- Sep 21, 2017 -
In the process of enjoying the radio hobby, the hand is indispensable as a "treasure" - liberating people from the equipment, allowing the radio to follow people, rather than letting people go to the radio. Hand station contributed. In fact, want to turn the radio into the size of the present, the designer is also a painstaking effort!
The original radio equipment is very large, for the urgent need to transfer information between the two police and the army in terms of, although not easy to carry, but still a warm welcome. After all, for them, the real-time information than to reduce their weight more important. The Victorian police shown in the figure above may be the first police in the world to use radio equipment in patrols. The Marconi telegraph occupies a full space in the rear of a patrol car, and when the operator replies to the incident, the patrol car arrives at the crime scene in time.
For the army, the more hope is that the commander's command can be passed to each subordinate combat unit. For a large regimental headquarters, it is not difficult to use a radio or a mule to be a radio station, and to a smaller combat unit (such as an infantry class, a tank), want to equip them with radio Taiwan is not that easy. In fact, in the early days of World War II, many tanks of the Soviet army still use the flag as a means of mutual communication. And how to make the radio equipment more lightweight, simple has become a radio communication problems to be solved.
In general, we believe that the first radio station, which was widely called "Walkie-Talkie", was the SCR-300 invented by Motorola (and of course only Galvin Manufacturing Company) in World War II. But this radio and we now know the "handheld radio" there is a certain difference, because it is actually a back on the back of the infantry radio. This station in FM mode work in 40 ~ 48MHz, for the infantry to provide communication support.
The real sense of the "hand radio (Handheld Radio)" is the late launch of Motorola's SCR-536. This is a kind of AM mode work in the 3.5 ~ 6.0MHz between the individual radio. It uses a tube process and uses a dry battery in series to provide high voltage when the tube is operating. The switch is very unique - the antenna is fully pulled out, the power is turned on, and the antenna when the power is automatically closed. Its maximum power is only 360mW, working on the land when the furthest of 1.6 km can pass the target, while the effect at sea can be raised to nearly 5 km. In many classic film and television works and games, we can see it in the shadow.
After the war, the electronics industry and the radio industry have been further developed. The more excellent hand-held radio was designed out. Military and police for the time being (they have been at the forefront of technology), we can concentrate on talking about amateur radio handheld radio.
After World War II, a large number of military products were eliminated into the field of amateur radio. And its design ideas are also introduced into the field of amateur radio. The mainstream structure of the year or the tube as the center of the radio design, fragile, high operating voltage characteristics make portable radio design is very difficult. But with the invention of the transistor and practical, handheld radio station really began to stand on the amateur stage. The type of representative of this period we can see the stamp of the late King of Thailand HS1A:
To the transistor as the core, analog line for the composition of the analog hand-held walkie-talkie is a long period of time mainstream. At the same time, has begun to use the FM mode of the UV section of the intercom has become amateur radio enthusiasts for the best choice for local communications. This hand swept the world for decades, and in recent years, has been replaced by a new technology architecture, that is, SDR mode. SDR mode can be audio, radio frequency and other signals all sampling, the use of digital mode for processing. Many simple walkie-talkie only need a fixed FM modulation and demodulation algorithm chip can achieve all the features of the previous hand. Making the current walkie-talkie can do smaller, more refined, cheaper.
What is the future talk about the opportunity? We can see from the previous development clues: the most advanced technology must first be used in the human most concerned about the cutting-edge issues, whether military applications or transistor revolution, the development of modern communications technology, perhaps the next amateur radio Scale revolution, is driven by the promotion of mobile technology.