Saturday, July 1, 2017

Meteor Detection using National Weather Service weather stations

This is more of an update on what I've been doing since I got things working using TV station video carrier frequencies. Last time I was able to get what looked like a decent diurnal cycle out of a day's observation of Channel 2 (CHBX, Sault Ste. Marie, Ontario); before that I'd tried using regional weather service stations and been stymied by what looked like aircraft-created reflections. I live about 6 miles from Minneapolis-St. Paul International Airport (A Delta airline hub) and it has a lot of traffic.

Argo did so well at getting the most out of the TV data that I thought it worth trying with the weather stations.  It did not fail me.

Here is an 8 minute plot of activity at 162.475MHz:

It's a real mess, isn't it? Most if not all of that is air traffic. To see what it's telling us, let's start with a quieter time and add a little annotation:

The curved lines are reflections from aircraft arriving or departing the airport; the horizontal lines are the carriers from several weather stations. Note that they're slightly out of tune. The audio shift between them is roughly equal to the difference in the carrier frequencies, so all four are within about 45Hz of each other, an error of one part in four million. The strongest two stations ("B" and "C") are probably Rochester MN and Spooner, WI.

Argo shows the reflections clearly. The first diagram contains not just curves like these but other lines that probably represent flyovers, diversions, and other course changes aircraft make near an airport. Unfortunately, none of them look like the things I was able to see with TV.

I'll let the system run overnight and hope that the signals don't saturate like they have in the past. Maybe I'll see some meteor signatures in the flight free early hours of morning?

If I don't, I'm going to have to question the usefulness of weather stations for meteor detection. Even with that negative result I'll probably take my setup to this year's Nebraska Star Party where the aviation activity is considerably less.


The Virgo Cluster mosaic is now half done:

This is all I'm going to get this year, but it's not bad for such a terrible spring.


  1. As you probably noticed, there really are not any Argo directions. Two things that might help...
    Pressing Shift & + enlarges the Argo screen
    Pressing - (minus) reduces it when you go too far.

    Also I think you might have your frequency set a bit too high...see on page 5 for how Dennis sets his.

    I think you should look at 162.474MHz with SDRsharp and then click about 1K about that in the Argo full band view. If you are visually seeing your frequencies, you won't be able to hear the dopler shift from the meteors. The 1kHz will give a nice tone you can hear.

  2. You mentioned that you are going to the Nebraska Star Party. If you are really interested in Radio Astronomy consider the Green Bank StarQuest in WV sometime. I was there last summer and am going again this summer. One of the activities is getting trained to use a 40 foot dish. I returned last October for two nights to use it for the Galactic portion of the Astronomical League's Radio Astronomy program.

    Green Bank Star Quest XIV (July 19th - 22nd, 2017)

  3. I had noticed the missing manual aspect of Argo, and all the online HowTo's I could find were fairly terse about it. Thanks for the enlarge command info--I really wanted a larger display!

    About the 1KHz offset, I'm not sure about the applicability of what he writes about DTV broadcasting. I know that analog TV video carriers can be offset by 10kHz, but so far as I know the NWS uses no offsets. I use SDR#'s "zoom FFT" display to find the strongest signal, which in my case is at 162.47482MHz. I'm running the system with that setting right now, and it's showing me a ton of air traffic.

    I am using a bandwidth of 1kHz in SDR#, which I think is what you're suggesting in your third paragraph.

    My main doubt about using NWS stations is that the frequency reduces meteor reflections strength by 96%. I ran the system all last night and got nothing other than aircraft. I'll keep trying.

    I've gotten really good results with SDR# and Argo--I'll post some screen caps in a bit to show what I mean.

    People in my club who have visited Green Bank have raved about it. Right now that's not in my plans, and my interest in radio astronomy is focused on meteor detection. It's what I can do in my back yard without spending a lot of bucks and getting the neighbors riled up :)