Pop spark transmitter
A pop-spark transmitter (or creak- spark transmitter ) is a historical design of a transmission system and one of the first technically implemented high-frequency transmitters . Pop-spark transmitters were used to wirelessly transmit messages in the form of Morse code as part of radio telegraphy . In 1901 the Italian radio pioneer Guglielmo Marconi established the first radio link between North America and Europe via the North Atlantic with the pop-spark transmitter . In 1909, Marconi and Ferdinand Braun , who created the basic technical requirements for the Marconis transmitters, received the Nobel Prize for Physics “in recognition of their services to the development of wireless telegraphy” .
This first form of information transmission was called “spark telegraphy” or FT for short. The German company Telefunken derived its name from this in 1903. The pop spark transmitter was further developed in 1906 to become a similarly constructed extinguishing spark transmitter . The military was the first and most important promoter of the new technology.
Mode of action
In the simplified basic circuit shown on the right, the capacitor C1 is charged via the series resistor R to limit the current to a high voltage of a few kV up to 100 kV. The charging process is ended when the spark gap is ignited ; a discharge into the parallel resonant circuit consisting of C2 and a coil L takes place via the arc . The resonant circuit, which is adjusted to a specific resonance frequency using the values of C2 and L , transfers part of the energy to the antenna as a damped oscillation . When discharging, the arc produces a loud bang, like the thunder in a thunderstorm , from which the name of this type of transmitter is derived.
disadvantage
In the 1920s, pop spark transmitters were banned because they interfered with the reception of other transmitters due to the large bandwidth of the signal generated. As soon as the spark gap ignites, the frequency drops because of the parallel connection of the two capacitors C1 and C2. After the spark gap has been extinguished, the transmission frequency increases because only C2 is still connected to the coil. Another reason for the large bandwidth is that sparks generally generate a strongly distorted and thus broadband signal compared to the sinusoidal shape. This can easily be heard with the crackling noise of lightning thunderstorms on the radio on long, medium and short wave. In addition, with this transmission technology, the oscillating circuit is only triggered for a short time, which affects the build-up and thus the effect of the circuit. In addition, a lot of energy is lost by transferring the charge to C2, which reduces the transmission power.
literature
- John S. Belrose: Fessenden and Marconi: Their Differing Technologies and Transatlantic Experiments During the First Decade of this Century. International Conference on 100 Years of Radio, 5-7. September 1995, 1995, accessed March 29, 2016 .
