CN201387485Y - A Beidou satellite navigation system receiving module - Google Patents

Abstract

The utility model discloses a Beidou satellite navigation system receiving module, which comprises a frequency converter, a band-pass filter, a GPS radio frequency chip and a digital receiving processor electrically connected in sequence; the frequency converter converts the frequency of the Beidou satellite signal output by the low noise amplifier to obtain The carrier frequency is at the GPS L1 frequency signal; the bandpass filter allows the Beidou satellite signal whose carrier frequency is converted to the GPS L1 frequency to pass, and filters out other frequency signals and out-of-band noise output by the inverter; the GPS RF chip has a carrier frequency of GPS The Beidou signal at L1 frequency is amplified, double-converted, filtered, and AD-converted to obtain a digital baseband signal or a digital intermediate frequency signal; the digital receiving processor performs digital quadrature down-conversion, despreading, and demodulation on the signal output by the GPS RF chip , decoding, solving and other processing, to achieve positioning, timing and other functions. The utility model can significantly reduce the cost, power consumption and volume of the Beidou satellite receiving module.

Description

A Beidou satellite navigation system receiving module

technical field

The utility model relates to a receiving module of a satellite navigation system, in particular to a receiving module of a Beidou satellite navigation system.

Background technique

The "Beidou No. 1" satellite navigation system is a satellite navigation positioning and timing system independently developed by my country. Using this system, positioning, navigation, and precise timing can be realized. The receiving module and receiver are important components of the Beidou satellite system. The user can use the receiving module to perform positioning and timing, and it has a wide range of applications in the fields of positioning, navigation and communication. The receiving module can be embedded in other equipment that needs positioning or timing, and can also be installed integrally with the antenna and low-noise amplifier (LNA). The existing receiving module is mainly composed of a radio frequency channel and a digital receiving processing part. As shown in Figure 1, the radio frequency channel includes radio frequency amplification, first frequency conversion, AGC amplification, second frequency conversion, low-pass filtering, AD converter, etc. Because the Beidou-1 satellite navigation system uses a dedicated frequency to transmit signals, the existing receiving module generally uses multiple general-purpose devices to realize the radio frequency channel, which leads to the high cost and power consumption of the existing receiving module of the Beidou navigation system, and the receiving module The volume is larger. Although the existing Beidou-1 dedicated receiving channel chip reduces the size of the radio frequency channel, it still has the problems of high power consumption (about 600 milliwatts) and high cost (over 800 yuan).

Contents of the invention

Purpose of the invention: The purpose of this utility model is to provide a low-cost, low-power consumption, and small-volume Beidou satellite navigation system receiving module for the problems existing in the existing Beidou satellite navigation system receiving module.

Technical solution: a Beidou satellite navigation system receiving module, which includes a frequency converter, a band-pass filter, a GPS radio frequency chip and a digital receiving processor electrically connected in sequence; the frequency converter converts the frequency of the Beidou-1 satellite signal output by the low-noise amplifier , to obtain the signal with the carrier frequency at the GPS L1 frequency; the band-pass filter allows the Beidou-1 satellite signal with the carrier frequency converted to the GPS L1 frequency to pass, and at the same time filters out other frequency signals and out-of-band noise output by the frequency converter; the GPS radio frequency chip is The Beidou signal whose carrier frequency is the GPS L1 frequency is amplified, double-converted, filtered, and AD converted to obtain a digital baseband signal or a digital intermediate frequency signal; the digital receiving processor performs digital processing on the digital baseband signal or digital intermediate frequency signal output by the GPS RF chip. Orthogonal down-conversion, despreading, demodulation, decoding, and calculation processing to realize positioning and timing functions.

Wherein, the GPS L1 frequency is 1574.92-1575.92 MHz.

Wherein, the input end of the frequency converter is electrically connected with an amplifier, and the amplifier is set according to specific conditions.

Wherein, described band-pass filter is GPS L1 frequency point band-pass filter.

