Frequency stability tester for spaceflight responder

Abstract

The invention relates to the technical field of spaceflight responders, and provides a spaceflight responder frequency stability tester, which comprises a switch frequency division module used for connecting a tested spaceflight responder and selecting a test channel of the tested spaceflight responder according to a control instruction sent by a computer and software module, performing frequency division on the downlink signal of each test channel, and inputting the frequency into a frequency meter to measure the frequency of the downlink signal; and the computer and software module is used for sending a control instruction to the switch frequency division module, controlling the frequency meter, receiving the measured frequency of the downlink signal and calculating the frequency stability according to the frequency of the received downlink signal. The tester can automatically complete the frequency stability test, and the measured frequency stability test is more accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of aerospace transponders, and in particular to a frequency stability tester for aerospace transponders. Background Art

[0002] With the rapid development of modern science and technology, a large number of high-tech achievements have been applied to aerospace transponder equipment. In the manufacturing and maintenance process of a certain aerospace transponder, frequency stability, as a core performance indicator, directly affects the reliability and accuracy of system communication. However, the existing long-term frequency stability test method mainly relies on manual operation of the spectrum analyzer, which has problems such as long test cycle and limited data collection, and cannot fully reflect the stability of the actual signal. Summary of the invention

[0003] In view of the above-mentioned problems, the present invention aims to provide a frequency stability tester for aerospace transponders, which can automatically test the frequencies of two downlink signals and directly calculate the frequency stability of the signals, thereby facilitating the debugging, testing and acceptance of aerospace transponders and accurately reflecting the frequency stability of the output signals of aerospace transponders.

[0004] The present invention provides an aerospace transponder frequency stability tester, comprising:

[0005] The switch frequency division module is used to connect to the space transponder under test, select the test channel of the space transponder under test according to the control instructions sent by the computer and the software module, and divide the downlink signal of each test channel and input it into the frequency meter to measure the frequency of the downlink signal;

[0006] The computer and software module are used to send control instructions to the switch frequency division module and control the frequency meter, and to receive the measured frequency of the downlink signal and calculate the frequency stability according to the received frequency of the downlink signal.

[0007] In some embodiments, the switch frequency division module includes:

[0008] A switch unit, used to select a test channel of the tested aerospace transponder according to control instructions sent by the computer and software module;

[0009] A frequency division unit, used for performing frequency division processing on the downlink signal of the test channel selected by the switch unit;

[0010] The power supply unit is used to supply power to the switch frequency division module.

[0011] In some embodiments, the switch unit is implemented using a PIN switch.

[0012] In some embodiments, the power supply unit is implemented using a plurality of DC / DC power conversion circuits and filter circuits.

[0013] In some embodiments, the frequency dividing unit includes a first frequency divider and a second frequency divider connected to each other.

[0014] In some embodiments, the frequency dividing unit includes a first frequency divider, a filter, and a second frequency divider connected in sequence.

[0015] In some embodiments, the frequency dividing unit includes a first frequency divider, a first attenuator, a filter, a second frequency divider, and a second attenuator which are connected in sequence.

[0016] In some embodiments, the first frequency divider is an 8-divider and the second frequency divider is a 4-divider.

[0017] In some embodiments, the switch frequency division module is connected to the tested aerospace transponder via a fixed attenuator.

[0018] In some embodiments, the computer and software modules include:

[0019] Human-machine interface, used to provide a user interface for user settings, user operations and test result display;

[0020] The frequency value cycle test module is used to cycle test the frequency of the downlink signal of the test channel of the tested space transponder according to the test time interval, total test time and other parameters set by the user and record them;

[0021] A frequency stability calculation module, used to calculate the frequency stability according to the frequency of the received downlink signal, and calculate the frequency stability within a period of time;

[0022] Frequency value report output module, used to save the measured frequency according to a fixed template;

[0023] The control panel parallel port driver module is used to send control instructions to the switch driver module through the computer parallel port.

