Generating Method and Device, Receiving Method and Device for Dual-Frequency Constant Envelope Signal with Four Spreading Signals

• US 20160191187A1
• Filed: 11/22/2013
• Published: 06/30/2016
• Est. Priority Date: 11/23/2012
• Status: Active Grant

• Current Assignee: Tsinghua University
• Original Assignee: Tsinghua University
• Inventors: YAO, Zheng, LU, Mingquan
• Granted Patent: US 9,680,594 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01S 19/02 Details of the space or ground control segments
• CPC Class Codes: G01S 19/30 code related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/37 Hardware or software details of the signal processing chain
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04J 13/0003 Code application, i.e. aspects relating to how codes are applied to form multiplexed channels
• CPC Class Codes: H04J 13/18 Allocation of orthogonal codes

Abstract

The application relates to a generating method and device, receiving method and device for a dual-frequency constant envelope multiplexed signal with four spreading signals. According to the method, the four baseband spreading signals s₁(t), s₂(t), s₃(t), s₄(t) can be modulated to a frequency f₁ and a frequency f₂ respectively, so as to generate the constant envelope multiplexed signal on a radio carrier frequency f_p=(f₁+f₂)/2, where the signals s₁(t) and s₂(t) are modulated on the frequency f₁ with carrier phases orthogonal to each other, the signals s₃(t) and s₄(t) are modulated on the frequency f₂ with carrier phases orthogonal to each other, f₁>f₂. The method comprises: determining a power ratio allocated to the four baseband spreading signals s₁(t), s₂(t), s₃(t), s₄(t) in the constant envelope multiplexed signal; storing an additional phase lookup table, wherein the table includes additional phases of an in-phase baseband component I(t) and a quadrature-phase baseband component Q(t) of the constant envelope multiplexed signal; obtaining an additional phase θ of a segment of the current time by looking up the additional phase lookup table; and generating an in-phase baseband component I(t) and a quadrature-phase baseband component Q(t) of the constant envelope multiplexed signal, and generating the constant envelope multiplexed signal S_RF(t) based on the obtained additional phase θ.

Claims

1. A method for generating a dual-frequency constant envelope multiplexed signal with four spreading signals, in which the four baseband spreading signals s₁(t), s₂(t), s₃(t), s₄(t) are modulated to a frequency f₁ and a frequency f₂ respectively, so as to generate the constant envelope multiplexed signal on a radio carrier frequency f_p=(f₁+f₂)/2, where the signals s₁(t) and s₂(t) are modulated on the frequency f₁ with carrier phases orthogonal to each other, and the signals s₃(t) and s₄(t) are modulated on the frequency f₂ with carrier phases orthogonal to each other, f₁>

f₂, wherein the method further comprises;

determining a power ratio allocated to the four baseband spreading signals s₁(t), s₂(t), s₃(t), s₄(t) in the constant envelope multiplexed signal;

storing an additional phase lookup table, wherein the table includes additional phases of an in-phase baseband component I(t) and a quadrature-phase baseband component Q(t) of the constant envelope multiplexed signal, and the table is configured by dividing a subcarrier period T_s of the baseband spreading signal into multiple segments and by determining, at each segment of the multiple segments, an additional phase θ

for a state among 16 states of value combination of the four baseband spreading signals s₁(t), s₂(t), s₃(t), s₄(t) in the constant envelope multiplexed signal, based on the determined power ratio of the four baseband spreading signals s₁(t), s₂(t), s₃(t), s₄(t);

obtaining, according to a segment of the subcarrier period of the baseband spreading signal and to a state of the value combination of the four baseband spreading signals s₁(t), s₂(t), s₃(t) and s₄(t) corresponding to the current time, an additional phase θ

of a segment of the current time by looking up the additional phase lookup table;

generating an in-phase baseband component I(t) and a quadrature-phase baseband component Q(t) of the constant envelope multiplexed signal, and generating the constant envelope multiplexed signal S_RF(t) based on the obtained additional phase θ

, where

S_RF(t)=I(t)cos(2π

f_pt)−

Q(t)sin(2π

f_pt),

I(t)=A cos(θ

),

Q(t)=A sin(θ

),

f_p=(f₁+f₂)/2,

T_s=1/f_s,

f_s=(f₁−

f₂)/2,

where A is the amplitude of the constant envelope multiplexed signal S_RF(t).

