New Developments
This edition of the Observational Status Summary includes descriptions of two new instrumental developments that will radically enhance the VLBA's capabilities.
- 2-Gbps Continuum Bandwidth: New technologies for digital signal processing, data recording, and correlation, have made possible an expansion of the VLBA's continuum bandwidth to 256 MHz per polarization. This corresponds to a recorded data rate of 2 Gigabits per second (Gbps), a 16-fold increase over the sustainable rate of 128 Megabits per second that was available when the VLBA was inaugurated, and 4 times the current standard data rate. The signal/noise ratio in a typical continuum observation will be improved by factors of 2-4.
Overviews of the new wideband instrumentation are presented in sections on the ROACH Digital Backend and Mark 5C Recorder. More detailed information is available in the Sensitivity Upgrade memo series. Questions can be submitted via the NRAO Helpdesk.
- Wideband 6-cm Receiver: The VLBA's original 6 cm receivers are being replaced with substantially upgraded systems based on the EVLA design. An expanded tuning range, covering 3.9 - 7.9 GHz, will enable observations of the 6.7-GHz methanol maser line, and reduced system noise will enhance continuum sensitivity by about 35%. This receiver system supports a full 4-IF data-transmission configuration, allowing dual-polarization observations at two widely separated frequencies in the overall range.
Installations of upgraded receivers, and the accompanying new feeds, have been completed at eight stations. Full ten-station operation is scheduled to become available in August 2012.
Preliminary information on the new receiver system's performance is incorporated in the "Receiver Frequency Ranges & Performance" table elsewhere in this document. An NRAO eNews article (Walker & Hayward 2011) presents a comprehensive description of the new receiver and its first light in November 2011.
