Aircraft Scatter


Scattering or reflecting radio signals off of objects in the sky is used by radio amateurs to increase communications range whether they are doing Meteor Scatter, EME, Aurora, Sporadic E, or other modes of communication.

Aircraft can also be used to increase communications range, by using Aircraft Scatter.  Recently I became much more interested in Aircraft Scatter when I learned that Rex Moncur VK7MO and David Smith VK3HZ have completed Aircraft Scatter contacts of up to 842 km on 10 GHz and 462 km on 24 GHz.  Their paper describing these achievements is here.

This page is divided into the following sections:

Software to Assist with Aircraft Scatter Operations
Aircraft Scatter Theory: The bistatic radar equation, and more
How to Get Started
Receiving Local Aircraft Over the Air
Information Sources Regarding Direct Reception of ADS-B Signals
Excellent Aircraft Scatter Information Sources on the Web
Software to Assist with Aircraft Scatter Operations:

To do aircraft scatter work, you need to know where the airplanes are.  The best way to do this is to get the Windows software PlanePlotter.  It only costs 25 Euros, and for that price you not only get the software, but you get access to their internet server that gives you real-time position data on many aircraft.  I usually see 50-110 aircraft flying over my region of the USA at any one time.  You can also hook up your own receiver to PlanePlotter and get local real-time aircraft position data.  It is very easy to get started receiving internet data with PlanePlotter; a brief tutorial is here.  I have included information below on how I set it up to receive data from an RTL-2832 Dongle and a 4-inch long antenna, as well as how I have used it with the internet data service.

PlanePlotter has the capability to send its data to another program via the Windows OLE facility.  This is very important, because as long as the aircraft data remains locked up within PlanePlotter, you cannot analyze it or extend it. 

I wrote a simple Visual Basic program that does analyze and extend the data collected by PlanePlotter, by using this OLE facility.  This Visual Basic program does the following important things (among others):

1.  It displays distance, bearing (Azimuth), and elevation data for the aircraft of interest, which you designate by double-left-clicking on its icon on the PlanePlotter display.

2.  It corrects the designated aircraft's position data for any change in position of the aircraft since position data was last collected from the aircraft, based on the aircraft's last known speed and heading.

3.  It corrects altitude data for the curvature of the Earth before doing calculation of the aircraft's elevation as seen from your QTH, and adds a correction for refraction by adjusting the radius of the earth R* to 4/3 R

4.  It also gives aircraft bearing, distance, and elevation data relative to a DX station located in the six-digit Maidenhead grid square of your choice.

5.  It calculates heading and distance data for the direct (Great Circle) path between you and the DX station.  It shows you this direct path between you and the DX station on the PlanePlotter Aircraft View screen, and automatically redraws this path when you change the grid square of the DX station (or your own station).  This makes it very easy to see if there are any airplanes positioned on or close to this line.  This is very important, because up to 20-30 dB of "forward scatter enhancement" is available if the plane is on (or extremely close to) this direct path.

6.  It gives Maidenhead grid square position data for the Home station, the DX station, and the aircraft location as well as Latitude and Longitude for each.

7.  It adds Maidenhead grid square boundary lines and labels to the PlanePlotter Aircraft View display.

8.  It saves all acquired aircraft data to an SQLite data base file, or if you prefer to a character-delimited text file, so that schedules can be constructed from the aircraft time/position data previously acquired.  In this way you can plan schedules just as you would for moonbounce or satellite work by using predictions of when the moon or a satellite would be positioned to allow for EME or satellite contacts.  In this case you use your database to predict when aircraft are likely to be where they need to be for you to use them as scattering objects.

9. It allows you to search the saved aircraft database from within the Visual Basic Program, with multiple search and sorting options, with no need for a separate SQLite database program.  See here for a description of these functions of the Scheduler form, and for a description of the Path Loss Calculator form and its functions.

