RU116298U1 - MULTI-SYSTEM RADIO FREQUENCY SATELLITE NAVIGATION RECEIVER UNIT - Google Patents

Abstract

1. Multi-system radio frequency unit of a satellite navigation receiver, manufactured using the system-on-chip technology, using the structure of the receiving path with one frequency conversion, capable of simultaneous operation with the global navigation satellite system of Russia (GLONASS), the US global positioning system (Global Positioning System - GPS), the global navigation satellite system of the European Union and the European Space Agency (Galileo), the global satellite navigation system of the PRC (Compass), containing a low-noise amplifier, a high-frequency amplifier and I and Q quadrature mixers common to receive signals from all systems, and having the ability to connect a combined GLONASS / GPS / Galileo / Compass passive antenna and combined GLONASS / GPS / Galileo / Compass active antenna, containing a power circuit with detection of connecting the combined active antenna and automatic switching to receive from the active antenna and disconnection a built-in low-noise amplifier connected to the input from a combined passive antenna, using a combined GLONASS / GPS / Galileo / Compass band-pass filter between the low-noise amplifier and the high-frequency amplifier, containing two intermediate frequency channels, each of which contains a phase shifter-combiner connected to the outputs of the quadrature mixers I & Q, analog switcher, IF filter with adjustable bandwidth, IF amplifier with gain control, output line buffer, 2-bit analog-to-digital converter with selectable thresholds, detector for analog and digital output C

Description

The utility model relates to multi-system radio-frequency units of a satellite navigation receiver (SAR), which can be widely used for simultaneously receiving navigation signals from several navigation systems, for example: the global navigation satellite system of Russia (GLONASS), the global positioning system of the USA (GPS) ), the global navigation satellite system of the European Union and the European Space Agency (Galileo), the global satellite navigation system of China (Compass).

It is known that the simultaneous use of signals from several navigation systems provides several advantages [1], where it is indicated that the simultaneous use of two systems GLONASS (Russia) and GPS (USA) can radically increase the accuracy of determining coordinates to a level that is unattainable when using any single system.

A device for receiving signals from satellite navigation systems GPS, Galileo and GLONASS [2], used to build a radio frequency unit according to a superheterodyne receiver with two transformations. This device contains the following blocks: common high-frequency (HF) first and second band-pass filters, a low-noise amplifier (LNA) and a first mixer, one common frequency synthesizer for generating the frequencies of the first and second local oscillators and the clock frequency, two intermediate frequency (IF) channels, each of which includes a first-pass IF filter, a second mixer, an IF amplifier with gain control, and an analog-to-digital converter (ADC).

The disadvantages of the aforementioned device are the high power consumption, the inability to connect active and passive antennas, the inability to integrate the two filters of the first IF and, as a consequence, the large dimensions of the device.

A known method and system for constructing a common radio frequency unit for receiving signals from satellite navigation systems GPS, Galileo and GLONASS [3], in which the receiver contains a common high-pass filter, a high-frequency amplifier with automatic gain control (AGC) and common quadrature mixers. The signal processing path after quadrature mixers is common for all systems, and the separation into separate frequency bands is performed by digital filters after common ADCs.

The disadvantage of such a receiver is low noise immunity: the presence of interference located in the frequency range of one of the received systems can lead to blocking of the common IF path, which makes it impossible to receive signals from all three systems.

Also known device two-system radio frequency unit of the satellite navigation receiver [4]. The radio frequency unit contains a common radio frequency input, a signal splitter and two integrated circuit (IC) crystals, one of which receives GLONASS signals, and the second - GPS systems.

The disadvantages of such a radio frequency unit manufactured by the system-in-case technology are increased dimensions (22 mm × 12 mm), high power consumption, low reliability due to the need to use several integrated circuits (ICs), the inability to organize work with two antenna inputs : for connecting passive and active antennas.

