connecting means to a level measuring means;
Determining a frequency to be measured based on the impedance characteristics and measurement conditions;
Measuring a signal level through the connection means at the determined frequency to be measured;
A level adjustment method for a signal generator, comprising: correcting the correction value based on the measured measurement result.

Images