2. The method as claimed in claim 1, wherein the additional phase lookup table is configured by:

obtaining a preset in-phase baseband component Î

(t) and a preset quadrature-phase baseband component {circumflex over (Q)}(t);

{circumflex over (I)}(t)=Z(t)×

sgn[sin(2π

f_st+φ

(t))],

{circumflex over (Q)}(t)=Z′

(t)×

sgn[sin(2π

f_st+φ

′

(t))],

wherein sgn stands for the sign function

3. The method as claimed in claim 2, wherein the procedure of dividing a subcarrier period T_s of the baseband spreading signal into multiple segments based on the determined power ratio of the four baseband spreading signals s₁(t), s₂(t), s₃(t), s₄(t) comprises:

calculating an additional phase 0=atan 2({circumflex over (Q)}(t), Î

(t)) in a subcarrier period T_s of the baseband spreading signal for each state of value combination of the four baseband spreading signals s₁(t), s₂(t), s₃(t), s₄(t), based on the determined power ratio of the four baseband spreading signals s₁(t), s₂(t), s₃(t), S₄; and

determining phase-shifting time points of the additional phase θ

in the subcarrier period T_s of the baseband spreading signal, and dividing the subcarrier period T_s of the baseband spreading signal into multiple segments according to the phase-shifting time points.

4. The method as claimed in claim 1, wherein the power ratio of the four baseband spreading signals s₁(t), s₂(t), S₃(t), S₄(t) is 1:

3;

1;

3, and the subcarrier period T_s of the baseband spreading signal is divided into 12 segments with equal length, and the additional phase lookup table is in the form of Table 1 or Table 2;

7. A constant envelope multiplexed signal generated by the method or the device for generating the dual-frequency constant envelope multiplexed signal with four spreading signals as claimed in any preceding claim.

8. An apparatus comprising means adapted to process a constant envelope multiplexed signal generated by the method or the device for generating the dual-frequency constant envelope multiplexed signal with four spreading signals as claimed in any preceding claim.

9. A constant envelope multiplexed signal receiving device to receive the constant envelope multiplexed signal generated by the method or the device for generating the dual-frequency constant envelope multiplexed signal with four spreading signals as claimed in any preceding claim.

10. A signal receiving device to receive the constant envelope multiplexed signal as claimed in any preceding claim, or the constant envelope multiplexed signal generated by the method or the device for generating the dual-frequency constant envelope multiplexed signal with four spreading signals as claimed in any preceding claim, which comprises:

a receiving unit for receiving the constant envelope multiplexed signal;

a demodulation unit for demodulating a signal component modulated on the frequency f₁ of the received constant envelope multiplexed signal, and for demodulating a signal component modulated on the frequency f₂ of the received constant envelope multiplexed signal; and

a processing unit for obtaining baseband spreading signals s₁(t) and s₂(t) based on the demodulated signal component which is modulated on the frequency f₁, and for obtaining baseband spreading signals s₃(t) and s₄(t) based on the demodulated signal component which is modulated on the frequency f₂.

11. A signal receiving method for receiving the constant envelope multiplexed signal as claimed in any preceding claim, or the constant envelope multiplexed signal generated by the method or the device for generating the dual-frequency constant envelope multiplexed signal with four spreading signals as claimed in any preceding claim, which comprises:

receiving the constant envelope multiplexed signal;

demodulating a signal component modulated on the frequency f₁ of the received constant envelope multiplexed signal, and for demodulating a signal component modulated on the frequency f₂ of the received constant envelope multiplexed signal; and

obtaining baseband spreading signals s₁(t) and s₂(t) based on the demodulated signal component which is modulated on the frequency f₁, and for obtaining baseband spreading signals s₃(t) and s₄(t) based on the demodulated signal component which is modulated on the frequency f₂.

