UBC Theses and Dissertations
Coherent local oscillators for a 21 cm. supersynthesis experiment Shimozawa, David Tetsuo
A method based on phaselock techniques, for synchronizing the local oscillator signals in a proposed two-dish supersynthesis at 1420 MHz is presented. To demonstrate the feasibility of this method, the design and construction of a working system that provides phase-coherent, 1390 MHz signals at two sites, separated by a time-varying path length, is described. The phase accuracy of this system is ±5°. A provision for introducing a known phase difference between the two signals, in a manner that is suitable for interfacing with a digital computer, is included. Also, operation of the system over a frequency range greater than the expected range of doppler shift is possible, without the risk of locking to a wrong sideband. Transistor microwave oscillators at 1.4 GHz are used as voltage-controlled oscillators in this system. The performance of these devices is compared with that of the conventional voltage-controlled crystal oscillator/multiplier chain. Test results are given, which indicate that the system is suitable for use in an operational environment.