CN205562813U - Satellite navigation signal testing system based on big dipper intermediate frequency signal gathers - Google Patents

Abstract

The utility model discloses a satellite navigation signal testing system based on Beidou intermediate frequency signal collection. The system includes a Beidou intermediate frequency signal collector and a Beidou baseband signal processor for mutual data transmission, wherein the Beidou intermediate frequency signal collector includes sequentially connected radio frequency Front-end module, RF front-end data processing module, A/D sampling module and data transmission module. The micro-navigation test system designed according to the utility model can carry out signal acquisition to the Beidou radio frequency signal, and convert it into a digital intermediate frequency data stream as the signal source of the satellite navigation test, and input the signal source to the subsequent Beidou baseband signal processor for information The solution processing of the Beidou signal processing, thereby providing hardware device support for the test work of Beidou signal processing.

Description

A satellite navigation signal test system based on Beidou intermediate frequency signal acquisition

technical field

The utility model belongs to the field of satellite navigation, more specifically, relates to a satellite navigation test system based on Beidou intermediate frequency signal collection.

Background technique

The field of satellite navigation technology is currently widely used, and my country is also stepping up the construction of the Beidou satellite navigation system. Now a Beidou regional satellite navigation system constellation of 5GEO+3IGSO+4MEO has been formed, and it will be expanded to have about 30 satellites by 2020. Global satellite navigation system. For the market and various users, the terminal equipment application technology of GPS, Beidou and other satellite navigation systems is one of the key technologies.

At present, satellite navigation receivers are mostly based on digital processing technology-specific chips (ASICs) and fast microprocessors for application calculations. The disadvantages are that the algorithms are fixed and the hardware architecture is not easy to change. The above applications have different requirements for the receiver, so it is necessary to change the functional structure of the receiver to meet the more flexible and sufficient navigation signal test requirements.

Utility model content

In view of the above defects or improvement needs of the prior art, the utility model provides a satellite navigation signal test system based on Beidou intermediate frequency signal collection, and its purpose is to propose a test system for Beidou intermediate frequency signals that is especially suitable for marine environments. This provides a system hardware platform for testing different types of Beidou receiver signal processing for marine applications.

In order to achieve the above object, according to one aspect of the present invention, a satellite navigation test system based on Beidou intermediate frequency signal collection is provided, which is characterized in that the system includes a Beidou intermediate frequency signal collector for mutual data transmission and a Beidou baseband signal processing device, wherein the Beidou intermediate frequency signal collector includes a radio frequency front-end module, a radio frequency front-end data processing module, an A/D sampling module and a data transmission module connected in sequence.

Further, the radio frequency front-end module includes a Beidou antenna, a two-stage low-noise amplifier and a band-pass filter connected in sequence.

Further, the radio frequency front-end data processing module includes a quadrature demodulator and a radio frequency local oscillator frequency synthesizer connected to it to provide an oscillation source for it.

Generally speaking, compared with the prior art, the above technical solution conceived by the utility model can obtain the following beneficial effects: the Beidou radio frequency signal can be collected and converted into a digital intermediate frequency data stream as a satellite navigation test. The signal source is input to the subsequent Beidou baseband signal processor for information processing, thereby realizing the test work of Beidou signal processing.

Description of drawings

Fig. 1 is the overall structure schematic diagram of the satellite navigation test system realized according to the utility model;

Fig. 2 is the module structural representation of the Beidou intermediate frequency signal collector in the satellite navigation test system realized according to the utility model;

Fig. 3 is a schematic diagram of the detailed structure of the module of the Beidou intermediate frequency signal collector in the satellite navigation test system realized according to Embodiment 1 of the utility model;

Fig. 4 is a schematic diagram of the module structure of the Beidou baseband signal processor in the satellite navigation test system realized according to the first embodiment of the utility model.

detailed description

In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model, and are not intended to limit the utility model. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute conflicts with each other.

The test system realized according to the utility model mainly includes the following two parts: as shown in Figure 1, the navigation test system involved in the utility model includes a Beidou intermediate frequency signal collector and a Beidou baseband signal processor for mutual data transmission.

As shown in Figure 2, it is a schematic diagram of the system composition of the Beidou intermediate frequency signal collector realized according to the utility model, wherein the Beidou intermediate frequency signal collector mainly completes the high-speed collection and processing of the Beidou radio frequency signal, which specifically includes the interconnected RF radio frequency front end , RF radio frequency front-end data processing, A/D module and data transmission module, the A/D module completes data sampling and quantification, and the data transmission module mainly provides data transmission protocol and interface.

Embodiment one

The part shown in Figure 3 is a detailed schematic diagram of a specific Beidou intermediate frequency signal acquisition module. The Beidou intermediate frequency signal collector implemented according to this embodiment mainly includes the following parts:

1. RF front-end module

The design of the RF front-end module mainly includes the Beidou second-generation B1 antenna for collecting signals, and the two-stage front-end low-noise amplifier LNA connected to it. RF band-pass filter (SAW filter), in the actual test, each stage of LNA achieves a gain of 15dB, and the combined gain of the two stages of LNA is about 30dB. In the actual channel, the insertion loss of the two stages of SAW is included, and the attenuation of the final stage PI matching network , line and connector insertion loss, etc., the total loss is about 10dB, and the actual two-stage low-noise amplifier is cascaded to obtain a gain of 20dB.

