As far as 49.337Mhz, nothing specific to that frequency although if it was man made it would be a bit different. The range 49-50MHz is designed for broadcast but unknown who would be using it. Possibly HAM broadcast.
Another possibility is a small amount of solar radiation, not likely but remotely possible.
You can get an idea of what frequencies to use or know about from this chart -
http://www.acma.gov.au/~/media/Spect...2013%20pdf.pdf