A new receiver for the SRT has been designed and built at Haystack Observatory to enable interferometry with two or more antennas. The block diagram and picture of the receiver are shown in the linked files. All the necessary hardware for the receiver, including the control computer, is contained in one box. The system has a motherboard which communicates to the hardware using USB 2.0 and runs under Linux Gentoo. The system is capable of performing interferometry and thus has an inbuilt correlator that operates in real time. For the correlation to be fast enough, a Digital Signal Processor (DSP) has been used to crunch the fast fourier transforms necessary for the calculation of cross-correlation. All the embedded code in the DSP is written in assembly and C. Furthermore, in order to enable VLBI-mode interferometry with unconnected antennas, the receiver has a GPS timing capability.
Since the box containing the new receiver is large, it can be setup inside the control room and connected to the antenna with an optical fiber. The antenna contains the feed system and a pre-amplifier. The block diagram of the helical feed is shown here. The pictures below shows the pre-amp and a closeup of the antenna with the new feed.
