Today the Search Engine Google is showinga Doodle for Valdemar Poulsen.

Google is celebrating Danish engineer ValdemarPoulsen’s 148th Birthday in a few countries with a doodle.

Valdemar Poulsen was born on 23rd November1869.

He was a Danish engineer who made significantcontributions to early radio technology.

He developed a magnetic wire recorder calledthe telegraphone in 1898 and the first continuous wave radio transmitter, the Poulsen arc transmitter,in 1903, which was used in some of the first broadcasting stations until the early 1920s.

The magnetic recording was demonstrated inprinciple as early as 1898 by Valdemar Poulsen in his telegraphone.

Magnetic wire recording, and its successor,magnetic tape recording, involve the use of a magnetizable medium which moves past a recordinghead.

An electrical signal, which is analogous tothe sound that is to be recorded, is fed to the recording head, inducing a pattern ofmagnetization similar to the signal.

A playback head (which may be the same asthe recording head) can then pick up the changes in the magnetic field from the tape and convertthem into an electrical signal.

Poulsen obtained a Telegraphone Patent in1898, and with his assistant, Peder O.

Pedersen, later developed other magnetic recorders thatrecorded on steel wire, tape, or disks.

None of these devices had electronic amplification,but the recorded signal was easily strong enough to be heard through a headset or eventransmitted on telephone wires.

At the 1900 World's Fair in Paris, Poulsenhad the chance to record the voice of Emperor Franz Josef of Austria which is believed tobe the oldest surviving magnetic audio recording today.

Poulsen developed an arc converter in 1908,referred to as the "Poulsen Arc Transmitter", which was widely used in radio before theadvent of vacuum tube technology.

The system was able to communicate betweenLyngby and Newcastle with a 100-foot mast.

He died on 23rd July 1942.