Hardware Hacking

I started out to build a project based along similar lines to the 21Mhz interferometer receivers used by the Fringe Dwellers..

However, I have found HF frequencies below 40Mhz are very noisy and I suspect this is the same in most suburban areas. However using a WinRadio and tuning through the bands suggested for radio astronomy observations I found that the 74Mhz band was the lowest frequency I could find that was reasonably quite.

The 74Mhz band was heavily used by commercial users in previous years, but with the advent of mobile phones and other digital technologies, I assume the band now is used to a lesser degree. This was also confirmed by investigating who uses the band by visiting the ACMA website. As a result I have found what I think is a sweet spot at 73.5Mhz for the Adelaide metropolitan area, but this will be different for other areas of Australia.

The only down side in using this frequency is that it is not suitable for Jupiter observations as the natural signal emitted signals peak at around 8 to 11Mhz and reduce at higher frequencies rarely emitting above 30Mhz.