2. RF front-end data processing

Among them, the RF front-end data processing uses the chip AD8347 as the main module. AD8347 is a single-chip, broadband 2.7GHz quadrature demodulator, and the specific model is SI4133 to provide it with a radio frequency integrated chip. The frequency synthesis chip contains 3-way PLL phase-locked loop, each PLL is composed of PD phase detector, LF loop filter, VCO voltage-controlled oscillator and programmable frequency divider. The 10MHz 1PPM temperature-compensated crystal oscillator is used as the reference frequency source, and the RF output is matched to the load through the LC series matching network. The range of the external inductance of the first RF channel is 0~4.6nH, and the range of the external inductance of the second RF channel is 0.3nH ~6.2nH.

3. A/D sampling module

Among them, the A/D sampling module is set after the RF front-end data processing for data sampling. The AD on the actual board adopts the AD9233-125 chip of Analog Device Company, which is a single-chip, 12-bit, 125MSPS analog-to-digital converter ADC. 1.8V single power supply, built-in a high-performance sample-and-hold amplifier SHA and on-chip reference voltage source, the highest sampling rate can reach 125MHz, 12-bit resolution, the analog bandwidth can reach up to 650MHz, can be used for direct RF band-pass sampling, using differential The AD9233 achieves optimal performance when driven by . The analog intermediate frequency signal enters the amplifying channel after capacitive AC coupling.

4. Data transmission module

The data transmission module includes data front-end processing and interface processing. The front-end processing is to transfer the data transmitted by the A/D sampling module to the FPGA as the data transmission module. Here, it is necessary to pay attention to the clock interface of the FPGA, and its internal PLL The input requires a dedicated clock pin input, where the FPGA data is processed and then transmitted to the USB2.0 interface for data processing and then transmitted to the Beidou baseband signal processor, where the USB2.0 interface uses the CY7C68013-56 interface chip.

Wherein as shown in Figure 4, it is a schematic diagram of the module composition structure of the Beidou baseband signal processor realized according to the present invention, wherein, the Beidou baseband signal processor collects corresponding data from the intermediate frequency signal collector through the capture module, and captures the signal Input tracking module, the tracking module mainly includes a code tracking loop and a carrier tracking loop, the Beidou baseband signal processor is mainly used to process the signal sent by the above-mentioned Beidou intermediate frequency signal collector, and the processor mainly completes data processing, each Initialization of channels (each channel refers to multiple satellite signal channels received), reading and storage of lead, instant and lag related values of each channel, loop control and performance testing of carrier tracking loop and code tracking loop to ensure data Reliability of processing, reading and storage of TIC time observation data, carrier phase assisted pseudo-range smoothing processing, tracking Doppler Kalman filter processing, signal frame data reading and navigation message analysis, satellite positioning calculation and velocity calculation, Various functions such as framing and deframing of the serial port protocol, such as data reception, processing and calculation, among which the modules of the above-mentioned Beidou baseband signal processor are integrated in a DSP or programmable logic chip, through the cooperation with the power supply and logic program The above processing is completed.

Among them, after the Beidou intermediate frequency signal collector completes the signal collection, the Beidou baseband signal processor is used to process the signal. From this data processing process, the test data information of satellite navigation is extracted to process the test information. This data processing process uses the same method as the current one. It only needs to use the same data process as in the technology and select a data processing chip, and the detailed data processing process will not be repeated here.

Those skilled in the art can easily understand that the above descriptions are only preferred embodiments of the present utility model, and are not intended to limit the present utility model. Any modifications, equivalent replacements and modifications made within the spirit and principles of the present utility model Improvements and the like should all be included within the protection scope of the present utility model.

Claims (3)

1. the satellite navigation signals test system gathered based on Big Dipper intermediate-freuqncy signal, it is characterised in that This system includes Big Dipper intermediate-freuqncy signal harvester and the Big Dipper baseband signal processor being electrically connected to each other, At RF front-end module that wherein Big Dipper intermediate-freuqncy signal harvester includes being sequentially connected with, radio-frequency front-end data Reason module, A/D sampling module and data transmission module.

2. the satellite navigation signals test gathered based on Big Dipper intermediate-freuqncy signal as claimed in claim 1 is System, it is characterised in that described RF front-end module includes Beidou antenna, the two-stage low noise being sequentially connected with Acoustic amplifier and band filter.

3. the satellite navigation signals test gathered based on Big Dipper intermediate-freuqncy signal as claimed in claim 2 is System, it is characterised in that described radio-frequency front-end data processing module include quadrature demodulator and with its phase It is linked as its RF local oscillator that oscillation source is provided frequency to combine.