10.  This program also includes a Path Loss Calculator form that will calculate path loss for the path from the DX station to the aircraft to you, and if you enter transmit power, receive noise figure, and antenna gains for the stations at both ends of the path, it will show you the signal margin for a 100 Hz CW bandwidth for both the path and the reverse path.  This calculator uses the standard bistatic radar equation.  It does not include the effects of forward scatter enhancement that may give additional enhancement of 20-30 dB under certain conditions where the aircraft is on or very close to the direct path line between the two stations, as described by Rex Moncur in this paper.  However, the calculator does indicate when the geometry is favorable for forward scatter enhancement, by coloring the Path Loss and Received Signal Text Boxes red under these conditions.  You can then mentally add 20-30 dB to estimate what your signal margin would be when the effects of forward scatter enhancement are included.  In addition to calculating the aircraft scatter path loss for actual aircraft, it will also allow you to calculate the path loss that would occur for a hypothetical aircraft of size designated by you for an arbitrary location on the PlanePlotter Aircraft View display, selected by positioning the mouse cursor at that point.  In this way you can analyze potential scattering objects without having to wait for an actual aircraft to arrive at the point of interest.

This program and PlanePlotter complement each other nicely.  PlanePlotter gathers the aircraft from the PlanePlotter Internet Server, and provides a nice visual display of the aircraft.  By double-left-clicking on an aircraft seen in the PlanePlotter Aircraft View window, that aircraft is "Designated" by PlanePlotter and all of its position data are sent to the Visual Basic Program, which then derives a lot of important additional parameters that allow you to optimize your aircraft scatter operations.

 At the very top of this webpage is a screen grab of PlanePlotter and my Visual Basic Program running together.  If you right click on that image, and then click on "View Image" and then left click on the image, it will be enlarged and you can see more detail.  Or, you can look below for the screen shots for the individual program windows.  The following text describes the screenshots below.  Note the plane with a blue ring around it that is in Western Pennsylvania near Pittsburgh, on the blue direct path line that runs between the home station near Reading, PA and the DX station in mid-Ohio (EN80ag).  This plane is the "Designated" plane.  You can see on the right side of the Visual Basic window that the plane is flying at 33000 feet, and that it is traveling at 576.2 knots, with a heading of 59.2 degrees.  This means that it is moving along a heading (azimuth) of 59.2 degrees with respect to True North.  Of course, this is NOT the same as its azimuth from the home station [W3SZ].  That azimuth was 272.22 when the plane sent its data at 01:07:46 UTC, but it has since moved on and is now at azimuth 274.6 and is 293.95 km from the Home station, as you can see on the left side of the Visual Basic program window. Immediately below is the individual PlanePlot screen shot:

Note the direct path Home-Midpoint-DX Station line.  The midpoint, like the home QTH and the DX station points, is labeled.  When you change the grid square of either the Home station or the DX station in my Visual Basic program, this line is instantly redrawn to connect the Home and DX Stations.  It is a very helpful operating aid.  Don't worry that the line doesn't parallel the lines of latitude [grid square lines]; this is a result of  the fact that the path is a Great Circle, and lines of latitude are not

Here is a screen where there were three planes following the direct path between me and the EN80gg DX station.  This would bode well for making a contact.  The first plane is a Virgin Airways flight from SFO to PHL.  The second is a US Air flight from SFO to PHL.  The third is a US Air flight from PHX to PHL.  With these three planes all traveling along the direct path, it would be just like a meteor shower in terms of having multiple sequential reflectors!

Note that in addition to adding the path line for the direct route between the home and the DX stations, I have also added outlines and labels for the grid squares for the Eastern USA.  I did this by creating a GPX file that contains the information needed to make these additions to the Google Map used in PlanePlotter.  Here is a link to the file I used to make and label the grid squares.  You are welcome to use it elsewhere with Google Maps if you wish.  Here is PlanePlotter zoomed out, so you can see the region I covered with the grid squares:

Click here to see a webpage with a screen grab of the main form of my Visual Basic program, with some annotation that explains the information displayed and the various buttons.  At some point, you should also read about the Scheduler form and the Path Loss Calculator form, if you didn't already do that.  Then come back to this page.  As you can see in the screen grab below, the program displays in a large scrolling text window in the center data from all of the planes being tracked by PlanePlotter, and on the right the received parameters for a single aircraft that has been chosen as the "designated aircraft" by double left-clicking on its airplane icon in the PlanePlotter Aircraft View Window. This data on the right was correct at the time that it was received from the plane, but is not correct thereafter, because the plane is constantly changing position.  The data at the lower left corner of the window IS correct at the time that you are viewing it, to within the accuracy permitted by the stability of the aircraft's heading and speed, because it is constantly being recalculated by the Visual Basic program for times between the receipt of new data from the Internet. When new data is received, the position interpolation algorithm begins using that new data.  The interpolation is sufficiently accurate that the data progression continues smoothly when new data is received, rather than showing evidence of a discontinuity that would occur were there large errors introduced by errors in the interpolation process or timing.  Of course, when the aircraft is turning or changing speed as when taking off or landing, the interpolated data will suffer.  Some sample data is presented here.

