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:

• Cassagrainian Optical System
  • Ground Shield
  • 300 mm Diameter Parabolic Primary Mirror
  • 91 mm Diameter Hyperbolic Secondary Mirror, Supported 84 mm Above the Primary by G-10
• Liquid Helium Cooled Dewar
  • Quartz Window
  • Corrugated Horn Waveguide
  • Coupler
  • 145 GHz SIS Mixer at about 3K
  • HEMT Amplifier at about 12K
• Analog Channelizer Card
  • 4.5 and 5.5 GHz Off-the-Shelf Mixers
  • 4 500 MHz Wide TChebyshev Band-Pass Filters
• Digitizer and Correlator Card
  • Attenuator Chips
  • 1 GHz 2-Bit Digitizer with Built-In 2 Times Multiplexer Chips
  • 8 Times Multiplixer Chips
  • Reprogrammable FPGA Xilinx XCV1000 Correlator Chips
• Data PC
  • National Instruments DIO-96 Data Acquisition Card
  • Hard Drive Storage
  • Telemetry Modem and Transmitter
• Snoopy PC

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:

• Local Oscillator Box
• Dewar Backpack
  • 100 MHz Phase Locked Loop 145 GHz Local Oscillator Supply
  • SIS and HEMT Bias Supply Cards
  • 3K Cold Head and 300K Backpack Temperature Servo Cards
• Dewar Refrigerator System
  • Cryo-Star 3K Liquid Helium Cold Head
  • Liquid Helium Compressor
• Electronics Cooling System
  • Water Chiller, Heater, and Pump
  • Digitizer Crate Fans
• Power Supply
  • Several Kilowatt Generator
  • Main Power Box
  • Digitizer Power Supplies
• Base
  • Physical Structure and Pointing System
  • Wiring and Cabling
• Data Acquisition Control System
  • Digital Control Pointing PC
  • Correlation and Housekeeping Storage Data PC
  • Data Recording Snoopy PC
  • User Interface PC