Using Sky Pipe

University of Alberta observatory domes


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How to Use Radio Sky Pipe

What will you "see" when using Sky Pipe? 

This is the main window in Radio Sky Pipe. What you are looking for is "blips" like the ones you see in the chart above - 3 radio signals reflected off meteor trails that caused the sound level in the radio to rise. 

Setting Up the Software

Start the program. Open the options menu on Sky Pipe. There are several tabs across the top. The first is the Connections Tab. Don't use this selection since it sets up Internet connectivity, a feature that will not be required for this project. The second tab is the Logging tab. This screen allows you to set the sample rate and select the type of sound card you are using on your computer. Select a sound card that uses 16 bit mono operation at 8 or 11 kHz speed.

To Start Recording

To begin recording, click the "Start Chart" button. If you have the radio connected to the sound card of the computer a trace will begin running on the chart showing variations in the audio level being emitted from the radio. 

(Show a picture of the setup. Antenna with coax connector, matching transformer, connection to the rear of the receiver. Then a cable coming from the audio output to the sound card. Get a picture of various types of sound card inputs that may be typical on school computers. Give directions on which jack to plug the mono cable into.)

How to test that your set up is working

Turn your receiver on and tune to a radio station in your area, say 92.5 FM. Adjust the volume control on your desktop at the tray on the bottom right. Open the volume control from the Properties tab by right clicking on the speaker icon on the tray. Under options in the file menu, click on the Recording option, and make sure that all the line, aux, mic, and other input categories are selected so that they will detect the input from the receiver. Turn the power to the speakers on. You should be able to hear the radio station sound coming fromthe speakers, and you should be able to see variation in the output on the chart trace in Sky Pipe.

Once you have the radio sound playing on the speakers and can see the trace on the chart, turn the radio dial to your off station frequency, where no radio station can normally be heard in your area, say 92.1, as in the Edmonton area. You should see a drop in the signal level being displayed on the chart, plus you will hear noise from the computer's speakers. This is as it should be, and the basic arrangement for detecting over the horizon radio stations using meteor trails.

Chart Features

Play with the chart feature. Once you have recorded the trace of a radio station, followed by the noise of a normally empty channel, stop the chart by pushing the "Stop Chart" button. You will be prompted to save the file, which you should do. Sky Pipe will set up a file structure for storing the data you have just recorded.

To load the data from that file once again to view it using Sky Pipe, open the drop down file menu and select Load Data File. Follow the directory or folder structure to the location of the file, or you can also go to File/Recent Saved option. Files are named automatically by Sky Pipe unless changed by you. It is wise to use Sky Pipe's naming conventions since it uses the date and time of the start of the file to identify it. 

Because timing is extremely important with this project, having the time stamped right on the file is very helpful. Files are named with the last two digits of the year first, followed by two digits indicating the month, two indicating the hour (24 hour clock), two showing the minutes, and two showing the seconds. Open the file that corresponds to the start time of the original file you just created.

Sky Pipe will take a little while to open the file depending on how large the file is. A six hour file, for example may take up to a minute to load. The faster the processor on the computer the faster the file will load. Once you've loaded the file, several buttons appear on the left hand side of the chart area. These will affect where the signal trace appears on the screen, and how many data samples will appear on the screen. You can zoom in and out using the x button, You can scroll to the right or to the left (forward and backward in time) using the y button. You can scroll up and down using the z/a buttons. Etc.

Counting Hits 

How do I know when I have scored a hit, or that a meteor has crossed the path between the transmitter and the receiver? For our purposes, we will use a standard to determine if a hit is really a hit. There are several ways of confirming accuracy of observations. One is to assume that any meteor reflection will send the volume of the audio signal from the receiver up over the baseline, very much the same as having the radio tuned to a radio station drove the trace on the chart higher than the baseline noise when the receiver was tuned off channel. 

Let's say that a meteor hit is any rise in the trace that goes at least 25% higher than the top of the baseline. In other words, take a ruler, measure the average thickness of the baseline, from bottom to top of the noise. If the signal rises above the top of the baseline noise by more than a quarter of that average spread measured with the ruler, then we will call that a hit.

The second way to measure if this is a hit or not is to have audio from the radio connected to a VCR, as described at this link. It must also be attached to cable TV output so it can be time stamped against a cable station's time display. When you see a hit on the screen, note the time stamp, then search the video tape for the same approximate time, rewind it about 20 seconds, and listen to the sound recorded while Sky Pipe was recording the sound volume levels. If you hear a burst of music or talking, and it corresponds to the time recorded on Sky Pipe, you can be sure you have detected a meteor hit.


Copyright 1999-2015 by Sky Scan, Edmonton, Alberta, Canada. 

We gratefully acknowledge the financial support of the 

Edmonton Centre of the Royal Astronomical Society of Canada, Department of Physics (University of Alberta)

and the

Natural Sciences and Engineering Research Council of Canada

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