Simple Experiment and Suggestions

This section describes how to carry out a simple experiment in meteor observing by radio, including some guidelines for determining whether your location will support more advanced work. Radio meteor observing is best attempted in the amateur 6 meter (50 MHz), lower VHF Television (54 - 87 MHz)  or FM (88 - 109 MHz) bands. 

There are advantages and disadvantages to each. MITROS is presently configured for FM operation so that's what we'll confine ourselves to here. This is also where it's easiest for the neophyte to make a beginning because FM tuners are readily available.

Equipment:

• FM receiver connected to speakers or headphones. This can be a hi-fi component unit (preferred) or part of an integrated system. We haven't tried a Walkman class device but it might work. If the receiver does not have a means for connecting an external antenna, find another one. Check the manual. It should, however, be possible to improve signal strength in vicinity of a Walkman type unit by passing the output of a good antenna through a suitable radiator (i.e. a loop of some sort) near the receiver. That's beyond the scope of further discussion here.

• It will prove a big help and is practically essential for serious work if the receiver has a means for disabling "Muting" and can be set to "DX" as an alternative to "Local" mode. Local mode reduces the receiver's sensitivity while Muting makes it impossible to hear the weakest events.
  
  
• An outdoor antenna of the sort carried by most suppliers (Radio Shack, for example) of such things for home reception of FM. A 3 or 4 element Yagi type is adequate but if you plan getting serious with this, buy a 5 or 6 element unit to begin with. With so many people having switched to cable or satellite these days you might find a neighbor willing to let you have the Yagi in his garage for nothing. You do not need the elaborate type of contraption designed to receive UHF television as well (unless you can get one for free, of course). Keep it simple. It's also easy building your own by scaling a plan from one of the ARRL manuals already mentioned. Alternatively, simply try running a 2 meter or so length of wire out of doors at a good height. Some minimal results might be possible even with such desperate arrangements.
  
   

Procedure:

• Scan the FM band for vacant local channels and write them down. If the tuner has programmable channel selection, make use of this to save the empty channels for future use. A local station on any channel makes it useless for meteor work. In large urban areas this may pose an insurmountable problem and in the worst case you may have to enlarge your experiment to include the identified television and amateur bands. This will require different equipment but the principles and methods are similar.
  
  
• Tune the receiver to any one of these empty channels. You should hear only a hissing sound (unless a meteor event is in progress!).
  
  
•  Aim the antenna towards a distant urban center.  Make certain there is an FM transmitter there broadcasting on the vacant channel you selected (use the FM Database). A horizontal layout is best and, of course, the higher the better. The ideal range is around 1000 km but much shorter distances can also be useful. North America - the US in particular - is practically infested with FM stations. You could easily get lucky on the first attempt. If things are working you should hear 10 to 20 snatches of broadcasts during an hour. These will range from fractions of a second to several seconds, sometimes allowing for station identification. If you hear a station continuously, it's too close to be useful. Try a different channel.

If you want to cheat, try this around local 4 AM when there is a meteor shower in progress (check the Calendar link) and the in-fall rate is accordingly much higher. Why 4 AM? During early morning hours at your location the Earth's rotation is advancing the circumference of the planet against the the planet's orbital direction of travel. That means the component of meteor velocity in opposition to the Earth's orbital motion is increased  with the result there is additional heat of entry and denser ion concentrations formed.

To further ensure quality of the experiment, go to this site operated by the US Federal Communications Commission. Optimize your antenna orientation and channel selection with what you find:

Here you can discover exactly what transmitters are on your available open channels, where they are, how many hours per day they transmit and just about anything else you might need to know about them. The FCC are the people who license the stations to begin with. You simply cannot find more up-to-date or complete information anywhere else. Canadian stations near the US border are also included although with less detail. Depending on what open channels you have, pick the strongest station you can find in a direction that's convenient.

That's it. If you get results of the sort suggested you are ready to perform simple, manual determination of meteor in-fall rates simply by listening. The problem is that the method becomes tedious and does not support much analysis beyond simple counting.