12. A signal receiving device to receive the constant envelope multiplexed signal as claimed in any preceding claim, or the constant envelope multiplexed signal generated by the method or the device for generating the dual-frequency constant envelope multiplexed signal with four spreading signals as claimed in any preceding claim, wherein the additional phase lookup table is stored in the signal receiving device and the signal receiving device comprises:

a receiving unit for receiving the constant envelope multiplexed signal;

a demodulation unit for demodulating the received constant envelope multiplexed signal with a central frequency of f_p=(f₁+f₂)/2 so as to obtain the demodulated baseband signal;

an additional phase looking up unit for obtaining, based on the additional phase lookup table, an additional phase θ

corresponding to each state among states of value combination of the four baseband spreading signals s₁(t), s₂, s₃, s₄;

a local replica generating unit for generating, based on the obtained additional phase θ

, a local replica Í

_i(t) of an in-phase baseband signal and a local replica {tilde over (Q)}_i(t) of a quadrature-phase baseband signal corresponding to each state; and

a calculating unit for calculating a correlation between the generated Ĩ

_i(t) and {tilde over (Q)}_i(t) corresponding to each state with the demodulated baseband signal, to determine the baseband spreading signals s₁(t), s₂(t), s₃(t), s₄(t) of the demodulated baseband signal, so as to achieve the acquisition and tracking of the constant envelope multiplexed signal.

13. A signal receiving method for receiving the constant envelope multiplexed signal as claimed in any preceding claim, or the constant envelope multiplexed signal generated by the method or the device for generating the dual-frequency constant envelope multiplexed signal with four spreading signals as claimed in any preceding claim, wherein the signal receiving method comprises:

storing the additional phase lookup table;

receiving the constant envelope multiplexed signal;

demodulating the received constant envelope multiplexed signal through a central frequency of f_p=(f₁+f₂)/2 to obtain the demodulated baseband signal;

obtaining, based on the additional phase lookup table, an additional phase θ

corresponding to each state among states of value combination of the four baseband spreading signals s₁(t), s₂(t), s₃(t), s₄(t);

generating, based on the obtained additional phase θ

, a local replica Ĩ

_i(t) of an in-phase baseband signal and a local replica {tilde over (Q)}_i(t) of a quadrature-phase baseband signal corresponding to each state;

calculating a correlation between the generated Ĩ

_i(t) and {tilde over (Q)}_i(t) corresponding to each state with the demodulated baseband signal, to determine the baseband spreading signals s₁(t), s₂(t), s₃(t), s₄(t) of the demodulated baseband signal, so as to achieve the acquisition and tracking of the constant envelope multiplexed signal.

14. A signal receiving device to receive the constant envelope multiplexed signal as claimed in any preceding claim, or the constant envelope multiplexed signal generated by the method or the device for generating the dual-frequency constant envelope multiplexed signal with four spreading signals as claimed in any preceding claim, wherein the additional phase lookup table is stored in the signal receiving device and the signal receiving device comprises:

a receiving unit for receiving, filtering and amplifying the constant envelope multiplexed signal, wherein a central frequency of the filtering and amplifying is set at (f₁+f₂)/2;

a demodulation unit for converting a carrier frequency of the signal component to be processed to a corresponding intermediate frequency, converting the signal component from analog to digital by sampling and quantizing the signal, and obtaining a receiver in-phase baseband signal SI(t) and a receiver quadrature-phase baseband signal SQ (t) by multiplying the converted digital intermediate frequency signal by an in-phase carrier and a quadrature-phase carrier respectively;

an additional phase looking up unit for generating a spreading sequence of four baseband spreading signals with spreading chip waveform assignment, and generating, based on all the possible value combinations of the binary baseband local signal replica of the four baseband spreading signals, an in-phase baseband signal local replica Ĩ

