meteor detection using radio
The graphics below are example meteor detections that have been recorded from our home radio meteor detector. To view the recent data please visit the Live data feed.
The number of meteors are automatically compiled into the heat plots below using a program called colorgramme. The day of the month follows across the X axis with the hour in UT plotted on the Y axis. For each hour of a given date the number of meteors are displayed as a colour. The furthest column indicates the colours assigned to different numbers.
This graphical representation allows you to quickly see at what time and date an increase in the number of detections was observed. This is of course important as we start to approach meteor shower peaks as these should be easily determined on the heat plots if you have a reliable set up without too many false detections.
As an example the first graphic for January, there was a peak of 14 meteors observed between 06:00hrs - 07:00 hrs UT on the 8th January 2020.
The data collected is uploaded hourly to the Radio Meteor Observing Bulletin (www.RMOB.org)
Meteors that enter the atmosphere have ionisation trails of excited molecules that we observe as bright streaks. Those ionised areas are more reflective to radio waves and it is this characteristic that can be used to detect a meteor at any time of day.
Using radio these meteors can be broadcast as distinct and unique audible pings. There are two methods that can be used, back-scatter (radar) method, the transmitter and receiver are located together and there is forward-scatter where the signal is reflected forward to the receiver, which is located many kilometres from the transmitter. It is the forward scatter method that we use and can be set up with some simple equipment.
The information used to collate the above graphs is automatically collected from Spectrum Lab. The Spectrum Lab software allows the audio pings to be displayed visually on a waterfall spectrum. When a meteor is detected it logs this as a detection. An example of what meteor detections look like on the spectrum are illustrated below
Description of how to install a home meteor detector.
I will describe the steps I have taken to get my meteor detector set up. I will try to defer from too much detail as there is already a wealth of excellent guides available, of which I will include links to those I feel are most pertinent and of interest. It is no way the definitive guide and I am still learning as I go so if I have omitted something or have done something long winded I apologise in advance and welcome feedback. Both the British Astronomical Association and The Society of Popular astronomy have excellent guides with further details.
What you will need:
- NooElec R820T2 SDR / DVB-T USB dongle
- SDR software
- Spectrum lab software
- VB Cable driver
- 3 element Yagi Aerial. The aerial can be made rather simply using a guide provided by the Sky at Night. All the details can be found at the Britastro website https://www.britastro.org/radio/downloads.html
I did make my own aerial that I used for several years with great success however wanting to have a permanent fixture at home I opted to have an aerial made and I can recommend that you take a look at The DX Shop.
I use the GRAVES transmitter located in Dijon, France which transmits signals at 143.048.500Hz. This is a common transmitter frequency used by many meteor detectors. There are other transmitters and frequency ranges that can be utilised but the GRAVES radar is the frequent one used for UK/ Northern Europe.
To detect the frequency on the PC we need a radio receiver known as an SDR or Software defined radio and many use the Funcube dongle, however these retail at around £100.00. I have found that we can utilise the Noo Elec R820T2 dongle which comes in at the much kinder price tag of £20.00. A good site to refer to for more information regarding this dongle is www.rtl-sdr.com. If you are interested, the dongle can also be used to obtain weather information from satellites, aviation tracking etc. For a small price you get a rather versatile bit of kit.
1. Installing the Dongle.
I use a PC with Windows 10, if you use a windows version previous to version 7 of the work flow is likely to be different and you may have to search around to find compatible software and more specific instructions based on you operating system.
From the following website (https://airspy.com/download/) download the SDR# software as a zip file into an easy to find directory.
Plug in the USB dongle and allow windows to recognise and install. Do not install any software that is provided with the dongle.
Once installed by windows, open up the SDR software zip folder and extract the files.
Open up the extracted folder and navigate to the sdrsharp folder. Within this directory there is a file titled "Zadig.exe" click and run as administrator.
Go to Options and select list all devices.
