Channel compensation method for large-bandwidth frequency hopping signals

Abstract

The invention provides a channel compensation method for a large-bandwidth frequency hopping signal. The channel compensation method comprises the following steps: step 1, generating a measurement signal frequency hopping pattern: step 101, generating a uniform sequence; step 102, carrying out randomization processing; step 103, performing frequency mapping; step 2, up-conversion; step 3, down conversion; step 4, estimating amplitude and phase of a measurement signal; step 5, matrix loop filtering; and step 6, linear interpolation and compensation. The invention provides a scheme for generating a frequency hopping pattern aiming at a measurement signal through a uniform sequence and random sequence mixed interpolation processing method, and meanwhile, the uniformity required by measurement and the randomness required by frequency hopping communication are ensured. According to the invention, amplitude estimation and loop filtering are carried out on a measurement signal at a receiving end, and a channel compensation scheme under a large frequency hopping bandwidth is completed through linear interpolation. Compensation of large-bandwidth channel amplitude and phase can be completed in the communication process, extra hardware cost does not need to be increased, and the method has good application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of satellite communications, relates to a large-bandwidth frequency-hopping signal, and in particular to a channel compensation method for a large-bandwidth frequency-hopping signal. Background Art

[0002] Frequency hopping communication technology has been widely used in satellite anti-interference communication, covert communication, electronic countermeasures and other fields due to its good anti-interference ability. In the frequency hopping system, the transmitter takes out the frequency control code from the frequency hopping frequency table through the frequency hopping pattern, and controls the transmission signal to perform frequency hopping transmission on a wider frequency band, thereby increasing the anti-interference and anti-interception capabilities.

[0003] In existing frequency hopping communication systems, the frequency hopping bandwidth usually ranges from 100MHz to 2GHz. When the frequency hopping bandwidth is further increased, it is limited by channel characteristics, especially the inconsistency of amplitude and phase under large bandwidth, making it difficult for the receiver to achieve ideal performance when recovering the frequency hopping signal. The above problems have greatly affected the application of large bandwidth frequency hopping technology. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a channel compensation method for large-bandwidth frequency-hopping signals to solve the technical problem of amplitude-phase inconsistency under large bandwidth in the frequency-hopping communication system in the prior art.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0006] A channel compensation method for a large bandwidth frequency hopping signal, the method comprising the following steps:

[0007] Step 1: Generate the measurement signal frequency hopping pattern:

[0008] Step 101, uniform sequence generation:

[0009] Use m sequence to generate uniform sequence;

[0010] Step 102, randomization processing:

[0011] First, a random base sequence is generated, and then the uniform sequence obtained in step 101 is operated on the random base sequence to complete the randomization process and obtain a randomized sequence;

[0012] Step 103, frequency mapping:

[0013] Performing frequency mapping on the randomized sequence obtained in step 102 to complete the generation of a frequency hopping pattern of the measurement signal;

[0014] Step 2: Up-conversion:

[0015] At the transmitting end, the measurement signal needs to be up-converted, and the up-converted local oscillator is the frequency point corresponding to the measurement signal frequency hopping pattern generated in step 1;

[0016] Step 3, down-conversion;

[0017] At the receiving end, the signal needs to be down-converted to recover the baseband measurement signal;

[0018] Step 4, measuring signal amplitude and phase estimation;

[0019] Performing amplitude estimation and phase estimation on the frequency hopping signal after down-conversion at the receiving end obtained in step 3 to obtain an amplitude estimation value and a phase estimation value;

[0020] Step 5: Matrix loop filtering;

[0021] The amplitude estimation value and the phase estimation value obtained in step 4 are subjected to first-order loop filtering to obtain a filtered amplitude estimation value and a filtered phase estimation value;

[0022] Step 6: Linear interpolation and compensation:

[0023] The filtered amplitude estimation value and the filtered phase estimation value obtained in step 5 are linearly interpolated and compensated to form amplitude and phase error curves of the large bandwidth channel.

[0024] Compared with the prior art, the present invention has the following technical effects:

[0025] (I) The present invention proposes a scheme for generating a frequency hopping pattern for a measurement signal by a method of mixed interpolation processing of a uniform sequence and a random sequence, while ensuring both the uniformity required for measurement and the randomness required for frequency hopping communication.