I used Vincenty's Direct and Inverse Formulas to calculate all position data.  It's said to be accurate to within 0.5 mm!  The original paper is here .  There is some example C# and Java code here.


The Visual Basic Program has two additional forms, or windows that are very helpful.  The second form does path loss and signal margin calculations so that you can see what your chances of success are for any given aircraft. To the left is a picture of the path loss form, which takes its position information from the main form.  You only need to enter Tx power for both stations, antenna gain for both stations, and Noise Figure for both stations to calculate signal margin.  The path loss calculation requires no data entry by you, assuming that you entered home and DX locations on the main form, and have designated an aircraft to act as the reflector by left double-clicking on it in the PlanePlotter Aircraft View window.  On the Path Loss Calculator form, you can select different sized reflectors (from Lear Jet to 747), and choose from among 8 amateur bands.   Additionally, the calculator  indicates the possibility of forward scatter enhancement when the geometry suggests that this may occur, by coloring the Path Loss, Received Signal, and Aircraft Position text boxes red under these conditions.  You can either calculate path loss for the Designated Aircraft, or for an arbitrary location of the PlanePlotter Aircraft View display by clicking your mouse on that arbitrary location on the PlanePlotter Aircraft View display.  The Path Loss Calculator Form pictured on the left was being used to calculate the path loss for an arbitrary point, selected by the mouse as described above, along the direct path between FN20ag and EN80gg.

The third form allows you to search the SQLite aircraft data base that you can make with this Visual Basic program by geographic area, or for specific times and dates, and also to order (sort) the search results by multiple parameters.

Click here for more details on the Path Loss Calculator and Scheduler/Database forms.

The source code for the Visual Basic program along with its executable (AirCraftScatterOLE.exe), the source code, and some other related files are at:

This zip file contains a CAB folder containing the files needed to install and run the program, the program setup.exe, and the file SETUP.LST.

To get started:

1. Unzip the zip file

2. Install the Visual Basic Program by double-left-clicking setup.exe. The setup program will put the Program on your Windows drive in the directory /AirCraftScatterOLE, along with the files SZPlanePlot.ini and dbBasic.sqlite which the program needs to run. 

3. The EastUSA-GS.gpx and SZPlaneplot.gpx files are also placed by the installer into this /AirCraftScatterOLE directory.  However, you need to move them into the default "Charts" directory for PlanePlotter.  For my installation here, that is the directory "C:/COAA/PlanePlotter/Chart files/", but if you changed the default for your installation when you installed PlanePlotter, then you will need to put these files into the directory that you chose as your default "Charts" directory.   Put those files there now.

4.  You need to have PlanePlotter running before you start the Visual Basic program.

 5. When you first run the Visual Basic program, after making sure that you have the .ini and .gpx files where they belong (as described above), you need to tell the Visual Basic program where to put NEW .gpx files when it rewrites them, so that PlanePlotter can find these new files as well.  If the Visual Basic program can't find the directory containing these files when it starts, then it will open an "Open Common Dialog Box" as shown below so that you can show it the directory where the files reside.  The first time you run the Visual Basic program, if this Dialog Box does not open automatically, you will need to open it by left-clicking on the "File" toolbar item at the top left of the Visual Basic program's SZ-PlanePlot form.  Once you have opened this Dialog Box, you need to use the icons on the Dialog Box form to take it to where you have put the file SZPlaneplot.gpx, and then click on the "Open" button at the lower right portion of the dialog box to save the file location.  Immediately below is a picture of the "Open Common Dialog Box".  The default filename (SZPlaneplot.gpx) is already typed in for you when this box opens, and it is the only name that the program will accept:

6. Next you need to set up PlanePlotter so that it can use the .gpx files generated by the Visual Basic program to draw the line between the home station and the DX station, and to draw the grid squares and grid square labels.  To set up PlanePlotter in this fashion, you make sure it is pointing to the same directory that you just set up for the Visual Basic program above.  To do this, you need to click on the "Options" item in PlanePlotter's toolbar menu at the top left of the PlanePlotter screen.  Then you need to select "Chart" and then "GPX Overlay" and then "Define a GPX File for Chart Overlay".  This will bring up a window that asks for a file name.  Below is a picture of what that window looks like.  Notice that it has the same look and the same Directory and File names that you just saw/set up in the Visual Basic program above:

