SRT-2 Team Summary
The SRT-2 project is to test and operate a new instructional radio telescope. The SRT-2 is a replacement for the SRT telescope originally designed at Haystack Observatory and purchased from CASSI corporation. It is a complete redesign of the original SRT concept. The system is designed primarily to observe the 21-cm galactic HI line.
Student from the Radio Astronomy course (29:186, Spring 2010) constructed the antenna and receiver. This year's students (Spring 2012) will build and test the antenna motion control system and the spectrometer . There will be two teams of students responsible for the antenna motion control and receiver/spectrometer subsystems respectively. We expect to have a complete operating system by early May 2012.
Antenna
The original SRT used a parabolic dish and 2-axis motorized mount originally designed for TV satellite reception. We found that the mount was not reliable, especially with the high wind loading of the 3 m diameter dish, and after 2 years of use,the mount weld broke and the dish surface lost several panels. The SRT-2 design uses an array of four 45-element Yagi antennas built by Directive Systems arranged in a 2x2 array. The antenna gain should be 26 dB, with a FWHM primary beam of 8 deg, similar to a 3 m dish. The mount is be a commercial 2-axis positioner (Yaesu G5500) with a serial interface, so that the telescope can be controlled and its position displayed on a sky map using an inexpensive planetarium program (Starry Night Pro 6).
Receiver and Spectrometer
The receiver is a conventional single-conversion heterodyne design. The first low noise amplifier (25 dB gain, 0.7 dB NF) and narrowband filter (10 MHz centered at 1420 MHz) will be located at the antenna. The down-converted IF frequency (150 MHz, 10 MHz BW) will likely be a commercially available USB-based spectrum analyzer. We will develop simple Python programs to display, average, and baseline-subtract spectra.
Project Notes
All - A good general online reference for radio astronomical instrumentation (antennas, receivers, and spectrometers) is the Haystack Observatory SRT site.