[0024] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0025] 1. The frequency stability test measured by the present invention is more accurate: frequency stability refers to the maximum value of the frequency accuracy change within a specified time, and there are two ways to express it: absolute frequency stability and relative frequency stability. The frequency stability index proposed in the present invention is expressed by the relative frequency accuracy within a period of time, and the test duration is clarified. If the test equipment can collect more frequency data within the specified time, it can more accurately reflect the frequency stability of the signal, which also reflects the influence of factors such as temperature change, voltage change and circuit parameter instability on the circuit.

[0026] 2. The tester of the present invention can automatically complete the frequency stability index test, and the software operation interface is simple and easy to use, which improves the product debugging efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the structure of a frequency stability tester for aerospace transponders in an embodiment of the present invention.

[0028] Figure 2 Schematic diagram of the composition of the power supply unit in the switch frequency division module in an embodiment of the present invention.

[0029] Figure 3 Schematic diagram of the composition of the switch unit in the switch frequency division module in the embodiment of the present invention.

[0030] Figure 4 Schematic diagram of the composition of the frequency division unit in the switch frequency division module in the embodiment of the present invention.

[0031] Figure 5 Schematic diagram of the functional software composition of the computer and software modules in the embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Example

[0035] See also Figure 1 The embodiment of the present invention provides a frequency stability tester for aerospace transponders, comprising:

[0036] The switch frequency division module is used to connect to the space transponder under test, select the test channel of the space transponder under test according to the control instructions sent by the computer and the software module, and divide the downlink signal of each test channel and input it into the frequency meter to measure the frequency of the downlink signal;

[0037] The computer and software module are used to send control instructions to the switch frequency division module and control the frequency meter, and to receive the measured frequency of the downlink signal and calculate the frequency stability according to the received frequency of the downlink signal.

[0038] In some embodiments, the switch frequency division module is connected to the tested space transponder via a fixed attenuator, and the fixed attenuator is used to attenuate the signal amplitude of the downlink signal of the test channel of the tested space transponder, usually by 20 dB. In some practical applications, the switch frequency division module, the fixed attenuator and the tested space transponder are connected via a high-frequency cable.

[0039] In some embodiments, the switch frequency division module includes:

[0040] A switch unit, used to select a test channel of the tested aerospace transponder according to control instructions sent by the computer and software module;

[0041] A frequency division unit, used for performing frequency division processing on the downlink signal of the test channel selected by the switch unit;

[0042] The power supply unit is used to supply power to the switch frequency division module and can provide DC voltages such as +5V, -5V, and +3V.

[0043] In some embodiments, the power supply unit is implemented using a plurality of DC / DC power conversion circuits and filter circuits. Figure 2 The power supply unit includes a first DC / DC power conversion circuit, a second DC / DC power conversion circuit, a third DC / DC power conversion circuit and a filter circuit; the +28V DC voltage is converted into a +5V DC voltage by the first DC / DC power conversion circuit, which can be realized by using a DC / DC HHW28S5F power supply module. The first DC / DC power conversion circuit has input filtering, push-pull transformation, rectification and filtering to output a stable +5V DC voltage, and the power supply circuit has a short-circuit protection function. Furthermore, the +5V DC voltage is output after the filter circuit for use by the switch unit, making the power output more stable and pure.

[0044] Furthermore, the +5V DC voltage can be converted into a +3V DC voltage by a second DC / DC power conversion circuit for use by the frequency division unit. The second DC / DC power conversion circuit can be implemented by an integrated voltage regulator of model PTH05000W, which has a standard +5V voltage input, an output voltage range of 0.9V to 3.6V, and an output current of up to 6A, which can meet the voltage and current requirements of the circuit design.

[0045] Finally, the +5V DC voltage is converted into a -5V DC voltage by the third DC / DC power conversion circuit, and used as the -5V voltage input required by the switch unit. The third DC / DC power conversion circuit can be converted by tps63700, with an input voltage range of 2.7V to 5.5V, an output voltage range of -2V to -15V, and a maximum output current of 0.36A, which can also meet the voltage and current requirements of the circuit design.

