CN112379338A - Near-constant-modulus band-limited random noise waveform modulation method - Google Patents
Near-constant-modulus band-limited random noise waveform modulation method Download PDFInfo
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- 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
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Abstract
The invention discloses a near constant modulus band-limited random noise waveform modulation method, which comprises the steps of setting a threshold according to the peak-to-average ratio requirement of the band-limited random noise waveform, randomly modulating a noise sequence on a subcarrier corresponding to a preset bandwidth of a frequency domain by using a multi-carrier orthogonal modulation mode, namely an OFDM mode to generate a band-limited random noise waveform which is not subjected to peak-to-average ratio inhibition, calculating the peak-to-average ratio, judging whether the peak-to-average ratio needs to be optimized according to the threshold, recording the peak value, the peak value point and the peak value symbol of the band-limited random noise waveform after the optimization step, determining an optimization coefficient according to the peak-to-average ratio, generating a random frequency point sine waveform according to the optimization coefficient, performing phase shift according to the phase corresponding to the peak value point to generate a sine optimized waveform, performing peak-to-average ratio optimization on the band-limited random noise waveform, performing peak-to-average ratio threshold judgment on the optimized band-limited random noise waveform, and outputting the waveform which meets the peak-to- A noise waveform.
Description
Technical Field
The invention belongs to the field of noise processing, relates to a waveform modulation technology, and particularly relates to a near-constant-modulus band-limited random noise waveform modulation method.
Background
Compared with the conventional radar, the noise radar has stronger anti-reconnaissance anti-interference capability, and the design of the low peak-to-average ratio band-limited random noise waveform is a great problem in the design of the noise radar waveform. Because of the limitation of the dynamic range of hardware equipment such as digital-to-analog converters, power amplifiers and the like, the passing of a large peak-to-average ratio waveform can cause larger distortion of the waveform, and particularly for power amplification devices, because a radar transmitter in engineering usually puts the power amplification devices in a saturation region for seeking the extreme amplification of waveform energy, the waveform is often required to have a low peak-to-average ratio, even a constant modulus waveform, such as a single-frequency point sine waveform or a chirp waveform and the like. The band-limited random noise waveform is random and irregular in time-frequency domain, so that the peak-to-average ratio of the waveform is difficult to control, and under the condition, the waveform is difficult to ensure not to be distorted in the amplification process. The invention provides a band-limited random noise waveform modulation technology with extremely low peak-to-average ratio and approximate constant modulus, solves a major engineering problem of noise radar waveform modulation, and can be used as a waveform modulation technology of a detection and interference integrated system.
Disclosure of Invention
The invention provides a near-constant-modulus band-limited random noise waveform modulation method, which can modulate and generate a near-constant-modulus band-limited random noise waveform with a peak-to-average ratio infinitely close to two, the time-frequency domain of the waveform shows stronger randomness and irregularity, and the frequency domain energy is only distributed in a specified frequency domain area. The waveform modulation method provided by the invention can provide a band-limited random noise waveform with an extremely low peak-to-average ratio and an approximate constant modulus for the noise radar, so that the waveform of the noise radar is not limited by the linear range of a device in the amplification process, the maximum amplification gain is obtained, and a great engineering problem of waveform modulation of the noise radar is solved. The invention aims to provide a near-constant-mode band-limited random noise waveform modulation method.
The purpose of the invention can be realized by the following technical scheme:
a near constant modulus band-limited random noise waveform modulation method comprises the following steps:
s1, setting a peak-to-average ratio threshold according to the peak-to-average ratio requirement;
s2, modulating a random sequence on a subcarrier with a specified bandwidth by using an OFMD method to generate a band-limited random noise waveform;
s3, recording the peak value of the band-limited random noise waveform, and calculating and recording the peak-to-average ratio of the band-limited random noise waveform;
s4, carrying out threshold judgment on the peak-to-average ratio;
s5, recording the peak position and the peak sign of the limited random noise waveform under the condition that the peak-to-average ratio of the limited random noise waveform is greater than the peak-to-average ratio threshold, and calculating an optimization coefficient according to the peak size and the peak-to-average ratio;
s6, generating a sine waveform according to the bandwidth limitation and the optimization coefficient;
s7, calculating an optimized phase according to the peak position and the peak sign, and shifting the phase of the sine waveform to generate a sine optimized waveform;
s8, optimizing the peak-to-average ratio of the bandlimited random noise waveform by using the sine optimized waveform to obtain the optimized bandlimited random noise waveform;
s9, return to step S3.
