Abstracts ~ SARA 2014 Western Regional Conference 22 ~ 23 March 2014
Introduction to Amateur Radio Astronomy, Tom Hagen. Amateurs have a number of opportunities to pursue radio astronomy as a hobby in the Hz to GHz frequency range. At the lowest frequencies, radio frequency (RF) energy in the audio frequency range (wavelengths of hundreds of miles) can be detected with a natural radio receiver comprising a whip antenna and a high input impedance audio amplifier. At higher frequencies, ionospheric solar disturbance monitoring may be done with a computer sound card and a simple pre-amplifier in the 15-48 kHz range. Radiated disturbances from the planet Jupiter can be heard on shortwave receivers around 20 MHz. Other bands centered on 38, 408, and 611 MHz are available too. One of the most important bands is the 21 cm neutral hydrogen HI emission line at 1.42 GHz. Many amateurs use re-purposed C-band satellite dishes to make observations and even complete RF contour maps of the sky at this wavelength. Finally, a surplus Ku band TV satellite dish (Dish Net or Direct TV dish) can be made into an “Itty Bitty Telescope” (IBT) to demonstrate the principles of thermal emission from bodies at room temperature, such as trees, cars, humans, and so on at the operating frequency of around 12 GHz. And last if not least, SARA members get the opportunity to use a 40 foot diameter dish at Green Bank, WV, to do observations on 21 cm!
Cosmology Observations at OVRO, Stephen Muchovej. In less than a century we have advanced from knowing almost nothing about the Universe as a whole to measuring it with exquisite precision. This revolution in our understanding is made possible through the discovery and precise measurements of the Cosmic Microwave Background (CMB), the relic light left over from the Big Bang. Scientists have been active in the study of the CMB since the 1980s. Whereas first efforts focused on CMB detections, these have evolved into precise measurements of its anisotropy and secondary effects, both of which inform us about the nature of the Universe and its expansion. In his talk, Dr. Muchovej will present an overview of cosmological studies undertaken at OVRO, from the initial measurements of the CMB to the latest efforts in mapping the so‐called “Dark Age” of the Universe.
Digital Processing for Radio Astronomy, David Hawkins. Radio astronomy signal processing is increasingly performed using digital techniques. Digital signal processing is “imperfect,” but its imperfections are well understood (quantization and aliasing). Digital hardware allows the creation of systems containing many copies of digital processing subsystems, each with identical performance; something that is more difficult to achieve with analog subsystems. The real‐world is still analog, so analog‐to‐digital converters are required to convert to the digital domain as soon as it becomes feasible. Dr. Hawkins will review the 20GHz clock frequency analog‐to‐digital converters and the field programmable gate array (FPGA)‐based digital signal processing being used in CARMA’s next generation correlator systems. The technology details are similar to those used in “software defined radio,” so will be familiar to the SARA audience. The presentation will include slides, and a hardware “show and tell.”
Radio Meteor Detection in Roswell, New Mexico, Stanley A. Nelson. This paper and Power Point presentation describes the author’s twenty year involvement in radio forward scatter meteor detection and logging. He will begin with a brief history of meteor detection by radio beginning in the 1940s. The forward scatter concept and practical amateur techniques to detect the occurrence of meteors will be outlined. He will note the various frequencies used with the challenge to adapt to the changes in the available carrier frequencies used for meteor monitoring. They include services like SNOTEL, CW Radar via AFSSS (originally NAVSPASUR), WWV signals, and the loss of analog TV and the opportunities using digital TV carriers. Also, the collaboration with SpaceWeatherRadio.com and Dr. Tony Philips will be highlighted and our on-going involvement providing the public the opportunity to listen to live meteor activity via the web.
Measuring the Field Strengths of VLF Stations, Tom Hagen. This presentation is about an attempt to get calibrated measurements of the magnetic field strengths of the various VLF stations used by the SuperSID program as reference sources to detect sudden ionospheric disturbances (SID’s). Presently, data coming in from the various SuperSID stations around the world is uncalibrated in amplitude. When a SID is detected, there is a measurable change in relative signal strength, but actual field strengths are unknown. Different stations around the world report different SID levels for a given event. Are the causes of these differences loop antennas, preamp gains, sound card settings, sound card gain, or actual differences in field strength levels? And from a system design standpoint, the range of field strengths typically encountered would be good to know for improving and standardizing the design of pre-amps and loop antennas.
An Off-The-Shelf 611 MHz Total Power Radio Telescope, Ken Redcap. In the US, TV Channel 37 (608 - 614 MHz) is allocated to radio astronomy. This project is a work in progress and is my first effort on a radio telescope to detect energy in this frequency range. The telescope is being set up at the McMath Hulbert Solar Observatory in Lake Angelus, MI (McMathHulbert.Org). All electronic components and antennas (2) required were purchased on Amazon except for the low noise amplifier. All freeware software components were derived from sites with various versions of SDR# like SDRSharp.Com. Inspiration for the project comes from Kurt Kinghorn's presentation at the 2013 SARA Western Conference on low cost radio telescopes using off- the-shelf TV receiver antennas and an article in the August, 2013 SARA Journal about a low cost HI receiver.
Characterizing and Stabilizing a Radio Jove Receiver for 24/7 remote operation, Keith Payea, AG6CI, SARA Member. This presentation covers a series of tests which were performed by the author to characterize the frequency stability of a Radio Jove receiver used at the Robert Ferguson Observatory for public outreach and education. Our casual observations were that the receiver drifted over the course of a few hours, but no hard data was available. Based on the results of the tests and the target environmental conditions a method for stabilizing the receiver was designed, built, and tested. The result is a frequency stable receiver which can be left unattended for long term continuous operation.
Noise and Noise Figure Measurements Tutorial, Whitham D. Reeve. With the exception of some solar radio bursts, the extraterrestrial emissions received on Earth’s surface are very weak. Noise may mask or corrupt these weak emissions and places a limit on the minimum detection capabilities of a radio telescope. An understanding of noise and its measurement will help minimize its effects. This presentation is a tutorial that describes the basic characteristics of noise including noise temperature and noise power and how noise is measured.
Transforming an Itty-Bitty into a Serious Radio Telescope by putting it on "Steroids”. Curt Kinghorn. The ubiquitous Ku Band satellite dish can be converted into an “Itty-Bitty,” a fun device that is very useful in demonstrating the fundamental principles of radio astronomy. But, the Itty-Bitty lacks the discrimination and amplification power to be a serious radio telescope. In this project, the Itty-Bitty is put on “steroids” and transformed into a serious radio astronomy instrument by replacing the Itty-Bitty’s RF/IF/Detector unit with a serious radio receiver and replacing the audible tuning indicator with an electronic strip recorder. Issues related to converting the Itty-Bitty including aiming, “finding” the intermediate frequency (IF) coming from the dish’s LNB, system gain and powering the LNB will be discussed. If you have a “spare” computer lying around, the entire telescope can be built for less than $500.