SkyDemon Forums

ADS-B data into Skydemon with a Raspberry Pi

http://forums.skydemon.aero/Topic14379.aspx

By Wobblewing - 1/30/2015 12:06:18 AM

Hi,

What with all of this NATS ADS-B trial initiative, there should be good ways of detecting and plotting traffic now on Skydemon with a low cost ADS-B Receiver, to give us a very low cost PCAS.

So, working on a Raspberry Pi ADS-B receiver solution (super cheap! ~£50 or less - keep it open source), based on dump1090 or modesdeco2, but wondering if it's possible to adapt the FLARM interface to get traffic data displayed on Skydemon.  There is an ADSB2FLARM software module kicking around in the 'virtual radar' development community.

How does SD handle this?  Is there a better way to feed this data into SD?  Which interface would be recommended?  How about over Bluetooth?  If this is available is there a document describing the message format?

The Air-connect TCP/IP style isn't so attractive, since it's harder/more expensive to set up a WiFi Access Point with the RPi using a USB WiFi dongle.   (EDIT: Seems it's possible with a USB WiFi stick to create an AP, so maybe ok this way)

Cheers
Andy
By nkriek - 10/1/2016 5:47:09 PM

GEAR - 10/1/2016 12:28:22 PM
nkriek - 10/1/2016 12:08:21 PM
schweboo - 2/3/2016 1:00:56 PM
I have consulted those who understand this stuff and quote:

"Virtually all receivers employ what is know as the "superheterodyne" (superhet) design. The incoming signal is mixed with a very low power locally created signal to produce an intermediate frequency where most of the signal amplification takes place. This locally created signal is known as the "local oscillator" and it is, in effect, an extremely low power transmitter.

Dongles like the one we use actually convert down to baseband where digital signal processing (DSP) is used to render the required signals. The superhet concept still applies, so in theory, at least, it is possible for interference from the local oscillator to occur. It is, however, an extremely improbable effect. It would only occur in the event of a fairly significant malfunction in the dongle's electronics, as the local oscillator should not be tuned to anywhere near any of the frequencies that we use. I don't discount it by any means but there are other places I'd be looking first".

I have bought the components and want to build the PilotAware unit. My iPad does not have the GPS chip and I use the Dual150 (GPS and Glasnoss) connected via Bluetooth to the iPad. Would you recommend routing the Dual system via the PilotAware or the iPad? Any tips, information etc you can send me to assist in the building of the unit will be much appreciated.
Neels

As far as I am aware, the latest implementation of PilotAware employs a GPS dongle in one of the Raspberry Pi USB Ports.  When Running PilotAware with Sky Demon you need to tell Sky Demon to connect to FLARM. Then PilotAware supplies the GPS fix to Sky Demon and the Dual150 GPS device is not used.  However if the PilotAware device was to fail or Hang up you would then need to instruct SkyDemon to take its GPS input from the Dual150.


Thank you George