Closest to the claimed technical solution, a multi-system radio frequency unit SNP МАХ2769В (manufactured by MAXIM) was chosen [5]. The radio frequency unit SNP МАХ2769В is made in the form of ICs based on the "system on a chip" technology, and can work with navigation signals from four navigation systems, namely, the US global positioning system (GPS), Russia's global navigation satellite system (GLONASS), and global navigation satellite systems of the European Union and the European Space Agency (Galileo), China's global satellite navigation system (Compass). The MAX2769B radio frequency unit is designed according to a single conversion scheme, can operate in low-frequency or zero-frequency IF modes and contains all the blocks for constructing the radio frequency path, including LNA with two inputs, I and Q quadrature mixers, an IF filter with the ability to suppress a mirror channel, amplifiers Programmable gain IF, voltage-controlled oscillator (VCO), reference oscillator, frequency synthesizer, two ADCs and an interface. The output signals of the MAX2769B RF unit can be either digital from the built-in ADCs or differential analog ones.

The disadvantage of the MAX2769B radio frequency unit is that it cannot operate simultaneously on the signals of the global navigation satellite system of Russia (GLONASS) and the rest of the declared navigation systems, namely the US global positioning system (GPS), the global navigation satellite system of the European Union and the European Space Agency (Galileo) and China's global satellite navigation system (Compass). Thus, to receive the signals of all four declared navigation systems, it is necessary to build a radio frequency unit using at least two IP MAX2769B ICs, one of which processes the signals of the GLONASS system, and the second - signals of the GPS, Galileo and Compass systems. The disadvantage of this solution is that the dimensions of the radio-frequency unit increase, the power consumption increases, the design reliability decreases due to the increased number of elements used, and the operation modes of the radio-frequency unit are complicated.

This utility model claims a multi-system radio frequency unit of a satellite navigation receiver, the technical result of which is to increase the accuracy of determining coordinates, reduce the dimensions of the device and power consumption, increase the reliability of the design.

The proposed multi-system radio-frequency unit of the satellite navigation receiver is manufactured using the "system on a chip" technology, using the structure of the receiving path with one frequency conversion, is configured to simultaneously work with the global navigation satellite system of Russia (GLONASS), the US global positioning system (Global Positioning System - GPS), the global navigation satellite system of the European Union and the European Space Agency (Galileo), the global satellite navigation PRC systems (Compass), contains a low-noise amplifier, a high-frequency amplifier and I and Q quadrature mixers common for receiving signals of all systems and has the ability to connect a combined GLONASS / GPS / Galileo / Compass passive antenna and a combined GLONASS / GPS / Galileo / Compass active antenna, contains a power circuit with detecting the connection of the combined active antenna and automatically switching to reception from the active antenna and disconnecting the built-in low-noise amplifier connected to the input from the combined passive antenna; GLONASS / GPS / Galileo / Compass frequency bandpass filter between a low-noise amplifier and a high-frequency amplifier, contains two intermediate frequency channels, each of which contains a phase shifter-adder connected to the outputs of quadrature mixers I and Q, an analog switch, an intermediate frequency filter with an adjustable passband , intermediate frequency amplifier with gain control, linear output buffer, two-bit analog-to-digital converter with threshold selection, analog and digital output signal detector a digital-to-analog converter for controlling the gain of an intermediate-frequency amplifier through a serial interface containing an automatic calibration system for an intermediate-frequency filter band, a frequency synthesizer consisting of a voltage-controlled oscillator, a voltage-controlled oscillator frequency divider to form the clock frequency of the correlators, a clock divider and a reference divider frequencies for forming a comparison frequency, a frequency-phase detector, a synthesis filter pa frequency with the phase locked loop frequency generator of quadrature LO signals for the quadrature mixers, a serial interface to control operating modes of the radio-frequency parts multisystemic unit,

This technical result is achieved due to the fact that the multi-system radio-frequency unit of the satellite navigation receiver separates the GLONASS signal into the first intermediate frequency channel and the combined GPS / Galileo / Compass signal into the second intermediate frequency channel using the built-in broadband phase shifter-adders.

