Time-division duplex frequency-modulated continuous wave radar system and method for time-division duplex frequency-modulated continuous wave radar system

Abstract

A time division duplex frequency modulation continuous wave (FMCW) radar system includes P transmitting circuits and M receiving circuits. The P transmitting circuits are used for transmitting a plurality of FMCW signals, the pth transmitting circuit is coupled to a single-pole Qp throw (SPQpT) radio frequency switch, the SPQpT radio frequency switch is coupled to a Qp antenna, Qp and P are positive integers, and p is a positive integer not greater than P. The M receiving circuits are used for receiving a plurality of reflected FMCW signals, the mth receiving circuit is coupled to a single-pole Nm-throw (SPNmT) radio frequency switch, the SPNmT radio frequency switch is coupled to the Nm antennas, Nm and M are positive integers, and m is a positive integer not greater than M.

Description

Technical Field

[0001] The present invention relates to a frequency modulation continuous wave (FMCW) radar system, and in particular to a time division duplexed (TDD) FMCW radar system. Background Art

[0002] Frequency Modulation Continuous Wave (FMCW) radar system is a special type of radar system that can measure the distance and speed of moving objects. This measurement is achieved by continuously changing the frequency of the transmitted signal with a known slope over a fixed period of time by modulating the signal. FMCW radar systems can use a variety of frequency modulation techniques such as sawtooth modulation, triangle modulation, sine wave modulation, square wave modulation, and step modulation. Among them, sawtooth and triangle wave modulation are most widely used to change the frequency of FMCW radar systems.

[0003] FMCW radar systems measure the frequency difference (Δf, caused by the flight time of the electromagnetic waves) between the transmitted and received echo signals to calculate the distance, and also measure the phase difference of the object's motion to calculate the object's speed.

[0004] In a 1T1R (one transmitting antenna and one receiving antenna) FMCW radar system, the transmitting antenna transmits an FMCW signal, and the FMCW signal reflected by the target is received by the receiving antenna. The output of the receiving antenna is provided to the mixer of the receiving circuit through a low noise amplifier. In the mixer, a part of the transmitted FMCW signal is mixed with the reflected FMCW signal to generate an intermediate frequency (IF) signal, which can be used to determine the distance and / or speed of the object based on the frequency difference and / or phase difference. The frequency of the IF signal is the frequency difference between the transmitted FMCW signal and the reflected FMCW signal.

[0005] However, the 1T1R FMCW radar system is not enough to analyze the angle of an object. Multiple transmit antennas and multiple receive antennas provide better angle information for analyzing the direction of an object. Traditional multi-transmit and multi-receive antennas use multiple transmit circuits and multiple receive circuits. Each transmit path has a dedicated transmit circuit, and each receive path has a dedicated receive circuit. Therefore, the circuit of the FMCW radar system consumes a lot of power and occupies a large area. Summary of the invention

[0006] A time division duplexed (TDD) frequency modulation continuous wave (FMCW) radar system includes P transmitting circuits and M receiving circuits. The P transmitting circuits are used to transmit multiple FMCW signals, the p-th transmitting circuit is coupled to a single pole Qp throw (SPQpT) radio frequency (RF) switch, the SPQpT RF switch is coupled to a Qp antenna, Qp and P are positive integers, and p is a positive integer not greater than P. The M receiving circuits are used to receive multiple reflected FMCW signals, the m-th receiving circuit is coupled to a single pole Nm throw (SPNmT) RF switch, the SPNmT RF switch is coupled to Nm antennas, Nm and M are positive integers, and m is a positive integer not greater than M.

[0007] An embodiment of the present invention provides a method for a time division duplexed (TDD) frequency modulation continuous wave (FMCW) radar system. The method includes transmitting multiple FMCW signals through P transmitting circuits and receiving multiple reflected FMCW signals through M receiving circuits. The p-th transmitting circuit is coupled to a single pole Qp throw (SPQpT) radio frequency (RF) switch, the SPQpT RF switch is coupled to Qp antennas, Qp and P are positive integers, p is a positive integer not greater than P, and the m-th receiving circuit is coupled to a single pole Nm throw (SPNmT) RF switch, the SPNmT RF switch is coupled to Nm antennas, Nm and M are positive integers, and m is a positive integer not greater than M. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a block diagram of a 1T1R frequency modulation continuous wave (FMCW) radar system according to an embodiment of the present invention.

