Whistle-like signal in Amateur Radio 40m band

OZ9AEC has found a strange signal in the 7 MHz band using his AMSAT-UK FUNcube Dongle with an HF up-converter.

A strange whistle-like signal received on the 40 meter band using Gqrx software defined radio receiver and a Funcube Dongle equipped with a shortwave converter. The signal appears to be amplitude modulated with suppressed lower side band (just like UVB-76 😉 ) Is it an ionosonde or a numbers station?

Watch Mystery whistle signal on 40 meter band

Gqrx Software Defined Receiver Software http://www.oz9aec.net/index.php/gnu-radio/gqrx-sdr

How to receive and decode NOAA APT images with AMSAT-UK FUNcube Dongle and Gqrx

An HF Converter for FCD http://www.ct1ffu.com/site/index.php?option=com_content&view=article&id=178&Itemid=104

You can join the FUNcube Yahoo Group at http://uk.groups.yahoo.com/group/FUNcube/