Development of Software‐Defined Multichannel Receiver for EAR

Abstract

The Equatorial Atmosphere Radar (EAR) is a very high frequency Doppler radar operated with an active phased‐array antenna system at 47 MHz. It is located at the equator in Kototabang, West Sumatra, Indonesia (0.20°S, 100.32°E) and was established with a single receiving channel. Here, we present the development of a multichannel receiver system for EAR using a combination of the Universal Software Radio Peripheral X300 (USRP X300) series and GNU Radio software. Two USRP X300 devices, corresponding to four receiving channels, were synchronized using 10‐MHz reference clocks and a one‐pulse per second signal. Received signals were collected by the existing EAR antennas, fed to the USRPs for digital conversion, and then stored on a hard disk drive. Signal postprocessing was carried out to estimate wind velocity profiles. Wind profiles estimated using full correlation analysis indicate that the spaced antenna method from multichannel receivers agrees well with EAR standard observational data.

Evaluation of EAR Spaced Antenna Performance Using Multiple Receiving Antennas Orientations

“…It is worth noting that the EAR standard data are expected to produce less error in this case, because the standard data use all of the five beams (vertical and four oblique with 10° zenith angle) steered on a pulse‐to‐pulse basis but the FCA‐estimated data uses only the vertical beam. The OLS linear regression is therefore suitable to represent the performance of the FCA‐estimated horizontal wind where the error is expected to be larger based on previous work in Aris et al (2019). Both results from Figures 8and 9 are produced by averaging more than 1 hr of data.…”

“…However, there was an additional procedure, phase correction, in the real-time signal processing to overcome the slight imperfection in the synchronization of the multiple X300 channels. As described in the previous work (Aris et al, 2019), a slight phase difference existed between all channels, on the same board and across different boards, because there was no internal mechanism to perform phase alignment. Therefore, an external mechanism had to be implemented for phase correction across all channels.…”

“…The recorded data in the previous study required a large amount of HDD space in order to be stored for post processing (Aris et al, 2019). To overcome this limitation, a software system that combines the radar data acquisition and the atmospheric radar signal processing was developed.…”

“…The details of the EAR system design and specifications are well elaborated by Fukao et al (2003). Furthermore, Aris et al (2019) described the configuration of the newly installed multichannel receiver, which consists of a USRP X300 device being fed by a signal distributed from the directional coupler. This configuration is utilized so that the EAR standard observation system (single receiver) could be retained in operation alongside the multichannel system.…”

“…Recently, research has been carried out by Aris et al (2019) to enable the SA capability for the Equatorial Atmosphere Radar (EAR) with the development of a software‐defined multichannel receiver. The EAR is a 47‐MHz Doppler radar located in West Sumatra, Indonesia (0.20°S, 100.32°E).…”