Radar measurement for estimation of biomass in forest stands
An estimate of the biomass in a forest stand can be obtained from satellite data. There are also optical methods that measure the individual tree and thus replace manual measurement.
Ground based methods that measure along a path are a compromise in terms of capacity and accuracy. The method considered here is based on the change in the propagation of electromagnetic waves that takes place when the waves pass through a forest. This corresponds to the relation that is known as Fermat's principle. Through accurate measurements, differences in the detected distance can be used as an indication of the biomass in a stand.
For this, portable broadband antennas are used in combination with software radio techniques. The concept relates to replacing electronics by software in a computer. This makes it possible to do signal processing in a USRP module without having to design electronic circuits.
The method has been developed for a couple of years and can now be used in the field. The principle, in simple terms, is that the distance between the antennas is measured with the FMCW method, a form of frequency modulation. The measurements detect small differences in distance that depend on the properties of the forest. A thick forest produces a larger difference in distance while a thin, sparse forest produces a smaller difference.
Article in journal (Refereed)
- Sandström, S., Akeab, I. (2016). A study of some FMCW radar algorithms for target location at low frequencies. Radio Science. 51. 1676-1685.
- Sandström, S., Akeab, I. (2016). Accurate hybrid techniques for the method of moments in 2D. AEU - International Journal of Electronics and Communications. 70. 539-543.
- Sandström, S., Akeab, I. (2014). Scaling and sparsity in an accurate implementation of the method of moments in 2-D. Radio Science. 49. 643-652.
- Sandström, S. (2012). An extension of the Fock current distribution functions. AEU - International Journal of Electronics and Communications. 66. 540-546.
- Sandström, S. (2012). Some further results for the computation of uniform Fock functions. Telecommunications and Radio Engineering. 71. 117-122.
- Sandström, S. (2008). A remark on the computation of Fock functions for negative arguments. AEU - International Journal of Electronics and Communications. 62. 324-326.
- Sandström, S., Ackren, C. (2007). Note on the complex zeros of H'nu(x)+ izHnu(x)= 0. Journal of Computational and Applied Mathematics. 201. 3-7.