PCM code stream modulation transmitting circuit

Abstract

The invention relates to a PCM (Pulse Code Modulation) code stream modulation transmitting circuit, which is characterized in that the modulation transmitting circuit is used for modulating and outputting a PCM code stream; the modulation transmitting circuit comprises two circuits, wherein the first circuit is used for converting a PCM code stream into a differential analog baseband signal; and the second circuit is used for modulating the input differential analog baseband signal and then outputting the modulated signal. The method is matched with a PCM architecture-based acquisition system and a wireless transmission system, and can directly modulate and transmit a PCM code stream output by KAM equipment; and meanwhile, the advantages of the wireless telemetry technology can be combined, so that both the wireless telemetry technology and the wireless telemetry technology are taken into consideration, and the advanced level of the domestic similar technology is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of wireless testing, and in particular provides a PCM code stream modulation transmitting circuit. Background Art

[0002] The main rotor is the most important component of the lift required for helicopter flight. Once the helicopter rotor system is damaged, it may cause a helicopter-level accident, causing immeasurable losses to personnel and property. Therefore, measuring and recording the load data of the main lift system such as the main rotor shaft and main blades under various complex flight conditions has become an indispensable subject in the design finalization test flight of the AC332 aircraft.

[0003] The helicopter rotor system is mainly composed of rotating mechanical parts. The commonly used rotor system testing methods include the slip ring method and the non-contact data transmission method.

[0004] The premise of the collector ring method is that the mechanical installation conditions must be met, that is, the rotor structure can be installed with collector rings. First, the collector ring is installed on the rotating part; second, the test signal transmission, control, and time synchronization are achieved through slip rings and brushes. However, the contact resistance between the collector ring and the brush, the frictional heating during rotation, and the thermocouple effect will bring interference signals, limit the life of the brush, and cause great inconvenience to use and maintenance.

[0005] When the rotor system structure is limited and the collector ring cannot be installed, a non-contact transmission method can be selected. This method is simple to maintain and inspect during flight tests, and the system reliability is high, but there are certain problems in power supply: when using rechargeable batteries for power supply, the battery capacity requirements are relatively large; when using lithium batteries with a high capacity-to-weight ratio, the effects of temperature, centrifugal force, etc. must also be considered, which is still very inconvenient during flight tests.

[0006] Therefore, the main rotor load test technology based on wireless transmission, including the research on PCM code stream compilation and output technology of KAM collector load data, the research on collector slip ring mounting assembly design and installation technology, the research on wireless telemetry transmission technology of main rotor load test data, and the research on test system construction and integration technology, is realized by combining PCM code stream with wireless telemetry transmission system to test and measure the rotor load strain parameters of AC332 helicopter, providing technical guarantee and support for the main rotor test of new AC332 helicopter.

[0007] Among the key technical points in the above technologies, the PCM code stream compilation and output technology of the KAM collector payload data still has defects, and the PCM code stream cannot be directly modulated and transmitted. Summary of the invention

[0008] The purpose of the present invention is to match a circuit for directly modulating and transmitting a PCM code stream output by a KAM device based on a PCM architecture acquisition system and a wireless transmission system.

[0009] The technical solution of the present invention is:

[0010] Provided is a PCM code stream modulation and transmission circuit, the modulation and transmission circuit is used to modulate and output a PCM code stream;

[0011] The modulation and transmission circuit includes two circuits, the first circuit is used to convert the PCM code stream into a differential analog baseband signal;

[0012] The second circuit is used for modulating the input differential analog baseband signal and then outputting it.

[0013] Furthermore, the first circuit includes a SN65HVD20 interface chip, and the B pin and the A pin of the SN65HVD20 interface chip are respectively connected in series with a resistor R12 and a resistor R20 as a PCM code stream input terminal, and a resistor R15 is connected in series between the B pin and the A pin;

[0014] The RO pin of the SN65HVD20 interface chip is used as a single-ended signal output, and the single-ended signal is connected to the positive input of the AD8139 differential ADC driver after passing through a voltage divider resistor, and is divided into two outputs through the AD8139 differential ADC driver. Each output is filtered out by a 7th-order low-pass filter to remove high-frequency components and then output as a baseband signal;

[0015] The second circuit includes an ADRF6755 RF modulation chip. The IBBP pin and IBBN pin of the ADRF6755 RF modulation chip are used as inputs to receive two baseband signal outputs. After modulation by the ADRF6755 RF modulation chip, the RFOUT pin of the ADRF6755 RF modulation chip is output, and the output of the RFOUT pin is output as a modulated signal after passing through a 7th-order low-pass filter.

[0016] Furthermore, the modulated signal is connected to a radio frequency amplification circuit.

