• [Overview]
• [His life]
• [Videos & interviews]
• [Patents]
• [References]

Latest page update: 3-April-2022 (added Fig. 15B and 15C)

Previous update: 1-January-2022 (added ref. 89 and text);11-Sept-2021 (added ref. 230Z and patents 481703 & 482281); 9 July 2019

©2004-2022 F. Dörenberg, unless stated otherwise. All rights reserved worldwide. No part of this publication may be used without permission from the author.

OVERVIEW

Rudolf Hell explained the purpose of the Hell-Schreiber as follows [see p. 2 and §10b in ref. 1]:

"Das Entwicklungsziel, ein für Presseempfang brauchbares Gerät zu schaffen, konnte nur mit einem denkbar einfachen Schreibgerät erreicht werden." "Die Entwicklung des Hell-Schreibers erfolgte speziell im Hinblick auf die drahtlose Übertragungstechnik"

"The objective of the development was a practical device for the reception of messages from news agencies. This could only be achieved with a very simple teleprinter." "The development of the Hell-printer was specifically done for wireless communication."

It went into service with press agencies and news media in 1934. The Hellschreiber is a Typenbildfernschreiber, basically a "character-image tele-writer" or "print-telegraph". Copies of Dr. Hell's patents related to the Hellschreiber are available below.

"Ich habe nie etwas gemacht, nur um Geld zu verdienen. Es ging mir um den Fortschritt und die praktische Anwendung"

"I‘ve never done anything just to earn money. For me, the important things were progress and practical applications."

In 1926 and 1927, Hell published a number of amateur radio publications for the do-it-yourself construction of antennas and equipment, including a receiver/printer for text transmissions [e.g., ref. 62, 77, 78].

Fig. 1: Two of the books (co-)authored by Rudolf Hell

In his 1927 book "Bildfunk" [ref. 77], Rudolf Hell already applied the basic concepts that he would use in the Hellschreiber a couple of years later:

"Zur Übertragung wird das Bild im Bildsender in einzelne Bildelemente zerlegt, die in Stromimpulse verwandelt werden. Der Empfänger schreibt entsprechend den ankommenden Stromimpulsen selbsttätig Punkte und Striche in richtiger Reihenfolge auf das Empfangsblatt."

"For transmission, the sender decomposes the image into individual pixels that are converted into current pulses. The receiver mechanically prints the arriving pulses as a an equivalent sequence of dots and line segments."

The Hellschreiber is a simple and robust system that was developed specifically to provide readable, error-free communication, even on low-quality radio and land-line telephone links and in mobile applications. This made it particularly suitable for press agencies, diplomatic and military communications (incl. in combination with crypto machines), communication over high-voltage power-lines [ref. 29, 53], police communication [ref. section 10a in ref. 1 (Medium Wave network), 73], and… amateur radio! It is based on raster-scan transmission of text characters , and printing the received signals as-is (no decoding required) with a helical scan mechanism. In other words: a simple form of fax, or remote dot-matrix printer. See more details on my "How it works" and "Photos" pages.

Wireless services of news agencies such as the Deutsches Nachrichtenbüro (DNB), Deutsche Presse-Agentur (DPA), the Allgemeiner Deutscher Nachrichtendienst (AND), and Reuters [ref. 47], transmitted their messages in Hell-format. See the Presse-Hell pages. Reuters started its to the European continent in 1934. Broadcasting was primarily done on long-wave frequencies, to get continental coverage. Ref. 6. In the post-WWII years, agencies such as the Deutsche Allgemeine Nachrichten Agentur (DANA), Deutsche Nachrichtenagentur (DENA), the Deutsche Presse Dienst (DPD), Deutscher Sportverlag (DSV), and Telegrafnoie Agentstvo Sovetskogo Soiuza, (TASS, Telegraph Agency of the Soviet Union) also used the Hell format. TASS continued Hellschreiber broadcast at least through the mid-1950s.

