JPH07111489A - Method for calculating loss of transmission line - Google Patents

Abstract

PURPOSE:To obtain a method for calculating a loss by which an accurate level loss is obtained from a few continuous data and its range is expanded by calculating the loss from a characteristic of level loss data measured while varying a signal frequency. CONSTITUTION:A signal output terminal 1 of a signal generator 9 and a measurement terminal 2 of a level meter 11 are connected to a signal terminal 3 of a device to be tested 5, a signal input terminal 4A of a measurement device 7A or a signal input terminal 4B of a measurement device 7B. Then the output level of the signal generator 9 is made constant and the level loss of a transmission line 8 is measured by the level meter 11 while varying the frequency at a predetermined interval for a frequency band required for the test. Then the frequency characteristic of the level loss is calculated to decide an approximated polynomial to which the frequency - level loss characteristic is adapted and the coefficient is calculated by a matrix. Thus, when the signal frequency is known, the level loss is easily calculated based on the polynomial and the coefficient. Furthermore, the loss is predicted even in a range in excess of a measurement limit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of calculating a level loss value which occurs in a signal transmission line during information communication.

[0002]

2. Description of the Related Art The level loss of a signal transmission line can be actually measured and easily obtained if the frequency of a signal to be used is determined. However, if the frequency of the signal used is not constant, even if the level loss is measured in advance, the data will be discrete, and if the frequency of the signal actually used is not known, the level loss can always be calculated accurately. Not necessarily.

[0003]

In the above prior art,
When obtaining the level loss value from discrete data, it is necessary to always have all the discrete data as necessary data, and a large amount of data is required for accurate calculation. In addition, there is a problem that it is limited only to the measurable range.

[0004]

The method of the present invention solves the above-mentioned characteristics, allows an accurate level loss value to be easily obtained from a continuous and small amount of data, and extends the range beyond the measurement limit. It provides a transmission line loss calculation method that can predict the level loss data generated in a transmission line by changing the frequency of the signal using a signal generator and a signal level measuring device. A characteristic is that a suitable polynomial is determined from the characteristics of the loss data, a coefficient is calculated by calculation, and a level loss value is calculated from the polynomial and the coefficient.

When the frequency of the signal to be used is not constant and there are many transmission lines in an automatic test equipment such as a radio communication device, each transmission is predicted using a signal generator and a signal level measuring device. The level loss data of the path is measured by switching the frequency, the polynomial that fits is determined from the characteristics of the discrete frequency vs. level loss data, the coefficient is calculated by calculation, and the level loss value is calculated from the polynomial and the coefficient. It is characterized by doing.

When a communication device is tested, a signal causes a level loss in the process of passing from the generation end to the end point on the transmission path. This loss depends on the frequency of the transmitted signal and affects the quality of the transmitted signal. As described above, the level loss value can be easily calculated from the polynomial and its coefficient if the frequency of the signal is known. During the test, if the frequency of the signal used for each test changes,
It is possible to easily calculate the level loss value from the frequency and correct the level of the influence of the transmission line on the signal for each frequency. Further, since the regression equation is used, it is possible to predict even in a range exceeding the measurement limit. When calculating the level loss value from discrete data, all discrete data are always held as necessary data, and a large amount of data is required for accurate calculation. Since it can be calculated from the data of only the coefficient and the coefficient, the amount of the data is remarkably small, and it is possible to absorb the measurement error of the data obtained in advance by appropriately selecting a suitable regression equation.

[0007]

1 is an explanatory view of an embodiment of the method of the present invention in an automatic measuring apparatus for wireless communication equipment. In FIG. 1, 5 is a device under test (wireless communication device), 7A and 7B are measuring devices connected to the device under test 5 through a signal transmission line 8 via an interface device 6, and 8A is a signal transmission section. 9 is a standard signal generator, 10A is a fixed attenuator for matching, 1 is a signal output terminal, 11 is a level meter, 10B is a fixed attenuator for matching 2 is a measuring terminal, 3 is a signal input / output terminal of the device under test 5, 4A, 4B
Are signal input / output terminals of the measuring instruments 7A and 7B. In wireless communication equipment, testing is generally required in the allocated frequency band and a frequency band that is several times that frequency band. In this case, in order to obtain accurate data, it is necessary to correct that the level loss of the signal transmission section 8A in the measuring device differs depending on the frequency of the signal to be measured. This implementation method is
(1) The signal output terminal 1 of the signal generator 9 and the measurement terminal 2 of the level meter 11 are used to correct the error between the measuring instruments used.
Are connected, the output level of the signal generator 9 is made constant, and the frequency band required for the test is varied at regular intervals, and the level meter 11 measures the level loss each time. Next (2)
It is the signal transmission section 8A where the loss is desired to be measured. Machine under test 5
Signal terminal 3 and the signal input terminal 4A of the measuring instrument 7A or 7B
Alternatively, the signal output terminal 1 of the signal generator 9 and the measurement terminal 2 of the level meter 11 are respectively connected to 4B, and the level loss of the transmission line is measured by the level meter 11 by changing the frequency in the same manner as (1). (3) The frequency characteristic of level loss is calculated from (1) and (2). (4) An approximate polynomial with which the frequency-level loss characteristic is suitable is determined, and its coefficient is calculated from the determinant.

For example, a fourth-order approximation polynomial is shown as a calibration data calculation formula.

[Table 1] Next, the calibration data is shown in the following table.

[Table 2] The calibration curve is shown in FIG.

[0009]

As described above, according to the present invention, the level loss data generated in advance in the transmission line is measured by changing the frequency of the signal using the signal generator and the signal level measuring device, and the individual level is measured. A feature is that a suitable polynomial is determined from the characteristics of the loss data, a coefficient is calculated by calculation, and a level loss value is calculated from the polynomial and the coefficient. The value can be determined and the range can be extended beyond the measurement limit.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the method of the present invention in an automatic measuring device of a wireless communication device.

FIG. 2 is a calibration curve diagram showing a frequency-level loss relationship in the present invention.

[Explanation of symbols]

 5 device under test 6 interface device 7A measuring device 7B measuring device 8 transmission line 8A signal transmission section 9 standard signal generator 10A fixed attenuator for matching 10B fixed attenuator for matching 11 level meter

Claims (2)

[Claims] 1. A signal generator and a signal level measuring device are used to measure level loss data generated in advance in a transmission line by changing the frequency of the signal, and a polynomial to be fitted is determined from the characteristics of each level loss data. Then, the coefficient is calculated by calculation, and the level loss value is calculated from the polynomial and the coefficient thereof. 2. When the frequency of the signal to be used is not constant and there are many transmission lines, the level loss data of each transmission line is preliminarily measured by switching the frequency, and the discrete frequency-to-level loss is measured. The transmission path loss calculating method according to claim 1, wherein a suitable polynomial is determined from the characteristics of the data, and the coefficient is calculated by calculation.