P4D.7
A radar rain profiler using a MATLAB based DSP system
Dirk Klugmann, Institute for Tropospheric Research, Leipzig, Germany; and J. Weickert, P. Holstein, D. Mackenzie, and O. Holinski
Setting up a system for Digital Signal Processing (DSP), and implementing data processing and retrieval algorithms is a highly elaborative task. The amount of work can be severely reduced - simultaneously significantly enhancing the DSP system's flexibility - by using development environments that provide a high number of the necessary functions and interfaces. We will present a 24 GHz FM-CW Doppler radar front-end at vertical incidence. The radar front-end is connected to a DSP system based on a TI C30 family Digital Signal processor. The system was implemented for its application with a radar rain profiler using the MATLAB development environment (MDE) and an additional DSP hardware specific MATLAB toolbox. Steering and controlling the radar operation as well as sweep synchronous data sampling has been implemented using the MDE. The DSP software for the analyzer is a library written in assembly language. In addition, the MDE also was used to generate code for data processing, retrieval and data storage on the host computer.
The DSP hardware, Harmonie by SINUS Messtechnik GmbH, was originally developed for "acoustic" spectroscopy. It covers the frequency range up to a sampling rate of 51.2 kHz. The DSP hardware specific MATLAB toolbox was applicable to the new task without severe problems. This shows the power and the flexibility of the MDE and of the modular coding philosophy. The MATLAB code can be used in the MDE in an interpreter operation mode for highest flexibility. It also is available in compiled form, which does not require the MDE for operation. In both modes the system can be set up and running (including radar hardware) within 5 minutes. Due to the multiple input and output channels (2, 4 and 8 each available, boards can be cascaded) of the DSP hardware it is even possible to set up a small network of radar rain profilers operating absolutely synchronous. The DSP hardware provides 7 additional low speed input channels. These can be easily used to record data from additional instruments, e.g. actual weather data, due to the power and the flexibility of the MDE, the hardware specific MATLAB toolbox and the modular code philosophy.
Due to the restricted sampling range the radar rain profiler is only able to cover 8 height ranges with a velocity range of 20 m/s - distributed by user decision in the range -20 m/s to 0 m/s up to 0 m/s to +20 m/s. This meets the intention of the system, which shall serve as Doppler profiler for precipitation near ground. The user interfacecoded under the MDE will be presented and explained. Furthermore, calibration measurements and sample results recorded under different rain conditions will be displayed and discussed.
The presented DSP hardware in its future, somewhat extended form is sufficient for a high number of tasks in atmospheric research and remote sensing. However, many applications in remote sensing require DSP systems with a higher performance. In this context it is noteworthy that the MDE actually supports direct access for two DSP types. One of these types is the TI 32C6x family. For DSP hardware containing a supported Digital Signal processor it is possible to implement comparable DSP code packages that enable the direct access to the processor.
Poster Session 4D, Signal Processing Poster
Sunday, 10 August 2003, 1:30 PM-3:30 PM
Previous paper Next paper