Fig. 2: Map of the wireless Hellschreiber-network of the German DNB press agency ca. 1939

(source: figure 1 in ref. 6)

The Wehrmacht is the combined army ("Heer"), navy ("Kriegsmarine"), and air force ("Luftwaffe") in Germany from 1935-1945. The Hell-system was used for military field operations. Hence, the Wehrmacht Hellschreibers are also referred to as Feldfernschreibers or Feld-Hellschreiber. They entered into service ca. 1935 - in time for the start of the war [see p. 50 of ref. 48]. Feld-Hell machines were also used by the armed forces of other countries (e.g., until ca. 1960 in Sweden). There are indications that Feld-Hell machines ("teletipo de campaña") were used by the Spanish armed forces, in particular the national army, during various conflicts: the Spanish Civil War 1936-39, World War II (a Spanish legion in the USSR), and the Ifni Wars (Spanish West Sahara and around the Moroccan coastal city of Sidi Ifni) 1956-58. The Italian army also used Feld-Hell machines ("telescrittore campale", "telescrivente da campo"), see the Italian Hell-telegram here. The Finnish armed forces - with German supplies - used Feld-Hellschreiber in the Karelia region during the 1941-1944 "Continuation War" against Russia. The Hungarian army also used Feld-Hell machines, with legends in Hungarian.

The Luftwaffe also used Hellschreiber technology for aerial navigation, as part of the "Bernhard" system. The ground-station transmitted the momentary azimuth of its rotating narrow-beam antenna in Hell format on VHF (30-33.3 MHz); ref. 3. Its airborne counterpart is a small Hell-printer, the FuG 120 "Bernhardine" ("UKW-Richtstrahl-Drehfunkfeuer Empfänger" or "Receiver for rotational directional VHF beam beacon". It was installed in various aircraft types, esp. night fighter versions, such as the Messerschmitt Me262 (one of my all time favorite aircraft), Junkers Ju 88G, Arado Ar234 [ref. 4], and Dornier Do-335.

The Kriegsmarine used Hellschreiber as part of the on-board intercom system [ref. 75], as well as ship-to-ship and ship-to-shore communication. This included broadcasts from Germany to (submerged) submarines worldwide, with the 1 megawatt "Goliath" VLF transmitter near Berlin.

The German military has operated the Hellschreiber in combination with the famous Enigma encryption system [ref. 31, 32, 52], e.g., for message exchanges between headquarters in European capitals (Athens/Greece-Vienna/Austria, ref. 3). In 1944 the Hell Co. developed the "Hell-Geheimschreiber" encryption machine. It used 235 possible codes for each 7x5 dot character, using a one-time-pad encryption algorithm with a period of 1014 [ref. 5]. Apparently only half dozen or so of these machines were ever made. They were used in U-Boot, and on Kriegsmarine ships in the Mediterranean in 1945. The Hell Co. resumed the design and manufacture of crypto systems in the 1950s.

During the war, the Reichsbahn (German national railways) used "Presse Hell" Hellschreiber broadcasts over short-wave radio, to disseminate train schedules, etc. Its messages were intercepted by the BBC Monitoring Service (BBCMS) [ref. 69]. After the war, the Deutsche Bahn used well over a thousand Hellschreiber machines [ref. 70].

Commercial use of Hell-systems continued well into the 1980s.

HIS LIFE

Rudolf Hell was born on 19 December 1901 at the local freight railway station of Eggmühl (Lower Bavaria, 15 km south of Regensburg, 90 km northeast of Munich) where his father, Karl Hell, was station master for the Königlich-Bayrische Eisenbahngesellschaft (Royal Bavarian Railway Co.). It is here were Rudolf was exposed to telegraphy at an early age. His mother, Lidwina, was the daughter of a farmer and beer brewer. Rudolf had two older brothers, Karl and Max. The area was a battlefield in 1809, when Napoleon's army defeated the Austrian army under Archduke Karl.

Fig. 3: Karl, Max, and Rudolf (left to right) - 1919

(courtesy C. Onnasch and B. Fuchs, ref. 6, used with permission)

At the age of six, his father was transferred some 160 km (100 mi) north to the freight station in the town of Eger, then in the Austro-Hungarian empire - now a border-town in the Czech Republic and named "Cheb" since 1945. This is where he attended elementary school for four years. He was a bit of an outsider and didn't hang out with the kids in the street. Apparently he had a pale complexion. Attempts were made to strengthen him, and bring color to his cheeks with red wine.

