Photonics Local Oscillator Receiver, GLT Project
Internal photos of Photonics LO Receiver instrument. Left - top view of optical and RF components and DC power supplies. Right - bottom view of optical components, DC power supply and ADAM monitor and control.
This instrument works in conjunction with the Photonics LO Transmitter unit and accepts a single input fiber over 1557.2 nm carrying three RF signals: 100 MHz maser reference, 15.75 GHz pilot tone, and 18-31.5 GHz LO. The 100 MHz tone is phase locked to a 10 MHz crystal and serves as a low frequency reference within the antenna receiver cabin. The 18-31.5 GHz LO is sent to the Signal Test Source for distribution to the receivers and generation of mm-wave test injection tones. The 15.75 GHz pilot tone is filtered and retransmitted down the same fiber back to the Photonics LO Transmitter unit at a wavelength of 1561.1 nm for roundtrip phase stability monitoring. This instrument was design and constructed in the ASIAA Hilo office by Derek Kubo and EAO, and was deployed into the telescope at Thule Air Base in November of 2017.