[0009] Figure 2 is a schematic diagram of a ranging method of a 1T1R frequency modulated continuous wave (FMCW) radar system according to an embodiment of the present invention.

[0010] Figure 3 is a schematic diagram of a speed measurement method of a 1T1R frequency modulated continuous wave (FMCW) radar system according to an embodiment of the present invention.

[0011] Figure 4 is a schematic diagram of an angle measurement method of a 1T2R frequency modulated continuous wave (FMCW) radar system according to an embodiment of the present invention.

[0012] Figure 5 4T4R time-division duplex FMCW radar system according to an embodiment of the present invention.

[0013] Figure 6 4T4R time-division duplex FMCW radar system according to an embodiment of the present invention.

[0014] The reference numerals are described as follows:

[0015] 100: Radar system

[0016] 102: Oscillator

[0017] 104: Power Amplifier

[0018] 106: Transmitting antenna

[0019] 108: Object

[0020] 110: Receiving antenna

[0021] 112: Low Noise Amplifier

[0022] 114: Mixer

[0023] 116: Analog-to-digital converter

[0024] 118: Digital Signal Processor

[0025] 120: Machine Learning Processor

[0026] 200: Ranging Method

[0027] 202: Transmit signal

[0028] 204: Reflected signal

[0029] 206: Beat frequency signal

[0030] 300: Speed ​​measurement method

[0031] 302: IF sampling data

[0032] 304: Spectrum

[0033] 306: Analysis chart

[0034] 400: Angle measurement method

[0035] 402, 404: Receiving antenna

[0036] 500: RF front-end circuit

[0037] 502, 504: Power amplifier

[0038] 506, 508: Low noise amplifier

[0039] 510, 512, 514, 516: SPDT RF switches

[0040] Tx1, Tx2, Tx3, Tx4: Transmitting antennas

[0041] Rx1, Rx2, Rx3, Rx4: receiving antennas

[0042] 600: Timing diagram DETAILED DESCRIPTION

[0043] Figure 11 is a block diagram of a 1T1R (one transmitting antenna and one receiving antenna) frequency modulation continuous wave (FMCW) radar system 100 according to an embodiment of the present invention. The 1T1R FMCW radar system 100 includes an oscillator 102, a power amplifier 104, a transmitting antenna 106, a receiving antenna 110, a low noise amplifier 112, a mixer 114, an analog to digital converter (ADC) 116, a digital signal processing (DSP) processor 118, and a machine learning (ML) processor 120. The oscillator 102 generates an FMCW signal having sawtooth modulation, triangle modulation, sine wave modulation, square wave modulation, or step modulation for the mixer 114 and the power amplifier 104. The power amplifier 104 amplifies the FMCW signal to generate an amplified FMCW signal and transmits it to the transmitting antenna 106. The transmitting antenna 106 uses the amplified FMCW signal to transmit a transmission signal to detect an object 108. The object 108 reflects the transmit signal to generate a reflected signal to the receive antenna 110. The receive antenna 110 receives the reflected signal to generate a received signal and transmits it to the low noise amplifier 112. The low noise amplifier 112 amplifies the received signal to generate an amplified received signal for use by the mixer 114. The mixer 114 mixes the FMCW signal with the amplified received signal to generate an intermediate frequency (IF) signal for the ADC 116. The ADC 116 receives the IF signal and converts it into digital raw data for use by the DSP processor 118. The DSP processor 118 performs DSP on the digital raw data to generate a feature map for the ML processor 120. The ML processor 120 analyzes the feature map through the ML model to generate an analysis result.

[0044] Figure 2 2 is a schematic diagram of a distance measurement method 200 of a 1T1R frequency modulated continuous wave (FMCW) radar system 100 according to an embodiment of the present invention. In this embodiment, the FMCW signal is a linear frequency modulation signal, whose bandwidth is B and the linear frequency modulation period is T. Figure 2 In the example, since the distance between the 1T1R FMCW radar system 100 and the object 108 is R, there is a delay time t between the transmitted signal 202 and the reflected signal 204. d Therefore, the delay time t d can be defined as follows:

[0045]

[0046] where c is the speed of light.