_i(t) and a quadrature-phase baseband signal local replica {tilde over (Q)}_i(t) corresponding to each combination in the additional phase looking up unit, at each epoch, wherein the number of value combinations is denoted as g, g=2^N, where there are N data channels, and for a special case S_i={{tilde over (s)}₁, {tilde over (s)}₂, {tilde over (s)}₃, {tilde over (s)}₄} among the g value combinations, the generating rule of Ĩ

_i(t) and {tilde over (Q)}_i(t) is same as the transmitting device, and for obtaining the additional phase of the current time by looking up the additional phase lookup table;

a local replica generating unit for generating the in-phase baseband signal local replica Ĩ

_i(t) and the quadrature-phase baseband signal local replica {tilde over (Q)}_i(t), where

Ĩ

_i(t)=cos(θ

_i)

{tilde over (Q)}_i(t)=sin(θ

_i); and

a calculating unit for obtaining the i-th (i=1, 2, . . . , g) group of a first in-phase correlation value corr1I_i and a first quadrature-phase correlation value corr1Q_i by multiplying the i-th (i=1, 2, . . . , g) group of the in-phase baseband signal local replica Ĩ

_i(t) with the in-phase baseband signal SI(t) and the quadrature-phase baseband signal SQ(t) and sending the multiplying results into an integration and dumping filter for coherent integration with duration of TI, and for obtaining the i-th (i=1, 2, . . . , g) group of the second in-phase correlation value corr2I_i and the quadrature-phase correlation value corr2Q_i by multiplying each group of the quadrature-phase baseband signal local replica {tilde over (Q)}_i(t) with the in-phase baseband signal SI(t) and the quadrature-phase baseband signal SQ(t) and sending the multiplying results into the integration and dumping filter for the coherent integration with duration of TI;

for obtaining the i-th (i=1, 2, . . . , g) group of in-phase combination correlation value I′

_i and the quadrature-phase combination correlation value Q′

_i by combining the first in-phase correlation value corr1I_i and the first quadrature-phase correlation value corr1Q_i of the i-th group with the second in-phase correlation value corr2I_i and the second quadrature-phase correlation value corr2Q_i of the i-th group as;

15. A signal receiving method for receiving the constant envelope multiplexed signal as claimed in any preceding claim, or the constant envelope multiplexed signal generated by the method or the device for generating the dual-frequency constant envelope multiplexed signal with four spreading signals as claimed in any preceding claim, wherein the signal receiving method comprises:

storing the mentioned additional phase lookup table;

receiving, filtering and amplifying the constant envelope multiplexed signal, wherein a central frequency of the filtering and amplifying is set at (f₁+f₂)/2;

converting a carrier frequency of the signal component to be processed to a corresponding intermediate frequency, and converting the signal component from analog to digital by sampling and quantizing the signal, and obtaining a receiver in-phase baseband signal SI(t) and a receiver quadrature-phase baseband signal SQ(t) by multiplying the converted digital intermediate frequency signal by an in-phase carrier and a quadrature-phase carrier respectively;

generating a spreading sequence of four baseband spreading signals with spreading chip waveform assignment, and generating, based on all the possible value combinations of the binary baseband local signal replica of the four baseband spreading signals, an in-phase baseband signal local replica Ĩ

_i(t) and a quadrature-phase baseband signal local replica {tilde over (Q)}_i(t) corresponding to each combination, at each epoch, wherein the number of value combinations is denoted as g, g=2^N, where there are N data channels, and for a special case S_i={{tilde over (s)}₁, {tilde over (s)}₂, {tilde over (s)}₃, {tilde over (s)}₄} among the g value combinations, the generating rule of Ĩ

_i(t) and {tilde over (Q)}_i(t) is same as the transmitting device, and for obtaining the additional phase θ

_i of the current time by looking up the additional phase lookup table;

generating the in-phase baseband signal local replica Ĩ

_i(t) and the quadrature-phase baseband signal local replica {tilde over (Q)}_i(t), where

Ĩ

_i(t)=cos(θ

_i)

