diff --git a/doc/papers/2011/europar/dispersed-signal.jgr b/doc/papers/2011/europar/dispersed-signal.jgr index 51da2bc66a1ce05a347892834a6b89499395fce1..e43738454ffe427cef25575831b5d62863e36cbe 100644 --- a/doc/papers/2011/europar/dispersed-signal.jgr +++ b/doc/papers/2011/europar/dispersed-signal.jgr @@ -15,6 +15,14 @@ newgraph size 2 shell : seq 0 3 | awk '{ f = (512 + 200 + $1 * 1/16/3)*200/1024; printf "hash_label at %d : %.3f\n",$1,f; }' +newline + linetype dotted + pts 0.82 -1 0.82 4 +(* +copycurve + pts 0.52 -1 0.52 4 +*) + newline color 0 0 1 linethickness 2.0 @@ -22,24 +30,15 @@ newline pts shell : ./dispersed-signal-data-2.sh 0 -newline - color 0 0 1 - linethickness 2.0 - linetype solid +copycurve pts shell : ./dispersed-signal-data-2.sh 1 -newline - color 0 0 1 - linethickness 2.0 - linetype solid +copycurve pts shell : ./dispersed-signal-data-2.sh 2 -newline - color 0 0 1 - linethickness 2.0 - linetype solid +copycurve pts shell : ./dispersed-signal-data-2.sh 3 @@ -63,6 +62,10 @@ newgraph shell : seq 0 3 | awk '{ f = (512 + 200 + $1 * 1/16/3)*200/1024; printf "hash_label at %d : %.3f\n",$1,f; }' nodraw +newline + linetype dotted + pts 0.82 -1 0.82 4 + newline color 1 0 0 linethickness 2.0 @@ -70,24 +73,15 @@ newline pts shell : ./dispersed-signal-data-2.sh 0 noshift -newline - color 1 0 0 - linethickness 2.0 - linetype solid +copycurve pts shell : ./dispersed-signal-data-2.sh 1 noshift -newline - color 1 0 0 - linethickness 2.0 - linetype solid +copycurve pts shell : ./dispersed-signal-data-2.sh 2 noshift -newline - color 1 0 0 - linethickness 2.0 - linetype solid +copycurve pts shell : ./dispersed-signal-data-2.sh 3 noshift diff --git a/doc/papers/2011/europar/lofar.pdf b/doc/papers/2011/europar/lofar.pdf index 16b8a995b9ebca62ea6be6ac4d045f57336b2228..0ec923afd8d24217b9fd3032cd771fe9ef60e869 100644 Binary files a/doc/papers/2011/europar/lofar.pdf and b/doc/papers/2011/europar/lofar.pdf differ diff --git a/doc/papers/2011/europar/lofar.tex b/doc/papers/2011/europar/lofar.tex index 5249c58a20731eb908410f1b965a79cc89d93a03..5c0c5a3d1d983e3328e1572d8716303421b5764b 100644 --- a/doc/papers/2011/europar/lofar.tex +++ b/doc/papers/2011/europar/lofar.tex @@ -229,7 +229,7 @@ Another major component in the pulsar-observation pipeline is real-time dedisper \end{minipage} \end{figure} -Dedispersion is performed in the frequency domain, effectively by doing a 4K~Fourier transform (FFT) that splits a 12~KHz channel into 3~Hz subchannels. The phases of the observed samples are corrected by applying a Chirp function~\cite{...}, i.e., by multiplication with precomputed, subchannel-dependent, complex weights. These multiplications are programmed in assembly, to reduce the computational costs. A backward FFT is done to revert to 12~KHz channels. +Dedispersion is performed in the frequency domain, effectively by doing a 4K~Fourier transform (FFT) that splits a 12~KHz channel into 3~Hz subchannels. The phases of the observed samples are corrected by applying a chirp function~\cite{...}, i.e., by multiplication with precomputed, channel-dependent, complex weights. These multiplications are programmed in assembly, to reduce the computational costs. A backward FFT is done to revert to 12~KHz channels. Figure~\ref{fig:dedispersion-result} shows the effectiveness of channel-level dedispersion, where we observed pulsar J0034-0534 with a pulse period of 1.88~ms. By applying dedispersion, the effective time resolution is improved from 0.51~ms to 0.082~ms, revealing a more detailed pulse and a better signal-to-noise ratio. Dedispersion thus contributes significantly to the data quality, but it also comes at a significant computational cost due to the two FFTs it requires. It demonstrates the power of using a \emph{software\/} telescope: the pipeline component was implemented, verified, and optimized in only one month time.