Further, the near-constant modulus band-limited random noise waveform refers to a band-limited random noise waveform whose peak-to-average ratio can be infinitely approximated to two, and the peak-to-average ratio threshold in step S1 refers to an arbitrary value that is greater than and approximated to two.
Further, the waveform peak value refers to the larger absolute value of the waveform positive peak value and the waveform negative peak value.
Further, when the threshold is determined in step S4 that the peak-to-average ratio of the band-limited random noise waveform is greater than the peak-to-average ratio threshold, ending the peak-to-average ratio optimization process, where the obtained band-limited random noise waveform is a near-constant-modulus band-limited random noise waveform that meets the peak-to-average ratio condition; and entering a peak-to-average ratio optimization process when the threshold judges that the peak-to-average ratio of the random noise waveform with the limit is smaller than the peak-to-average ratio threshold, and performing peak-to-average ratio optimization.
Further, the peak sign of the band-limited random noise waveform in step S5 is either a positive sign or a negative sign; the optimization coefficient is obtained by calculating the peak value and the peak-to-average ratio.
Further, the frequency point of the sine waveform in step S6 is a random frequency point that meets the bandwidth limitation, and the amplitude of the sine waveform is equal to the optimization coefficient.
Further, the sine-optimized waveform generated after the phase shift in step S7 is still the peak point at the peak point of the band-limited random noise waveform, and the peak sign of the sine-optimized waveform at this point is opposite to the peak sign of the band-limited random noise waveform.
Further, the peak-to-average ratio optimization principle in step S8 is to add the sine-optimized waveform and the band-limited random noise waveform so that the peak of the band-limited random noise waveform is cancelled by the peak at this point of the sine-optimized waveform, thereby achieving the peak-to-average ratio suppression effect.
The invention has the beneficial effects that:
the near-constant-mode band-limited random noise waveform modulation technology provided by the invention generates a band-limited random noise waveform through OFDM modulation, and utilizes a method of optimizing the peak point of the band-limited random noise waveform by using a random frequency point sine optimized waveform with opposite phases at the peak position of the band-limited random noise waveform to inhibit the peak-to-average ratio of the band-limited random noise waveform to obtain a low peak-to-average ratio band-limited random noise waveform approximate to a constant mode, thereby laying a foundation for the engineering practice of a noise radar system and a detection interference integrated system on the basis of a waveform design method.
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In order to facilitate understanding for those skilled in the art, the present invention will be further described with reference to the accompanying drawings.
FIG. 1 is a flow chart of the implementation of the near-constant modulus bandlimited random noise waveform modulation technique of the present invention;
FIG. 2 is a diagram of the time-frequency domain of a bandlimited random noise waveform for OFDM modulation in accordance with the present invention;
FIG. 3 is a time-frequency domain diagram of a sinusoidal waveform of random frequency points with uniformly distributed frequency points according to the present invention;
FIG. 4 is a plot of a peak plot of a limited random noise waveform and a corresponding sinusoidally optimized waveform of the present invention;
FIG. 5 is a time-frequency domain diagram of a near-constant modulus bandlimited random noise waveform generated according to different peak-to-average ratio threshold requirements in the present invention.
Detailed Description
As shown in fig. 1, the present invention is a near-constant modulus bandlimited random noise waveform modulation technique, comprising the following steps:
s1, because different radar systems have different requirements on the peak-to-average ratio of radar waveforms, in actual engineering practice, the peak-to-average ratio condition required to be achieved by the waveforms needs to be set according to requirements, and the requirement on the peak-to-average ratio of the waveforms is set to be less than or equal to gamma (gamma is greater than 2), namely the threshold of the peak-to-average ratio is gamma.