[0046] See also Figure 3 . In some embodiments, the switch unit is implemented by a PIN switch. The PIN switch is contactless and has no limit on the number of switches. The signal can be turned on and off by turning the PIN switch on and off. Since the input frequency is higher than 5GHz, the isolation requirement for the test channel is high. If the isolation between the two downlink signals is not enough, the frequency detected by the frequency meter will be confused. Therefore, when selecting a PIN switch, a device with higher channel isolation should be selected. For example, a single-pole triple-throw switch with model TGK3-E23-111-W202-55 can be used. Its frequency range is 4 to 8GHz, the insertion loss is ≤3dB, the standing wave coefficient of the port is ≤1.6, the isolation is ≥60dB, the switching speed is ≤50ns, and it can be controlled by TTL level. The power supply voltage requirement is ±5V. The smaller standing wave of the device is also convenient for impedance matching between devices during design. The fast switching speed and small insertion loss can meet the requirements of the test equipment.

[0047] The frequency division unit is used to divide the downlink signal of the test channel selected by the switch unit in order to meet the measurement frequency range requirements of the frequency meter, and the signal level after the frequency division must also meet the input level requirements of the frequency meter. Specifically, the frequencies of the downlink signals of the aerospace transponder test channel are 5318.75MHz and 5259.6MHz respectively. Since the frequency range of the frequency meter test is DC to 225MHz, the downlink signal of the aerospace transponder test channel also needs to be divided by the frequency division unit and can only be sent to the frequency meter for testing after meeting the test range of the frequency meter.

[0048] In some embodiments, the frequency division unit is used to perform 32-frequency division processing on the downlink signal of the test channel selected by the switch unit. Figure 4 The frequency division unit includes an 8-frequency divider and a 4-frequency divider connected to each other, so as to divide the downlink signal of the test channel selected by the switch unit by 8 first and then by 4 to achieve 32-frequency division processing.

[0049] The 8-divider can use the single-chip divider model HMC434, which is an ultra-low noise, ultra-small surface-mount plastic-sealed divider, powered by a single +3V DC power supply, with a maximum input frequency of 8GHz, an input signal level of -5dBm to +12dBm, an output signal level of about -2dBm, and a required current of about 60mA.

[0050] The 4-way frequency division can use the single-chip frequency divider model HMC433, which is an ultra-low noise, ultra-small surface-mount plastic-sealed frequency divider, powered by a single +3V DC power supply, with a maximum input frequency of 8GHz, an input signal level range of -12dBm to +12dBm, an output signal level of about -3dBm, and a required current of about 50mA.

[0051] The usage of the above 8-divider and 4-divider is similar, with some differences in the peripheral bias circuit. The circuit is simple and the price is cheap. Their biggest feature is that the output signal has very low additional sideband noise, which has little effect on the noise performance of the receiving system.

[0052] According to the characteristics of phase noise, the divider will improve the phase noise of the input signal, but the internal circuit of the divider may worsen the phase noise. Therefore, in this embodiment, the internal noise characteristics of the selected divider are focused on. The selected divider is an ultra-low noise divider, and the phase noise at the deviation signal of 100Hz reaches -140dBc / Hz, which is much higher than the phase noise level of the input signal to be tested -125dBc / Hz, so the entire divider circuit has no effect on the phase noise of the input signal.

[0053] In some embodiments, after the two output signals pass through the 8-frequency divider circuit, the output signal frequencies are 664.84375MHz and 657.45MHz respectively. To make the output signal purer, a first-stage filter is designed, and a dielectric filter of model BPF54EC30A can be used. The filter has a center frequency of 650MHz, a bandwidth of ±15MHz, an insertion loss of ≤1.5dB, a standing wave of ≤1.5, a small size, and a low price, which meets the design requirements. Therefore, the frequency division unit includes an 8-frequency divider, a filter, and a 4-frequency divider connected in sequence.

[0054] In some embodiments, since the PIN switch and the frequency divider have certain requirements on the input signal level, appropriately adding a π-attenuator facilitates both the adjustment of the signal level and the debugging of the switch frequency divider. Thus, the frequency division unit includes an 8-frequency divider, a first attenuator, a filter, a 4-frequency divider and a second attenuator connected in sequence.