[0017] Furthermore, the second circuit also includes a loop filter, which is composed of a capacitor C74, a resistor R39, a capacitor C77, a resistor R41, a capacitor C86, a resistor R40 and a capacitor C87; one end of the resistor R41, the capacitor C74 and the capacitor C77 are all connected to the CP pin of the ADRF6755 RF modulation chip, the other end of the capacitor C77 is connected in series with the resistor R39 and then grounded, the other end of the capacitor C74 is grounded, the other end of the resistor R41 is simultaneously connected to one end of the capacitor C86 and the resistor R40, the other end of the resistor R40 and one end of the capacitor RC87 are connected to the VTUNE pin of the ADRF6755 RF modulation chip; the other end of the capacitor RC87 is grounded.

[0018] Furthermore, in the first 7th-order low-pass filter for filtering out high-frequency components, one end of capacitor C15, capacitor C16 and inductor L4 are all connected to the negative output of the AD8139 differential ADC driver, the other end of inductor L4 is connected to one end of capacitor C17 and inductor L6, the other end of inductor L6 is respectively connected to one end of capacitor C18, capacitor C13 and capacitor C12, the other end of capacitor C12 is output to the second circuit, and the other ends of capacitor C15, capacitor C16, capacitor C17, capacitor C18 and capacitor C13 are all grounded.

[0019] Furthermore, in the second 7th-order low-pass filter for filtering out high-frequency components, one end of capacitor C23, capacitor C35 and inductor L5 are all connected to the positive output of the AD8139 differential ADC driver, the other end of inductor L5 is connected to one end of capacitor C36 and inductor L7, the other end of inductor L7 is respectively connected to one end of capacitor C53, capacitor C57 and capacitor C20, the other end of capacitor C20 is output to the second circuit, and the other ends of capacitor C23, capacitor C35, capacitor C36, capacitor C53 and capacitor C57 are all grounded.

[0020] Furthermore, the V terminal of the AD8139 differential ADC driver is connected to +5V, and the G terminal of the AD8139 differential ADC driver is grounded.

[0021] Furthermore, the positive and negative outputs of the AD8139 differential ADC driver are both connected in series with resistor R27 and resistor R11.

[0022] Furthermore, the negative input of the AD8139 differential ADC driver is respectively connected to one end of the resistor R22 and one end of the capacitor C30, and the other end of the capacitor C30 is respectively connected to one end of the resistor R26 and the positive output of the AD8139 differential ADC driver; the other end of the resistor R26, the other end of the resistor R22, one end of the capacitor R22 and one end of the resistor R25 are connected, the other end of the resistor R25 is connected in series with the resistor R30 and then grounded, and the other end of the capacitor C22 is grounded.

[0023] Furthermore, the vocm terminal of the AD8139 differential ADC driver is respectively connected to one end of the capacitor C21, one end of the resistor R23 and one end of the resistor R28, the other end of the resistor R23 is connected to +5V, and the other end of the resistor R28 is grounded.

[0024] In the present invention, the parameters of the resistance and capacitance of the resistors and capacitors related to the SN65HVD20 interface chip and the AD8139 differential ADC driver are all matching settings of the SN65HVD20 interface chip and the AD8139 differential ADC driver, which can be adaptively set by those skilled in the art according to needs and are common knowledge.

[0025] The advantages of the present invention are: the present invention is matched with the acquisition system and wireless transmission system based on the PCM architecture, and can directly modulate and transmit the PCM code stream output by the KAM device; it can make the most of the existing acquisition equipment resources, and at the same time, it can also combine the advantages of wireless telemetry technology to take both into account and reach the advanced level of similar domestic technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a circuit diagram of a first circuit of the present invention;

[0027] Figure 2 is a circuit diagram of the second circuit of the present invention. DETAILED DESCRIPTION

[0028] The disclosed examples will be more fully described with reference to the accompanying drawings, in which some (but not all) of the disclosed examples are shown. In fact, many different examples may be described and these examples should not be construed as limited to the examples set forth herein. Instead, these examples are described so that this disclosure will be thorough and complete and will fully convey the scope of the disclosure to those skilled in the art.

[0029] Provided is a PCM code stream modulation and transmission circuit, the modulation and transmission circuit is used to modulate and output a PCM code stream;

[0030] The modulation and transmission circuit includes two circuits, the first circuit is used to convert the PCM code stream into a differential analog baseband signal;

[0031] The second circuit is used for modulating the input differential analog baseband signal and then outputting it.

