Just as a long journey begins with the first step, the project you elect must start with a clear idea of your objectives. Do you wish to study the sun? Jupiter? Make meteor counts? Do you wish to engage in imaging radio astronomy? What you decide will not only determine the type of equipment you will need, but also the local radio spectrum. The following is some specific information which may help you decide on a project commensurate with your technical abilities.
VLF solar flare observations
For VLF solar flare observations you will need a strip chart recorder and a radio receiver capable of operating in the noisy 20 to 100 kilohertz radio band. These receivers are quite simple and may be home constructed. We can supply the plans for several type of receivers. There are two equally effective ways to do this work.
1) The receiver is tuned to a locally usable part of this radio spectrum and earth atmospheric noises originating from lightning strikes around the equator are monitored. These are conveyed around the earth's surface by the ionospheric D layer. A solar flare causes x-rays to strike the D layer, greatly enriching its electron count. This makes the layer a much more efficient waveguide for this noise and the result is a sudden enhancement of atmospheric noise detected by the receiver and the strip chart recorder.
2) An equally effective method in the same radio band is to tune up on a distant, marginally received radio beacon, and look for enhancements of the signal. The end result of a solar flare produces the same data. i.e. a sudden rise in received energy, tailing off to the normal level in a period from 15 minutes to an hour as the D layer once again assumes its normal equilibrium.
Solar flare work in other bands:
Solar flares may also be monitored in all of the free shortwave bands as enhancements of radio noise. We can also supply you with information for this type reception. In general, you would need a good communications receiver, operated without limiters(AGC turned off), a strip chart recorder, and perhaps an audio cassette recorder.
Meteor counts by radio:
Counts of meteor infall provide valuable data to the American Meteor Society. Radio detection of meteors is about 10 times more effective than optical observations. Moreover, this may be done in the daytime hours. The arrival of a meteor in the earth's upper atmosphere produces a sharp pinging sound of about a second's duration. A good receiver tuned to a marginally received radio beacon and a strip chart recorders or a computer are all you need to get started. A cassette audio recorder is useful during strong meteor showers.
Radio noise observations from Jupiter:
Sporadic noise which is not always present, may be monitored from Jupiter with a good antenna system and a communications receiver tuned to a "dead" portion of the 18 to 22 Mhz radio band. Receivers fully capable of doing the work can be purchased very reasonably at some of the ham radio flea markets. Owners of such receivers may have already heard noise from Jupiter without realizing the source. Once heard it is easily identified. It sounds like frequent rushes of noise, like a rapid ocean surf, punctuated by a quivery subsecond structure. If correlated with transits of Jupiter's inner moon, Io, the data is useful and publishable. Observing is difficult or impossible for three months of the year when Jupiter is close to the sun (an active sun can confuse the data).
Imaging radio astronomy:
This work is best done at the VHF, UHF and microwave frequencies. Paraboloid antennas become viable options at about 1/2 meter wavelengths and below(600 mhz and above). Above 600 mhz you may use phased arrays of antennas such as Yagis and helices. Read-out equipment includes a D.C. amplifier, strip chart recorder or a computer. Audio monitoring is also useful to determine if the received noise is truly celestial. Best results for this type of work will only be achieved in radio quiet locations. If your local environment is noisy, it is best to move the observatory to the country. Idle farm land can sometimes be leased quite inexpensively for this purpose. You may also be able to get land use in a remote county park for such activity with proper approach and proposal to your local county commissioners.
Is amateur radio astronomy instrumentation expensive?
Technical information freely circulated in our monthly journal helps amateurs to obtain good low noise equipment from off the shelf assemblies, or to build their own units. The actual cash investment in radio astronomy equipment need not exceed that of any other hobby.
What books can help me get started and learn about the amateur effort?
Some books have been published by SARA members,
and others are available from regular book dealers. A more complete reference
list is kept by SARA Membership Services. In addition, our Journal regularly
publishes book reviews of interest to our members.
LINKS BOTH AMATEUR & PROFESSIONAL
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