S2, supposing that the time sequence of the noise radar system requires the pulse waveform time width to be tau, and the central frequency point to be f0Bandwidth of B, radar system transmission sampling rate
When OFDM modulation is performed on a random sequence, there is a subcarrier interval of the OFDM modulation
Let the random sequence length be
The initial position of modulation is
At subcarrier, before
Zero-valued sequence, random sequence c, modulated by subcarrierslCan be expressed as:
cl＝χk+ρki (1)
χk,ρkis a random sequence. From the symmetry of the real signal frequency domain, with respect to
The symmetrical subcarriers must modulate a random sequence clConjugation of (2)Sequence cr：
cr＝χk-ρki (2)
Zero-value sequences are modulated by other subcarriers, and band-limited random noise waveforms y (t) can be obtained, wherein the time-frequency domain of two example band-limited random noise waveforms a and b is shown in fig. 2.
S3, searching for peak value max y (t) m of time domain modulus of band-limited random noise waveform y (t)yAnd calculating the peak-to-average ratio beta of y (t) by using a peak-to-average ratio calculation formula as follows:
s4, carrying out threshold judgment on the peak-to-average ratio, if the peak-to-average ratio beta is less than or equal to gamma, outputting a band-limited random noise waveform y (t), namely the required band-limited random noise waveform, if the peak-to-average ratio beta is more than gamma, further optimizing the peak-to-average ratio, and executing a peak-to-average ratio optimization process S5-S9.
S5, recording the time position t of the peak value of the y (t) time domain module value0Record y (t)0) Is a positive sign "+" or a negative sign "-", and the optimization coefficient ξ (m) is calculated according to a formulayβ), the calculation formula is as follows:
s6, limiting the frequency bandwidth range in the waveform
Randomly selecting a frequency point fφ，fφSubject to
Are distributed uniformly internally, i.e.
Generating a sinusoidal waveform φ (t):
φ(t)＝ξsin(2πfφt),t∈(0,τ) (5)
as shown in FIG. 3, two random frequency points selected according to the band-limited range
And
a time-frequency domain plot of the modulated sinusoidal waveform.
S7, recording the time position t of the peak value of the time domain module value according to the y (t)0And recorded y (t)0) The symbol calculates an optimized phase value ω. By shifting ω toward the sinusoidal waveform φ (t) such that: when y (t)0) Sine waveform with positive sign at t0Taking the trough value when y (t)0) Sine waveform with negative sign at t0Taking the wave peak value. The calculation formula of the optimized phase value ω is as follows:
wherein, the sine wave form phi (t) is shifted to obtain the sine optimized wave form phiω(t)：
As shown in FIG. 4, the a waveform is at the peak taThe sign of the peak at (a) is negative and the corresponding sine optimized waveform at (t)aIs located at a wave crest; b waveform at peak tbThe sign of the peak at (a) is positive and the corresponding sine optimized waveform at (t)bWhere is the trough.
S8 optimizing the waveform phi by sineω(t) optimizing the peak-to-average ratio of the band-limited random noise waveform y (t) to obtain an optimized band-limited random noise waveform y' (t):
y'(t)＝y(t)+φω(t) (8)
s9, the optimized band-limited random noise waveform y' (t) is brought back to the process S3 to calculate the peak-to-average ratio, and then the process S4 is executed to judge the threshold. And finally obtaining the near-constant modulus band-limited random noise waveform meeting the requirement of the peak-to-average ratio threshold after multiple times of optimization. As shown in fig. 5, the pulse waveform a is a near constant modulus band-limited random noise waveform obtained by modulation under the condition that the peak-to-average ratio threshold γ is 4, and the peak-to-average ratio β is 3.99; the pulse waveform b is a near constant modulus band-limited random noise waveform obtained by modulation under the condition that the peak-to-average ratio threshold gamma is 3, and the peak-to-average ratio is beta is 2.99; the pulse waveform c is a near constant mode band-limited random noise waveform obtained by modulation under the condition that the peak-to-average ratio threshold gamma is 2.3, and the peak-to-average ratio is 2.29; the pulse waveform d is a near constant mode band-limited random noise waveform modulated under the condition that the peak-to-average ratio threshold gamma is 2.01, and the peak-to-average ratio thereof is 2.009.