Again, this directory will be the default "Charts" directory for PlanePlotter.  If your installation is like mine, it will be "C:/COAA/PlanePlotter/Chart files/" (this is where PlanePlotter keeps its Chart files by default).  So you need to select this directory, select the file "SZPlaneplot.gpx" and click "Open".  Then select "Display all GPX Overlays" and "Toggle GPX Overlay [F8]", both of which are immediately below the "Define a GPX File for Chart Overlay" selection noted above.  Then the desired line marking the path between you and the DX station should then immediately appear on your PlanePlotter Aircraft View screen.  You can toggle the DX path line and the grid square lines and labels on and off by clicking F8 while in PlanePlotter.  Any time you change the location of the Home Grid Square or the DX Grid Square this path line will change to fit the new locations.  When you select "Display all GPX Overlays" in PlanePlotter, ALL .gpx files in this default directory will be displayed by PlanePlotter.  This is a very powerful thing, and it only applies for this default directory.  That's it!  You should be ready to run PlanePlotter and this Visual Basic Program!  Again, don't forget that PlanePlotter must be running for you to run the Visual Basic program.

7.  Finally, don't forget to set your UTC offset in the lower right hand corner of the main form.  East of Greenwich is positive, West of Greenwich is negative.  So here in Reading, PA the correct setting during Daylight Saving Time is -4, and during the rest of the year it is -5.

Here are some initial tests using this PlanePlotter/Visual Basic combination and the W3CCX beacon in FM29jw, 73.89 km away.  The screen below shows the W3CCX beacon on 5760.196 displayed on Linrad, along with PlanePlotter and the SZ-PlanePlot Visual Basic add-on.  You can see the direct path between my location near Reading and the beacon, along an azimuth of 119.82 degrees.  You can see that an aircraft has just passed perpendicularly across this direct path, and you can see the doppler-shifted trace spanning approximately 1000 Hz moving down in frequency from the beacon trace.  This occurred just when the ADS-B data from PlanePlotter and the Visual Basic program said the plane would cross the direct path to the beacon, which is where I had my 30 inch dish antenna pointed.  So this suggests that the timing provided by the combination of programs is satisfactory for using the positioning data obtained from these programs for aircraft scatter work.

You can see similar examples, also on 5760.196 MHz , and also with the dish antenna pointed along the direct path here, here, and here.  When an aircraft is traveling directly along the direct path, the Doppler shift from each observer to the aircraft will be maximized, but one one leg of the path will have negative Doppler shift and one leg will have positive shift, due to the fact that the plane is moving away from one station and towards the other, so there will be some cancellation and thus a reduction of the Doppler shift for the entire path, consisting of both legs.  The exact Doppler shift seen for any situation will depend on the geometry.  Ron Cook VK3AFW, Rex Moncur VK7MO, and David Smith VK3HZ have a nice paper on this at:

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Aircraft Scatter Theory: The bistatic radar equation, and more

Aircraft scatter is NOT magic.  You still need to consider the path-loss equations, and in addition the less than perfect reflective characteristics of the aircraft.  The aircraft gives you an (imperfect) reflective surface that is positioned high in the sky, allowing you to extend your horizon.  But if you have insufficient signal to make up for the path losses, including the losses sustained at the imperfect reflection from the aircraft, you will not be able to hear the other station or make a contact.  The radar equation can be used to figure out whether or not a contact can likely be completed; it relates power at the receiver to power at the transmitter, taking into account path losses and system characteristics.  Emil Pocock W3EP wrote a nice discussion of this applied to amateur radio aircraft scatter in The ARRL UHF/Microwave Experimenter's Manual, pages 3-28 and 3-29.  He reformed the equation in terms of path loss:

total loss (in dB) L = 10 log (( lambda**2) * S / (((Rt)**2) * (Rr)**2))) - 153 where
Rt = distance from transmitter to reflector in km
Rr = distance from receiver to reflector in km
lambda = wavelength in meters
S = radar cross section of the aircraft

"S", the radar cross section of the aircraft, will obviously depend upon the aspect the aircraft presents to the observer, and it may also have a frequency dependence if certain materials are used.  Emil gave estimated values of 2 M**2 for a Lear Jet, 8 for a Douglas DC-9, 16 for a Boeing 707, and 63 for a Boeing 747.

