|The MINT Telescope||PrincetonCMB|
· Data Aquisition
· Local Oscillator
The MINT telescope
MINT conditions the 139-141 GHz and 149-151 GHz signals from the sky first with an SIS, then with a HEMT, and finally correlates everything digitally. As an interferometer operating at 145 GHz, MINT is not very succeptible to point source contaminations. With its digital correlator, MINT is not terribly succeptible to thermal variations in its electronics, and can recover the power spectra of its signals.
How does MINT work? The signal from the sky shines on each of the four telescopes, then continues along the following path:
Basically, the SIS very noisily mixes down the signal by 145 GHz -- using the phase maintained by the phase locked loop that supplies the local oscillations -- into a 4 to 6 GHz signal. The HEMT somewhat noisily amplifies the signal, then passes it to the channelizer, which splits the signal into 4 500 MHz wide bands, and mixes down these bands. Each digitizer and correlator board looks at one of the bands from all 4 of the telescopes, first digitizing the band at 1 GHz (twice the Nyquist), and then performing a Monte Carlo calculation (using the random system noises of the telescopes) to extract the correlations between lagged and unlagged pairs of the telescopes.
Of course, there are many other major components to MINT: