CN106018988A - Multistage frequency converter noise coefficient automatic scanning measuring method - Google Patents

Abstract

The invention discloses an automatic scanning measurement method for the noise coefficient of a multi-stage frequency converter, which belongs to the technical field of automatic testing. The invention realizes the automatic control of the output frequency of the first local oscillator source of the tested part by adjusting the radio frequency range of the multi-stage frequency converter; by using the loss compensation function, the noise source super-noise ratio calling error introduced by the radio frequency frequency adjustment is compensated, and finally The automatic and fast frequency sweep measurement of the noise figure of multi-stage frequency converters is realized, which solves the serious shortage of the existing manual and point frequency measurement methods in terms of measurement speed, and greatly improves the measurement efficiency of the noise figure of multi-stage frequency converters.

Description

An Automatic Scanning Measurement Method for Noise Figure of Multi-stage Frequency Converter Devices

technical field

The invention belongs to the technical field of automatic testing, and in particular relates to an automatic scanning measurement method for the noise coefficient of a multi-stage frequency converter.

Background technique

Frequency conversion devices are the core components of radio frequency and microwave transceivers. Radar, satellite and radio communication systems usually use multi-level frequency conversion receiving schemes. The noise performance of multi-level frequency converters has a direct impact on the sensitivity of the receiver system. With the rapid development of electronic technology, the ability of the receiver system to deal with weak signals is gradually improved and enhanced, and the demand for the performance test of the noise figure of the receiver is increasingly urgent. Accurate measurement of the noise figure of multi-stage inverter devices can not only speed up design verification, improve production efficiency and test system operation status, but also directly determine the success or failure of system development and final application.

The main components of a multi-stage frequency conversion device (taking two-stage frequency conversion as an example) are shown in Figure 1. The first-stage frequency converter usually adopts a high-frequency mixing scheme, so that the image frequency response can be effectively suppressed only by using a low-pass filter at the input end. The first-stage frequency converter and the scanning first local oscillator source (LO ₁ ) convert the broadband input radio frequency signal (RF) to a fixed intermediate frequency (IF ₁ ); IF ₁ is mixed with a fixed second local oscillator (LO ₂ ) to output the first Second intermediate frequency (IF ₂ ). The filter before the first-stage frequency converter in Figure 1 determines the sideband selection for the noise figure measurement of the frequency converter. In the example, the lower sideband is selected, and the amplifier does not affect the setting of related parameters during the noise figure measurement process.

The current general method for measuring the noise figure of multi-stage frequency converter devices is as follows:

Firstly, the noise meter should be calibrated. The calibration connection is shown in Figure 2. The calibration steps are as follows:

Step 1: Turn on the noise meter, load the excess noise ratio (ENR) value of the noise source used, and preheat the noise meter;

Step 2: Select the measurement mode as down-converter, variable LO, and lower sideband;

Step 3: In the mode setting, set the intermediate frequency to IF ₂ ;

Step 4: Press the calibration key twice to calibrate the noise meter. Since the noise meter only receives the signal of the intermediate frequency IF ₂ , it is only calibrated at the IF ₂ frequency point.

Then connect the DUT, as shown in Figure 3, to measure the DUT.

Press the frequency/number key to set the fixed frequency as the starting RF frequency point, manually calculate and set the corresponding first local oscillator source frequency, and obtain the noise figure of the RF starting frequency point of the DUT. Set the RF frequency point of the DUT and the corresponding local oscillator frequency point in turn to obtain the noise figure of the DUT in the full frequency band.

Disadvantages of prior art solutions:

In this example, the frequency range of the first local oscillator source is determined, the intermediate frequency IF ₂ is a parameter that must be input, and the receiver channel of the noise meter is set according to the frequency of this IF ₂ during measurement; the noise meter is based on the set sideband , RF and IF frequency relationship to realize the automatic control of the local oscillator frequency. The frequency relationship is as follows: LO-RF=IF (lower sideband); RF-LO=IF (upper sideband); RF=LO (double sideband). In this example, the sideband of the first frequency converter is selected as the lower sideband, and the noise meter in the prior art can only control the local oscillator frequency according to the relationship of LO ₁ =RF+IF ₂ , and the actual operating frequency of the first local oscillator is LO ₁ =RF+ IF ₁ , so the noise meter cannot automatically control the actual output frequency of the first local oscillator source, which is why the existing technology cannot realize the automatic frequency sweep measurement of the noise figure of the multi-stage frequency conversion device, so the RF frequency and the first local oscillator can only be measured point by point. The manual point frequency setting of the local oscillator frequency has slow measurement speed and low efficiency, which cannot well meet the measurement needs of mass production.

Contents of the invention

In view of the existing technology, the noise meter cannot automatically control the output frequency of the first local oscillator source when measuring the noise figure of multi-stage frequency conversion devices, and can only manually set the frequency of the radio frequency and the output frequency of the first local oscillator source point by point, and measure the speed Slow and low efficiency are serious shortcomings. The present invention proposes an automatic scanning measurement method for noise coefficient of multi-stage frequency converter devices. The method is reasonable in design, overcomes the deficiencies of the prior art, and has good popularization value.

In order to achieve the above object, the present invention adopts the following technical solutions:

An automatic scanning measurement method for noise figure of a multi-stage frequency conversion device, using a noise figure test system, the noise figure test system includes a noise meter and a noise source;

The automatic scanning measurement method of the noise figure of the multi-stage frequency conversion device is carried out according to the following steps:

Step 1: Calibrate the noise meter;

Step 2: Connect the multi-level frequency conversion device DUT: Connect the input end of the DUT to the output end of the noise source, connect the output end of the DUT to the RF input port of the noise meter through the line, and connect the DUT’s first The program-controlled interface of the local oscillator source of the primary frequency converter is connected to the program-controlled interface of the noise meter through a GPIB cable or a network cable;

Step 3: Set the noise meter to control the local vibration, and set the local vibration power according to the local vibration power requirements of the device under test for the local vibration source of the first-stage inverter;

Step 4: Adjust the RF frequency of the DUT, that is, adjust RF _actual = LO ₁ -IF ₁ to RF _adjustment = LO ₁ -IF ₂ , and set the start frequency and stop of the noise meter according to the adjusted RF frequency range Frequency, to set other relevant parameters including the number of measurement points and averaging;

Step ₅ : _The noise meter performs scanning measurement according to the _adjusted start frequency and stop frequency, and automatically controls the local The output frequency of the vibration source is synchronously tracked and scanned from the start frequency of the local oscillator source of the first-stage inverter to the stop frequency, and the adjusted radio frequency and the synchronous scan of the local oscillator source of the first-stage inverter are kept to obtain the noise figure The frequency sweep measurement result is denoted as NF _measurement .

Preferably, in step 5, the method for automatically correcting the frequency sweep measurement result NF _measurement according to the correction formula NF _correction =NF _measurement +ENR _{RF (actual)} -ENR _{RF (adjustment)} specifically includes

Step 5.1: Establish the loss compensation table before the DUT, specifically including

Step 5.1.1: Press the loss compensation key of the noise meter, and configure the loss compensation type as: table before DUT;

Step 5.1.2: Press the temperature menu key of the noise meter, and input the temperature value before DUT;

Step 5.1.3: Press the menu key of the loss compensation table of the noise meter to create the loss compensation table before the DUT;

Step 5.2: Set the frequency of the loss compensation table as the adjusted RF frequency, and input the corresponding compensation value according to the compensation value calculation formula (1) according to the SNR value of the noise source calibration frequency;

Compensation value = ENR _{RF (adjustment)} - ENR _{RF (actual)} (1);

Step 5.3: Set the state of the loss compensation table. During the calibration of the noise meter, set the loss compensation as follows: the state before DUT is off, and set the configuration type of the loss compensation as follows during the measurement: table before DUT;

Step 5.4: Correct the ENR value ENR _{RF(adjustment)} in the RF _adjustment range to the corresponding ENR value ENR _RF(actual) in the RF _actual range, and obtain the actual noise figure of the DUT after correction.

Beneficial technical effects brought by the present invention:

The present invention proposes an automatic scanning measurement method for the noise factor of a multi-stage frequency conversion device. Compared with the prior art, the present invention realizes the output frequency of the first local oscillator source of the device under test by adjusting the radio frequency range of the multi-stage frequency conversion device. Automatic control; by using the loss compensation function, the noise source super-noise ratio call error introduced by the adjustment of the radio frequency is compensated, and finally the automatic, fast, and frequency-sweeping measurement of the noise figure of the multi-stage frequency converter is realized, which solves the problem of the existing manual, point-frequency The serious shortage of measurement speed has greatly improved the measurement efficiency of the noise figure of multi-stage frequency converter devices, and has a wide range of applications.

