Welcome to mysteries of radio

This website is intended to describe some of the mysterious signals that can be

heard on the high frequency radio band.

You will learn about the strange European pirates stations called Echo Charlie's who chat over thousands of kilometres and mysterious stations that chant nothing but numbers over the air and then disappear.

So what is the high frequency band?

The High frequency (HF) band is a large radio band that extends from

3 MHz to 30 MHz or a wavelength of 100 metres to 10 metres.

The high frequency band is divided into sub bands by wavelength in

metres. These wavelength bands are then allocated to different users.

Legitimate users include

•  Utilities stations such as long distance military, maritime and aeronautical communications.

•  International broadcast stations such as the BBC world service, voice of America and Radio Netherlands .

•  Amateur radio

•  Citizen Band services

So what is special about the high frequency band?

Radio waves in this part of the radio frequencies (FR) spectrum

Can bounce or propagate between the earth and the Ionosphere

Allowing the radio waves to travel hundreds or thousands of

kilometres.

The lower frequencies between approximately 3 MHz and 9 MHz

propagate best in local hours of darkness.

The higher frequencies between approximately 12 MHz and 30 MHz

Propagate best in local hours of daylight.

The frequencies between approximately 9 MHz and 12 MHz can usually be heard at any time.