The foregoing is merely exemplary and illustrative of the present invention and various modifications, additions and substitutions may be made by those skilled in the art to the specific embodiments described without departing from the scope of the invention as defined in the following claims.
Claims (8)
1. A near constant mode band-limited random noise waveform modulation method is characterized by comprising the following steps:
s1, setting a peak-to-average ratio threshold according to the peak-to-average ratio requirement;
s2, modulating a random sequence on a subcarrier with a specified bandwidth by using an OFMD method to generate a band-limited random noise waveform;
s3, recording the peak value of the band-limited random noise waveform, and calculating and recording the peak-to-average ratio of the band-limited random noise waveform;
s4, carrying out threshold judgment on the peak-to-average ratio;
s5, recording the peak position and the peak sign of the limited random noise waveform under the condition that the peak-to-average ratio of the limited random noise waveform is greater than the peak-to-average ratio threshold, and calculating an optimization coefficient according to the peak size and the peak-to-average ratio;
s6, generating a sine waveform according to the bandwidth limitation and the optimization coefficient;
s7, calculating an optimized phase according to the peak position and the peak sign, and shifting the phase of the sine waveform to generate a sine optimized waveform;
s8, optimizing the peak-to-average ratio of the bandlimited random noise waveform by using the sine optimized waveform to obtain the optimized bandlimited random noise waveform;
s9, return to step S3.
2. The method according to claim 1, wherein the near constant modulus band-limited random noise waveform is a band-limited random noise waveform whose peak-to-average ratio is infinitely close to two, and the threshold of the peak-to-average ratio in step S1 is an arbitrary value greater than two and close to two.
3. The method according to claim 1, wherein the peak value of the waveform is the larger of the absolute values of the positive peak value and the negative peak value of the waveform.
4. The modulation method of near-constant-modulus band-limited random noise waveform according to claim 1, wherein in step S4, when the threshold is determined that the peak-to-average ratio of the band-limited random noise waveform is greater than the peak-to-average ratio threshold, the peak-to-average ratio optimization process is ended, and the obtained band-limited random noise waveform is a near-constant-modulus band-limited random noise waveform meeting the peak-to-average ratio condition; and entering a peak-to-average ratio optimization process when the threshold judges that the peak-to-average ratio of the random noise waveform with the limit is smaller than the peak-to-average ratio threshold, and performing peak-to-average ratio optimization.
5. The near-constant modulus band-limited random noise waveform modulation method according to claim 1, wherein the peak sign of the band-limited random noise waveform in step S5 is either a positive sign or a negative sign; the optimization coefficient is obtained by calculating the peak value and the peak-to-average ratio.
6. The method for modulating the near-constant modulus band-limited random noise waveform of claim 1, wherein the frequency points of the sine waveform in step S6 are random frequency points meeting the bandwidth limitation, and the amplitude of the sine waveform is equal to the optimization coefficient.
7. The method of claim 1, wherein the sinusoidal optimization waveform generated after the phase shift in step S7 is still a peak point at the peak point of the bandlimited random noise waveform, and the sign of the peak of the sinusoidal optimization waveform at the point is opposite to the sign of the peak of the bandlimited random noise waveform.
8. The modulation method according to claim 1, wherein the peak-to-average ratio optimization principle in step S8 is to add the sine-optimized waveform and the band-limited random noise waveform, so that at the peak point, the peak of the band-limited random noise waveform is cancelled by the peak at the peak point of the sine-optimized waveform, thereby achieving the peak-to-average ratio suppression effect.
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| CN114726492A (en) * | 2022-03-09 | 2022-07-08 | 芯翼信息科技(上海)有限公司 | Method, terminal and storage medium for correcting peak-to-average ratio of demodulation reference signal |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114726492A (en) * | 2022-03-09 | 2022-07-08 | 芯翼信息科技(上海)有限公司 | Method, terminal and storage medium for correcting peak-to-average ratio of demodulation reference signal |
| CN114726492B (en) * | 2022-03-09 | 2024-04-12 | 芯翼信息科技(上海)有限公司 | Peak-to-average ratio correction method, terminal and storage medium for demodulation reference signal |
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