Formatter

The formatter selects the desired bit streams from the samplers, adds time tags, and supports various other functions required to record efficiently on the VLBA's original tape-based data acquisition system. Although no longer required for disk-based recording, these functions are still used in the transitional Mark 5A system mentioned in Section 6.16. Auxiliary detection of up to 16 pulse-calibration tones are state counts also is supported in the formatter. This subsection will become obsolete when the new digital back ends are installed on the VLBA in 2009.