In this case, when separating GLONASS and GPS / Galileo / Compass signals, the multi-system radio frequency unit uses a common mixer I and a common mixer Q and two broadband phase shifter-combiners, connected in such a way that each of the phase shifter-combiners form together with a common mixer I and a common mixer Q two mixers, each of which is made in structure with suppression of the mirror frequency. It also uses the conversion frequency for common quadrature mixers I and Q, with respect to which the combined signal spectrum of all navigation systems is located symmetrically.

At the same time, the inventive multi-system RF frequency block SNP uses the gain control of the intermediate frequency amplifier by control signals from the built-in digital-to-analog converter controlled via a serial interface, or by using the built-in automatic gain control system that works from the output analog or digital signals with a control threshold from the built-in digital -analog converter, so that the integral percentage of exceeding two-bit thresholds analog-to-digital converters is equal to the direct or additional code of the built-in digital-to-analog converter.

The claimed utility model is illustrated by a figure, which shows a structural diagram of the proposed multi-system radio-frequency unit of the satellite navigation receiver, manufactured using the technology "system on a chip."

As can be seen from the figure, the RF unit 1 has a terminal 2 and a connector 3 for connecting a combined GLONASS / GPS / Galileo / Compass passive antenna 4 and a combined GLONASS / GPS / Galileo / Compass active antenna 5, respectively. The combined GLONASS / GPS / Galileo / Compass passive antenna 4 through pin 2 is connected to the input of the built-in low-noise amplifier 6 (LNA), the output of which is connected to the input of the combined GLONASS / GPS / Galileo / Compass band-pass filter 7. Combined GLONASS / GPS / Galileo / Compass the active antenna 5 through connector 3 is connected to the input of the combined GLONASS / GPS / Galileo / Compass bandpass filter 7 and to the output of the active antenna power circuit 8, which generates the supply voltage for the active antenna, detects the connection of the combined active antenna, limits the current through the power circuit active antenna in the case of short-circuit and short-circuit in the absence of active antenna circuit supply automatically switches to receiving signals from the active antenna 5 and disable operation of LNA 6 to save power consumption radio frequency unit. When the active antenna 5 is disconnected or a short circuit occurs in the power circuit of the active antenna, circuit 8 turns on the built-in LNA 6 and automatically switches to receiving signals from the combined passive antenna 4.

The high-frequency path 9 of the multi-system radio frequency unit 1 is common for signals of all navigation systems, for example: the global navigation satellite system of Russia (GLONASS), the global positioning system of the USA (Global Positioning System - GPS), the global navigation satellite system of the European Union and the European Space Agency (Galileo ), China's global satellite navigation system (Compass). The output of the combined GLONASS / GPS / Galileo / Compass band-pass filter 7 is connected to the input of the RF amplifier 10, the output of which is connected to the inputs of the quadrature mixers 11 (I) and 12 (Q), to which the quadrature heterodyne signals from the quadrature signal driver of the local oscillator 13 are supplied.

The outputs of the quadrature mixers 11 and 12 are connected to the inputs of the analog switches 14 and 15 and the inputs of the phase shifters-adders 16 and 17, the outputs of which are connected to the second inputs of the analog switches 14 and 15, with the help of which the operating modes of the intermediate frequency path are selected.

The RF unit 1 contains two identical intermediate frequency (IF) paths 18 and 19. The IF paths include customizable IF filters 20 and 21, the inputs of which are connected to the outputs of the analog switches 14 and 15, and the outputs to the inputs of the intermediate frequency amplifiers (IF) 22 and 23 with automatic gain control (AGC). The outputs of the UPCH 22 and 23 are connected to the inputs of the differential analog buffers 24 and 25 and the inputs of the analog-to-digital converters (ADCs) 26 and 27, the outputs of which together with the outputs of the differential analog buffers 24 and 25 are connected to the terminals 28 and 29, through which the signals of the navigation systems in analog or digital form are fed to an external correlator 30. The detection of the output analog and digital signals of the IF path is carried out by detectors 31 and 32, which have the ability to set the detection level from the built-in digital-to-analog converters atelers (DACs) 33 and 34, the code for which is set via the serial interface unit 35. The output control signals of the detectors 31 and 32 are fed to the control inputs of the gain amplifiers 22 and 23, forming the AGC system. The AGC of the IF path can operate in several modes:

