For a more detailed overview covering most of the technical and theoretical details mop is based on see this paper

If you are just planning on using MOP, the following description should be sufficient.

What is it good for?
MOP (Meteor Observation Project) is a DOS- program to detect radio meteors. The advantage compared to many other programs is that you don't have to build a special interface to connect your receiver with your computer. All you need to run this program is a PC (Pentium recommended), a SSB receiver for VHF, a 8 or 16Bit soundcard and, last but not least, a simple cable from your receiver to your soundcard.

How does radio meteor observation work?
First you have to tune your receiver on the frequency of a transmitter that is about 500-1500 km away (So far, that you normally can't here it anymore). Now, if a meteor enters the earth atmosphere, the radio waves will be reflected by its ionisized trail. The duration of such a reflection can vary, from less than a second, up to some minutes.
To detect a meteor with MOP you have to tune your SSB receiver about 1,5kHz lower, if it is a USB receiver (LSB, 1,5kHz higher), than the carrier frequency of the transmitter is. If there's a reflection you will here a 1,5kHz tone. (i.e. I observed signales from SK4MPI on 144.412 kHz, so I tuned my USB receiver on 144.110,5kHz.) Now you just have to connect your receiver with your soundcard, and you can start the observation.

How MOP recognizes tones
MOP recognizes tones by a self-developed and effective method. It uses the Fast Fourier Transformation (FFT) that produces a spectrum of the incoming signal. We do not use the time dependent signal for any further calculations, every further work uses the spectrum. The average of all the values in the spectrum is calculated that lay between the two filter limiters, shown by the two arrows. If one value of the spectrum is much higher than the normal noise, then there must be a peak (a tone-signal). Take care that the squelch of your receiver is open, otherwise MOP could make mistakes.

How to optimise the values for your receiver and what do they mean?

• Sensitivity: Like already said, MOP calculates the average of the values in the spectrum between the filter limiters. The sensitivity is the value that says how much higher than the average a value in the spectrum has to be, so that MOP recognizes it as a tone. A sensitivity of 5 means, that a tone is detected if one value of the FFT is at least five times higher than the average. Which means, the higher the value of the sensitivity the worse the real sensitivity. So, take care that you put the sensitivity value to the lowest possible, but without wrong detections. We will offer some wav-files with meteorscatter-signals on our web-page. So you have the possibility to check out different configurations under "real" conditions.
• Values over average: This value sets how many values have to be higher than the threshold, set by the sensitivity, to recognize a tone. That means, it says how broad the signal should be. If the observed signal is an unmodulated carrier, this value should not be higher than 2, if MOP should be sensible enough to detect also weak bursts or pings. While observing FM, AM, high speed CW carriers or other signals with a large band width, this value can be set higher. But keep that value as small as possible, to achieve good results.
• Max. Frequency: Here you can change the frequency range of the NF-signal. So, if you want to observe a signal that is 3000 Hz high, you have to put this value to at least 3000 Hz. But there is one more important thing you change by this parameter: The sample rate gets changed here, too. You can calculate the sample rate (in samples per second) by this formula: Sample_Rate=2*Max_frequency. If you put the max. frequency (and by this the sample rate) too high, you won't be able to continue detection without enhancing you probability of making mistakes, because the relevant part of the spectrum is compressed more and more. The sensibility won't be that good anymore.
• Filter limiters: Under the spectrum you can find two arrows, with which you can select the part of the spectrum you want to look for peaks (tones) in. The average of the values given by the spectrum, is calculated only with the values between the two filter limiters. So do not make too narrow filters! If there is a tone in a very narrow filter it won't be able to recognize it, because the average of the values between the limiters will rise, too. Choose your filter limiters in a way, that big noise peaks or interferences, perhaps caused by your computer, are staying outside the filter.
• Now, in version 1.1 there are two more smaller red arrows under the spectrum. These limiters make it possible to have very narrow filters. The average is still calculated by the values between the bigger white arrows. For changing the new filter, just click on "narrow filter",  you can change them in the same way as the wide filters (the blue ones in Version 1.0).
• (If you select wide filters, Version 1.1 works exactly like version 1.0)
• Get sample: This button is made, to get a new sample on the screen. It helps you setting up your filter limiters.

The results of an observation
The results of your observations get written in a file called "stat.ms". Take care: If you start a new observation the old file will be overwritten. So rename it when an observation is complete. In the file there is written: Date, Time and Duration of the burst.

Copyright 2000 by THE AUTHORS: DL2NFX Michael, DL8NEQ Andi
 

special thanks to:

   the author of the fft c-code we used:
                                      Jens Jorgen Nielsen
                                          Bakkehusene 54
                                          DK-2970 Horsholm
                                          DENMARK

   the authors of the Sound Blaster c-code we used:
                                      David Baggett, Gerhard Kordmann,
                                          who wrote the code based on the Sound Blaster Freedom project and Linux code
 

Hmmmm.... what did actually we do???????? ;-)