CN105699989B - Method and terminal for compensating Doppler frequency of Beidou RDSS terminal - Google Patents
Method and terminal for compensating Doppler frequency of Beidou RDSS terminal Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
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Abstract
A method for compensating Doppler frequency of a Beidou RDSS terminal comprises the steps of calculating the frequency offset of a local crystal oscillator of the terminal when the terminal is in a static state; and when the terminal moves at a high speed, calculating an emission code NCO frequency control word and an emission PLL parameter by using the frequency offset of the local crystal oscillator and the carrier frequency control word output by the digital receiving circuit (4), controlling the emission code NCO output by using the emission code NCO frequency control word, and controlling BPSK modulation by using the emission PLL parameter. After the technical scheme is adopted, the radio frequency circuit of the user terminal is the same as that of a common user terminal, a market mainstream RDSS radio frequency chip can be used, and the user terminal can stably and reliably realize the RDSS service request under the high dynamic condition only by modifying software. Compared with the prior art, the technical scheme has the advantages of simple circuit structure, strong universality, small size and low power consumption.
Description
Technical Field
The invention relates to a method and a terminal for compensating the Doppler frequency of a Beidou RDSS terminal, in particular to a method and a corresponding terminal for compensating the Doppler frequency of a signal transmitted by the Beidou RDSS high-dynamic terminal.
Background
In 1994, the beidou Satellite navigation test system begins to be built up to the present, and the application of the beidou Satellite navigation system RDSS (radio determination Satellite Service) subsystem in various industries is becoming mature day by day, so that wide social and economic benefits are generated. The special functions of quick positioning, position reporting and short message communication enable the application of the terminal to the aviation and aerospace fields to be increased day by day, however, due to the high-speed motion of carriers such as airplanes and the like, huge Doppler frequency is introduced when signals transmitted by Beidou RDSS high-dynamic user terminals are received by an RDSS subsystem, so that service requests of the user terminals cannot be normally received by the RDSS subsystem, and the user terminals cannot be normally positioned and bidirectionally communicated. Therefore, the Beidou RDSS high dynamic user terminal must compensate the Doppler frequency in the transmitted signal.
The technical scheme proposed by chinese patent application publication No. 102223164a, "implementation method for frequency offset correction system for high dynamic process" uses 3 crystal oscillators, measures the doppler frequency in the received signal by counting method, adjusts the DDS frequency control word of the transmission code clock and the frequency of the local crystal oscillator of the transmission BPSK modulation circuit, and implements the doppler frequency compensation of the transmitted signal. However, the counting method has large delay, and the problem of untimely compensation exists in the ultrahigh dynamic state; meanwhile, the 3 crystal oscillators are adopted, so that the complexity of the circuit is increased. In addition, the scheme utilizes a 10M crystal oscillator as a frequency reference, and does not consider that the 10M crystal oscillator also has frequency deviation; the compensation of the Doppler frequency of the transmitting carrier is realized by adjusting the frequency of the transmitting crystal oscillator.
The technical scheme proposed by chinese patent "a fast doppler compensation circuit and method based on DDS" with application publication number CN104252000A is to use 1 high stability crystal oscillator, calculate the doppler frequency in the received signal according to the output of carrier tracking loop, adjust the frequency control word of transmitting PN code clock DDS and transmitting intermediate frequency carrier DDS, form digital intermediate frequency BPSK modulated signal, and send it to the transmitting antenna after digital-to-analog conversion, filtering, amplification, up-conversion and power amplification. The technology has the advantage of real-time compensation, but the frequency offset of the crystal oscillator is not considered in the scheme, and when the frequency offset of the crystal oscillator is large, extra Doppler frequency offset can be introduced; meanwhile, the BPSK transmitting modulation circuit is complex, a common RDSS radio frequency chip in the market cannot be used, and the purposes of miniaturization and low power consumption cannot be achieved; the compensation of the Doppler frequency of the transmitting carrier is realized by adjusting a DDS input frequency control word of a digital waveform former.
Disclosure of Invention
The technical scheme can use a market mainstream RDSS radio frequency chip, has the advantages of simple circuit structure, small volume and low power consumption, and can solve the practical application defects of complex transmitting circuit, delayed Doppler frequency compensation, no consideration of frequency offset of a crystal oscillator and the like in the prior art.