From the drop down list select Bulk-In, interface (Interface 0) and ensure the settings are as illustrated in the image below.
Then select Install Driver. Warning! Do not select USB Receiver, this will likely mess up your keyboard / mouse connection of they are wireless and you will have to mess around trying to roll back drivers etc. (I speak from experience)
Your dongle should now be installed.
2 Installation of Software
Now the dongle is installed we can now concentrate on the software.
The software used is as follows:
SDRSharp - This is the software that is used to tune your NooElec dongle to the frequency of choice.
Spectrum Lab - Is a powerful audio monitoring tool that allows you to display the results visually.
VBCable driver; This acts as a virtual cable to used to allow the two pieces of software to allow the input from SDR# to be monitored and tracked through Spectrum Lab.
2.1. Install VB Cable driver
This is simple and straightforward to install, just download from the internet a simple search for VB cable driver will get you to the download site you need. Open the zip folder and open the setup file. Once again, you can extract the zip folders to a suitable location and within the extracted folder there is the .exe file. Titled "VBCABLE_controlpanel.exe" if you wish you can create a shortcut to this too.
2.2. Install SDRSharp
You should have already downloaded this software installation from the earlier steps, From the same folder in which the Zadig.exe file was found, there is also a link to the SDRSharp.exe. If you have followed the instructions above and unzipped the folder to a location on the C drive, you can copy a shortcut to the .exe folder onto your desktop. You can just click the .exe file and it will open up the software.
2.3. Install Spectrum Lab
Again Spectrum Lab is easy to find for download with a simple google search, and install from the downloaded file.
We should now be ready to start setting up the software specifics.
3. Setting up the software
Open SDRSharp and click the cog icon to open up the settings tab. From the device drop down list select Generic RTL-2832U-OEM and select the same settings as detailed below. The RF gain, we will come back to once we have everything working and need to refine the aerial settings. Click Close.
Remaining within SDRSharp we now need to make some selections.
Select the filter as Blackman-Harris 4
Ensure correct IQ is selected
The Next step is to select the audio output. This is where the USB cable driver is used as a "virtual audio cable between SDRSharp and Spectrum Lab. From the audio outputs list select the option for VB cable output.
The frequency should now be set to 143.048.500. This can be done by typing in the frequency or using the mouse to click the numbers in the frequency display.
You can click the Play icon now to test that everything is running. If you do not receive any errors then we can presume for now that everything is OK. If you have the aerial already set up, you may start to see activity on the frequency chart. We can ignore that for now and move onto Spectrum Lab.
3.3 Spectrum Lab
Prior to setting up spectrum lab, we can cheat and use a predefined config file that has all the software settings, apart from a few minor details.
An improved set of actions has been created by Blackwater skies and I suggest visiting that site for the improved ini files and detailed explanation on features and functions.
This will set everything up for you except for one thing. You will need to go into the options to set the input and output.
If you select options and then audio settings you need to make sure that the input is set to the VB cable option and then the output you can select your PC audio output. Save the settings. What you need to do now is do a complete system reset.
Then open up SDR sharp and select play
Start up Spectrum Lab - the software may start running automatically. You will see the screen starting to scroll, you might hear the noise of the hissing radio. If this does not happen go into start stop and select start sound thread.
Then everything from this point is now about tweaking settings, you might need to adjust volumes and also the contrast on the spectrum lab feed.
Ensure that the aerial is pointing approx South / East, Elevated without obstruction is best.
It will take some patience and careful refining over time but you should start to get detections, on average I'd expect to get 1 detection per hour.
RMOB – Set-up to collect and publish monthly radio meteor data in 1993, this continues in the same format, and provides a means of contacting other enthusiasts to swap data and ideas for observing and analyses.
Radio Meteor Observatories On-line – Contains “live” radio meteor data published on the Internet.
Colorgramme/HROfft software example – A guide to the use of the Colorgramme & HROfft software.