arXiv subjects
Publications and source records attributed to V Chandrasekar.
This paper elaborates the signal processing techniques for weather radars and their relative merits with respect to a similar phased array configuration. As will be shown in paper that this sub-aperture based configuration gives spatial resolution improvement compared to its phased array counterpart. This is the major benefit and a number of smaller benefits which are elaborated here for weather radar system.
The NASA dual-frequency, dual-polarization, Doppler radar (D3R) is an important ground validation tool for the global precipitation measurement (GPM) mission dual-frequency precipitation radar (DPR). The D3R has undergone extensive field trials starting in 2011 and continues to provide observations that enhance our scientific knowledge. To further enhance its capabilities, the Intermediate frequency (IF) electronics, digital receiver and waveform generation subsystems have been upgraded. Due to the new, more flexible architecture, this upgrade enables more research frontiers to be explored with better performance. One of the primary motivations for this upgrade is to enable enhanced radar sensitivity and increase range resolution to 30 meters. In this work, the D3R system upgrade will be discussed with a focus on the key upgrade design features to obtain better sensitivity and a flexible waveform capability.
This paper develops the use of Inter-pulse frequency diversity scheme for a weather radar system. It establishes the performance of frequency diversity technique comparing it with other inter-pulse schemes for weather radar systems. Inter-pulse coding is widely used for second trip suppression or cross-polarization isolation. Here, a new inter-pulse scheme is discussed taking advantage of frequency diverse waveforms. The simulations and tests of performance are evaluated keeping in mind NASA dual-frequency, dual-polarization, Doppler radar (D3R). A new method is described to recover velocity and spectral width due to incoherence in samples from change of frequency pulse to pulse. This technique can recover the weather radar moments over a much higher dynamic range of the other trip contamination as compared with the popular systematic phase code, for second trip suppression and retrieval.
This paper describes the design and implementation of intra-pulse polyphase codes for a weather radar system. Algorithms to generate codes with good correlation properties are discussed. Thereafter, a new design framework is described, which optimizes the polyphase code and corresponding mismatched filter, using a cost/error function, especially for weather radars. It establishes the performance of these intra-pulse techniques with specific application towards second trip removal. The developed code is implemented on NASA D3R, which is a dual-frequency, dual-polarization, Doppler weather radar system.