The invention provides a method for compensating the Doppler frequency of a Beidou RDSS terminal, which comprises the steps of calculating the frequency offset of a local crystal oscillator of the terminal when the terminal is in a static state; when the terminal moves at a high speed, the frequency deviation of the local crystal oscillator and the carrier frequency control word output by the digital receiving circuit are utilized to calculate the frequency control word of the transmitting code NCO and the transmitting PLL parameter, the frequency control word of the transmitting code NCO is utilized to control the output of the transmitting code NCO, and the transmitting PLL parameter is utilized to control BPSK modulation.
The invention also provides a Beidou RDSS terminal which comprises a receiving antenna, a down converter, an ADC, a digital receiving circuit, a local crystal oscillator frequency deviation calculating unit, a transmitting compensation parameter calculating unit, a transmitting code NCO, a spread spectrum, a BPSK modulation, a PA and a transmitting antenna, wherein the digital receiving circuit outputs a carrier frequency control word and a code frequency control word to the local crystal oscillator frequency deviation calculating unit and the transmitting compensation parameter calculating unit, the local crystal oscillator frequency deviation calculating unit outputs a local crystal oscillator frequency deviation to the transmitting compensation parameter calculating unit, the transmitting compensation parameter calculating unit outputs a transmitting code NCO frequency control word and a transmitting PLL parameter to the transmitting code NCO and the BPSK modulation respectively, the transmitting code NCO outputs a signal to the spread spectrum, and the spread spectrum outputs a spread spectrum code to the BPSK modulation.
Furthermore, when the terminal is in a static state, the local crystal oscillator frequency offset calculation unit calculates the local crystal oscillator frequency offset of the terminal; and when the terminal moves at a high speed, the transmitting compensation parameter calculating unit calculates the NCO frequency control word of the transmitting code and the transmitting PLL parameter by using the frequency offset of the local crystal oscillator and the carrier frequency control word output by the digital receiving circuit.
Further, the local crystal oscillator frequency offset calculation unit calculates the local crystal oscillator frequency offset of the terminal using the time stamp signal output from the GNSS receiver.
After the technical scheme is adopted, the radio frequency circuit of the user terminal is the same as that of a common user terminal, a market mainstream RDSS radio frequency chip can be used, and the user terminal can stably and reliably realize the RDSS service request under the high dynamic condition only by modifying software. Compared with the prior art, the technical scheme has the advantages of simple circuit structure, strong universality, small size and low power consumption.
Drawings
FIG. 1 is a frame structure diagram of a Beidou RDSS terminal of the invention;
fig. 2 is a basic principle flow chart of the method for compensating the doppler frequency of the beidou RDSS terminal of the present invention.
Detailed Description
The invention will now be described in detail with reference to the preferred embodiments thereof.
Fig. 1 is a structural diagram of a Beidou RDSS terminal framework of the invention. The basic components included in the present solution include a receiving antenna 1, a down-conversion 2, an ADC (Analog Digital Converter) 3, a Digital receiving circuit 4, a local crystal oscillator frequency offset calculating unit 5, a transmission compensation parameter calculating unit 6, a transmission code NCO (Numerically controlled oscillator) 7, a spreading code 8, a BPSK (Binary Phase Shift Key) modulation 9, a PA (Power Amplifier) 10, and a transmitting antenna 11, and the specific implementation is shown in fig. 1. The output of the receiving antenna 1 is connected with the input end of the down-conversion 2, the output of the down-conversion 2 is connected with the input end of the ADC3, the output of the ADC3 is connected with the input end of the digital receiving circuit 4, the carrier frequency control word and the code frequency control word output by the digital receiving circuit 4 are both connected with the input ends of the local crystal oscillator frequency deviation calculating unit 5 and the emission compensation parameter calculating unit 6, meanwhile, the time scale signal output by the GNSS (Global navigation satellite System) receiver is connected with the input end of the local crystal oscillator frequency deviation calculating unit 5, the frequency deviation of the local crystal oscillator output by the local crystal oscillator frequency deviation calculating unit 5 is connected with the input end of the emission compensation parameter calculating unit 6, the emission code NCO frequency control word and the emission PLL parameter output by the emission compensation parameter calculating unit 6 are respectively connected with the input ends of the emission code NCO7 and the BPSK modulation 9, the output of the emission code NCO7 is connected with the, the spread code output by the spread spectrum 8 is connected with the input end of BPSK modulation 9, the output of BPSK modulation 9 is connected with the input end of PA10, and the output of PA10 is connected with the input end of a transmitting antenna 11.