The receiving module of the utility model is realized by adopting a new radio frequency channel of the receiving module of the Beidou satellite navigation system. That is to use a general-purpose frequency conversion chip with small size and low cost, first convert the carrier frequency of the Beidou satellite signal to the GPS L1 frequency range; The Beidou signal is amplified, frequency-converted, filtered, and AD-converted to obtain a digital baseband signal or a digital intermediate frequency signal; and then received and processed by a digital receiving processor to realize digital quadrature down-conversion, despreading, demodulation, decoding, and resolution And other processing, to achieve positioning, timing and other functions, in order to achieve the purpose of reducing the number of radio frequency channel devices, thereby reducing the module volume, reducing module cost and power consumption.

Beneficial effects: (1) Compared with the prior art, the receiving module of the Beidou satellite navigation system of the present utility model only uses 1 frequency conversion chip and 1 GPS radio frequency chip in the radio frequency channel part, and the devices used are greatly reduced, and the occupied circuit board The area can be reduced to less than 2 square centimeters, thereby reducing the volume of the entire receiving module. (2) Since the GPS radio frequency chip is specially designed for low-power GPS terminals, its power consumption is less than 100 milliwatts. With the addition of frequency converters and amplifiers, the power consumption of the entire radio frequency channel can be reduced to less than 300 milliwatts. (3) Since the output of frequency converters and GPS radio frequency chips is very large, their prices are both several dollars, so that the cost of the radio frequency channel part of the Beidou satellite system receiving module in batches can be reduced to about 150 yuan.

Description of drawings

Below in conjunction with accompanying drawing, the utility model is described further.

Figure 1 is a structural block diagram of the receiving module of the existing Beidou satellite navigation system.

Fig. 2 is a structural block diagram of the receiving module of the Beidou satellite navigation system of the present invention.

Figure 3 is a block diagram of the MAX2769 chip.

Detailed ways:

As shown in Figure 1, the radio frequency channel of the existing Beidou satellite navigation system receiving module generally mainly includes the first mixer, the first intermediate frequency bandpass filter, the first intermediate frequency variable gain amplifier, the second mixer A frequency converter, a second intermediate frequency bandpass filter, a second intermediate frequency amplifier and an analog-to-digital converter. The digital receiving processor generally consists of a programmable logic array (FPGA) that realizes functions such as digital quadrature down-conversion, spread spectrum code capture and tracking, demodulation and decoding, and a microprocessor that realizes information processing functions such as position and time resolution. device composition. In the first mixer, the Beidou-1 satellite signal with a carrier frequency of 2491.75MHz is mixed with the first local oscillator signal to obtain the first intermediate frequency signal with a frequency of 200-900MHz (the specific frequency of the first intermediate frequency can be selected in multiple ways) ; After being filtered by the first intermediate frequency band-pass filter, the first intermediate frequency signal is sent to the first intermediate frequency variable gain amplifier behind, which amplifies the received signal, and its gain is generally automatically adjusted according to the power of the received signal. Amplifiers are usually called AGC amplifiers; the first IF signal amplified by AGC is mixed with the second local oscillator signal in the second mixer to obtain a second IF signal with a frequency of about 12.24MHz; the second IF bandpass filter The filter is generally a low-pass filter, which filters out the sum frequency component and high-frequency noise generated by the second mixer; the second intermediate frequency signal is further amplified by the second intermediate frequency amplifier, and then the digital intermediate frequency signal is obtained by the analog-to-digital converter , The analog-to-digital converter generally adopts an 8-bit converter.

The principle of the utility model is to convert the frequency of the Beidou No. 1 satellite signal to the GPS L1 frequency, and then use the GPS chip to realize the function of receiving the radio frequency channel, and the digital processing part still adopts the existing technology. The receiving module of the utility model can be applied in a receiver or other equipment requiring positioning and timing. This embodiment is described by taking the application in a receiver as an example. The receiving module is installed in the receiver, and the receiver also includes a receiving antenna and a low noise amplifier.

