Erhard Kietz
Erhard Karl Kietz (born August 22, 1909 in Leipzig ; † April 6, 1982 in Blütlingen ) was a German physicist . He researched the constancy of frequencies for video signals.
Life
Erhard Karl Kietz was born as the eldest child of Anna and Georg Kietz, a math teacher, on August 22, 1909 in Leipzig. He came from a musical family and played the cello and piano.
He graduated from the Nikolai-Gymnasium in Leipzig and then studied physics , mathematics and chemistry at the University of Leipzig , where he received his doctorate in February 1938. rer. nat. received his doctorate . From May 1929 to February 1938, while studying at the university, he worked as assistant to August Karolus in the laboratory of the Physics Institute at the University of Leipzig. After receiving his doctorate, he worked in the same laboratory from March 1938 to May 1945 with independent development work in the fields of television , high-frequency and amplifier technology. His main field of work was television and the generation of highly constant vibrations using tuning forks and quartz crystals. During the Second World War it was buried twice in bombing raids on the Physics Institute.
On August 9, 1941, he married Gisela Raschig, b. June 1, 1917. On June 15, 1945, the US military evacuated him, his wife, their two young children and his laboratory colleague Herbert Mangold with his wife and daughter to Unterhaching near Munich .
The eldest son died in 1947 at the age of five of blood poisoning , as a result of a protracted otitis media in the difficult months before the end of the war and from a lack of penicillin in the post-war period. The family, now with six children aged eleven to nine months, emigrated to the USA on May 15, 1956 on the cargo steamer Witmarsum via Hamburg.
On June 10, 1956, the ship arrived in Houston , Texas, from where the family made 700 km south to Elsa . However, there was no work for a physicist here, so the family moved to Altadena in California in September 1956 at the suggestion of an acquaintance who had emigrated from Germany a few years earlier . Erhard Kietz was employed in the research department of Consolidated Electrodynamics in Pasadena , where he worked under Adrian B. Cook on the implementation of the recording device technology. In January 1959, the family moved to Menlo Park , south of San Francisco , when the area was still developing as Silicon Valley , where Erhard Kietz had an electrical engineering position in the research and development department headed by Charles P. Ginsburg the month before Ampex Corporation in Redwood City , California. In 1971 he retired from Ampex Corporation .
He felt a stranger to Erhard Kietz in American society. The longing for home grew; he and his wife were considering returning to Germany. After his wife had a fatal accident in a car accident in 1967, he took his two youngest daughters, who were still minors, on the Bremen passenger ship from New York to Bremerhaven in July 1971 . He settled in Dankoltsweiler (Baden-Württemberg). He died on April 6, 1982 in Blütlingen (Lower Saxony).
Scientific contributions
Erhard Kietz's scientific career began with his doctoral thesis, experiments on the frequency constancy of electrically driven tuning forks , which was accepted by the university's faculty in Leipzig in February 1938 and published in Dresden in 1939. This work was of great interest because applications like radar and video require a very constant amount of time.
In the first quartz watches, as the forerunners of the oscillating quartz, there were tiny electrically driven tuning forks, which were then translated into the watch hands .
His early work on the development of television included work on a 10-channel and 200-channel television system for a giant screen, a 1000-line television system, and research on the behavior of photoelectric cells at radio frequency.
Kietz made a significant contribution to basic research and the practical development of magnetic recording of video signals.
The two biggest problems that had to be solved were the high demands on time stability during playback and overcoming the bandwidth limitations of the previous magnetic recording technology. A high bandwidth of the recording could be achieved by four heads rotating rapidly across the tape, which enabled a very high head to tape speed translation with slow tape running. Using this new technology, the bandwidth could be extended to three orders of magnitude: from 18 kHz with standard fixed heads to 20 MHz with rotating heads. In connection with this, the uninterrupted switchover from one head to the next had to be solved. The principle of rotating heads was used in all professional and later in all home video recorders.
The time base correction was initially very complex technology (individual video lines were recorded with a cathode ray on a rotating disk and scanned at another point with a second cathode ray), later implemented with semiconductor circuits.
