阅读说明：本技术 一种测量一体化***高频头噪声系数的方法 (Method for measuring noise coefficient of tuner of integrated satellite television ) 是由 秦顺友 王聚亮 于 2020-07-27 设计创作，主要内容包括：本发明公开了一种测量一体化卫星电视高频头噪声系数的方法,属于卫星电视接收站天线技术领域。本发明首先将一体化卫星电视高频头置于微波吸波箱内,利用频谱分析仪测量一体化卫星高频头接收环境噪声的归一化噪声功率,并用温度计测量出微波吸波箱的环境温度；然后由测量的归一化噪声功率和环境温度,计算出一体化卫星电视高频头的噪声系数。该方法操作简单,易于实施,能够得到精确的测量结果,具有较强的推广和应用价值。(The invention discloses a method for measuring noise coefficient of an integrated satellite television tuner, and belongs to the technical field of satellite television receiving station antennas. Firstly, placing an integrated satellite television tuner in a microwave wave absorption box, measuring the normalized noise power of the integrated satellite tuner for receiving environmental noise by using a spectrum analyzer, and measuring the environmental temperature of the microwave wave absorption box by using a thermometer; and then calculating the noise coefficient of the integrated satellite television tuner according to the measured normalized noise power and the measured ambient temperature. The method is simple to operate, easy to implement, capable of obtaining accurate measurement results and high in popularization and application value.)

1. A method for measuring the noise coefficient of an integrated satellite television tuner is characterized by comprising the following steps:

(1) placing the integrated satellite television tuner in a microwave wave absorption box, and measuring the normalized noise power N received by the integrated satellite television antenna feed source by a spectrum analyzer₀Measuring the ambient temperature t of the microwave absorption box by using a thermometer;

(2) according to normalized noise power N₀And ambient temperature t, calculated as a whole using the formulaNoise figure of the satellite television tuner:

in the formula:

NF-noise coefficient of integral satellite television tuner, unit: dB;

N₀-normalized noise power measured by the spectrum analyzer, in units: dBm/Hz;

L_RF-radio frequency cable loss between the integrated satellite television tuner and the spectrum analyzer;

k-boltzmann constant, unit: J/K;

t-ambient temperature of the microwave absorption box, unit: DEG C;

G_LNB-gain of integrated satellite television tuner.

2. The method for measuring the noise figure of the integrated satellite television tuner as claimed in claim 1, wherein the step (1) is implemented by: firstly, establishing a test system, and electrifying and preheating system instrument equipment to ensure that the test system instrument equipment works normally; then setting state parameters of the spectrum analyzer, and measuring the normalized noise power received by the integrated satellite television tuner by using the noise measurement function of the spectrum analyzerN ₀(ii) a In addition, the ambient temperature of the microwave absorption box measured by the thermometer is recordedt。

Technical Field

The invention relates to the technical field of satellite television receiving station antennas, in particular to a method for measuring noise coefficients of an integrated satellite television tuner.

Background

A satellite tv receiving station system generally comprises a satellite tv receiving antenna, a feed source, a tuner (also called a low noise block converter, denoted by LNB), a tv receiver, a smart card, a switch, and a feeder line. The high frequency head is one of the important devices of the satellite receiving system, the noise coefficient is the most important technical index, the performance of the high frequency head directly affects the image quality received by the satellite television, and therefore, the accurate measurement of the noise coefficient of the high frequency head is very important. The conventional Y factor method is adopted to measure the noise coefficient of the satellite television tuner at present. However, most of the existing satellite television receiving antenna feed sources and tuners are integrated together and are integrally processed and produced, and the integrated tuners cannot be separated from each other. The antenna feed source is a single-port device, the integrated tuner is also a single-port device, and the traditional Y factor method for measuring the noise coefficient of the integrated satellite television tuner has the following limitations:

1. the noise coefficient of the integrated satellite television tuner is measured by using a traditional Y factor method, and the measurement result contains the feed source loss contribution of a satellite television receiving antenna, so that the noise coefficient of the tuner cannot be separated;

2. the traditional method for measuring the noise coefficient of the integrated satellite television tuner by the Y factor method is an approximate test method, does not consider the influence of the loss of a radio frequency cable, and cannot accurately measure the noise coefficient of the integrated tuner.

Disclosure of Invention

The invention aims to avoid the defects in the background art and provides a method for measuring the noise coefficient of an integrated satellite television tuner, which is simple and easy to implement and has high accuracy of the measurement result.

In order to achieve the purpose, the invention adopts the technical scheme that:

a method for measuring the noise coefficient of an integrated satellite television tuner comprises the following steps:

(1) placing the integrated satellite television tuner in a microwave wave absorption box, and measuring the normalized noise power N received by the integrated satellite television antenna feed source by a spectrum analyzer₀Measuring the ambient temperature t of the microwave absorption box by using a thermometer;

(2) according to normalized noise power N₀And ambient temperatureAnd (c) calculating the noise coefficient of the integrated satellite television tuner by using the following formula:

in the formula:

NF-noise coefficient of integral satellite television tuner, unit: dB;

N₀-normalized noise power measured by the spectrum analyzer, in units: dBm/Hz;

L_RF-radio frequency cable loss between the integrated satellite television tuner and the spectrum analyzer;

k-boltzmann constant, unit: J/K;

t-ambient temperature of the microwave absorption box, unit: DEG C;

G_LNB-gain of integrated satellite television tuner.

