  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.
