Shortwave radio

This may be my least read blog and certainly will rate a 10 on the geek scale, but here goes. I have been listening to shortwave broadcasting since the early 1970's. I go through periods of listening and then getting busy and letting it go. Oddly, I have picked it up with the conditions are better for listening and let it go when the conditions favorable to long distance transmission begin to fade. This cycle is due the 11 year cycle of solar activity. For stations to be heard from over the horizon, the signal must bounce off the F2 layer in the ionosphere, roughly 100-150 miles above the surface of the earth. The solar conditions create the F2 layer as the sun floods the atmosphere with charged particles off which the signal is reflected. Then the signal is reflected off the surface of the planet and back into the ionosphere. This is called propagation. The signal may hop many times before being received by an antenna. Each bounce takes energy from the signal, weakening it and adding noise.

Radio sets started with crystals, then to vacuum tubes, the to solid state chips and now the new hardware solution is a simple chip that routes the radio signal to a computer. The antenna receives an analogue signal and the new Software Designed Radio coverts the analogue signal to a digital signal and feeds it into the computer and the computer's sound card. The advantages are enormous. As the processing occurs on the computer, a display is available for the listener to use to tune the desired frequency. The signal is displayed along with any other signals nearby. The display offers data to the strength of the signal and any signal which is close in frequency that may interfere with reception.

A SDR uses a computer program that is accessed by the user and the user may choose among several software packages. I have four I am testing at the moment. I'd love to find a decent book of instruction for sdr displays.

The subject of antenna theory is quite daunting. Even a cursory glance into the science of capturing faint electrical impulses leads into a morass of math and physics far beyond my comprehension. So, I keep it simple. Now I have an 27m (80 ft.) inverted - L long wire into a 9:1 balan into 50 ohm coax leading back into the shack. Reception is good and the low noise floor is excellent. Best antenna I've built. I have plans for another oriented in the direction of Europe and Africa.

There are many things to listen too on the high frequency bands. International stations, regional stations, Ham radio and utilities, International and Regional (stations intended for local audiences) broadcasts can very interesting and informative, getting news and interesting stories not covered in the American press. There is the access to very different music from around the world. DXing is part of shortwave listening that concerns itself with catching the rare and difficult signal. That's what I do. In the last few weeks, I have logged stations from South and Central America; Colombia, Venezuela, Chile, Brazil and others. Lots of North Africans, Egypt, Tunisia, Morocco, etc. Not much luck with sub-Saharan Africa yet. Southeast Asia, Australia, New Zealand, South Korea and other countries. So far I've logged most of the Europeans. Logging a station requires a positive identification, such as an announced station identification, confirming data, as in the World Radio and TV Handbook.

The most profound change since my last foray into the world of radio is the availability.of data. I can check many sources for information. This is so different than when I used to twirl the dial and try to guess what I was hearing. These days I can log on to the website of a station and sometimes here the broadcast to confirm what I'm hearing. It is a different DX world out there.