[0026] (II) The present invention proposes to perform amplitude estimation and loop filtering on the measurement signal at the receiving end, and complete the channel compensation scheme under large frequency hopping bandwidth through linear interpolation. The compensation of large bandwidth channel amplitude and phase can be completed during the communication process without adding additional hardware cost, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The figure is a principle block diagram of the channel compensation method for large bandwidth frequency hopping signals of the present invention.

[0028] The specific contents of the present invention are further explained in detail below in conjunction with embodiments. DETAILED DESCRIPTION

[0029] It should be noted that, unless otherwise specified, all sequences and methods in the present invention adopt sequences and methods known in the prior art.

[0030] In the present invention, a large bandwidth frequency hopping signal refers to a frequency hopping signal greater than 2 GHz.

[0031] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0032] Example:

[0033] This embodiment provides a channel compensation method for a large bandwidth frequency hopping signal. Figure 1 As shown, the method comprises the following steps:

[0034] Step 1: Generate the measurement signal frequency hopping pattern:

[0035] Step 1 includes the following steps:

[0036] Step 101, uniform sequence generation:

[0037] In this step, in order to ensure basic measurement performance, the measurement signal should be evenly distributed in the entire frequency band within the cycle time. The uniform sequence generation adopts a typical m-sequence, which has the characteristics of periodicity.

[0038] Use m sequence to generate uniform sequence;

[0039] In step 101, the input conditions of the uniform sequence are the uniform sequence period L and the sequence initial phase, and the set X of the output sequence of the uniform sequence can be expressed as:

[0040] X={x i}, where i∈[0,L-1]

[0041] Where:

[0042] x i represents the generated uniform sequence;

[0043] i represents the serial number;

[0044] L represents the uniform sequence period.

[0045] In step 101, the method for generating the uniform sequence is:

[0046]

[0047] Where:

[0048] [c1c2…c n ] represents the coefficients of the m-sequence generating polynomial;

[0049] n represents the number of m-sequence shift registers.

[0050] Step 102, randomization processing:

[0051] In this step, in order to ensure the concealment performance of frequency hopping communication, the generated uniform sequence needs to be randomized.

[0052] First, a random base sequence is generated, and the uniform sequence obtained in step 101 is operated with the random base sequence to complete the randomization process and obtain a randomized sequence;

[0053] In step 102, the set Y of random base sequences is expressed as:

[0054] Y={y j}, where j∈[0,Q-1]

[0055]

[0056] Where:

[0057] y j represents the generated random base sequence;

[0058] j represents the serial number;

[0059] Q represents the value range of the sequence number of the random base sequence;

[0060] BW represents the system frequency hopping bandwidth;

[0061] SP min Indicates the minimum frequency hopping interval;

[0062] L represents the uniform sequence period.

[0063] In step 102, the set Z of randomized sequences is expressed as:

[0064]

[0065] Where:

[0066] z m represents the sequence after randomization;

[0067] m represents the sampling point number.

[0068] In this step, it should be noted that x i With y j The jump frequency is different. j The hopping frequency is the system hopping rate, but x i The hopping frequency is the ratio of the system frequency hopping rate to Q.

[0069] In this step, typical methods for generating random base sequences include Gold sequence, chaotic sequence, etc. In this embodiment, there is no restriction on the method for generating the base sequence.

[0070] Step 103, frequency mapping:

[0071] The randomized sequence obtained in step 102 is frequency mapped to complete the generation of the measurement signal frequency hopping pattern.

[0072] In step 103, the mapping process is:

[0073]

[0074] Where:

[0075] F m Indicates the actual output frequency;

[0076] F0 represents the starting frequency of the available bandwidth;

[0077] BW represents the available frequency bandwidth;

[0078] SP min Indicates the minimum frequency hopping interval;

[0079] z m Represents the sequence after randomization.

[0080] Step 2: Up-conversion:

[0081] At the transmitting end, the measurement signal needs to be up-converted, and the up-converted local oscillator is the frequency point corresponding to the measurement signal frequency hopping pattern generated in step one.

[0082] In step 2, the frequency hopping signal S after up-conversion at the transmitting end uc It is expressed as:

[0083] S uc =s(t)*exp(j2πf m t)+n(t)

[0084] Where:

[0085] s(t) represents the input signal;

[0086] j is the imaginary number symbol;

[0087] exp() represents the natural exponential function;

[0088] f m Indicates the real-time frequency hopping frequency;

[0089] n(t) represents the system noise.