- with linear differential outputs, while the AGC operates on the output linear signals,

- with digital outputs from the built-in two-bit ADC 26 and 27, the thresholds of which are set via the serial interface 35, and the signals for the detectors 31 and 32 of the AGC systems are taken from the outputs of the UPCH 22 and 23,

- with digital outputs from the built-in two-bit ADCs 26 and 27, the signals for the detectors 31 and 32 of the AGC systems are taken from the outputs of the ADCs 26 and 27, and the detection threshold is set using the DACs 33 and 34 through the serial interface 35 so that the integral percentage digital magnitude signals equal to the direct or additional code specified on the DAC 33 and 34.

The passband of the inverter filters 20 and 21 is automatically adjusted when the power of the RF unit is turned on using the auto-tuning system 36, using the frequency of the external reference generator 37 as the reference frequency. If necessary, the passband of the inverter filters can be changed by setting the appropriate code via the serial interface 35.

The radio frequency unit includes a frequency synthesizer 38, which generates a signal with a frequency two or four times higher than the required frequency for quadrature mixers. The frequency synthesizer 38 consists of a voltage-controlled oscillator (VCO) 39, the differential output of which is connected to the inputs of the quadrature signal driver of the local oscillator 13 and the VCO frequency divider 40, which generates a clock frequency signal used to operate the external correlator 30. The output of the frequency divider 40 is connected to the input of the divider frequency 41, forming the divided VCO frequency supplied to the frequency-phase detector (ChFD) 42. At the second input of the ChFD 42, a comparison frequency signal generated by the reference frequency divider 43 is supplied output from the external reference generator 37. The output of the PFD 42 is connected to the input of the built-in filter 44 of the synthesizer 38 with phase-locked loop (PLL). The output of the filter 44 is connected to the control input of the VCO 39. The division factors of the dividers 40, 41, and 43 can be either programmable via a serial interface, or, in a particular case, fixed. The band of the frequency synthesizer 38 can be adjusted by adjusting the filter 44, the parameters of which are set via the serial interface 35. The VCO 39 has a system for automatically adjusting the subband that is triggered by turning on the power of the radio frequency unit or when a corresponding command is sent via the serial interface 35.

The receiving path of the radio frequency block is made according to the scheme with one conversion with a low IF and using common quadrature mixers. The RF part of the path from the antenna to the output of the quadrature mixers is common to the signals of all navigation systems, which minimizes power consumption and reduces overall dimensions by minimizing the number of external elements. In particular, only one external high-pass filter is used that transmits signals from all systems. To convert the signals of all navigation systems, one common source of quadrature signals of the local oscillator, formed using a fully integrated frequency synthesizer, is used.

The receiving path from the outputs of the quadrature mixers to the outputs of the inverter can be configured in various ways via a serial interface. In particular, to increase the noise immunity, the receiving path can be switched using analog switches 14 and 15 to the mode with separation of the signals of the GLONASS system and GPS, Galileo and Compass systems into separate IF channels. In this case, the signals from the outputs of the quadrature mixers are fed to the broadband phase shifters-adders 16 and 17, which in a wide frequency range carry out a phase shift of the output signals from the quadrature mixers and sum them. In this case, the useful signal is added in phase, while the mirror signal in relation to the useful signal is in antiphase. The phase shifters-adders 16 and 17 are constructed in the same way, but are connected to the outputs of the common quadrature mixers in such a way that only the GLONASS signal passes to the output of one phase shifter-adder, and the GPS, Galileo and Compass signals go to the outputs of the second. Thus, interference in the GLONASS signal band will be suppressed at the output of the adder phase shifter for GPS, Galileo and Compass, and, conversely, interference in the signal band, for example, GPS will be suppressed at the output of the adder phase shifter for GLONASS. In this case, the narrow-band interference will not be able to block the reception of signals at once for all systems of a multi-system SPS constructed using the radio frequency unit according to the claimed utility model, which increases the reliability of determining coordinates in difficult reception conditions, i.e. increases the noise immunity of the SNP.

