A practical algorithm for wideband bandwidth synthesis (WBWS) for geodetic VLBI (very long baseline interferometry) is presented in this paper. A conventional bandwidth synthesis technique was developed for geodetic VLBI in the 1970s in order to increase the resolution of the observed delay by synthesizing multiple receiving frequency windows. The synthesized bandwidth has been expanding over the years and is now about 1 GHz. Recently, a wideband VLBI system consisting of multiple wideband frequency windows with a width of 1 GHz each and a total bandwidth exceeding 10 GHz, has been proposed by the International VLBI Service for Geodesy and Astrometry (IVS) in order to achieve millimeter precision of position measurements. WBWS is a technique used for data processing in a wideband VLBI system. In conventional bandwidth synthesis, phase calibration (PCAL) signals are artificially injected at a front end and used to synthesize the channels. However, an algorithm without the use of PCAL signals was developed for WBWS so that it can be applied to a system without PCAL equipment. The algorithm includes the estimation of the differential total electron content in the ionosphere working with data with signal-to-noise ratios as low as 10 per band. The algorithm was successfully applied to 24 h continuous wideband VLBI observations.
[1]
C C Counselman,et al.
Very-Long-Baseline Radio Interferometry: The Mark III System for Geodesy, Astrometry, and Aperture Synthesis
,
1983,
Science.
[2]
Alan Whitney,et al.
Precision Geodesy Using the Mark-III Very-Long-Baseline Interferometer System
,
1985,
IEEE Transactions on Geoscience and Remote Sensing.
[3]
Toshihisa Sato,et al.
The first US-Japan VLBI test observation by use of K-3 system at the Radio Research Laboratories.
,
1984
.
[4]
Precision Geodesy via Radio Interferometry
,
1972,
Science.
[5]
Gino Tuccari,et al.
Design Aspects of the VLBI2010 System. Progress Report of the IVS VLBI2010 Committee, June 2009.
,
2009
.
[6]
A. Rogers.
Very Long Baseline Interferometry with Large Effective Bandwidth for Phase‐Delay Measurements
,
1970
.
[7]
Alan E. E. Rogers,et al.
A very-long-baseline interferometer system for geodetic applications
,
1976
.
[8]
Tetsuro Kondo,et al.
High-order Sampling Techniques of Aliased Signals for Very Long Baseline Interferometry
,
2012
.
[9]
Tetsuro Kondo,et al.
KSP bandwidth synthesizing software
,
1999
.