{tilde over (Q)}_i(t)=sin(θ

_i); and

obtaining the i-th (i=1, 2, . . . , g) group of a first in-phase correlation value corr1I_i and a first quadrature-phase correlation value corr1Q_i by multiplying the i-th (i=1, 2, . . . , g) group of the in-phase baseband signal local replica Ĩ

_i(t) with the in-phase baseband signal SI(t) and the quadrature-phase baseband signal SQ(t) and sending the multiplying results into an integration and dumping filter for coherent integration with duration of TI, and for obtaining the i-th (i=1, 2, . . . , g) group of the second in-phase correlation value corr2I_i and the quadrature-phase correlation value corr2Q_i by multiplying each group of the quadrature-phase baseband signal local replica {tilde over (Q)}_i(t) with the in-phase baseband signal SI(t) and the quadrature-phase baseband signal SQ(t) and sending the multiplying results into the integration and dumping filter for the coherent integration with duration of TI;

obtaining the i-th (i=1, 2, . . . , g) group of in-phase combination correlation value I′

_i and the quadrature-phase combination correlation value Q′

_i by combining the first in-phase correlation value corr1I_i and the first quadrature-phase correlation value corr1Q_i of the i-th group with the second in-phase correlation value corr2I_i and the second quadrature-phase correlation value corr2Q_i of the i-th group as;

16. A program comprising executable instructions to implement the method, device, apparatus in any preceding claim, or to generate a signal in any preceding claim.

17. A machine-readable storage for storing a program as claimed in claim 16.

5. A device for generating a dual-frequency constant envelope multiplexed signal with four spreading signals, in which the four baseband spreading signals s₁(t), s₂(t), s₃(t), s₄(t) are modulated to a frequency f₁ and a frequency f₂ respectively, so as to generate the constant envelope multiplexed signal on a radio carrier frequency f_p=(f₁+f₂)/2, where the signals s₁(t) and s₂(t) are modulated on the frequency f₁ with carrier phases orthogonal to each other, the signals s₃(t) and s₄(t) are modulated on the frequency f₂ with carrier phases orthogonal to each other, f₁>

f₂, wherein the device further comprises;

an additional phase lookup table storing unit for storing the additional phase lookup table, wherein the table includes additional phases of an in-phase baseband component I(t) and a quadrature-phase baseband component Q(t) of the constant envelope multiplexed signal, and the table is configured by dividing a subcarrier period T_s of the baseband spreading signal into multiple segments and by determining, at each segment of the multiple segments, an additional phase θ

for a state among 16 states of value combination of the four baseband spreading signals s₁(t), s₂(t), s₃(t), s₄(t) in the constant envelope multiplexed signal, based on the determined power ratio of the four baseband spreading signals s₁(t), s₂(t), s₃(t), s₄(t);

an lookup unit for obtaining, by looking up the additional phase lookup table according to a segment of the subcarrier period of the baseband spreading signal and to a state of the value combination of the four baseband spreading signals s₁(t), s₂(t), s₃(t) and s₄(t) corresponding to the current time, an additional phase θ

of a segment of the current time;

a generating unit for generating an in-phase baseband component I(t) and a quadrature-phase baseband component Q(t) of the constant envelope multiplexed signal, and generating the constant envelope multiplexed signal S_RF(t) based on the obtained additional phase θ

, where

S_RF(t)=I(t)cos(2π

f_pt)−

Q(t)sin(2π

f_pt),

I(t)=A cos(θ

),

Q(t)=A sin(θ

),

f_p=(f₁+f₂)/2,

T_s=1/f_s,

f_s=(f₁−

f₂)/2,

where A is the amplitude of the constant envelope multiplexed signal S_RF(t).

6. The device as claimed in claim 5, wherein the power ratio of the four baseband spreading signals s₁(t), s₂(t), s₃(t), s₄(t) is 1:

3;

1;

3, and the subcarrier period T_s of the baseband spreading signal is divided into 12 segments with equal length, and the additional phase lookup table stored in the additional phase lookup table storing unit is in the form of Table 1 or Table 2;