[0032] The first circuit includes a SN65HVD20 interface chip, wherein the B pin and the A pin of the SN65HVD20 interface chip are connected in series with a resistor R12 and a resistor R20 respectively as a PCM code stream input terminal, and a resistor R15 is connected in series between the B pin and the A pin;

[0033] The RO pin of the SN65HVD20 interface chip is used as a single-ended signal output, and the single-ended signal is connected to the positive input of the AD8139 differential ADC driver after passing through a voltage divider resistor, and is divided into two outputs through the AD8139 differential ADC driver. Each output is filtered out by a 7th-order low-pass filter to remove high-frequency components and then output as a baseband signal;

[0034] The second circuit includes an ADRF6755 RF modulation chip. The IBBP pin and IBBN pin of the ADRF6755 RF modulation chip are used as inputs to receive two baseband signal outputs. After modulation by the ADRF6755 RF modulation chip, the RFOUT pin of the ADRF6755 RF modulation chip is output, and the output of the RFOUT pin is output as a modulated signal after passing through a 7th-order low-pass filter.

[0035] The modulated signal is connected to a radio frequency amplification circuit.

[0036] The second circuit also includes a loop filter, which is composed of a capacitor C74, a resistor R39, a capacitor C77, a resistor R41, a capacitor C86, a resistor R40 and a capacitor C87; one end of the resistor R41, the capacitor C74 and the capacitor C77 are all connected to the CP pin of the ADRF6755 RF modulation chip, the other end of the capacitor C77 is connected in series with the resistor R39 and then grounded, the other end of the capacitor C74 is grounded, the other end of the resistor R41 is simultaneously connected to one end of the capacitor C86 and the resistor R40, the other end of the resistor R40 and one end of the capacitor RC87 are connected to the VTUNE pin of the ADRF6755 RF modulation chip; the other end of the capacitor RC87 is grounded.

[0037] In the first 7th-order low-pass filter for filtering out high-frequency components, one end of capacitor C15, capacitor C16 and inductor L4 are all connected to the negative output of the AD8139 differential ADC driver, the other end of inductor L4 is connected to one end of capacitor C17 and inductor L6, the other end of inductor L6 is respectively connected to one end of capacitor C18, capacitor C13 and capacitor C12, the other end of capacitor C12 is output to the second circuit, and the other ends of capacitor C15, capacitor C16, capacitor C17, capacitor C18 and capacitor C13 are all grounded.

[0038] In the second 7th-order low-pass filter for filtering out high-frequency components, one end of capacitor C23, capacitor C35 and inductor L5 are all connected to the positive output of the AD8139 differential ADC driver, the other end of inductor L5 is connected to one end of capacitor C36 and inductor L7, the other end of inductor L7 is respectively connected to one end of capacitor C53, capacitor C57 and capacitor C20, the other end of capacitor C20 is output to the second circuit, and the other ends of capacitor C23, capacitor C35, capacitor C36, capacitor C53 and capacitor C57 are all grounded.

[0039] The V terminal of the AD8139 differential ADC driver is connected to +5V, and the G terminal of the AD8139 differential ADC driver is grounded.

[0040] The positive and negative outputs of the AD8139 differential ADC driver are connected in series with resistors R27 and R11.

[0041] The negative input of the AD8139 differential ADC driver is respectively connected to one end of the resistor R22 and one end of the capacitor C30, and the other end of the capacitor C30 is respectively connected to one end of the resistor R26 and the positive output of the AD8139 differential ADC driver; the other end of the resistor R26, the other end of the resistor R22, one end of the capacitor R22 and one end of the resistor R25 are connected, the other end of the resistor R25 is connected in series with the resistor R30 and then grounded, and the other end of the capacitor C22 is grounded.

[0042] The vocm terminal of the AD8139 differential ADC driver is respectively connected to one end of the capacitor C21, one end of the resistor R23 and one end of the resistor R28, the other end of the resistor R23 is connected to +5V, and the other end of the resistor R28 is grounded.

[0043] The description of different advantageous arrangements has been presented for purposes of illustration and description, but the description is not intended to be exclusive or limited to examples of the disclosed form. Many modifications and variations will be apparent to those of ordinary skill in the art. Additionally, different advantageous examples may describe different advantages over other advantageous examples. The selected example or examples are chosen and described in order to best illustrate the principles of the examples, the practical application, and to enable those of ordinary skill in the art to understand the disclosure with various examples with various modifications suitable for the particular use contemplated.

Claims

1. A PCM code stream modulation transmitting circuit, characterized in that: The modulation transmission circuit is used to modulate and output the PCM code stream; The modulation and transmission circuit includes two circuits, the first circuit is used to convert the PCM code stream into a differential analog baseband signal; The second circuit is used for modulating the input differential analog baseband signal and then outputting it.