If we use this equation to evaluate the path loss for a Boeing 707-sized plane for 10  GHz work with the plane at the midpoint between two stations 500 km apart, we get a path loss of 267 dB.  By comparison, the EME path loss for 10 GHz at perigee would be 287 dB.  The path loss over 500 meters in free space would be 167 dB.  So aircraft scatter loses an extra 100 dB relative to free space loss, and over a 500 kM path is only 20 dB worse than moon bounce!  If you were using a 30 inch dish and 4 watt transmitter and had a receive sensitivity of -130 dBm, then over a 500 km free space path you would have a fade margin of 71.2 dB.  With aircraft scatter you would be 29 dB BELOW the noise.  So aircraft scatter is useful only if you have a high ERP as well as a sensitive receiver. With the same receiver characteristics but with 100 watts transmit power and a 3 meter dish, your fade margin for a 500 km path in free space would be 109 dB.  So for aircraft scatter you would be 9dB out of the noise and could make a CW contact.  Note that the Australians used 10 watts and a 34 dBi dish at one end and 8 watts and a 32 dBi dish at the other end of a 628 km path, but they used JT65C to give additional gain.  For 5 GHz, the path loss for the same aircraft scatter path would be 261 dB rather than 267 dB.  You can check the math if you wish by using 6.25E11 meters for the radar cross section of the moon and 356,000 km as perigee, and solving the radar equation for the path loss with the moon as the reflector.  You will get 287 dB.  As noted above, this program will do path loss calculations for the selected DX station and aircraft of your choice.  More information on that is on a companion web page.  Here is a screen shot of the EN90gg <>FN20ag path I use for illustration:  with the parameters chosen, the signals are just out of the noise.  It is interesting to watch the signal as the aircraft approaches one end of the path; the signal level increases, but the close-in station needs to have elevation control: see the illustration here.  You can see the path and the designated aircraft on the PlanePlotter screen, and the signal strength parameters on the Path Loss Calculator form.  VK2KU has also noted that the signal strength peaks when the aircraft is near either of the ends of the path, and dips in the middle.

However, there is some potential MAGIC that may crop up: up to 20-30 dB of signal enhancement may occur when the aircraft is located on or very near to the direct path line between the two stations.  This enhancement is called "forward scattering" enhancement and falls off extremely rapidly if the aircraft is positioned even slightly off of this line.  Rex Moncur VK7MO has an excellent paper discussing this here, and VK2KU Guy Fletcher discussed it as well in the paper mentioned immediately above.  This enhancement is also frequency-dependent, as noted in the above papers, and likely of reduced utility on 10 GHz and higher, due to the very narrow lobes of the scattering produced at this higher frequency.  VK7MO and David Smith, VK3HZ discuss this here.  Note that Rex and David were able to make use of this phenomenon on both 10 and 24 GHz, in spite of the frequency constraints noted above.  Using a "new" WSJT mode called ISCAT-A for 10 and 24 GHz Aircraft Scatter, Rex and David have completed Aircraft Scatter contacts of up to 842 km on 10 GHz and 462 km on 24 GHz.  Their paper describing these achievements is here.  Rex describes this new mode like this: 

"This mode is around 15 dB more sensitive than FSK441 and is a further development of ISCAT which is included in the publicly released version of WSJT9. The new version includes both ISCAT-A and ISCAT-B with ISCAT-B being the old ISCAT included in the publicly available version. Joe Taylor kindly developed ISCAT-A to meet our requirements for aircraft scatter at 10 GHz. It can be run in 15 second periods and can cope with very rapid Doppler variations of up to 1000 Hz/min as occur at 10 GHz when an aircraft crosses the path at right angles. It also copes well with the short bursts of a few seconds that we receive at 10 GHz and has an averaging feature that allows it to take advantage of longer but weaker bursts".

Rex was kind enough to send me some plots of forward scatter enhancement as it occurred on the 561 km path between his QTH and that of VK3GHZ.  The top plot is a waterfall plot of frequency vs time and the bottom graph shows signal strength vs time.  You can see that the Aircraft Scatter signal peaks at 30 dB above the noise on this 561 km path!

