| 1. |
- Ulander, Lars, 1962, et al.
(författare)
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Time series of P- and L-band forest backscatter from BorealScat
- 2017
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Ingår i: International Geoscience and Remote Sensing Symposium (IGARSS). - 9781509049516 ; , s. 4310-4313
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Konferensbidrag (refereegranskat)abstract
- This paper describes results from BorealScat, which is a tower-based P/L/C-band radar being developed by Chalmers in the forest site Remningstorp, Sweden. The objective is to investigate the radar signatures in varying environmental conditions. The 50-m tower has been built adjacent to a forest stand, with above-ground biomass of 300 tons/ha and dominated by Norway spruce (Picea abies (L.) Karst.). The radar consists of an antenna array at the top of the tower connected to a 20-port vector network analyser (VNA) with low-loss cables. The first version of BorealScat performs polarimetric and tomographic measurements in the frequency range 420-1375 MHz. Meteorological and soil moisture measurements are also available. We present first results from a time series collected 16-27 December 2016 during which air temperature varied in the range -4° to 8°C.
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| 2. |
- Zeng, Xuezhi, 1980, et al.
(författare)
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Investigation of stimulus signals for a time domain microwave imaging system
- 2017
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Ingår i: IET Microwaves, Antennas and Propagation. - : Institution of Engineering and Technology (IET). - 1751-8725 .- 1751-8733. ; 11:11, s. 1636 - 1643
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Tidskriftsartikel (refereegranskat)abstract
- Two different types of time domain signals, pulse and pseudo random noise (PN) sequence, were investigated for a time domain microwave imaging system in order to study the effect of stimulus signals on the system performance. The system's measurement accuracy was investigated when the two different stimulus signals were used, respectively. An imaging test was performed in order to show the effect of transmitted waveforms on the imaging quality. The results suggest that the PN sequence in general gives higher measurement accuracy than the pulse. Better imaging results, although not significant, were also obtained when the pseudo random sequence was employed.
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| 3. |
- Zeng, Xuezhi, 1980, et al.
(författare)
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Noise performance comparison between two different types of time-domain systems for microwave detection
- 2017
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Ingår i: International Journal of Microwave and Wireless Technologies. - 1759-0787 .- 1759-0795. ; 9:3, s. 535-542
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Tidskriftsartikel (refereegranskat)abstract
- This paper compares the noise performance of two different types of time-domain microwave detection systems: a pulsed system and a pseudo-random noise sequence system. System-level simulations and laboratory-based measurements are carried out in the study. Results show that the effect of timing jitter is more significant on the measurement accuracy of the pseudo-random noise sequence system than that of the pulsed system. Although the signal power density of the pseudo-random sequence system is tens of dBs higher than that of the pulsed system over the frequency band of interest, the signal-to-noise ratio difference between these two systems can be just a few dBs or even smaller depending on the jitter level.
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| 4. |
- Zeng, Xuezhi, 1980, et al.
(författare)
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Time domain microwave imaging system for biomedical applications
- 2017
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Ingår i: European Microwave Week 2016: "Microwaves Everywhere", EuMW 2016 - Conference Proceedings; 46th European Microwave Conference, EuMC 2016. - 9782874870439 ; , s. 679-682
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Konferensbidrag (refereegranskat)abstract
- A time domain microwave imaging system for biomedical applications was developed using off-the-shelf components. Two different types of signals: a pulse and a pseudo random sequence, were employed as stimulus signal. The system's measurement accuracy and imaging functionality were investigated when these two different stimulus signals were used respectively. The results show that the system has a higher dynamic range when the pseudo random sequence was used. An imaging test also indicates the advantage, although not significant, to using the pseudo random sequence than the pulse.
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