Unknown broadcast on 8000 kHz, periodically transmitting

[SW Observer]

Today from 1900z until 2130z I heard an unusual station on 8000 kHz on the Twente WebSDR.

This station makes an unusual sounding pulse every few seconds, followed by a burst of noise. Occasionally the noise and carrier will stop, and scrambled voice will be heard, though this may or may not be related. Myself and several other monitors on the Twente WebSDR gave the station the unofficial name 'XDE' the DE representing 'Doppler Effect', as it appeared so on the Waterfall view and it somewhat resembles a Doppler pulse.

Here is a recent 17 minute recording of the broadcast:

http://www.youtube.com/watch?v=b03eOy3zgDM

[cmradio]

That frequency is assigned "Fixed Satellite (Earth to satellite)" and "Research" - could be the eggheads at CSA/ESA/NASA calibrating

Peace!

[Token]

Not a radar.  And not sure it has anything much to do with frequency allocations either.  I have seen this same signal, or one very much like it, on 7001.5, 12000, 14000, and now 8000 kHz.

It might be worth noting this signal was in full AM.

My guess is an audio test tone into a transmitter to check the passband of the system.  The tone was using a triangle sweep, sweeping 0 to 5 kHz and then reversing direction and sweeping 5 to 0 kHz, and a 6 second cycle time.

Image of the spectrogram here:


T!