2. A PCM code stream modulation transmitting circuit as claimed in claim 1, characterized in that: The first circuit includes a SN65HVD20 interface chip, wherein the B pin and the A pin of the SN65HVD20 interface chip are connected in series with a resistor R12 and a resistor R20 respectively as a PCM code stream input terminal, and a resistor R15 is connected in series between the B pin and the A pin; The RO pin of the SN65HVD20 interface chip is used as a single-ended signal output, and the single-ended signal is connected to the positive input of the AD8139 differential ADC driver after passing through a voltage divider resistor, and is divided into two outputs through the AD8139 differential ADC driver. Each output is filtered out by a 7th-order low-pass filter to remove high-frequency components and then output as a baseband signal; The second circuit includes an ADRF6755 RF modulation chip. The IBBP pin and IBBN pin of the ADRF6755 RF modulation chip are used as inputs to receive two baseband signal outputs. After modulation by the ADRF6755 RF modulation chip, the RFOUT pin of the ADRF6755 RF modulation chip is output, and the output of the RFOUT pin is output as a modulated signal after passing through a 7th-order low-pass filter.

3. A PCM code stream modulation transmitting circuit as claimed in claim 1, characterized in that: The modulated signal is connected to a radio frequency amplification circuit.

4. A PCM code stream modulation transmitting circuit as claimed in claim 1, characterized in that: The second circuit also includes a loop filter, which is composed of a capacitor C74, a resistor R39, a capacitor C77, a resistor R41, a capacitor C86, a resistor R40 and a capacitor C87; one end of the resistor R41, the capacitor C74 and the capacitor C77 are all connected to the CP pin of the ADRF6755 RF modulation chip, the other end of the capacitor C77 is connected in series with the resistor R39 and then grounded, the other end of the capacitor C74 is grounded, the other end of the resistor R41 is simultaneously connected to one end of the capacitor C86 and the resistor R40, the other end of the resistor R40 and one end of the capacitor RC87 are connected to the VTUNE pin of the ADRF6755 RF modulation chip; the other end of the capacitor RC87 is grounded.

5. A PCM code stream modulation transmitting circuit as claimed in claim 1, characterized in that: In the first 7th-order low-pass filter for filtering out high-frequency components, one end of capacitor C15, capacitor C16 and inductor L4 are all connected to the negative output of the AD8139 differential ADC driver, the other end of inductor L4 is connected to one end of capacitor C17 and inductor L6, the other end of inductor L6 is respectively connected to one end of capacitor C18, capacitor C13 and capacitor C12, the other end of capacitor C12 is output to the second circuit, and the other ends of capacitor C15, capacitor C16, capacitor C17, capacitor C18 and capacitor C13 are all grounded.

6. A PCM code stream modulation transmitting circuit as claimed in claim 1, characterized in that: In the second 7th-order low-pass filter for filtering out high-frequency components, one end of capacitor C23, capacitor C35 and inductor L5 are all connected to the positive output of the AD8139 differential ADC driver, the other end of inductor L5 is connected to one end of capacitor C36 and inductor L7, the other end of inductor L7 is respectively connected to one end of capacitor C53, capacitor C57 and capacitor C20, the other end of capacitor C20 is output to the second circuit, and the other ends of capacitor C23, capacitor C35, capacitor C36, capacitor C53 and capacitor C57 are all grounded.

7. A PCM code stream modulation transmitting circuit as claimed in claim 1, characterized in that: The V terminal of the AD8139 differential ADC driver is connected to +5V, and the G terminal of the AD8139 differential ADC driver is grounded.

8. A PCM code stream modulation transmitting circuit as claimed in claim 1, characterized in that: The positive and negative outputs of the AD8139 differential ADC driver are connected in series with resistors R27 and R11.

9. A PCM code stream modulation transmitting circuit as claimed in claim 1, characterized in that: The negative input of the AD8139 differential ADC driver is respectively connected to one end of the resistor R22 and one end of the capacitor C30, and the other end of the capacitor C30 is respectively connected to one end of the resistor R26 and the positive output of the AD8139 differential ADC driver; the other end of the resistor R26, the other end of the resistor R22, one end of the capacitor R22 and one end of the resistor R25 are connected, the other end of the resistor R25 is connected in series with the resistor R30 and then grounded, and the other end of the capacitor C22 is grounded.

10. A PCM code stream modulation transmitting circuit as claimed in claim 1, characterized in that: The vocm terminal of the AD8139 differential ADC driver is respectively connected to one end of the capacitor C21, one end of the resistor R23 and one end of the resistor R28, the other end of the resistor R23 is connected to +5V, and the other end of the resistor R28 is grounded.

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