[0090] Step 3, down-conversion;

[0091] At the receiving end, the signal must be down-converted to restore the baseband measurement signal.

[0092] In step 3, the frequency hopping signal R after down-conversion at the receiving end uc (t) is expressed as:

[0093] R uc (t) = s(t) * ΔA e exp(jΔθ e t*T)+n(t)

[0094] Where:

[0095] s(t) represents the input signal;

[0096] j is the imaginary number symbol;

[0097] exp() represents the natural exponential function;

[0098] ΔA e represents the residual amplitude error;

[0099] Δθ e t represents the residual phase error.

[0100] T represents the signal period;

[0101] n(t) represents the system noise.

[0102] Step 4, measuring signal amplitude and phase estimation;

[0103] Performing amplitude estimation and phase estimation on the frequency hopping signal after down-conversion at the receiving end obtained in step 3 to obtain an amplitude estimation value and a phase estimation value;

[0104] In step 4, the method for estimating the amplitude and phase of the measurement signal is:

[0105]

[0106]

[0107] Where:

[0108] represents the phase estimate;

[0109] represents the magnitude estimate;

[0110] k is the frequency number within the bandwidth;

[0111] t represents time;

[0112] R uc() represents the frequency hopping signal after down-conversion at the receiving end;

[0113] imag() represents the imaginary part function of a complex number;

[0114] real() represents a real-valued function;

[0115] abs() represents the absolute value function.

[0116] Step 5: Matrix loop filtering;

[0117] The amplitude estimation value and the phase estimation value obtained in step 4 are subjected to first-order loop filtering to obtain a filtered amplitude estimation value and a filtered phase estimation value;

[0118] In this step, different frequency points maintain different filtering dimensions. Matrix loop filtering can effectively avoid the impact of single-point abnormal jumps. Considering the complexity of implementation, matrix filtering adopts a first-order loop filtering solution.

[0119] In step 5, the first-order loop filtering method is:

[0120]

[0121]

[0122] Where:

[0123] represents the phase estimate;

[0124] represents the phase estimate after filtering;

[0125] represents the magnitude estimate;

[0126] represents the amplitude estimate after filtering;

[0127] k is the frequency number within the bandwidth;

[0128] t represents time;

[0129] a represents the loop filter coefficient;

[0130] Step six: linear interpolation and compensation.

[0131] The filtered amplitude estimation value and the filtered phase estimation value obtained in step 5 are linearly interpolated and compensated to form amplitude and phase error curves of the large bandwidth channel.

[0132] In step six, the linear difference and compensation method is:

[0133]

[0134]

[0135] Where:

[0136] θ e (m, t) represents the final amplitude error curve;

[0137] represents the phase estimate after filtering;

[0138] A e (m, t) represents the final phase error curve;

[0139] represents the amplitude estimate after filtering;

[0140] k is the frequency number within the bandwidth;

[0141] t represents time;

[0142] M represents the number of sampling points between two estimated values;

[0143] m represents the sampling point number.

[0144] The present invention generates a frequency hopping pattern for a measurement signal by a method of mixed interpolation processing of uniform sequences and random sequences, while ensuring the uniformity required for measurement and the randomness required for frequency hopping communication; amplitude estimation and loop filtering are performed on the measurement signal at the receiving end, and channel compensation under a large frequency hopping bandwidth is completed by linear interpolation.

[0145] The present invention overcomes the problems of amplitude and phase inconsistency under large bandwidth in the existing frequency hopping communication system, and can complete the compensation of large bandwidth channel amplitude and phase during the communication process without additional hardware cost, and has good application prospects.

Claims

1. A channel compensation method for a large bandwidth frequency hopping signal, characterized in that: The method comprises the following steps: Step 1: Generate the measurement signal frequency hopping pattern: Step 101, uniform sequence generation: Use m sequence to generate uniform sequence; Step 102, randomization processing: First, a random base sequence is generated, and then the uniform sequence obtained in step 101 is operated on the random base sequence to complete the randomization process and obtain a randomized sequence; Step 103, frequency mapping: Performing frequency mapping on the randomized sequence obtained in step 102 to complete the generation of a frequency hopping pattern of the measurement signal; Step 2: Up-conversion: At the transmitting end, the measurement signal needs to be up-converted, and the up-converted local oscillator is the frequency point corresponding to the measurement signal frequency hopping pattern generated in step 1; Step 3, down-conversion; At the receiving end, the signal needs to be down-converted to recover the baseband measurement signal; Step 4, measuring signal amplitude and phase estimation; Performing amplitude estimation and phase estimation on the frequency hopping signal after down-conversion at the receiving end obtained in step 3 to obtain an amplitude estimation value and a phase estimation value; Step 5: Matrix loop filtering; The amplitude estimation value and the phase estimation value obtained in step 4 are subjected to first-order loop filtering to obtain a filtered amplitude estimation value and a filtered phase estimation value; Step 6: Linear interpolation and compensation: The filtered amplitude estimation value and the filtered phase estimation value obtained in step 5 are linearly interpolated and compensated to form amplitude and phase error curves of the large bandwidth channel.

