Improving weather radar observations using pulse‐compression techniques

Abstract

Pulse-compression techniques have been used for many years to increase sensitivity and range resolution in military and air traffic control radar systems. However, their application to ground-based weather radar has, so far, been very limited and restricted to research applications. This article describes the practical implementation of pulse compression using non-linear frequency modulation (NLFM) in a commercial digital processor/receiver and demonstrates its application to operational weather radars.Three case studies are presented, including the first application of pulse compression to ground-based travelling wave tube (TWT) weather radars. TWT radars use coherent transmitters with relatively low peak power compared to traditional magnetron or klystron systems, so in this case the sensitivity gain is crucial. The cases are from two different operational radars and illustrate the improved range resolution and sensitivity gain obtained using NLFM pulses compared to traditional simple pulses. Observations obtained using NLFM 40 µs pulses were nearly 15 dB more sensitive than those recorded with lower resolution using 1 µs simple pulses. A comparison of concurrent precipitation observations obtained with a TWT radar using pulse compression and low peak power (NLFM 40 µs and 8 kW) and a nearby traditional magnetron weather radar (2 µs and 250 kW) is also presented. The higher power system was more sensitive by less than 4 dB, but the improved resolution in the pulse compression allowed for enhanced Doppler filtering of ground clutter.

Assessment of virtual towers performed with scanning wind lidars and Ka-band radars during the XPIA experiment

“…The increasing need of monitoring the atmospheric boundary layer for a broad range of technological and scientific pursuits -such as for meteorology (Banta et al, 2002;Calhoun et al, 2006;Emeis et al, 2007;Horanyi et al, 2015;Vanderwende et al, 2015;Bonin et al, 2015), renewable energy (Thresher et al, 2008;Jones and Bouamane, 2011;Aitken et al, 2014;Iungo, 2016) and air traffic management (George and Yang, 2012;Smalikho and Banakh, 2015) -has led to a rapid development of remotesensing measurement techniques, such as wind lidars Cariou, 2015;Simley and Pao, 2012;Iungo andPorté-Agel, 2013, 2014) and radars (Farnet and Stevens, 1990;O'Hora and Bech, 2007;Hirth and Schroeder, 2013;Hirth et al, 2015). Compared to classical meteorological towers, remote-sensing instruments allow easier deployment, enhanced capability of varying deployment locations and potentially lower costs.…”

A frequency-sharing weather radar network system using pulse compression and sidelobe suppression

“…The purpose of employing pulse compression in our system is entirely different from that in conventional single radar systems. In conventional single radars, pulse compression is employed in order to improve both performances of range resolution and sensitivity (i.e., target detection capability) under the limitation of peak power [12]. On the other hand, in the WRNS of this study, pulse compression is for removing interferences from other radars by employing mutually uncorrelated codes, which will be addressed in detail in Section 3.…”

“…Considering conditions (12) and (13) of an orthogonal code set, it is clear that the smaller the values of ASPs and CPs of a nearly orthogonal code set are, the closer the code set is to an orthogonal code set.…”

Automated Processing of Doppler Radar Data for Severe Weather Warnings

“…Extensive clear air echoes are commonly reported observed on the WSR-88D and primarily in certain parts of the United States (Wilson et al, 1998). Table 5 shows the sensitivity of a small sample of radars including the WSR-88D, WSR-98D (S Band radars) and three C Band radars, one of which is a low powered (8 kW), travelling wave tube (TWT) solid sate pulse compression radar (Joe, 2009;Bech et al, 2004;O'Hora and Bech, 2007). In units of dBZ, the sensitivity is a function of range.…”