Fig. 2 is a basic principle flow chart of the method for compensating the doppler frequency of the beidou RDSS terminal of the present invention. The method is carried out in 3 steps, as shown in FIG. 2.
In step 21, when the user terminal is powered on and is in a static state, the frequency offset of the local crystal oscillator of the user terminal is calculated by using a carrier frequency control word or a code frequency control word output by the digital receiving circuit 4 or by using a time scale signal output by a GNSS (Global Navigation Satellite System) receiver;
in step 22, the frequency offset of the local crystal oscillator obtained by calculation in step 21 and a carrier frequency control word or code frequency control word output by the digital receiving circuit 4 are used for calculating an NCO frequency control word of the emission code;
in step 23, the transmission PLL parameters are calculated using the frequency offset of the local crystal oscillator calculated in step 21 and the carrier frequency control word or code frequency control word output by the digital receiving circuit 4.
The first implementation mode comprises the following steps:
1) RDSS navigation signals broadcast by 5 geostationary orbit (GEO) satellites of a Beidou satellite navigation system (BDS for short) space constellation are received, filtered and amplified through a user terminal receiving antenna 1, then are subjected to down-conversion, amplification and filtering processing through a down-conversion circuit 2, and then are subjected to analog-to-digital conversion through an ADC3, and enter a digital receiving circuit 4 for processing such as capturing and tracking of the navigation signals.
2) The down-conversion 2, the ADC3, the digital receiving circuit 4, the transmitting code NCO7, the spread spectrum 8 and the BPSK modulation 9 all use the same frequency source, and the frequency source selects a low-acceleration sensitivity crystal oscillator.
3) If the user terminal is in a static state when being powered on, the local crystal oscillator frequency offset calculation unit 5 may calculate the frequency offset of the local crystal oscillator of the user terminal at this time by using the code frequency control word output by the digital receiving circuit 4:
(formula 1)
If a time scale signal output by a GNSS (Global Navigation Satellite System) receiver can be obtained, the local crystal oscillator frequency offset calculation unit 5 calculates the frequency offset of the local crystal oscillator of the user terminal when the carrier moves at a high speed in real time by using a counting method or other frequency measurement methods; otherwise, the frequency offset of the crystal oscillator calculated during starting can be approximately used by utilizing the characteristic that the crystal oscillator with low acceleration sensitivity is insensitive to acceleration stress.
The counting method is to calculate the frequency deviation of the local crystal oscillator by counting in the time interval of two continuous time scale signals output by the receiver by using a measured frequency source, and the frequency deviation is shown in a formula 2:
Where T is the time interval of two consecutive time scale signals, K is the count value, fosc_REFIs the nominal frequency of the measured frequency source.
4) When the carrier moves at a high speed, the transmission compensation parameter calculation unit 6 calculates the frequency control word of the transmission code NCO and the transmission PLL parameter by using the local crystal oscillator frequency offset calculated by the local crystal oscillator frequency offset calculation unit 5 and the code frequency control word output by the digital receiving circuit 4, so as to compensate the transmission code doppler frequency and the transmission carrier doppler frequency.
The calculation method of the frequency control word input by the transmitting code NCO7 is shown in formula 3:
FCWcode_txIs a frequency control word, f, input by the transmit code NCO7PNIs the spreading code rate, fs_REFIs the nominal frequency of operation of the digital receiving circuit 4 and the transmit code NCO7, N is the transmit code NCO7 and the digital receiving circuit 4 code NCO phase width, FCWcode_rxIs digital receptionThe code frequency control word output by the circuit 4,
is the local crystal oscillator frequency offset.