Fig. 4: The railway station of Eggmuehl ca. 1900 - father Hell (station master) at far left

(courtesy C. Onnasch and B. Fuchs, ref. 6, used with permission)

After finishing elementary school, he went to the Rudolphinium Oberrealschule (a form of secondary school). It was not named after young Rudolf, but in honor of King Rudolph I of Habsburg. Rudolf graduated in 1919. He was good at physics and math, mediocre at languages, and was poor at subjects that didn't interest him.

At the age of 18, he went to the Technische Hochschule München (Technical University in Munich) where he obtained his "Diplom-Ingenieur - Elektrotechnik" (Dipl.-Ing.) degree in 1923 (Master's Degree in Electrical Engineering). This is where he met Prof. Max Dieckmann (ref. 43, 230Z), who lectured on wireless telegraphy and was forced to rename his lecture "wireless television" to something less provocative. Dieckmann was already involved with scanning of text characters, converting them into electrical pulses and displaying them on a cathode ray tube (CRT) [ref. 44A/B/C]. The CRT was invented in 1895 by Nobel Prize laureate Karl Ferdinand Braun. To this day, it is still referred to as "Braunsche Röhre" ("Braunian Tube") in German speaking countries and in Japan. Dieckman was Braun's assistant 1905-1906. In 1925, Hell filed his first patent (with Dieckmann): an image decomposition tube ("Bildzerlegerröhre") - the invention of the video camera tube!

In 1927 Hell obtained his doctorate degree with a dissertation on "a direct-indicating radio direction finder for aviation" [ref. 79, 230Z], which became the basis for automatic guidance and auto-pilots of aircraft. The invention was licensed to Telefunken and to a US company for a tidy sum: 20,000 Reichsmark (the currency in Germany from 1924-1948); ref. 65. This is estimated (by me) to be the equivalent of roughly three quarters of a million US dollars (2008).

Fig. 5: Logos of the Hell company

In the late 1920, Hell considered the TV technology to be in an impasse, and switched over to facsimile. In May of 1929 (at the age of 28), he and his wife Martha moved to Berlin-Babelsberg, and had a furnished room in the house of an employee of the Auto-Union (a combination of the automobile and motorcycle companies DKW, Horch, Audi ("Horch" in Latin), and Wanderer). Shortly thereafter, he bought a house at Ihnestraße 41 in Berlin-Dahlem (it still exists today, see here). This is where the Dr.-Ing. Rudolf Hell Company was founded. The machine shop was in the basement, the design office and lab on the ground floor, the office in the hallway, and private quarters upstairs. Hell worked here with about a dozen employees.

Fig. 6: Rudolf Hell bought his first house in Berlin-Dahlem

(courtesy C. Onnasch and B. Fuchs, ref. 7, used with permission)

His patent entitled "Device for the electrical transmission of text characters" (nr. 540849, see the patents table below) represents the birth of the "Bildschreiber" (i.e., "image writer"). It was later named "Hell-Schreiber", after its inventor. This has turned out to be one of the turning points in telecommunication. The basic idea of decomposing graphical information into pixels and lines that are easy to process (generate, transmit, reconstitute) has been the theme of Hell's life work. He developed the Hellschreiber in 1929, and that same year he licensed the rights to the Siemens-Halske (S-H) company for 13,000 Reichsmark - about half a million US dollars (2008). His first customer was the German national railway company. The house in Berlin-Dahlem was paid for with this money, plus the proceeds of the sale of his car, and a 3000 Mark inheritance from his mother. Ref. 49. In 1931 the company moved to larger facilities in Berlin-Dahlem, and again in 1937 - to facilities in Berlin-Zehlendorf, at Kronprinzenallee 138 (renamed to Clayallee in 1949). The latter was only a couple of streets away from Hell's house in the Ihnestraße. In 1941/42, production facilities for the war effort of "Wehrbetrieb Dr. Hell" were added in Berlin-Teltow, at an industrial site at the southeast corner of Tempelhof airport, bounded by the Oderstraße and the Warthestraße, about 1 km north of the Teltow-canal. Here, Hellschreibers were manufactured, as well as equipment for the Kriegsmarine, radio compasses, radio direction-finding and crypto equipment. During 1942, the site was expanded with warehousing and baracks for German workers and Luftwaffe personnel, to increase production capacity (ref. 89). The Teltow facilities were dismantled by the Soviet occupational forces in 1946-1946 [ref. 81].

