We present a relatively simple time domain method for determining the bandpass response of a system by injecting a nanosecond pulse and capturing the system voltage output. A pulse of sub-nanosecond duration contains all frequency components with nearly constant amplitude up to 1 GHz. Hence, this method can accurately determine the system bandpass response to a broadband signal. In a novel variation on this impulse response method, a train of pulses is coherently accumulated providing precision calibration with a simple system. The basic concept is demonstrated using a pulse generator-accumulator setup realised in a Bedlam board which is a high speed digital signal processing unit. The same system was used at the Parkes radio telescope between 2-13 October 2013 and we demonstrate its powerful diagnostic capability. We also present some initial test data from this experiment.
@article{arxiv.1502.05862,
title = {Bandpass calibration of a wideband spectrometer using coherent pulse injection},
author = {Nipanjana Patra and Justin D. Bray and Paul Roberts and Ron D. Ekers},
journal= {arXiv preprint arXiv:1502.05862},
year = {2017}
}
Comments
11 pages, 9 figures, submitted to Experimental Astronomy