On June 15, 1960, Erhard Kietz published a summary of the work status on "Electronic Time Base Correction" for Ampex Corporation. Here, too, it is a question of an exact time base with errors of less than a tenth of a microsecond, without which video recorders cannot do.
Erhard Kietz's publication Transient-free and time-stable Signal Reproduction from Rotating Head Recorders appeared in the National Space Electronics Symposium Record, 1963, Miami Beach, Florida, Paper 4.3 and as a revision in February 1968. Authored together with his colleague Sid Damron he wrote the technical article Digital Recording at High Bit Rates, Reliability and Density in March 1967 .
In April 1967, Erhard Kietz wrote the lecture Developments in the Magnetic Recording of Multimegahertz Bandwidths , which was given by his colleague Sid S. Damron on April 25 for the broadband recording symposium at the Griffiss Air Force base in New York was held.
Sid Damron and Erhard Kietz, both employed by Ampex Corporation in Redwood City, California, collaborated on the publication of Exceptionally High-Density Data Recording in Modern Data , December 1968 (pp. 28-31)
On January 1st, 1971 his document was published for Ampex Corporation Electronic Track Alignment of Digital Signals recorded at High Density on a Multitrack Recorder .
As part of his scientific research, Kietz was engaged in commissions that mainly served military purposes and only secondarily civilian use. His research results were first used in the recording of radar signals from polar radar stations, later radar signals and images from soaring aircraft, and soon afterwards for high-resolution image recordings from spy satellites that flew around the world and were only supposed to transmit their images to earth at certain points. Its developments can also be viewed against the background that the radar and video flights over the Soviet Union and Cuba (1962) made it possible to obtain a more realistic assessment of the potential of Soviet ballistic missiles.
The progressive downsizing of devices was also achieved through the emergence of transistor technology and, a little later, through integrated circuits. Today's devices hardly give any indication of how much signal processing is necessary for video recording and playback. The first VCRs had several cabinets full of electronics.
The "newest" tape recorder, as well as an example of an anti-missile application of Ampex's signal recording-playback technique, can be seen in the articles in the Ampex Monitor 1961. In the late 1960s to the 1980s, Ampex video tapes like the Quadruplex were in all Used in television studios around the world.
During his employment at Ampex Corporation, Erhard Kietz was involved in several patents. He played a key role in the four patents:
| Patent ID | Filing date | content |
| US3131384 | August 29, 1960 | Recording and reproducing system |
| US3304377 | September 11, 1961 | Synchronizing system for video transducing apparatus utilizing composite information transducing and pilot signals |
| US3204047 | March 19, 1962 | Signal reproducing system with phase cancellation of unsired signal component |
| US3536856 | 20th September 1967 | Record-reproduce mode selection without mechanical relays |
Individual evidence
- ^ Charles P. Ginsburg
- ↑ Organizational list of the Ampex engineering department
- ^ Kietz: Dissertation
- ↑ Electronic Time-Base Correction ( Memento of the original from November 14, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Transient-free and Time-Stable Signal Repro ... ( Memento of the original from November 14, 2015 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Digital Recording at High Bit Rates ...
- ^ Developments in the Magnetic Recording of Multimegahertz Bandwidths
- ↑ Exceptionally High-Density Data Recording ( Memento of the original from November 14, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Electronic Track Alignment of Digital Signals ... ( Memento of the original from November 14, 2015 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
- ^ Richard Helms: Looking over my Shoulder pp. 267-268
- ↑ Ampex Monitor
- ↑ Patent US3131384
- ↑ Patent US3304377
- ↑ Patent US3204047
- ↑ Patent US3536856
Web links
- Literature by and about Erhard Kietz in the catalog of the German National Library
| personal data | |
|---|---|
| SURNAME | Kietz, Erhard |
| ALTERNATIVE NAMES | Kietz, Erhard Karl |
| BRIEF DESCRIPTION | German physicist |
| DATE OF BIRTH | August 22, 1909 |
| PLACE OF BIRTH | Leipzig |
| DATE OF DEATH | April 6, 1982 |
| Place of death | Blütlingen , Lower Saxony |