Amateur Radio in Hong Kong

Radio test with China,Japan,Russia,Korea and Taiwan
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What Is Amateur Radio
(The information provided on this page may be outdated and contains error, I welcome your comment)

Amateur Radio is a hobby that make use of radio equipment to communicate with people all over the world, this is open to the general public, and required by law the operator must obtain a license to operate the radio, they usually have to pass some kind of examination to get the license, and they are allowed to make, maintain and modify their own equipment and this is where the fun starts. Beside leisure chatting and make friends over the air, the nature of the hobby is to exchange ideas and experience on radio communication. By experiment with different communication modes and equipment setup, Amateur provide valuable information to the manufacturer to design better quipment, this will in turn benefit the commercial user, Amateur play an important role in the early days of radio communication development. In order to promote the hobby there are contests held by worldwide organizations and radio clubs, such as 'Fox Hunting' a game to locate hidden transmitter is a very hot one. Sometimes Amateur also provide communication support to the public in special events such as sports and games, and when required, will provide emergency communication link in case of national disaster. To prevent interfere with commercial and essential service there are restricted frequency and power level to use, which is governed by the IARU, as well as the local telecommunication authority. For instance Hong Kong belongs to region 3 in the band plan, may not communicate with the USA in some frequency only available in region 2. For those do not have a license to transmit, can become a shortwave listener(SWL) and this is also interesting. After a successful 2-way communication, operators will exchange QSL cards to confirm the contact, and by collecting such cards they can apply for the awards. The hobby has now become very hot in the USA and Japan, and there are over 1,000 licensed operator in Hong Kong.

Please also see The History of Telecommication

How Radio Signal Propagate

There are layers of thin air at the edge of the Earth, that receive strong radiation from the sun, causing them to ionize and able to reflect radio waves, such layers called the 'ionosphere'. There are 4 such layers namely D, E, F1 and F2, each of them responsible for reflecting different frequency range. The density of the ionosphere changes according to the 'Sun spot' activity, the higher the activity the stronger the ionization thus reflect radio waves better. The Sun spot activity is in a predictable 11 years halfcycle from peak to bottom, and then from bottom to peak the next 11 years. The height of the ionosphere also changes in time, this explain why distance shortwave station can not be heard all the time in one frequency, because the radio waves 'landed' on different region of the Earth after being reflected. To maintain reliable service the broadcaster will change frequency in different hours of the day and different season of the year, and transmit in more than one frequency so that they can be heard all the time all over the world. The ionosphere has very little effect on frequency above 50Mhz, at that frequency the wave length becomes too short that can penetrate the ionosphere and go straight to space, so satellite communication requires VHF or above.

Radio wave fall into three main categories with different usage :

HF (High Frequency 3-30Mhz)
Long Range communications : shipping, aircraft, worldwide broadcasting.
Effective range from 500 to thousands of Kilometers.

VHF (Very High Frequency 30-300 MHz)
Medium range communications : fleet vehicles, mobile, coastal shipping, air to tower and satellite communications.
Range 70-100km (aircraft several hundred km).

UHF (Ultra High Frequency 300-3000 MHz)
Local short range communications : hand-held radios, cellphone, TV and spacecraft to ground and satellite communications, signal can bounce off buildings and reflect until it is detected by a receiver.


My Gears


Homebrew

My homebrew power amp.
10Mhz-150Mhz up to 300W at 28V
Kits available at CCI
My mini SSTV converter
Built into a DB9 cover
How about a SSTV mic !
What is SSTV anyway ?
Commercial Products
A wonderful shortwave radio If you can't affort one
American Radio Relay League
Radio Society of Great Britain
Japan Amateur Radio League History Of Radio