Prototypes of the multi-system radio frequency unit SNP according to the "system on a chip" technology were made on the basis of the design documentation of NTLab-SYSTEMS CJSC and assembled in a 32-pin QFN type case with 0.5 mm pitch along the terminals and case dimensions: length - 5 mm, width - 5 mm, height - 0.9 mm. Tests have shown that they comply with the requirements that apply to measuring instruments of multi-system DSS.

1. I. Korneev, V. Nemudrov, V. Polshchikov, O. Lagutin. Specialized VLSI is the basis of the GLONASS / GPS digital navigation receiver. “Electronic Components”, No 4, 2007

2. US patent No.US 6600909 B1, 07.29.2003

3. Patent No. EP 2 194 393 A2, November 30, 2009

4. RF patent for utility model No. 77525, 06/17/2008

5. - http://www.maxim-ic.com/datasheet/index.mvp/id/7267

Claims (4)

1. A multi-system radio-frequency unit of a satellite navigation receiver manufactured using the "system on a chip" technology, using the structure of the receiving path with one frequency conversion, made with the possibility of simultaneous operation with the global navigation satellite system of Russia (GLONASS), the US global positioning system (Global Positioning System - GPS), the global navigation satellite system of the European Union and the European Space Agency (Galileo), the global satellite navigation system HP (Compass), which contains a low-noise amplifier, a high-frequency amplifier and I and Q quadrature mixers common for receiving signals of all systems and having the ability to connect a combined GLONASS / GPS / Galileo / Compass passive antenna and a combined GLONASS / GPS / Galileo / Compass active antenna, containing power circuit with detecting the connection of a combined active antenna and automatically switching to reception from the active antenna and disconnecting the built-in low-noise amplifier connected to the input from the combined passive antenna using GLONASS / GPS / Galileo / Compass integrated band-pass filter between a low-noise amplifier and a high-frequency amplifier, containing two intermediate frequency channels, each of which contains a phase shifter-adder connected to the outputs of quadrature mixers I and Q, an analog switch, an intermediate frequency filter with an adjustable passband , intermediate frequency amplifier with gain control, linear output buffer, two-bit analog-to-digital converter with threshold selection, analog and digital output si nalov, a digital-to-analog converter for controlling the gain of the intermediate frequency amplifier through a serial interface containing an automatic calibration system for the intermediate frequency filter band, a frequency synthesizer consisting of a voltage controlled oscillator, a voltage controlled oscillator frequency divider to form the clock frequency of the correlators, clock divider, reference divider frequencies for forming a comparison frequency, frequency-phase detector, synthesis filter a frequency torus with phase-locked loop, a quadrature signal generator for quadrature mixers, a serial interface for controlling the operating modes of the components of a multi-system radio frequency unit, characterized in that it separates the GLONASS signal into the first intermediate frequency channel and the combined GPS / Galileo / Compass signal into the second intermediate frequency channel using built-in broadband adder phase shifters. 2. The multi-system radio frequency unit of the satellite navigation receiver according to claim 1, characterized in that when separating the GLONASS and GPS / Galileo / Compass signals, it uses a common mixer I and a common mixer Q and two broadband phase shifter-adder, connected in such a way that each of the phase shifters - adders forms together with the common mixer I and the general mixer Q two mixers, each of which is made in structure with suppression of the mirror frequency. 3. A multi-system radio frequency unit of a satellite navigation receiver according to claims 1 and 2, characterized in that it uses a conversion frequency for common quadrature mixers, with respect to which the combined signal spectrum of all navigation systems is located symmetrically. 4. A multi-system radio-frequency unit of a satellite navigation receiver according to claims 1 and 2, characterized in that the amplification of the intermediate-frequency amplifier is set from the built-in digital-to-analog converter controlled via a serial interface, or by using the built-in automatic gain control system operating from output analog or digital signals with setting the control threshold from the built-in digital-to-analog converter, so that the integral percentage of excess over horns of two-bit analog-to-digital converters is equal to the direct or additional code of the built-in digital-to-analog converter.