1296MHz Transverter

This transverter was along time in development. It has not seen much service either but with more power and an antenna on the mast I am sure that it would have the potential to work much more. Anyway, there are some interesting propagation effects at these frequencies. Listening to SSB signals while mobile is quite interesting as the mobile flutter is so rapid. Rain scatter, aircraft reflections, etc are either not heard at lower frequencies or are not as pronounced as here. Take a moment to listen to the recording below it will give you some idea of what can be heard. An approaching low altitude aircraft increases the beacon frequency and signal strength.I guess these effects become more pronounced with increasing frequency.
Built 1995 2w out 1152MHz LO SBL1-X mixer mmics M67715 PA Best DX GW

GB3USK received on transverter and 144MHz SDR

23CMS DOPPLER SHIFT

Added 09/2009

Living in the Chippenham area of North Wiltshire we are all aware of the Hercules transport aircraft that circle around RAF Lyneham. When the wind is in the east they swing around just in front of my QTH, I guess to land into the wind.   It’s at this point when listening to the 23cms beacon GB3USK 1296.875 MHz, which is located near Bristol, that the signal starts to arrive at my antenna via two paths, one the usual ground wave and two, reflected off the aircraft.

The moving aircraft produces the amazing Doppler shift that can be seen here.  The signal shifts up in frequency as the plane approaches my QTH dropping as it moves away.  Someone clever may be able to work out its speed.



The CW at an angle is the reflected and Doppler shifted signal.  The straight trace the ground wave signal.



This is the ground wave signal with no aircraft in the air local to my QTH.

Here is an audio file of the beacon with Doppler recorded some time ago.
http://davidkearns.co.uk/g8tti/index_files/Doppler 13.9.02.WAV

If I can make a half decent video I'll put a link here.

Equipment used; 19element beam pointing towards Lyneham, HB 1296MHz transverter (144MHz IF hence the frequency readout of the software), HB 144MHz SDR, Rocky software.

Here is a video of an image reflection from GB3USK.