Description of drawings

FIG. 1 is a block diagram of an existing multi-stage frequency converter.

Figure 2 is a connection block diagram for calibrating the noise meter.

Fig. 3 is a connection block diagram for measuring the noise figure of an existing multi-stage frequency converter.

Fig. 4 is a connection block diagram of the noise figure testing system and the device under test of the present invention.

Fig. 5 is a block diagram of the flow chart of the automatic scanning measurement method for the noise factor of the multi-stage frequency conversion device of the present invention.

Fig. 6 is a schematic diagram of the setting interface of the loss compensation function of the noise meter, showing the setting of related parameters of the loss compensation function.

Fig. 7 is a schematic diagram of the editing interface of the loss compensation table of the noise meter, showing the editing of the loss compensation table.

detailed description

Below in conjunction with accompanying drawing and specific embodiment the present invention is described in further detail:

In this patent, the RF frequency of the DUT is adjusted according to LO ₁ and IF ₂ , and the adjustment is RF _adjustment = LO ₁ -IF ₂ . In this way, the noise meter can control the output frequency of the first local oscillator source, and keep the synchronous scanning of the radio frequency and the first local oscillator source, so as to realize the automatic scanning measurement of the noise figure.

The connection block diagram of noise figure test system and DUT is as shown in Figure 4, and described noise figure test system comprises noise meter and noise source;

The specific measurement method (as shown in Figure 5) is as follows:

Step 1: Calibrate the noise meter, the calibration connection is shown in Figure 2, and the calibration steps are the same as the existing technical solutions;

Step 2: Connect the multi-level frequency conversion device under test, the connection is shown in Figure 4, connect the input end of the test part to the output end of the noise source, and connect the output end of the test part to the RF input of the noise meter through the line Port, the program-controlled interface of the local oscillator source of the first-stage frequency converter of the DUT is connected to the program-controlled interface of the noise meter through a GPIB cable or a network cable;

Step 3: Press the LO control menu key on the noise meter, set the LO control state to ON, press the external LO power menu key, and set the local oscillator power according to the requirements of the DUT for the local oscillator power of the first local oscillator source;

Step 4: Adjust the RF frequency of the DUT, that is, adjust RF _actual = LO ₁ -IF ₁ to RF _adjustment = LO ₁ -IF ₂ , and set the start frequency and stop of the noise meter according to the adjusted RF frequency range Frequency, to set other relevant parameters including the number of measurement points and averaging;

Step ₅ : _The noise meter performs scanning measurement according to the _adjusted start frequency and stop frequency, and automatically controls the local The output frequency of the vibration source is synchronously tracked and scanned from the start frequency of the local oscillator source of the first-stage inverter to the stop frequency, and the adjusted radio frequency and the synchronous scan of the local oscillator source of the first-stage inverter are kept to obtain the noise figure The frequency sweep measurement result is denoted as NF _measurement .

In the present invention, during the noise figure measurement process, the noise meter automatically calls the RF _-adjusted start frequency and the corresponding super-noise ratio value of the stop frequency. After being filtered by the filters at all levels of the DUT, only the noise power output by the noise source within _{the actual} RF range can enter the DUT channel and output the intermediate frequency after two-stage mixing and filtering. The super-noise ratio value is corrected to the corresponding super-noise ratio value in the _actual RF range, so that the actual noise figure of the tested part after correction can be obtained, which is recorded as NF _correction .

NF _Correction = NF _Measured + ENR _RF(Actual) - ENR _RF(Adjusted) (1)

The user can manually correct the noise figure automatic frequency sweep measurement result of the multi-stage frequency conversion device according to the formula (1).

This patent provides an automatic correction method for using the loss compensation function of the noise meter to compensate the call difference of the noise source super-noise ratio introduced by the RF frequency adjustment. The specific steps are as follows:

Step 1: Establish the loss compensation table before the DUT

Step 1.1: Press the Loss Compensation key, and configure the Loss Compensation Type as: Form before DUT.

Step 1.2: Press the temperature menu key, input the temperature value before DUT, the setting interface is shown in Figure 6.

Step 1.3: Press the loss compensation table menu key to create a loss compensation table before the DUT, as shown in Figure 7.