The method for calculating the parameters of the transmitting PLL is shown in formula 4:
M is to satisfy the transmission PLL I/O clock frequency
(wherein fPLL_inFor transmitting PLL input clock frequency, fPLL_outFor transmit PLL output clock frequency, M and R are integers), f) transmit PLL divide ratio parameterPNIs the spreading code rate, fs_REFIs the nominal frequency of operation of the digital receiving circuit 4 and the transmit code NCO7, N is the transmit code NCO7 and the digital receiving circuit 4 code NCO phase width, FCWcode_rxIs a code frequency control word output by the digital receiving circuit 4,
is a local crystal oscillator frequency offset, M0Is the transmit PLL nominal parameter, operator
Indicating a rounding down.
5) The spread spectrum 8 performs spread spectrum operation on the transmission information and the spread spectrum code at the clock beat of the code output by the transmission code NCO 7.
6) The BPSK modulation 9 receives the transmission PLL parameter output by the transmission compensation parameter calculation unit 6, adjusts the frequency division ratio of the transmission PLL, realizes BPSK modulation of the transmission signal, amplifies the power of the transmission signal by the PA10, and transmits the transmission signal through the transmission antenna 11.
The second embodiment:
1) RDSS navigation signals broadcast by 5 geostationary orbit (GEO) satellites of a Beidou satellite navigation system (BDS for short) space constellation are received, filtered and amplified through a user terminal receiving antenna 1, then are subjected to down-conversion, amplification and filtering processing through a down-conversion circuit 2, and then are subjected to analog-to-digital conversion through an ADC3, and enter a digital receiving circuit 4 for processing such as capturing and tracking of the navigation signals.
2) The down-conversion 2, the ADC3, the digital receiving circuit 4, the transmitting code NCO7, the spread spectrum 8 and the BPSK modulation 9 all use the same frequency source, and the frequency source selects a low-acceleration sensitivity crystal oscillator.
3) If the user terminal is in a static state when being powered on, the local crystal oscillator frequency offset calculation unit 5 may calculate the frequency offset of the local crystal oscillator of the user terminal at this time by using the carrier frequency control word output by the digital receiving circuit 4:
This formula applies to radio frequency receive channels that employ a low local oscillator down-mixing scheme,
is a local crystal oscillator frequency offset, fs_REFIs the nominal frequency of operation of the digital receiving circuit 4, N is the NCO phase width of the carrier of the digital receiving circuit 4, fIF_REFIs the nominal carrier frequency, f, of the digital intermediate frequency signaldown_outIs the outbound downlink nominal carrier frequency, FCWcarrier_rxIs a carrier frequency control word output by the carrier tracking loop of the digital receiving circuit 4.
If a time scale signal output by a GNSS (Global Navigation Satellite System) receiver can be obtained, the local crystal oscillator frequency offset calculation unit 5 calculates the frequency offset of the local crystal oscillator of the user terminal when the carrier moves at a high speed in real time by using a counting method (see formula 2) or other frequency measurement methods; otherwise, the frequency offset of the crystal oscillator calculated during starting can be approximately used by utilizing the characteristic that the crystal oscillator with low acceleration sensitivity is insensitive to acceleration stress.
4) When the carrier moves at a high speed, the transmission compensation parameter calculation unit 6 calculates the frequency control word of the transmit code NCO and the transmission PLL parameter by using the local crystal oscillator frequency offset calculated by the local crystal oscillator frequency offset calculation unit 5 and the carrier frequency control word output by the digital receiving circuit 4, so as to compensate the transmit code doppler frequency and the transmit carrier doppler frequency.
The calculation method of the frequency control word input by the transmitting code NCO7 is shown in formula 6:
This formula is applicable to a radio frequency receive channel, FCW, that employs a low local oscillator down-mixing schemecode_txIs a frequency control word, f, input by the transmit code NCO7PNIs the spreading code rate, fs_REFIs the nominal frequency of operation of the digital receiving circuit 4 and the transmit code NCO7, N is the transmit code NCO7 and the digital receiving circuit 4 carrier NCO phase width,
is a local crystal oscillator frequency offset, fIF_REFIs the nominal carrier frequency, f, of the digital intermediate frequency signaldown_outIs the outbound downlink nominal carrier frequency, FCWcarrier_rxIs a carrier frequency control word output from the digital receiving circuit 4.
