研究成果藝廊
In-Phase/Quadrature Down Converter Production Bracket, YTLA Project
This photo represents the first production in-phase/quadrature down converter designed for the YTLA project as an upgrade to the AMiBA analog correlator system. The design was based on the results of a prototype development conducted the previous year.
Seven of these I/Q down converters were initially assembled and tested to support the Y-polarization commissioning work for our 7-element system. The concept is based on producing two local oscillators that are in phase quadrature with respect to each other and are used to separately down convert a single IF input signal (2-18 GHz) into two separate baseband (0-2 GHz) I and Q output signals. Each of these baseband signals consist of both sidebands, i.e., "lower sideband minus LO" and "LO minus upper sideband". A second quadrature performed within the digital domain allows the separation of lower and upper sidebands by trigonometric manipulation of even and odd functions. An additional seven units were subsequently produced to support the X-polarization. Designed by John Kuroda, Derek Kubo, assembled and tested by Solomon Ho, Jen-Chieh Cheng, and Ranjani Srinivasan. Digital backend sideband separation provided by Chaote Li, Homin Jiang.