Step 1.4: The frequency in the loss compensation table is the adjusted radio frequency RF _adjustment , and the value in the loss compensation table is: ENR _{RF (adjustment)} - ENR _{RF (actual)} (as shown in Table 1).

Table 1 Loss Compensation Table

frequency value RF _adjustment ENR _RF(Adjusted) -ENR _RF(Actual)

Step 2: Set the state of the loss compensation table. During the calibration of the noise meter, set the loss compensation as follows: the state before DUT is off. During the measurement process, set the configuration type of the loss compensation as follows: table before DUT.

The invention realizes the automatic control of the actual output frequency of the first local oscillator source of the tested part by adjusting the radio frequency range of the multi-stage frequency converter; by using the loss compensation function, the noise source super-noise ratio call error introduced by the radio frequency frequency adjustment is compensated, Finally, the automatic, rapid and frequency-sweeping measurement of the noise figure of the multi-stage frequency converter is realized, which greatly improves the measurement efficiency of the noise figure of the multi-stage frequency converter.

Of course, the above descriptions are not intended to limit the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention shall also belong to the present invention. protection scope of the invention.

Claims (2)

1. a multistage frequency conversion device noise coefficient automatic scanning survey method, it is characterised in that: use noise coefficient test system, Described noise coefficient test system includes acoustic meter and noise source；

Described multistage frequency conversion device noise coefficient automatic scanning survey method, is carried out in accordance with the following steps:

Step 1: acoustic meter is calibrated；

Step 2: access multistage frequency conversion device measured piece: the input of measured piece is connected to the outfan of noise source, measured piece Outfan by connection to the rf inputs mouth of acoustic meter, the program control of local vibration source of the first order converter of measured piece connects Mouth is connected to the programmable interface of acoustic meter by GPIB cable or netting twine；

Step 3: acoustic meter is set and local oscillator is controlled as opening, according to the measured piece local oscillation power to the local vibration source of first order converter Requirement arranges local oscillation power；

Step 4: be adjusted by the rf frequency of measured piece, will RF_Actual=LO₁-IF₁It is adjusted to RF_Adjust=LO₁-IF₂, It is correspondingly arranged the initial frequency of acoustic meter according to the radio frequency range after adjusting and terminates frequency, arranging and include measure dot number peace All at other interior relevant parameters；

Step 5: acoustic meter according to adjust after initial frequency and terminate frequency be scanned measure, and according to adjust after radio frequency, Frequency relation formula LO of intermediate frequency and local oscillator₁=RF_Adjust+IF₂Automatically control the output frequency of the local vibration source of first order converter, from The initial frequency lock-and-follow scan of the local vibration source of one-level converter, to terminating frequency, keeps the radio frequency after adjusting and first order frequency conversion The synchronous scanning of the local vibration source of device, obtains the sweep measurement result of noise coefficient, is designated as NF_Measure。

Multistage frequency conversion device noise coefficient the most according to claim 1 automatic scanning survey method, it is characterised in that: in step In rapid 5, according to correction formula NF_Revise=NF_Measure+ENR_{RF (actual)}-ENR_{RF (adjusts)}To sweep measurement result NF_MeasureAutomatically repair Positive method, specifically includes

Step 5.1: set up the loss balancing table before measured piece, specifically include

Step 5.1.1: press the loss balancing key of acoustic meter, configuration loss balancing type is: form before DUT；

Step 5.1.2: by the temperature Menu key of acoustic meter, Temperature numerical before input DUT；

Step 5.1.3: by the loss balancing table Menu key of acoustic meter, set up the loss balancing form before measured piece；

Step 5.2: the frequency arranging loss balancing table is the rf frequency after adjusting, and according to noise source excess noise ratio spot frequency The value of point inputs corresponding offset by compensation value calculation formula (1) successively；

Offset=ENR_{RF (adjusts)}-ENR_{RF (actual)}(1)；

Step 5.3: arrange the state of loss balancing table, is arranged loss balancing: DUT in acoustic meter calibration process as follows The Configuration Type of loss balancing, for closing, is arranged: form before DUT during measuring by front state as follows；

Step 5.4: by RF_AdjustIn the range of excess noise ratio value ENR_{RF (adjusts)}It is modified to RF_ActualIn the range of corresponding excess noise ratio value ENR_{RF (actual)}, the actual noise coefficient of measured piece after being revised.