The transmit PLL parameter calculation method is shown in equation 7:
The formula is suitable for radio frequency receiving channel adopting low local oscillator down-mixing scheme, and M is to make the frequency of the input and output clock of transmitting PLL meet
(wherein fPLL_inFor transmitting PLL input clock frequency, fPLL_outFor transmit PLL output clock frequency, M and R are integers), f) transmit PLL divide ratio parameterPNIs the spreading code rate, fs_REFIs the nominal frequency of operation of the digital receiving circuit 4 and the transmit code NCO7, N is the transmit code NCO7 and the digital receiving circuit 4 carrier NCO phase width,
is a local crystal oscillator frequency offset, fIF_REFIs the nominal carrier frequency, f, of the digital intermediate frequency signaldown_outIs the outbound downlink nominal carrier frequency, FCWcarrier_rxIs a carrier frequency control word, M, output by the digital receiving circuit 40Is the transmit PLL nominal parameter, operator
Indicating a rounding down.
5) The spread spectrum 8 performs spread spectrum operation on the transmission information and the spread spectrum code at the clock beat of the code output by the transmission code NCO 7.
6) The BPSK modulation 9 receives the transmission PLL parameter output by the transmission compensation parameter calculation unit 6, adjusts the frequency division ratio of the transmission PLL, realizes BPSK modulation of the transmission signal, amplifies the power of the transmission signal by the PA10, and transmits the transmission signal through the transmission antenna 11.
The above examples are merely illustrative of embodiments of the present invention, which are described in more detail and detailed, but are not to be construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (7)
1. A method for compensating Doppler frequency of a Beidou RDSS terminal comprises the steps of calculating the frequency offset of a local crystal oscillator of the terminal when the terminal is in a static state; when the terminal moves at a high speed, calculating a transmission code NCO frequency control word and a transmission PLL parameter by using the frequency offset of the local crystal oscillator and a carrier frequency control word output by the digital receiving circuit (4), controlling the transmission code NCO output by using the transmission code NCO frequency control word, and controlling BPSK modulation by using the transmission PLL parameter;
the method further comprises the following step that the frequency deviation calculation formula of the local crystal oscillator of the terminal is as follows:
wherein the content of the first and second substances,
is the local crystal oscillator frequency offset, FCW, of the terminalcode_rxIs a code frequency control word, f, output by the digital receiving circuit (4)PNIs the spreading code rate, fs_REFIs the nominal frequency of operation of the digital receiving circuit (4) and the transmission code NCO, N is the phase width of the transmission code NCO and the digital receiving circuit (4) code NCO.
2. The method of claim 1, further comprising the frequency control word input by said transmit code NCO being calculated by the formula:
wherein, FCWcode_txIs a frequency control word, f, of the transmit code NCO inputPNIs the spreading code rate, fs_REFIs the nominal frequency of operation of said digital receiving circuit (4) and said transmission code NCO, N is the phase width of said transmission code NCO and said digital receiving circuit (4) code NCO, FCWcode_rxIs a code frequency control word output by the digital receiving circuit (4),
is the local crystal oscillator frequency offset of the terminal;
the calculation formula of the transmission PLL parameters is as follows:
wherein M is such that said transmittingPLL input-output clock frequency satisfaction
Is transmitted, wherein fPLL_inFor the transmission PLL input clock frequency, fPLL_outOutputting a clock frequency for said transmit PLL, M and R being integers, fPNIs the spreading code rate, fs_REFIs the nominal frequency of operation of the digital receiving circuit (4) and the transmission code NCO, N is the phase width of the transmission code NCO and the code NCO of the digital receiving circuit (4), FCWcode_rxIs a code frequency control word output by the digital receiving circuit (4),
is the local crystal oscillator frequency offset, M, of the terminal0Is the transmit PLL nominal parameter, operator
Indicating a rounding down.
3. A method for compensating Doppler frequency of a Beidou RDSS terminal comprises the steps of calculating the frequency offset of a local crystal oscillator of the terminal when the terminal is in a static state; when the terminal moves at a high speed, calculating a transmission code NCO frequency control word and a transmission PLL parameter by using the frequency offset of the local crystal oscillator and a carrier frequency control word output by the digital receiving circuit (4), controlling the transmission code NCO output by using the transmission code NCO frequency control word, and controlling BPSK modulation by using the transmission PLL parameter;
the method further comprises that for the radio frequency receiving channel adopting the low local oscillator down-mixing scheme, the frequency offset calculation formula of the local crystal oscillator of the terminal is as follows:
wherein the content of the first and second substances,
is the local crystal oscillator frequency offset, f, of the terminals_REFIs the nominal frequency of operation of the digital receiving circuit (4) and the transmit code NCO, N is the phase width of the transmit code NCO and the carrier NCO of the digital receiving circuit (4), fIF_REFIs the nominal carrier frequency, f, of the digital intermediate frequency signaldown_outIs the outbound downlink nominal carrier frequency, FCWcarrier_rxIs a carrier frequency control word output by the carrier tracking loop of the digital receiving circuit (4).