Further, the specific manner of the step (1) is as follows: firstly, establishing a test system, and electrifying and preheating system instrument equipment to ensure that the test system instrument equipment works normally; then setting state parameters of the spectrum analyzer, and measuring the normalized noise power N received by the integrated satellite television tuner by using the noise measurement function of the spectrum analyzer₀(ii) a Furthermore, the ambient temperature t of the microwave absorption chamber measured by the thermometer is recorded.

Compared with the background technology, the invention has the following advantages:

1. the method can measure the noise coefficient of the integrated satellite television tuner;

2. the method has simple test system and good measurement repeatability;

3. the invention has good popularization and application values.

Drawings

FIG. 1 is a schematic block diagram of measuring noise figure of an integrated satellite television tuner.

Detailed Description

The technical solution of the present invention is further described with reference to the accompanying drawings and the detailed description.

Referring to fig. 1, the test system is composed of a microwave absorption box, a thermometer, a radio frequency test cable, a spectrum analyzer and an integrated satellite television tuner to be tested. Measuring the normalized noise power of the integrated satellite tuner for receiving the environmental noise by using a spectrum analyzer, and measuring the environmental temperature of the microwave absorption box by using a thermometer; and then calculating the noise coefficient of the integrated satellite television tuner according to the measured normalized noise power and the measured ambient temperature.

The method comprises the following steps:

(1) measuring the normalized noise power and the ambient temperature of the microwave absorption box: placing the integrated satellite television tuner in a microwave wave absorption box, measuring the normalized noise power received by the integrated satellite television antenna feed source by a spectrum analyzer, and using N₀Indicating, and measuring the ambient temperature of the microwave absorption box by a thermometer, and indicating by t;

(2) calculating the noise coefficient of the integrated satellite television tuner: normalized noise power N measured by a spectrum analyzer₀And measuring the ambient temperature t of the microwave absorbing box by using a thermometer, and calculating the noise coefficient of the integrated satellite television tuner by using the following formula:

in the formula:

NF-noise coefficient, dB of the integral satellite television tuner;

N₀-normalized noise power, dBm/Hz, measured by the spectrum analyzer;

L_RF-radio frequency cable loss between the integrated satellite television tuner and the spectrum analyzer;

k-Boltzmann constant, equal to 1.38 x 10^-23J/K；

t-ambient temperature of the microwave absorption chamber, DEG C;

G_LNB-gain of integrated satellite television tuner.

Wherein, in the step (1), the noise power and the ring of the microwave absorbing box are normalizedThe ambient temperature measurement method comprises the following steps: firstly, a test system is established, system instruments and equipment are powered on for preheating, so that the test system instruments and equipment work normally, state parameters of a spectrum analyzer are set, the noise measurement function of the spectrum analyzer is utilized to measure the normalized noise power received by an integrated satellite television tuner, and N is used₀Represents; the recording thermometer measures the ambient temperature of the microwave absorber, denoted by t. And calculating the noise coefficient of the integrated satellite television tuner by using the normalized noise power measured by the spectrum analyzer and the ambient temperature of the microwave absorption box measured by the thermometer.

The microwave absorbing box is used as a normal-temperature load, so that the integrated satellite television tuner receives black body radiation of the microwave absorbing material in a full airspace.

The following is a more specific example:

in this embodiment, the integrated satellite television tuner to be tested is a C-band integrated satellite television tuner, the input operating frequency range of the integrated satellite television tuner is 3.7 GHz-4.2 GHz, and the output frequency of the integrated satellite television tuner is 0.95 GHz-1.45 GHz after the integrated satellite television tuner is amplified and frequency-converted by the LNB of the integrated satellite television tuner. Measuring 4GHz noise coefficient of tuner, setting the center frequency of spectrum analyzer to 1.25GHz, and setting the loss of radio frequency cable between tuner and spectrum analyzer to 5dB, and its true value L_RF3.16; the gain of the integrated satellite television tuner is 60dB and the true value G_LNB＝1×10⁶. The method for measuring the noise coefficient of the integrated satellite television tuner comprises the following steps:

step 1: the normalized noise power and the ambient temperature of the microwave absorber were measured. As shown in figure 1, firstly, a test system is established, system instruments and equipment are powered on for preheating, so that the test system instruments and equipment work normally, state parameters of a spectrum analyzer are set, the noise measurement function of the spectrum analyzer is utilized to measure the normalized noise power received by an integrated satellite television tuner, and N is used₀Represents; the recording thermometer measures the ambient temperature of the microwave absorber, denoted by t.