Fig. 7: Hell Werke at the Kronprinzenallee in Berlin-Zehlendorf - built in 1937

(source: ref. 38)

Below is are listings for Rudolf Hell, from the telephone book of Berlin. Starting in 1937, he is listed as "Fernmeldetechnisches Institut" (Telecommunications Institute):

Fig. 8: Phonebook entries for Rudolf Hell (top to bottom: 1934-1943)

(source: Berliner Adressbücher 1799-1943, telephone & address books of Berlin)

During the latter half of the 1930s, the Hell company had the radio callsign D2bw. This was an experimental license. Transmitter location, maximum output power, frequency bands (incl. amateur radio bands), modulation (telegraphy/phone) and purpose were fixed. Communication with other licensees was typically not allowed. The license of 1938 indicates the permission to use Hellschreiber telegraphy with 100 watt, for the development of telemetry systems and radio communication systems, per instructions of the Wehrmacht and other government organizations.

Fig. 9: Entry in the 1935 radio license list

(source: ref. 61A)

Fig. 10: Entry in the 1938 radio license list

(source: ref. 61B)

Rudolf Hell as a private person did not hold a license. He does not appear on the 1936, 1937, or 1939 list of "Liebhaberfunker" (lit. "radio amateurs"), nor on the 1944 (short) list of "Kriegsfunkgenehmigungsinhaber" (war-time licensees). Ref. 61a/b/c. In 1926, he did co-author a hefty book about amateur radio antennas [ref. 63].

During the 1930s through 1945, the S-H company built large numbers (an estimated 50 thousand) of "Presse Hell" machines (for news agencies, etc.). According to Dr. Hell himself [ref. 6], the invention was an "Aha-Erlebnis" (a.k.a. "eureka moment"; the Greek εύρηκα roughly translates to "I have found it"), rather than the result of tedious research and development.

Fig. 11: The double-helix printer for rasterized text characters, patented by Rudolf Hell

(source: Figure 2 of the 1929 Hell patent)

Hell continued the development of Hellschreibers. Hell, like the entire industrial complex, was obliged to support the war effort. This included the development of Morse telegraphy (training) devices, metal detectors [ref. 74], fuses for mines, radio direction finders, and formation-flying flight-guidance systems. As a subcontractor to the C. Lorenz company, Hell developed and manufactured the UKE-5 and UKE-7 modules of the remote control & guidance receivers of the V2-missile [ref. 37]. He co-developed the first missile-borne data recorder, based on video-camera technology [ref. 82]. He was also involved with the development of crypto machines (e.g., patent 855876). At the end of the war, he had about 1000 employees at his two factories. All was lost by the end of the war, and he started all over again in 1947 [ref. 57]. He re-established his company for telecommunications and electronic image reproduction equipment in Kiel (port city in the far north of Germany). Late 1947, Siemens-Halske decided to abandon the telefax/telecopy business. During the spring of 1948, the Hell Co. acquired the rights, all documentation, and the entire parts stock for the sum of 70 thousand Reichsmark. Ref. 7.