Rex has further description of these plots here.

The calculator in my Visual Basic program indicates when there is present favorable geometry such that forward scatter enhancement is likely to occur by coloring the Path Loss, Received Signal, and aircraft position text boxes on the Path Loss Calculator Form RED under these conditions.  This is shown in the illustration of this Visual Basic form above, and I have repeated the illustration here on the left.












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How to Get Started:

So I think to start making Aircraft Scatter QSOs on the microwaves the path is to:

1.  Get Plane Plotter

2.  Download my program or get or write another to do similar things to what my program does (what I listed as the 10 things this program does at the top of this page).  You need this data to make a satisfactory run at doing aircraft scatter.  Otherwise, you are just sticking your head in the sand.

3.  Get WSJT 9 so you can run ISCAT-A

4.  Find a DX station who is also interested

5.  Use my program or a similar one to build a database of when aircraft are actually in suitable positions, or cull the flight schedules or use a site like where you can type in destination and origin cities and get a list of all flights, and determine favorable times for attempted contacts.  I use both.  The flightaware data gives you an idea of when planes "might" be where you want them to be.  Information gathered over a period of days or weeks using PlanePlotter and my Visual Basic program gives you actual data on when there were actually planes in the locations you require.  Believe it or not, airline schedules are not actually consistent from day to day!  The listed times may be consistent, but the actual flight times are not.

6.  Use the Path Loss Calculator form from my program (or do the math) to figure out your link budget, and thus determine the probability of success with and without forward scatter enhancement, using appropriate values for transmit power, antenna gain, and receiver noise figure.

7.  Give it a try using PlanePlotter, my program or equivalent, and ISCAT-A, at times determined as above.  With PlanePlotter and my program running during the QSO, you can see how things look second to second, and also see if new aircraft come into favorable positions for scatter.

8.  If you want, You can change the color of the Direct Path line, of the markers for the DXSTATION/HOMESTATION/MIDPOINT points, and for the DXSTATION/HOMESTATION/MIDPOINT text.  Making these changes is also a PlanePlotter function.  To make these changes, in PlanePlotter go to:

Options>>Chart>>Options.  On the Chart Options Menu page in the upper right corner is a set of buttons labeled "GPX overlay colours".  You can change the color for the various items.  The items that I use are:

Waypoints: I used as gridsquare center marker
Routepoints: I used for Home Station, Midpoint, DX Station markers
Route Segments: I used for the Direct Path Line between Home Station and DX Station
Track points: I used as gridsquare corners
Track segments: I used as gridsquare lines.
Labels: I used as labels for gridsquares, and for DXSTATION/HOMESTATION/MIDPOINT

You can change the color of each of these by clicking on the appropriate button on this PlanePlotter Chart Options page.

I chose the following colors after some experimentation:

Waypoints: white
Route points: blue
Route segments: blue
Trackpoints: white
Track segments: grey
Labels: black

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Receiving Local Aircraft Over the Air

I think the easiest and cheapest way to start receiving local aircraft, if you want to do that rather than (or in addition to) using the internet data, and the way I did it here, is to get one of the cheap RTL 2832 Dongles from Amazon, (where I got my most recent one, a "NooElec TV28T v2 USB DVB-T & RTL-SDR Receiver"), from AliBaba (which is where I got my first one in mid 2012, a TV28T from Newsky Tech Company, that uses the now discontinued E4000 chip), or from eBay. 

The best URL for getting software and guidance to get going on Windows is

There you can download the RTL1090 software that you can use to feed PlanePlotter or FlightRadar24.  The site also has an excellent MANUAL for getting started.  Look at the yellow-orange buttons at the top left of the webpage, and click on the one that says "Manual".  Then click on the blue letters that spell "Manual" that appear beneath the button, and you will have the manual on your screen.  All should be self-evident.  As they say, make SURE you do NOT install any of the software [drivers or otherwise] that came with the dongle! 