[0047] In the 1T1R FMCW radar system 100, the delay time t is calculated by the following method: d Since the signal is modulated as linear frequency modulation, the delay time t d The frequency offset f between the transmitted signal 202 and the reflected signal 204 is caused b Therefore, the transmission signal 202 is mixed with the reflection signal 204 by the mixer 114 to generate an intermediate frequency (IF) signal 206, and the beat frequency f is obtained by performing a fast Fourier transform (FFT) on the IF signal 206 by the DSP processor 118. b The slope of the linear FM wave is a constant, so the delay time t d It can also be calculated as follows:

[0048]

[0049] Therefore, the distance R can be calculated as follows:

[0050]

[0051] Where c is the speed of light, f b is the beat frequency measured from the IF signal 206, T is the period of the chirp, and B is the bandwidth of the chirp.

[0052] By using this formula, the distance of the object from the radar can be determined. If the FMCW radar system detects multiple objects at different distances, multiple peaks will appear in the FFT spectrum of the IF signal. Each peak can generate a distance, so that the DSP processor 118 will generate the corresponding distances of all objects.

[0053] Additionally, the range resolution and maximum range of the FMCW radar system 100 may be estimated by the DSP processor 118 as follows:

[0054]

[0055] Where c is the speed of light, B is the bandwidth of the linear frequency modulation, T is the period of the linear frequency modulation, and F s is the sampling frequency of the analog-to-digital converter (ADC). Therefore, the distance resolution can be designed based on the bandwidth B, and can be determined by the ADC sampling frequency F. s To define the maximum detection distance.

[0056] Figure 31 is a schematic diagram of a velocity measurement method 300 of a 1T1R frequency modulated continuous wave (FMCW) radar system 100 according to an embodiment of the present invention. The transmitter transmits N linear frequency modulation signals in the transmission signal 202, and the receiver receives N linear frequency modulation signals in the reflection signal 204. When the object moves, the phase difference (phase difference) between the N linear frequency modulations of the IF signal 206 can be calculated by the DSP processor 118 as:

[0057]

[0058] Where ω is the phase difference, T is the period of the linear frequency modulation, v is the velocity of the object (in the direction away from the radar system), and λ is the wavelength of the FMCW signal.

[0059] Therefore, calculating the phase difference ω is to calculate the velocity v of the object. Figure 3 , the IF signal 206 can be encapsulated into a data packet by the DSP processor 118 according to the linear frequency modulation shown in the IF sampled data 302. Each column contains a linear frequency modulation signal of the reflected signal 204. Then, the DSP processor 118 performs a fast Fourier transform (FFT) on the intermediate frequency sampled data 302 on the vertical axis (y-axis direction) to obtain the distance of the object in the spectrum 304. The horizontal axis (x-axis) of the spectrum 304 represents slow time, and the vertical axis (y-axis) represents distance. In the spectrum 304, two distances can be analyzed from the FFT operation, so the radar system detects at least two objects. Finally, the DSP processor 118 performs an FFT on the spectrum 304 on the horizontal axis (x-axis direction) to obtain the speed of the object in the analysis graph 306. The x-axis of the analysis graph 306 represents the speed, and the y-axis represents the distance. By analyzing the phase difference on the x-axis of the analysis graph 306, the velocity of the object can be calculated as follows:

[0060]

[0061] Among them, ω n is the phase difference of the nth object, T is the period of linear frequency modulation, v n is the speed of the nth object (direction away from the radar system), and λ is the wavelength of the FMCW signal.

[0062] In addition, the velocity resolution and maximum measurement velocity of the FMCW radar system can be estimated as follows:

[0063]

[0064] Where λ is the wavelength of the FMCW signal, T is the period of the linear frequency modulation, and T f is the total measurement time of multiple linear frequency modulations. Therefore, the velocity resolution can be calculated based on the total measurement time T fThe maximum measurement speed can be designed according to the period T of the linear frequency modulation.