Fig. 12: The first "Hell Werke" in Kiel (source: ref. 38)

Fig. 13: Dr. Hell reading the tape of a Hell "T empf 14" tape printer for news agency services

(Telefunken radio model "E400 Rö" next to the printer, with Siemens-Halske keying amplifier model "St.V.1" on top; courtesy C. Onnasch and B. Fuchs, ref. 7, used with permission)

Fig. 14: The lab in Kiel (far right: Rudolf Hell) in Kiel, 1951

Around that same time, an engineer at Sony in Japan reverse-engineered the Hellschreiber, and Sony manufactured 10 to 20 machines (ref. 9; photo and description is here). Early 1948, Siemens-Halske handed off their image transmission activities to Dr. Hell, with a 30-year contract. In 1956 he developed and produced the first practical fax machine: Kleinfaxgerät KF108 [ref. 59, 71, 76]. It uses a spinning drum - one of the two basic technologies (dating back at least as far as Frederick Collier Bakewell, 1848), the other being the flatbed scanner/printer (dating back at least to Alexander Bain, 1843). The received binary image is printed directly onto normal (!) paper with an inked sapphire-wheel, rather than by passing electrical current through impregnated paper (e.g., potassium ferro-cyanide or potassium iodide). However, Siemens abandoned these activities, as they saw no future in it [ref. 72]. Some twenty years later, Japanese companies very successfully revived it...

Fig. 15A: Kleinfaxgerät "KF108d" for DIN-A5 paper size

(with Siemens label, but developed and manufactured (1953-1958) by Hell GmbH)

In the photo above, the right-hand detail shows the printer mechanism that rests on the paper during the printing process (during scanning, it is parked in an upright position). Item a is toothed rubber wheel that rests on the paper and turns with it. The speed of this wheel is up-geared and drives a small rubber belt (item c). This belt continuously transfers ink from the narrow felt ink-roller (item b) to the tiny sapphire print wheel (item d). This print wheel is mounted in a small arm, and is pushed down onto the paper in the rhythm of the fax signal that is received from a scanning KF-108.

Fig. 15B: Kleinfaxgerät "KF108d" for DIN-A5 paper size

Fig. 15C: the inside of the KF 108 - left side and bottom

(source: eBay item 294866091545, 2022)

Fig. 15D: the inside of the KF 108 - front and rear

(source: eBay item 294866091545, 2022)

In the 1950s, Hell developed several mechanical crypto machines for the German Bundeswehr, using technology licensed from the Swiss-based Hagelin Crypto AG company (founded by crypto pioneer Boris Hagelin, with whom Hell had a good personal relationship, ref. 88A-88C). An example of this is shown below: the Hell H-54. This is a very compact (ca. 15x20cm) 6-wheel machine with a double printer (type-wheel, not Hell-spindle). This model was used until the late 1960s.

Fig. 16: Hell H-54 pin-wheel cypher machine

In 1959, the Hell company opened an offfice in Great Neck, Long Island, NY, for marketing, sales, and customer support: the Hell Color Metal Corporation (HCM). Around 1990,  when Dr.-Ing. Rudolf Hell GmbH merged with Linotype AG, the HCM company name appears to have changed to Hell Graphic Systems, with local offices in Melville/NY, Nashville/TN, and Tampa/FL and elsewhere. The Heidelberger Druckmaschinen AG acquired Linotype-Hell AG in 1995.

Hell also revolutionized pre-press processing for printed media (newspapers, magazines, etc.) by developing the fast and precise Klischograph. This provided one-step operation of image scan/transfer and engraving of printing blocks and plates (later expanded for color images). The color Klischograph (ref. 83) reduced the time required to generate a single set of A4-size plates from one week, to four sets in one day!

Fig. 17: Prototype of the Klischograph K151

In 1963, he invented the Chromagraph color scanner that provided 4-color separation [ref. 50]. The famous HallmarkCards company ran type DC-300 Chromagraph scanners around the clock (3 shifts) for many years (1970 - mid-1980s, ref. 80). Hell also revolutionized film scanning (exposure) technology, and in 1964 developed the world's first electronic type setting machine with digitized fonts: the Digiset (marketed in the USA by the Graphic Services Dept. of RCA as the "VideoComp" CRT typesetter). It had a digital magnetic core "font" memory (originally 24 kB in size) and CRT-projection onto film. In 1968, the "DS" (Datensichtgerät) was the first computer (Siemens, of course) with a keyboard, CRT monitor, and text editing software. Corporate management, in its usual "wisdom", declared this a dead-end technology and it was subsequently abandoned. The "DS" remained unsurpassed for 15 years, until IBM popularized a similar product in 1983: the PC.

