Sample clock frequency offset (SCFO) Resolution Team 3 (RT-3) investigation. (arXiv:1812.06972v1 [eess.SP])
<a href="http://arxiv.org/find/eess/1/au:+Carlson_B/0/1/0/all/0/1">Brent Carlson</a>, <a href="http://arxiv.org/find/eess/1/au:+Boven_P/0/1/0/all/0/1">Paul Boven</a>, <a href="http://arxiv.org/find/eess/1/au:+Caputa_K/0/1/0/all/0/1">Kris Caputa</a>
This Resolution Team 3 (RT-3) report contains the results of the
investigation of key aspects of the proposed Sample Clock Frequency Offset
(SCFO) scheme for the Mid SKA1 telescope. This is a scheme, first proposed by
one author (Carlson) at a meeting at the SKAO 25-Jan-2013, to digitize the
analog signal at each antenna at a slightly different sample rate and transmit
the data to the CSP Mid.CBF for subsequent digital re-sampling to a common
sample clock frequency before channelization, correlation, and beamforming. The
primary purpose for doing this is to cause de-correlation of sample
clock-related self-interference to be able to improve correlated and beamformed
signal quality. This report includes an investigation of the efficacy of the
method, investigation of its implementation by SADT, DISH, and CSP,
presentation of further supporting modeling results augmenting the original
modeling work, a note on expansion to SKA-2, as well as possible draw-backs and
concerns. Finally, there are potential additional benefits in signal quality in
implementing the SCFO scheme, in particular de-correlation of aliased RFI
(particularly for Nyquist Zone-2 digitized signals) as well as relaxation of
signal-chain anti-aliasing filters transition band roll-off and reject band
attenuation prior to digitization in the antenna.
This Resolution Team 3 (RT-3) report contains the results of the
investigation of key aspects of the proposed Sample Clock Frequency Offset
(SCFO) scheme for the Mid SKA1 telescope. This is a scheme, first proposed by
one author (Carlson) at a meeting at the SKAO 25-Jan-2013, to digitize the
analog signal at each antenna at a slightly different sample rate and transmit
the data to the CSP Mid.CBF for subsequent digital re-sampling to a common
sample clock frequency before channelization, correlation, and beamforming. The
primary purpose for doing this is to cause de-correlation of sample
clock-related self-interference to be able to improve correlated and beamformed
signal quality. This report includes an investigation of the efficacy of the
method, investigation of its implementation by SADT, DISH, and CSP,
presentation of further supporting modeling results augmenting the original
modeling work, a note on expansion to SKA-2, as well as possible draw-backs and
concerns. Finally, there are potential additional benefits in signal quality in
implementing the SCFO scheme, in particular de-correlation of aliased RFI
(particularly for Nyquist Zone-2 digitized signals) as well as relaxation of
signal-chain anti-aliasing filters transition band roll-off and reject band
attenuation prior to digitization in the antenna.
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