Gudday

I had my ADS-B 1090 MHz receiver hooked up to a CRO on the weekend to take some photos of the video.

Much to my surprise, not only did I see some ADS-B, Mode A and Mode C, but I also saw DME breakthrough.



ADS-B and SSR responses happen on 1090 Mhz, whilst aircraft interigate the brisbane DME on 1103 MHz.

The two large humps are an aircraft sending DME pulses, while the smaller spikes are SSR replys.

SSR replies are 0.45 us apart between elements. (20us overall)

DME spacing for channel 79X (1103 MHz is 12us)

I know it is the same aircraft DME and SSR because the amplitude and presence of the pulses corresponded with the distance from my receiver.

The breakthrough I was seeing on the CRO, aliigned with the audio I was hearing on my scanner on AM mode on 1103 MHz (DME A/C TX)

Here is are some photos, showing a capture of the video signals:-

SBS-1 video captures

http://tech-software.net/xpndr/