2. The channel compensation method for a large bandwidth frequency hopping signal according to claim 1, characterized in that: In step 101, the input conditions of the uniform sequence are the uniform sequence period L and the sequence initial phase, and the set X of the output sequence of the uniform sequence can be expressed as: X={x i }, where i∈[0,L-1] Where: x i represents the generated uniform sequence; i represents the serial number; L represents the uniform sequence period; In step 101, the method for generating the uniform sequence is: Where: [c1c2…c n ] represents the coefficients of the m-sequence generating polynomial; n represents the number of m-sequence shift registers.

3. The channel compensation method for a large bandwidth frequency hopping signal according to claim 1, characterized in that: In step 102, the set Y of random base sequences is expressed as: Y={y j }, where j∈[0,Q-1] Where: y j represents the generated random base sequence; j represents the serial number; Q represents the value range of the sequence number of the random base sequence; BW represents the system frequency hopping bandwidth; SP min Indicates the minimum frequency hopping interval; L represents the uniform sequence period; In step 102, the set Z of randomized sequences is expressed as: Where: z m represents the sequence after randomization; m represents the sampling point number.

4. The channel compensation method for a large bandwidth frequency hopping signal according to claim 1, characterized in that: In step 103, the mapping process is: Where: F m Indicates the actual output frequency; F0 represents the starting frequency of the available bandwidth; BW represents the available frequency bandwidth; SP min Indicates the minimum frequency hopping interval; z m Represents the sequence after randomization.

5. The channel compensation method for a large bandwidth frequency hopping signal according to claim 1, characterized in that: In step 2, the frequency hopping signal S after up-conversion at the transmitting end uc It is expressed as: S uc =s(t)*exp(j2πf m t)+n(t) Where: s(t) represents the input signal; exp() represents the natural exponential function; j is the imaginary number symbol; f m Indicates the real-time frequency hopping frequency; n(t) represents the system noise.

6. The channel compensation method for a large bandwidth frequency hopping signal according to claim 1, characterized in that: In step 3, the frequency hopping signal R after down-conversion at the receiving end uc (t) is expressed as: R uc (t)=s(t)*ΔA e exp(jΔθ e t*T)+n(t) Where: s(t) represents the input signal; j is the imaginary number symbol; exp() represents the natural exponential function; ΔA e represents the residual amplitude error; Δθ e t represents the residual phase error; T represents the signal period; n(t) represents the system noise.

7. The channel compensation method for a large bandwidth frequency hopping signal according to claim 1, characterized in that: In step 4, the method for estimating the amplitude and phase of the measurement signal is: Where: represents the phase estimate; represents the magnitude estimate; k is the frequency number within the bandwidth; t represents time; R uc ( ) represents the frequency hopping signal after down-conversion at the receiving end; imag() represents the imaginary part function of a complex number; real() represents a real-valued function; abs() represents the absolute value function.

8. The channel compensation method for a large bandwidth frequency hopping signal according to claim 1, characterized in that: In step 5, the first-order loop filtering method is: Where: represents the phase estimate; represents the phase estimate after filtering; represents the magnitude estimate; represents the amplitude estimate after filtering; k is the frequency number within the bandwidth; t represents time; a represents the loop filter coefficient.

9. The channel compensation method for a large bandwidth frequency hopping signal according to claim 1, characterized in that: In step six, the linear difference and compensation method is: Where: θ e (m, t) represents the final amplitude error curve; represents the phase estimate after filtering; A e (m, t) represents the final phase error curve; represents the amplitude estimate after filtering; k is the frequency number within the bandwidth; t represents time; M represents the number of sampling points between two estimated values; m represents the sequence number of the sampling points.

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