A Novel Real-Time Processing Wideband Waveform Generator of Airborne Synthetic Aperture Radar
"> Figure 1
<p>Common LFM signal generators: (<b>a</b>) the stored method [<a href="#B15-remotesensing-16-00496" class="html-bibr">15</a>]; (<b>b</b>) the DDS method [<a href="#B16-remotesensing-16-00496" class="html-bibr">16</a>].</p> "> Figure 2
<p>Block diagram of the real-time process. Compute serially and cache in parallel [<a href="#B18-remotesensing-16-00496" class="html-bibr">18</a>].</p> "> Figure 3
<p>A graphical representation depicting the timing of the signals produced within a PRF pulse.</p> "> Figure 4
<p>An example of a <math display="inline"><semantics> <mrow> <mn>3</mn> <mo>−</mo> <mi>o</mi> <mi>r</mi> <mi>d</mi> <mi>e</mi> <mi>r</mi> </mrow> </semantics></math> polynomial curve and piecewise linear, where <math display="inline"><semantics> <mrow> <mi>j</mi> <mo>=</mo> <mn>0</mn> <mo>,</mo> <mi>N</mi> <mo>,</mo> <mn>2</mn> <mi>N</mi> <mo>,</mo> <mo>⋯</mo> <mo>,</mo> <mi>S</mi> <mo>−</mo> <mi>N</mi> <mo>,</mo> <mi>S</mi> <mo> </mo> </mrow> </semantics></math>: (<b>a</b>) a <math display="inline"><semantics> <mrow> <mn>3</mn> <mo>−</mo> <mi>o</mi> <mi>r</mi> <mi>d</mi> <mi>e</mi> <mi>r</mi> </mrow> </semantics></math> polynomial curve divided by <math display="inline"><semantics> <mrow> <mi>N</mi> </mrow> </semantics></math>; (<b>b</b>) the division curve’s piecewise linear approximation.</p> "> Figure 5
<p>Block diagram of parallel signal generation in real-time. The circuits within the green dotted box represent the HLS IP.</p> "> Figure 6
<p>Experiment platform: (<b>a</b>) digital synthesis circuit; (<b>b</b>) block diagram of closed-loop test mode.</p> "> Figure 7
<p>The LFM signal has a bandwidth of 440 MHz and a time width of 120 µs: (<b>a</b>) the I and Q signal waveforms, captured by the high-speed oscilloscope, have a time width of 120 µs; (<b>b</b>) the spectrum of the modulated signal shows a center frequency of 9.6 GHz and a bandwidth of 440 MHz.</p> "> Figure 8
<p>Processed signal from closed-loop test mode: (<b>a</b>) the closed-loop recorded waveforms for signal I and signal Q; (<b>b</b>) the pulse compression result with a bandwidth of 440 MHz and a time width of 120 µs.</p> "> Figure 9
<p>The phase error of the system and approximate curves: (<b>a</b>) the mean phase error derived from 50 pulses and a 14-order polynomial curve; (<b>b</b>) piecewise linear divisions for different parameters of <math display="inline"><semantics> <mrow> <mi>N</mi> </mrow> </semantics></math>.</p> "> Figure 10
<p>The results of pulse compression with compensation: (<b>a</b>) The result of pulse compression when compensated with the polynomial curve. The result of pulse compression when compensated with an (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>N</mi> </mrow> </semantics></math> = 4, (<b>c</b>) <math display="inline"><semantics> <mrow> <mi>N</mi> </mrow> </semantics></math> = 8, or (<b>d</b>) <math display="inline"><semantics> <mrow> <mi>N</mi> </mrow> </semantics></math> = 16 piecewise linear curve.</p> "> Figure 11
<p>The signals with predistortion: (<b>a</b>) recorded waveforms of signal I and signal Q; (<b>b</b>) the result of pulse compression with predistortion.</p> ">
Abstract
:1. Introduction
2. Materials and Methods
2.1. Introduction of Common LFM Generation Methods
2.2. Improved Parallel Real-Time LFM Generation
2.3. Improved Parallel Polynomial Calculation Algorithm
2.4. Improved Parallel Real-Time LFM Signal Generation Method
3. Results
3.1. Results of the LFM Signal Generation
3.2. Results of Phase Compensation
3.3. Results of Signal with Compensation
3.4. Comparison of Different Methods
3.4.1. Comparison of Indicators
3.4.2. Comparison of Resource Utilization
4. Discussion
5. Conclusions
Author Contributions
Funding
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Parameter | Value |
---|---|
DAC sampling frequency | 2 GHz |
Bandwidth | 440 MHz |
Time width | 120 µs |
Carrier frequency | 9.6 GHz |
Pulse repetition frequency (PRF) | 600 Hz |
ADC sampling frequency | 2000 MHz |
Sampling points | 81,920 |
Method | Storage Method [15] | Serial Calculation Method [18] | Parallel Calculation Method |
---|---|---|---|
PSLR of ideal signal (dB) | −13.2592 | −13.2592 | −13.2592 |
ISLR of ideal signal (dB) | −10.1038 | −10.1038 | −10.1038 |
PSLR of signal without compensation (dB) | −10.5589 | −10.5613 | −10.6285 |
ISLR of signal without compensation (dB) | −9.0688 | −9.0698 | −9.0096 |
PSLR of signal with compensation (dB) | −13.0051 | −13.0138 | −13.0113 |
ISLR of signal with compensation (dB) | −10.747 | −10.748 | −10.746 |
Method | Storage Method | Serial Calculation Method | Parallel Calculation Method |
---|---|---|---|
The dedicated hardware storage resources (KB) | 937.5 | 0 | 0 |
The dedicated BRAM cache in FPGA | 14.4% | 14.4% | 0.4% |
The time necessary to prepare the waveform for processing | 38.5 ms | 2.5 ms | 1.7 µs |
The utilization of DSP resources in FPGA | 0 | 33% | 39% |
The utilization of LUT resources in FPGA | 9% | 23% | 26% |
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Chen, D.; Wei, T.; Li, G.; Feng, J.; Zeng, J.; Yang, X.; Yu, Z. A Novel Real-Time Processing Wideband Waveform Generator of Airborne Synthetic Aperture Radar. Remote Sens. 2024, 16, 496. https://doi.org/10.3390/rs16030496
Chen D, Wei T, Li G, Feng J, Zeng J, Yang X, Yu Z. A Novel Real-Time Processing Wideband Waveform Generator of Airborne Synthetic Aperture Radar. Remote Sensing. 2024; 16(3):496. https://doi.org/10.3390/rs16030496
Chicago/Turabian StyleChen, Dongxu, Tingcun Wei, Gaoang Li, Jie Feng, Jialong Zeng, Xudong Yang, and Zhongjun Yu. 2024. "A Novel Real-Time Processing Wideband Waveform Generator of Airborne Synthetic Aperture Radar" Remote Sensing 16, no. 3: 496. https://doi.org/10.3390/rs16030496