I got good results just using the little 4 inch-or-so long indoor antenna that came with the dongle, but much better results with an outside antenna and preamp mounted at the antenna.  I currently have a WIMO GP-1090 antenna and a Kuhne 1090 MHz mast-mount preamp and get excellent performance from them, as you can see here.  Here in FN20ag I have significant obstructions, and find that my typical range with the NooElec dongle is as follows:

NW 410 km
N     310 km
E     180 km
S     370 km
SW 200 km

You cannot expect optimal performance at 1.09 GHz without a mast-mounted preamp and low loss coax, unless your dongle is right at the antenna.  Furthermore, the dongles are extremely wideband by design, and have very poor strong signal tolerance.  Therefore, using an antenna with some frequency selectivity and a preamp with helical or other filters to remove signal outside the desired passband will greatly enhance performance, by preventing performance degradation from out-of-band strong signals.  So even if you have the dongle right at the antenna, adding a preamp with frequency selectivity will improve performance by attenuating out-of-band signals before they reach the dongle.

There is further information available at:

You can also play with things on Linux.  I did my original installation of the E4000 on Linux, but I haven't played with things on Linux since.  The following URL walks you through getting set up for Linux step by step.  It is simple as long as you follow the directions, and I had no problems with it. .  I have enjoyed playing with this, but if you have internet access, actual received "through-the-antenna" signals are redundant to the internet-received data, because the internet data is all time-stamped.  I don't use this at all to plan aircraft scatter operations or tests.  But its fun to play with, and I do upload my real-time aircraft data to the web for others to use.

You plug the RTL Dongle into the USB port on your Linux computer, and hook it up to the indoor stock 4 inch antenna that came with it.  You install gnuradio, the gr-air-modes application, and the VirtualRadar server program on your Linux box and launch gr-air-modes and then Virtual Radar, and the VirtualRadar server will start sending data to PlanePlotter that is running on your windows box.  This is a painless and very inexpensive way to see where the aircraft you might use for scatter are located.  Below is a screen shot of all of this running on my Linux box.  Again, you can see a larger version by right-clicking on the image and then clicking on "View Image":


Below is a graph of the elevation angles vs distance for planes that I have tracked here with PlanePlotter.  Only really close-in planes will have an elevation of above 2 degrees or so, so you don't need to have elevation control unless your antenna beamwidth is very narrow:

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Information Sources Regarding Direct Reception of ADS-B Signals

DL4MEA has a webpage describing a much more sophisticated receiver / decoder that he designed at: .  This device known as the "Mode-S Beast" and is described further and is for sale at: .

A technical description of the ADS-B system is at:

The ADS-B transmissions use Manchester coding, which is described at:

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Excellent Aircraft Scatter Information Sources on the Web:

There are some excellent pages discussing various aspects of using Aircraft Scatter for Amateur Radio purposes:

VK3HZ  and VK7MO have some great webpages and articles on Aircraft Scatter work that they have done on frequencies as high as 24 GHz.  They have done extensive investigation and have made aircraft scatter contacts on microwave frequencies up to 24 GHz, using JT65C and ISCAT (a new WSJT mode).  As noted above, they have completed Aircraft Scatter contacts of up to 842 km on 10 GHz and 462 km on 24 GHz.  They make extensive use of the ADS-B system and the PlanePlotter software, which are the techniques I described above.  I was pleased to see of their great success and accomplishments with these validates my plans and tells me that I am on the right track with my beginning efforts here.  You especially want to check out the sections of their webpages labeled "24 GHz Propagation Tests", "Radio Site Display", and "Aircraft Enhanced Propagation"! :

This page by VK3HZ gives links to multiple other Aircraft Scatter pages from Down Under:

SM6FHZ's aircraft scatter page:  He has an aircraft scatter path-loss Excel Spreadsheet here.

SM0DFP has a page describing his use of ADS-B signals to assist with airplane scatter contacts:

Here is an nice page on airplane scatter by GM4XCM:

Here is an interesting page on airplane scatter by G0ISW:

SM0LCB has an overlay for GoogleMaps to help you plan contacts: .   See also the bottom of this webpage for more:  Below is a picture of his GoogleMaps page showing a possible aircraft scatter path between my location and EN90gg.  This direct path information is included in the information given by my Visual Basic Program and PlanePlotter combination described above. 

A PowerPoint talk by DF9IC on airplane scatter:

The ADS-B system (Automatic Dependence Surveillance-Broadcast mode" is described by AE5X:

There is a nice Aircraft Scatter program called AirScout by Frank, DL2ALF which uses airplane data which is available from the web.  It runs on Windows.  You can read about this here, and download it from here.  Here is a screen grab of his program running here at W3SZ:

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