4. The method of claim 3, further comprising, for a radio frequency receive channel employing a low local oscillator down-mixing scheme, calculating the frequency control word input by the transmit code NCO by the formula:
wherein, FCWcode_txIs a frequency control word, f, of the transmit code NCO inputPNIs the spreading code rate, fs_REFIs the nominal frequency of operation of the digital receiving circuit (4) and the transmission code NCO, N is the phase width of the transmission code NCO and the carrier NCO of the digital receiving circuit (4),
is the local crystal oscillator frequency offset, f, of the terminalIF_REFIs the nominal carrier frequency, f, of the digital intermediate frequency signaldown_outIs the outbound downlink nominal carrier frequency, FCWcarrier_rxIs a carrier frequency control word output by the carrier tracking loop of the digital receiving circuit (4);
the calculation formula of the transmission PLL parameters is as follows:
wherein M is such that the transmit PLL input-output clock frequency is satisfied
Is transmitted, wherein fPLL_inFor the transmission PLL input clock frequency, fPLL_outOutputting a clock frequency for said transmit PLL, M and R being integers, fPNIs the spreading code rate, fs_REFIs the nominal frequency of operation of the digital receiving circuit (4) and of the transmission code NCO, N is the phase width of the transmission code NCO and of the carrier NCO of the digital receiving circuit (4),
is the local crystal oscillator frequency offset, f, of the terminalIF_REFIs the nominal carrier frequency, f, of the digital intermediate frequency signaldown_outIs the outbound downlink nominal carrier frequency, FCWcarrier_rxIs a carrier frequency control word, M, output by the carrier tracking loop of the digital receiving circuit (4)0Is the transmit PLL nominal parameter, operator
Indicating a rounding down.
5. A Beidou RDSS terminal comprises a receiving antenna (1), a down-conversion (2), an ADC (3), a digital receiving circuit (4), a local crystal oscillator frequency deviation calculating unit (5), an emission compensation parameter calculating unit (6), an emission code NCO (7), a spread spectrum (8), a BPSK modulation (9), a PA (10) and an emission antenna (11), and is characterized in that the digital receiving circuit (4) outputs carrier frequency control words and code frequency control words to the local crystal oscillator frequency deviation calculating unit (5) and the emission compensation parameter calculating unit (6), the local crystal oscillator frequency deviation calculating unit (5) outputs local crystal oscillator frequency deviation to the emission compensation parameter calculating unit (6), the emission compensation parameter calculating unit (6) outputs emission NCO frequency control words and emission PLL parameters to the emission code BPSK (7) and the emission PLL modulation (9) respectively, the transmitting code NCO (7) outputs a signal to the spread spectrum (8), the spread spectrum (8) outputs a spread spectrum code to the input connecting end of the BPSK modulation (9), the output of the BPSK modulation (9) is connected with the input top end of the PA (10), and the output of the PA (10) is connected with the input end of a transmitting antenna (11);
wherein the Beidou RDSS terminal is configured to perform the method of any one of claims 1-2, or to perform the method of any one of claims 3-4.
6. The terminal of claim 5, wherein the local crystal oscillator frequency offset calculation unit (5) calculates the local crystal oscillator frequency offset of the terminal when the terminal is in a stationary state; and when the terminal moves at a high speed, the transmission compensation parameter calculation unit (6) calculates the NCO frequency control word of the transmission code and the transmission PLL parameter by using the frequency offset of the local crystal oscillator and the carrier frequency control word output by the digital receiving circuit (4).
7. The terminal according to claim 6, wherein the local crystal oscillator frequency offset calculation unit (5) calculates the local crystal oscillator frequency offset of the terminal using the time stamp signal output from the GNSS receiver.
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