As shown in FIG. 2 , the embodiment includes an amplifier 5 , a frequency converter 1 , a bandpass filter 2 , a GPS radio frequency chip 3 and a digital receiving processor 4 that are electrically connected in sequence. The Beidou-1 satellite signal received by the receiving antenna of the receiver is amplified by the low-noise amplifier and then sent to the amplifier 5 for amplification. When the difference between the gain of the low-noise amplifier and the loss of the RF cable connecting the low-noise amplifier and the receiving module is greater than 40dB , amplifier 5 may not be used. The Beidou-1 signal amplified by the amplifier 5 is sent to the frequency converter 1, and the frequency converter 1 can use the built-in frequency synthesizer frequency conversion chip of RF Micro Devices (RFMD company), such as RF2051, RF2052, RF2053. Inverter 1 mixes the Beidou-1 satellite signal with a carrier frequency of 2491.75MHz and the local oscillator signal with a frequency of 916.33MHz to obtain a signal with a carrier frequency of GPS L1 frequency. According to the actual situation, the local oscillator frequency can be changed appropriately to obtain a signal with a carrier frequency in the range of 1574.92-1575.92MHz, that is, 1575.42±0.5MHz, but the optimum frequency is 1575.42MHz. Band-pass filter 2 is a GPS L1 frequency point band-pass filter, which can use surface acoustic wave filters such as TRIQUINT 856561. The band-pass filter 2 allows the Beidou-1 satellite signal whose frequency is converted to 1575.42MHz to pass, and sends it to the GPS radio frequency chip 3 behind. The GPS radio frequency chip 3 can use Maxim's MAX2769. Figure 3 shows the schematic diagram of the MAX2769 circuit. The chip consists of a low-noise amplifier, a quadrature mixer, a variable gain amplifier, an AD converter, and a frequency synthesizer. The Beidou-1 satellite signal converted to GPS L1 frequency can be sent to the internal low-noise amplifier (LNA) of the chip for amplification through the 25th or 27th pin, and the amplified signal is output from the 2nd pin, and then sent to the chip from the 5th pin Internal quadrature converter; in the quadrature converter, the carrier frequency is the GPS L1 frequency signal and the quadrature local oscillator signal output by the VCO inside the chip through the phase shifter; the output of the quadrature mixer is filtered on-chip After filtering by filter (FILTER), the quadrature baseband analog signal is obtained; the quadrature baseband analog signal is amplified by the internal variable gain amplifier of the chip, and after analog-to-digital conversion (ADC), the digital baseband signal of bit quantization is obtained, from the 20th, 21st , 17, 18 pin output. In this way, the radio frequency channel function of the existing Beidou-1 receiving module is realized. The digital receiving processor 4 receives and processes the digital baseband signal or the digital intermediate frequency signal, realizes the reception of the Beidou signal, and then realizes positioning and timing.

The utility model uses a general-purpose frequency conversion chip widely used in communication, radio and television, and a large number of GPS radio frequency chips used in GPS receivers. Compared with the receiving module of the existing Beidou satellite navigation system, it can achieve the same function. The volume of the receiving module is greatly reduced, and the cost and power consumption of the receiving module are significantly reduced.

The above is only a preferred embodiment of the utility model, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the utility model, some improvements and modifications can also be made, these improvements and Retouching should also be regarded as the scope of protection of the present utility model.

Claims (4)

1, a kind of Beidou satellite navigation system receiving module is characterized in that: it comprises frequency converter (1), bandpass filter (2), GPS radio frequency chip (3) and the digital received processor (4) that is electrically connected successively;

Frequency converter (1): the Big Dipper satellite signal to low noise amplifier output carries out frequency conversion, obtains the signal of carrier frequency in GPS L1 frequency;

Bandpass filter (2): allow carrier frequency shift pass through, other frequency signal and the out-of-band noise of the output of the frequency converter of filtering simultaneously to the Big Dipper satellite signal of GPS L1 frequency;

GPS radio frequency chip (3): to carrier frequency be that the Big Dipper signal of GPS L1 frequency amplifies, double conversion, filtering, AD conversion, obtain digital baseband signal or digital medium-frequency signal;

Digital received processor (4): digital baseband signal or digital medium-frequency signal to the output of GPS radio frequency chip carry out digital quadrature down coversion, despreading, demodulation again, decipher, resolve processing, realize location, time service function.

2, Beidou satellite navigation system receiving module according to claim 1 is characterized in that: described GPS L1 frequency is 1574.92～1575.92MHz.

3, Beidou satellite navigation system receiving module according to claim 1 is characterized in that: the input end of frequency converter (1) is electrically connected with amplifier (5).

4, Beidou satellite navigation system receiving module according to claim 1 is characterized in that: described bandpass filter (2) is a GPS L1 frequency bandpass filter.

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