scholarly journals A procedure to correct the effects of a relative delay between the quadrature components of radar signals at base band

2005 ◽  
Vol 23 (1) ◽  
pp. 39-46
Author(s):  
◽  
La Hoz ◽  
◽  
Keyword(s):  
Radar Data ◽  
Center Frequency ◽  
Digital Receiver ◽  
The Real ◽  
Incoherent Scatter ◽  
Singular Region ◽  
Analysis Strategies ◽  
Relative Delay ◽  
Base Band ◽  
Band Signal

Abstract. The real and imaginary parts of baseband signals are obtained from a real narrow-band signal by quadrature mixing, i.e. by mixing with cosine and sine signals at the narrow band's selected center frequency. We address the consequences of a delay between the outputs of the quadrature mixer, which arise when digital samples of the quadrature baseband signals are not synchronised, i.e. when the real and imaginary components have been shifted by one or more samples with respect to each other. Through analytical considerations and simulations of such an error on different synthetic signals, we show how this error can be expected to afflict different measurements. In addition, we show the effect of the error on actual incoherent scatter radar data obtained by two different digital receiver systems used in parallel at the EISCAT Svalbard Radar (ESR). The analytical considerations indicate a procedure to correct the error, albeit with some limitations due to a small singular region. We demonstrate the correction procedure on actually afflicted data and compare the results to simultaneously acquired unafflicted data. We also discuss the possible data analysis strategies, including some that avoid dealing directly with the singular region mentioned above.

Design and Implementation of Multi-Frequency Digital Receiver Based on FPGA

2014 ◽  
Vol 643 ◽  
pp. 117-123
Author(s):  
Yu Peng Liu ◽  
Chao Du ◽  
Dong Lin Liu
Keyword(s):  
Digital Technology ◽  
Wide Band ◽  
Radar System ◽  
Center Frequency ◽  
Beam Forming ◽  
Digital Receiver ◽  
Effective Implementation ◽  
Great Performance ◽  
Implementation Method ◽  
Band Signal

Recently, the concept of software radar has been proposed. The wide application of the digital technology has become a trend. With the development of modern radar system, the system requires higher and higher performance to the radar receiver. The technology of digital receiver has become an effective implementation method for high-accuracy and wide-band radar receiving systems. However, most of the digital receiver can only receive one wide-band signal with one center frequency. A multi-frequency digital receiver which can receive several center frequencies of signal simultaneously [1] is discussed in this paper. We also describe the theory and the design about digital receiver, introduce digital downconversion (DDC), FIR and decimation, digital beam forming and channel calibration. Based on the research, a realization of multi-frequency digital receiver based on FPGA is put forward. The analysis and simulation is made and the result shows the design of great performance.

Analysis of incoherent scatter radar data from non-thermal F-region plasma

1989 ◽  
Vol 51 (6) ◽  
pp. 483-495 ◽  
Author(s):  
K. Suvanto ◽  
M. Lockwood ◽  
K.J. Winser ◽  
A.D. Farmer ◽  
B.J.I. Bromage
Keyword(s):  
Radar Data ◽  
Incoherent Scatter Radar ◽  
Incoherent Scatter ◽  
F Region ◽  
Scatter Radar ◽  
Region Plasma

scholarly journals Modelling of N<sub>2</sub>1P emission rates in aurora using various cross sections for excitation

2009 ◽  
Vol 27 (6) ◽  
pp. 2545-2553 ◽  
Author(s):  
M. Ashrafi ◽  
B. S. Lanchester ◽  
D. Lummerzheim ◽  
N. Ivchenko ◽  
O. Jokiaho
Keyword(s):  
Cross Sections ◽  
Radar Data ◽  
Optical Measurements ◽  
Emission Rates ◽  
Incoherent Scatter ◽  
Temporal And Spatial ◽  
The Cross ◽  
Auroral Emissions ◽  
Auroral Imager ◽  
Magnetic Zenith

Abstract. Measurements of N21P auroral emissions from the (4,1) and (5,2) bands have been made at high temporal and spatial resolution in the region of the magnetic zenith. The instrument used was the auroral imager ASK, situated at Ramfjordmoen, Norway (69.6 N, 19.2 E) on 22 October 2006. Measurements from the European Incoherent Scatter Radar (EISCAT) have been combined with the optical measurements, and incorporated into an ionospheric model to obtain height profiles of electron density and emission rates of the N21P bands. The radar data provide essential verification that the energy flux used in the model is correct. One of the most important inputs to the model is the cross section for excitation to the B3Πg electronic state, as well as the cross sections to higher states from which cascading into the B state occurs. The balance equations for production and loss of the populations of all levels in each state are solved in order to find the cascade contributions. Several sets of cross sections have been considered, and selected cross sections have been used to construct "emission" cross sections for the observed bands. The resulting brightnesses are compared with those measured by ASK. The importance of specific contributions from cascading is found, with more than 50% of the total brightness resulting from cascading. The cross sections used are found to produce a range of brightnesses well within the uncertainty of both the modelled and measured values.

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