I am showing COAA
PlanePlotter as PC software here just because it is most
often used application
together with the Mode-S Beast. Several others should also run with it,
as there are:
- Jetvision.de "Globe-S", which should soon support the
- I guess that also Sprut's ADS-B Scope should do it
- I also believe that there is a software from USA that can
run with it, I was in contact with the author and also got some
postprocessed data back, but yet don't know more (funny, yes)
Basically, all PC software that can handle AVR format can be
used for the Mode-S Beast.
GUI: Graphical User Interface
Standard Connection 1CH via USB:
The basic connection is as simple as this graphic: Just
connect an antenna to the SMA connector,
and the USB cable to your PC. Do some simple installations scripts and
you are ready.
Standard Connection 2CH/4CH via USB, omni antenna plus yagis:
The big advantage of the Mode-S Beast is the possibility of connecting
more than just one antenna
to the receiver by using external miniADSB receivers. The 2CH unit
allows up to two antennas,
while the 4CH unit allows up to a total of 4 antennas to be connected.
Basically every receiver can be connected here as soon as its signal
level is around 1,65Vpp.
DC biasing is done separately anyway.
I am using exactly above configuration:
- The G7RGQ stacked omni directional antenna
connected to the internal receiver provides data from all directions,
see also my own comments on this
antenna and how to make it
- The 10ele yagi that I
have built using existing material using the yagi designer by
VK4DI, points to the closeby Munich airport and receives all ground
traffic from there. On the omni this did not show up, even it is just
20nm, due to mostly 2 reasons:
1) too less gain and so too weak signal of the omni and
2) too much FRUIT from other planes
This web page contains also a summary of accessoirs and add-ons for
Enhanced Connection 2CH/4CH (Antenna Segmentation):
There is a basic problem in the Mode-S transmissions, which is
so called FRUIT.
This means that the channel is acutally shared by many applications,
like DME (Distance Measuring Equipment)
and traditional radar (SSR). Even Mode-S consists of several data
formats, so called DF.
Mainly we are just interested in DF-17 frames, but may use the other
frame types as well.
Now it happens that the aircrafts transmit their frames in a nearly
There is some coordinaten by roll call, but this is done in each ground
station radar antenna for itself.
The aircrafts do not check if the 1090MHz channel is free before
starting their transmission.
Due to this, frames may overlap each other, better say, they really do.
See this little example:
Here we have 3 overlapping signals, there is a
traditional SSR radar signal in the preamble
of the weaker Mode-S signal and at the end a strong Mode-S signal starts
In radar world, all these unwanted signal overlaps are called
FRUIT (abb. tbd).
In transmission theory, it is called ALOHA effect, and it is limiting
the channel throughput down to 18%
of the possible channel capacity. In fact, when listening to Mode-S in
high traffic times,
I recognize a kind of a saturation when getting around 300 DF-11#/DF-17
One chance to overcome this problem is to implement a decoder
that is capable of handling this.
Since my decoder is designed for maximum sensitivity, it is not yet
able to do so.
I will add another decoder in the next firmware release that should be
able to handle it.
But yet this decoder is in the phase of an "idea".
Anyway, the better methode how to handle this problem is not
even let it exist.
We can easily split signals by using directional antennas.
In this case the signals just then overlap if they are received by the
So if we spit up the 360° around a location into several
- we limit FRUIT to just those signals coming from the same
- we can use higher gain antennas because they can be made
As shown here, each antenna is receiving a
90° wide sector.
This is the maximum, but the priciple already works with two antennas,
like shown by F5ANN, or three antennas.
Of course then it is possible to connect one even higher gain antenna
towards a hot spot.
There are many possible connections.
For such a system, I recoommend the so called AMOS antenna.