Technical Memo

Increasing SVLBI Sensitivity Through Higher Data Rates

Increasing SVLBI Sensitivity Through Higher Data Rates[pdf:95KB] is the third in a series of white papers by Jim Springett of NeoComm, to describe how to implement tracking stations for advanced Space VLBI missions in a low-cost manner. The first paper in the series is "Achieving Future SVLBI Gbps Data Rates". The second paper in the series is "SVLBI Ground Station Segmented Architecture"

This paper explores the tradeoffs that need to be made in selecting an observing bandwidth for future Space VLBI missions. It shows ways to manipulate the VLBI science data as the VLBI observing bandwidth is expanded from 256 MHz to 1024 MHz, so as to increase the mission sensitivity, yet keep the down-link data constrained within the bandwidth limits of the 37-38 GHz band. This manipulation involves some non-traditional approaches: data rate increases that are not multiples of 2 and/or 1-bit x 2-bit correlation.

The results show that simple manipulations are possible that offer modest increases in sensitivity, and that more complex (but still straightforward manipulations) can provide greater increases in sensitivity. The ultimate factor of 2 is achievable through analog modulations still to be verified.

(Joel Smith, 08-mar-2002)