Table of Contents
Initial Structure
Current Structure
Control Room
- Weniger 635B contains all of the control, testing and maintenance equipment for both the radio telescope and the
OSU PicoSatellite Program ground station.
Parabolic Dish, Resonator, Antenna and Low-Noise Block
- The dish has a diameter of 3.0 m (10 ft), and the beam waist in the focal plane is 21 cm at 1.4 GHz.
Thus, the gain is 23 dB.
- The resonator traps the electromagnetic radiation for a short time resulting in a power gain of 14 dB.
- The antenna is a simple quarter wavelength metal and ground plane dipole antenna.
- The most critical stage of the entire telescope is the initial ultra-low noise amplifier, filters,
second-stage amplifier and the down-converting mixer. This is referred to collectively as the low noise block or LNB.
- The local oscillator frequency is selected such that the down-converted 1.4 GHz signals appear between 73.0 and 74.6 MHz,
a band reserved for radio astronomy.
- The overall gain of the LNB is 40 dB, for a total gain of 77 dB.
Mechanical Structure and Electronics Bay
- The lightweight aluminum structure is driven by two Yaesu rotators providing azimuthal and elevation motion.
String potentiometers provide position information. Safety latches can be engaged to lock the dish in the
upright safety position when excessive wind-induced torque is detected.
- A weatherproof cabinet houses critical electronics (local oscillator, filters and final amplifier), a UPs,
a USB digital and analog IO device and motor controls.
Signal Analysis
- The down-converted signal passes through bandpass filters at 73 MHz and is further amplified by 25 dB. The net gain
for the signal at this point is 100 dB.
- The HP 8566 Spectrum Analyzer, donated donated by HP Corvallis is a major developmental and data acquisition
instrument. The noise floor is typically around -75 to -100 dBm (10 W), depending on the resolution bandwidth.
Linear data plot for which the emission from H atoms in the plane of the Milky Way has been down-converted to 71 MHz: |
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- Digital signal processing (DSP) configurations for field-programmable gate arrays (FPGA) have been developed by the
major radio astronomy groups around the world, with the CASPER project being the most visible. An FPGA
can be rapidly configured to perform as a filter, down-converter, spectrum analyzer, synchronous detector, pulse analyzer, autocorrelator
and more. We are following an approach based on different hardware but using the same DSP blocks.
The hardware consists of a Xilinx Spartan-6 FPGA and dual 14-bit 250 Msps analog to digital converters..
Future Plans
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