[0065] In order to measure the angle θ of an object, the number of receiving antennas should be greater than 1. Figure 4 4 is a schematic diagram of an angle measurement method 400 of a 1T2R frequency modulated continuous wave (FMCW) radar system according to an embodiment of the present invention. In this embodiment, there is one transmitting antenna and two receiving antennas. Due to the angle of arrival (angle of arrival; AoA) θ and the distance d between the two receiving antennas, the electromagnetic wave path difference is dsinθ, resulting in a phase difference between the receiving antenna Rx1 402 and the receiving antenna Rx2 404. The phase difference Δφ can be expressed as:

[0066]

[0067] Where λ is the wavelength of the FMCW signal, d is the distance between the two receiving antennas, and θ is the angle of arrival (AoA) from the object to the FMCW radar system. Therefore, when the distance and speed of the object are obtained in the analysis diagram 306, the phase difference of the signal in the receiving antenna Rx1 402 and the receiving antenna Rx2 404 can be calculated. Then, the angle of arrival (AoA) can be calculated by the following formula:

[0068]

[0069] For an FMCW radar system with multiple receiving antennas (greater than or equal to 2), the phase difference of the signal in the analysis graph 306 can be analyzed by the DSP processor 118 using an FFT operation to obtain the angle of arrival θ. The peaks in the analysis graph 306 represent objects with different speeds and distances. The result of applying the FFT operation to the signals in the multiple receiving antennas of the same peak in the analysis graph 306 represents the phase difference between the multiple receiving antennas. Therefore, the angle of arrival (AoA) can be estimated using the following formula:

[0070]

[0071] Where λ is the wavelength of the FMCW signal, d is the distance between the two receiving antennas, and θ n is the angle of arrival (AoA) of the nth object to the FMCW radar system, Δφ n is the phase difference between the two receiving antennas in the nth object.

[0072] In addition, the angular resolution and maximum measurement angle of the multi-antenna FMCW radar system can be estimated as follows:

[0073]

[0074] Where λ is the wavelength of the FMCW signal, n is the number of receiving antennas, d is the distance between the two receiving antennas, and θ is the angle of arrival. Therefore, the distance between the antennas is usually set to λ / 2 to obtain a maximum measurement angle of 90 degrees. The resolution of the angle of arrival θ res It mainly depends on the number of receiving antennas and the arrival angle θ.

[0075] Figure 5 Schematic diagram of a RF front-end circuit 500 of a 4T4R (four transmitting antennas and four receiving antennas) time-division duplex FMCW radar system according to an embodiment of the present invention. In this embodiment, the RF front-end circuit 500 includes two power amplifiers 502, 504, two low noise amplifiers 506, 508, four single pole double throw (SPDT) RF switches 510, 512, 514, 516, four transmitting antennas Tx1, Tx2, Tx3, Tx4 and four receiving antennas Rx1, Rx2, Rx3, Rx4. The present invention is not limited to 4T4R, and the RF switch is not limited to SPDT RF switch. The present invention includes a PTMR (P transmit M receive) time-division duplex FMCW radar system, and the RF switch can be an SPQT RF switch, where P, M, and Q are all positive integers.

[0076] Figure 6 6 is a timing diagram of a 4T4R time-division duplex FMCW radar system according to an embodiment of the present invention. First, the SPDT RF switch 510 is coupled to the transmitting antenna Tx1, the SPDT RF switch 512 is coupled to the transmitting antenna Tx3, the SPDT RF switch 514 is coupled to the receiving antenna Rx1, and the SPDT RF switch 516 is coupled to the transmitting antenna Rx3. The FMCW signals transmitted by the two transmitting antennas Tx1 and Tx3 are transmitted through Figure 6 The reflected signals Sa and Sb are composed of the reflected signals S1 and S3 of the transmitted signals transmitted by the transmitting antennas Tx1 and Tx3, and the reflected signals Sa' and Sb' are composed of the reflected signals S1' and S3' of the transmitted signals transmitted by the transmitting antennas Tx1 and Tx3. The relationship between these signals can be written as follows:

[0077] Sa=S1+S3,Sb=S1-S3,Sa ′ =S1 ′ +S3 ′ ,Sb ′ =S1 ′ -S3′

[0078] Therefore, the received signals S1, S3, S1', S3' can be calculated as follows:

[0079]

[0080] The benefit of using BPM modulation to transmit antennas Tx1 and Tx3 to transmit signals simultaneously is that the signal-to-noise ratio (SNR) is increased by 3dB, and the benefit of receiving antennas Rx1 and Rx3 to receive reflected signals simultaneously is that the angle of arrival (AoA) of the object can be estimated by the phase difference between the two receiving antennas Rx1 and Rx3. Then, SPDT RF switch 510 is coupled to transmitting antenna Tx2, SPDT RF switch 512 is coupled to transmitting antenna Tx4, SPDT RF switch 514 is coupled to receiving antenna Rx1, and SPDT RF switch 516 is coupled to receiving antenna Rx3. The FMCW signals transmitted by the two transmitting antennas Tx2 and Tx4 are transmitted through Figure 6 The reflected signals Sc and Sd are composed of the reflected signals S2 and S4 of the transmitted signals transmitted by the transmitting antennas Tx2 and Tx4, and the reflected signals Sc' and Sd' are composed of the reflected signals S2' and S4' of the transmitted signals transmitted by the transmitting antennas Tx2 and Tx4. The relationship between them can be expressed as follows:

[0081] Sc=S2+S4,Sd=S2-S4,Sc ′ =S2 ′ +S4 ′ ,Sd ′ =S2 ′ -S4′

[0082] Therefore, the corresponding received signals S2, S4, S2', S4' can be calculated as follows:

[0083]

[0084] Then, the SPDT RF switch 510 is coupled to the transmitting antenna Tx1, the SPDT RF switch 512 is coupled to the transmitting antenna Tx3, the SPDT RF switch 514 is coupled to the receiving antenna Rx2, and the SPDT RF switch 516 is coupled to the receiving antenna Rx4. The FMCW signals transmitted by the two transmitting antennas Tx1 and Tx3 are transmitted through Figure 6 The reflected signals Sa and Sb are composed of the reflected signals S1 and S3 of the transmitted signals transmitted by the transmitter antennas Tx1 and Tx3, and the reflected signals Sa' and Sb' are composed of the reflected signals S1' and S3' of the transmitted signals transmitted by the transmitter antennas Tx1 and Tx3. The relationship between them can be written as follows:

[0085] Sa=S1+S3,Sb=S1-S3,Sa ′ =S1 ′ +S3 ′ ,Sb ′ =S1 ′ -S3′

[0086] Therefore, the corresponding received signals S1, S3, S1', S3' can be calculated as follows:

[0087]

[0088] Finally, the SPDT RF switch 510 is coupled to the transmitter antenna Tx2, the SPDT RF switch 512 is coupled to the transmitter antenna Tx4, the SPDT RF switch 514 is coupled to the receiver antenna Rx2, and the SPDT RF switch 516 is coupled to the receiver antenna Rx4. The FMCW signals transmitted by the two transmit antennas Tx2 and Tx4 are transmitted by Figure 6 The reflected signals Sc and Sd are composed of the reflected signals S2 and S4 of the transmitted signals transmitted by the transmitting antennas Tx2 and Tx4, and the reflected signals Sc' and Sd' are composed of the reflected signals S2' and S4' of the transmitted signals transmitted by the transmitting antennas Tx2 and Tx4. The relationship between them can be written as follows:

[0089] Sc=S2+S4,Sd=S2-S4,Sc ′ =S2 ′ +S4 ′ ,Sd ′ =S2 ′ -S4′

[0090] Therefore, the corresponding received signals S2, S4, S2', S4' can be calculated as follows:

[0091]

[0092] By applying BPM to two transmit signals, the SNR can be increased by 3dB, and the angle of arrival AoA can be calculated by applying the two receive signals in two receive antennas. However, the present invention is not limited to BPM, and when P transmit antennas transmit FMCW signals simultaneously, P phase modulation (PPM) can be applied to P transmit circuits.

[0093] In summary, compared with the existing technology, the 4T4R time-division duplex FMCW radar system reduces power consumption and circuit area to achieve better performance.

[0094] The above descriptions are only preferred embodiments of the present invention. All equivalent changes and modifications made according to the claims of the present invention should fall within the scope of the present invention.

Claims

1. A time-division duplex frequency-modulated continuous wave radar system, comprising: P transmitting circuits are used to transmit multiple frequency modulated continuous wave signals, wherein the pth transmitting circuit is coupled to a single-pole Qp-throw radio frequency switch, and the single-pole Qp-throw radio frequency switch is coupled to Qp antennas, Qp and P are positive integers, and p is a positive integer not greater than P; and M receiving circuits are used to receive multiple reflected frequency modulated continuous wave signals, wherein the mth receiving circuit is coupled to a single-pole Nm-throw RF switch, and the single-pole Nm-throw RF switch is coupled to Nm antennas, Nm and M are positive integers, and m is a positive integer not greater than M.