[0055] In some embodiments, the computer and software module can send control instructions to the switch driver module through the parallel port and control the frequency meter through the GPIB interface card. Figure 5The computer and software modules include six functional modules: human-machine interface, frequency value cycle test module, frequency stability calculation module, frequency value report output module, frequency meter instrument drive module, and control board parallel port drive module; the functions of each module are as follows:

[0056] The human-machine interface is used to provide a user interface for user settings, user operations and test result display;

[0057] The frequency value cyclic test module is used to cyclically test the frequency of the downlink signal of the test channel of the tested space transponder according to the parameters set by the user, such as the test time interval and the total test time, and record the frequency;

[0058] The frequency stability calculation module is used to calculate the frequency stability according to the frequency of the received downlink signal, and calculate the frequency stability within a period of time (the time can be set as needed) according to the frequency stability calculation formula;

[0059] The frequency value report output module is used to save the measured frequency according to a fixed template;

[0060] The control panel parallel port driving module is used to send control instructions to the switch driving module through the computer parallel port to control the switch driving module to switch the test channel of the tested aerospace transponder.

[0061] In some embodiments, the software portion of the computer and software module can be developed based on development software on a Windows operating system. The specific development software and operating system can be selected according to actual conditions, for example, based on the Windows XP operating system, developed using NI's LabWindows / CVI 9.0.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A frequency stability tester for aerospace transponders, characterized in that: include: The switch frequency division module is used to connect the space transponder under test, select the test channel of the space transponder under test according to the control instructions sent by the computer and the software module, and divide the downlink signal of each test channel and input it into the frequency meter to measure the frequency of the downlink signal; The computer and software module are used to send control instructions to the switch frequency division module and control the frequency meter, and to receive the measured frequency of the downlink signal and calculate the frequency stability according to the received frequency of the downlink signal.

2. The frequency stability tester of the aerospace transponder according to claim 1, characterized in that: The switch frequency division module comprises: A switch unit, used to select a test channel of the tested aerospace transponder according to control instructions sent by the computer and software module; A frequency division unit, used for performing frequency division processing on the downlink signal of the test channel selected by the switch unit; The power supply unit is used to supply power to the switch frequency division module.

3. The frequency stability tester of the aerospace transponder according to claim 2, characterized in that: The switch unit is implemented by a PIN switch.

4. The frequency stability tester of the aerospace transponder according to claim 2, characterized in that: The power supply unit is implemented by using a plurality of DC / DC power supply conversion circuits and filter circuits.

5. The frequency stability tester for aerospace transponder according to claim 2, characterized in that: The frequency dividing unit includes a first frequency divider and a second frequency divider connected to each other.

6. The frequency stability tester for aerospace transponder according to claim 5, characterized in that: The frequency dividing unit includes a first frequency divider, a filter and a second frequency divider which are connected in sequence.

7. The frequency stability tester for aerospace transponder according to claim 6, characterized in that: The frequency dividing unit includes a first frequency divider, a first attenuator, a filter, a second frequency divider and a second attenuator which are connected in sequence.

8. The frequency stability tester of the aerospace transponder according to any one of claims 5 to 7, characterized in that: The first frequency divider is an 8-frequency divider, and the second frequency divider is a 4-frequency divider.

9. The frequency stability tester for aerospace transponder according to claim 1, characterized in that: The switch frequency division module is connected to the tested aerospace transponder via a fixed attenuator.

10. The frequency stability tester for aerospace transponder according to claim 1, characterized in that: The computer and software modules include: Human-machine interface, used to provide a user interface for user settings, user operations and test result display; The frequency value cycle test module is used to cycle test the frequency of the downlink signal of the test channel of the tested space transponder according to the test time interval, total test time and other parameters set by the user and record them; A frequency stability calculation module, used to calculate the frequency stability according to the frequency of the received downlink signal, and calculate the frequency stability within a period of time; Frequency value report output module, used to save the measured frequency according to a fixed template; The control panel parallel port driver module is used to send control instructions to the switch driver module through the computer parallel port.

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