Airplane scatter - connections reflected from the aircraft

The idea of ​​making a VHF connection by reflection from an aircraft is a relatively new technique, which is not yet used by many radio amateurs. The originator of the idea is Frank DL2ALF, which this method detected by listening to the beacon. This was then reflected in the program AirScout.

Demonstration of 70cm beacon reception using an Airplane scatter

Andrzej SO3Z wrote a very good presentation for beginners. The connection procedure itself is well described in http://www.dj5ar.de/?page_id=998 . It is similar to meteor scatter communication.

Airplane scatter is abbreviated AS on DX cluster, resp. ASC. Due to the wavelength, the airplane scatter is mainly used in bands 2m, 70cm a 23cm. Andrzej uses it mainly on 2m.

Airplane scatter

In principle, the signal from the aircraft is reflected as if it were a tropospheric layer. Reflections usually last about one minute, but a connection for a time via is not excluded 10 minutes as long as the route of the aircraft follows the line between the two stations. He also managed to connect with stations with 50W and 5el. yagi antennas at a distance 650 kilometers. The bigger the plane, the better the reflections. The clearer the horizon at both stations in a given direction and the antenna the higher, this makes the connection length longer.

The presentation about the airplane scatter-i was prepared in English by Henning DF9IC http://www.df9ic.de/doc/2006/sletten_2006/sletten06_airplane_reflection.ppt

Several airplane scatter recordings

1. reflection from an airplane flying in a line between stations, SA6AIN, SM6UQL, SK6QA, SA6AFQ, SA6CBY (50W + 5the)

2. SM6VKC 753km

3. V SPAC (similar to VHF PA) has SO3Z regular connections with DF9IC 697km a OZ3Z 588km (1) http://so3z.com/records/spac-2014-02/OZ3Z-JO45UM-588km-airplane-scatter.ogg

4. 2.subregional races 2014 – 144MHz SK6QA, SM6BFE, OZ3Z, S50G, HA8V, OM8AND, OE6HBF

AirScout DL2ALF

The author of the Airscout program is Frank DL2ALF http://www.airscout.eu/

The source of aircraft data is websites http://planefinder.net a http://www.flightradar24.com using ADB-S beacons.

The source of terrain and altitude data is GLOBE by default, however, you should switch to SRTM-3 data in the program settings, which take up less disk space. You can select SRTM1, which is a much more accurate satellite database, but we must have around 20 – 30 GB of free disk space.

How to set up AirScout?

In the main program menu, go to Options and define the area on the General tab, for which aircraft data and altitude data will be downloaded. Then click the Apply button. The picture shows an example of my settings (you can set a smaller area).

Main AirScout settings
Main AirScout settings

Then, on the SRTM3 tab, select the item as shown and click the Apply button.

SRTM3 settings in AirScout
SRTM3 settings in AirScout

Go to Download Data Files and in the window, which appears, click Start – downloading can take a long time - beware, large files !!!

Another thing is to turn on aircraft data on the Planes tab – select them as shown and click the Apply button. It is also worth raising the maximum altitude as a minimum, in which the aircraft is taken into account – there are flights above 12 000 m.

Flight data acquisition settings and flight altitude selection
Flight data acquisition settings and flight altitude selection

After turning on the sources with aircraft and downloading maps with altitude data, we can choose the basis of the map, which we will have visible in the program on the Map tab. Default for me - OpenStreetMap.

Map type in AirScout
Map type in AirScout

Now we should carefully adjust our QTH. We will set the brand and locator in the program settings, as shown in the figure.

Brand and locator settings
Brand and locator settings

Save the settings and close the options window.

On the map in the main window (our QTH) a red cursor should appear. Let's get closer, and adjust the exact position of the cursor by dragging it to the correct position – I'm doing it when zooming in 15.

QTH and the height of the antennas above the ground are very important for the calculations.

Exact location, height and height of the antenna above the ground
Exact location, height and height of the antenna above the ground

This completes the setup. We can test them by simulating them in the program by entering the brand and locator of the station.

AirScout tips and demos

Especially for connections to QRB 600 – 850 km depends very much on the refinement of the position, for example according to GPS or from the coordinates of the given station (QRZ.com a pod.). According to the 6-digit locator, for example, the connection to HB9GT is not established, but in reality its QTH in the given locator is 200m higher and the QSO is possible. This causes the horizon to be "exposed". A few examples below.

Explanation of connection via airplane scatter with OM8AND
Explanation of connection via airplane scatter with OM8AND
Explanation of fields in AirScout
Explanation of fields in AirScout
Aircraft for airplane scatter connection with HB9GT
Aircraft for airplane scatter connection with HB9GT
Several aircraft in line with HB9EFK
Several aircraft in line with HB9EFK
Airplane scatter connection line with OM8AND
Airplane scatter connection line with OM8AND
AirScout prediction for SO3Z connection - YU7ECD
AirScout prediction for SO3Z connection – YU7ECD
Airplane scatter SO3Z connection prediction - YU7ACO
Airplane scatter SO3Z connection prediction – YU7ACO

Here is the line for PA4EME – QSO possible only with the aircraft at a height slightly above 12000 m:

Airplane scatter prediction of connection with PA4EME only for aircraft over 12000m
Airplane scatter prediction of connection with PA4EME only for aircraft over 12000m

It is also necessary to keep in mind, that military planes also fly in the airspace, sometimes without the ADS-B transponder switched on. The flight altitude of military aircraft often exceeds 12 km – for example, a large drone RQ-4 flies 15-16 km above the ground, allowing longer communication via airplane scatter. Just look at flightradar24 on RQ-4 flying in Europe with the code "FORTE10". But there are also much larger machines, such as the B-52, B1, KC-135 and others.

Andrzej SO3Z

Airscout – reflections from airplanes

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