2. The time-division duplex frequency-modulated continuous wave radar system as claimed in claim 1, further comprising: A radio frequency phase-locked loop is coupled to the P transmitting circuits and the M receiving circuits, and is used to generate a phase-matched radio frequency signal for the plurality of frequency modulated continuous wave signals and the plurality of reflected frequency modulated continuous wave signals.

3. The time-division duplex FMCW radar system as claimed in claim 1, wherein the M receiving circuits include M mixers for mixing the multiple reflected FMCW signals with the multiple FMCW signals to generate a plurality of beat frequency signals.

4. The TDD FMCW radar system of claim 3, further comprising a processor for analyzing the plurality of beat frequency signals to generate distances, velocities and angles of a plurality of objects.

5. The TDD FMCW radar system as claimed in claim 4, wherein the processor is further configured to perform a fast Fourier transform on vertical axes of the plurality of beat frequency signals to generate a plurality of frequency spectra of the plurality of beat frequency signals, and generate the distances of the plurality of objects according to the plurality of frequency spectra.

6. The TDD FMCW radar system of claim 5, wherein the processor is further configured to perform a fast Fourier transform on horizontal axes of the multiple frequency spectra of the multiple beat frequency signals to generate speeds of the multiple objects.

7. A time-division duplex FMCW radar system as described in claim 4, wherein the processor is further used to perform a fast Fourier transform on the multiple reflected FMCW signals received by the M receiving circuits to generate the angles of the multiple objects according to the phase differences of the multiple reflected FMCW signals.

8. The time-division duplex FMCW radar system as claimed in claim 1, wherein the P transmitting circuits transmit the plurality of FMCW signals based on a P phase modulation method.

9. The time-division duplex frequency-modulated continuous wave radar system as described in claim 1, wherein P is 2, Q1 is 2, Q2 is 2, M is 2, N1 is 2, and N2 is 2.

10. The time-division duplex FMCW radar system as claimed in claim 9, wherein the P transmitting circuits transmit the plurality of FMCW signals based on a binary phase modulation method.

11. A method for a time division duplex frequency modulated continuous wave radar system, comprising: Transmitting a plurality of frequency modulated continuous wave signals through P transmitting circuits, wherein the pth transmitting circuit is coupled to a single-pole Qp-throw radio frequency switch, and the single-pole Qp-throw radio frequency switch is coupled to Qp antennas, Qp and P are positive integers, and p is a positive integer not greater than P; and Multiple reflected FMCW signals are received by M receiving circuits, wherein the mth receiving circuit is coupled to a single-pole Nm-throw RF switch, and the single-pole Nm-throw RF switch is coupled to Nm antennas, Nm and M are positive integers, and m is a positive integer not greater than M.

12. The method of claim 11, further comprising: A radio frequency signal matching the phases of the plurality of frequency modulated continuous wave signals and the plurality of reflected frequency modulated continuous wave signals is generated through a radio frequency phase locked loop.

13. The method of claim 11, wherein the M receiving circuits include M mixers, the method further comprising the M mixers mixing the multiple reflected FMCW signals with the multiple FMCW signals to generate a plurality of beat frequency signals.

14. The method of claim 13, further comprising analyzing the plurality of beat signals to generate distances, velocities, and angles of a plurality of objects.

15. The method of claim 14, further comprising: performing a fast Fourier transform on vertical axes of the plurality of beat frequency signals to generate a plurality of frequency spectrograms of the plurality of beat frequency signals; and The distances of the plurality of objects are generated according to the plurality of frequency spectrograms.

16. The method of claim 15, further comprising performing a Fast Fourier Transform on horizontal axes of the plurality of spectrograms of the plurality of beat frequency signals to generate velocities of the plurality of objects.

17. The method of claim 14, further comprising performing a fast Fourier transform on the multiple reflected FMCW signals received by the M receiving circuits to generate angles of the multiple objects based on phase differences of the multiple reflected FMCW signals.

18. The method of claim 11, wherein transmitting the plurality of frequency modulated continuous wave signals through the P transmitting circuits is transmitting the plurality of frequency modulated continuous wave signals through the P transmitting circuits based on a P phase modulation method.

19. The method of claim 11, wherein P is 2, Q1 is 2, Q2 is 2, M is 2, N1 is 2, and N2 is 2.

20. The method of claim 19, wherein transmitting the plurality of frequency modulated continuous wave signals through the P transmitting circuits is transmitting the plurality of frequency modulated continuous wave signals through the P transmitting circuits based on a binary phase modulation method.

Images