The Dr.-Ing. Rudolf Hell & Co. KG (KG = Kommanditgesellschaft) company was converted into Dr.-Ing. Rudolf Hell GmbH in 1971, when Siemens AG increased its 49% minority share in the company to an 80% majority share. The company became a wholly-owned subsidiary of Siemens AG on January 31, 1981 (ref. 84).

Trademarks of the Hell company - 1979

(source: ref. 85)

In 1978, Dr. Hell was awarded the prestigious Werner-von-Siemens-Ring for achievements in science and technology (ref. 49). He retired from active business activities in 1990.

On 11 March 2002, this pioneer of telecommunication passed away in Kiel, at the age of 100...

Fig. 18: Logo on the dinnerware of the Hell Co. in Kiel

Fig. 19: Commemorative post card from the 2005 German "National Stamp Day"

(note the "Presse Hell" printer in the black postmark stamp)

VIDEO AND AUDIO INTERVIEWS

AUDIO INTERVIEWS with Rudolf Hell (in his native language; © C. Onnasch, used with permission):

AUDIO DOCUMENTARIES:

PATENTS

The table below lists a selection of patents that list Rudolf Hell as the inventor, and are related to various aspects of Hellschreibers. Worldwide, he is listed as (co-)inventor on nearly 1000 patents. Patents most closely related to the basic principles of Hellschreibers have been highlighted with bold face font. Scanned copies of the original patents are available by clicking on the respective patent number. The table lists the publication date of the patent award. Application for the patent may have been filed several (sometimes many) years prior to the actual award. Also, the date from which the patent rights apply may be different from the filing and the publication date. See the actual patents for details.

Patent number	Patent office	Year	Inventor(s)	Patent owner(s)	Title (original)	Title (translated)
450187	DE	1925	Dr. Max Dieckmann, Dipl.-Ing. Rudolf Hell	Dr. Max Dieckmann, Dipl.-Ing. Rudolf Hell	Lichtelektrische Bildzerlegerröhre für Fernseher	Photo-electric image-decomposition ("dissector") tube for television
469012	RP	1926	Dr. Max Dieckmann, Dipl.-Ing. Rudolf Hell	Dr. Max Dieckmann, Dipl.-Ing. Rudolf Hell	Verfahren zur Gleichtrittregelung von Bildwalzen nach dem d'Arlincourtschen Prinzip	Method for synchronization of image drums, based on a noise-insensitive adaptation of the d'Arlincourt principle
481703	RP	1927	Dr. Max Dieckmann, Dipl.-Ing. Rudolf Hell	Dr. Max Dieckmann, Dipl.-Ing. Rudolf Hell	Funkentelegraphische Peileinrichtung	Direction-finding system for spark transmitter stations [RDF system with stationary loop and a reference antenna, fast switching between antennas, galvanometer "on course" instrument]. Follow-up patent 482281, also 1927, uses pair of switching valves instead of motorized inductive coupler.
540849	DE	1929	Dr.-Ing. Rudolf Hell	Dr.-Ing. Rudolf Hell	Vorrichtung zur elektrischer Übertragung von Schriftzeichen	Device for the electrical transmission of text characters
541935	DE	1930	Dipl.-Ing. Dr.-Ing. Rudolf Hellv	Dipl.-Ing. Dr.-Ing. Rudolf Hell	Vorrichtung zur elektrischer Übertragung von Schriftzeichen	Device for the electrical transmission of text characters   [addendum to 540849]
668821	DE	1933	Dr.-Ing. Rudolf Hell	Siemens & Halske AG	Empfangsanordnung für die Übertragung von Schriftzeichen	Receiving device for the transmission of text characters
658527	DE	1933	Dr.-Ing. Rudolf Hell	Siemens & Halske AG	Anordnung zur Gleichlaufregelung von Telegraphengeräten, welche Schriftzeichen in Bildpunkte zerlegt zeilenmäßig aufzeichnen	Arrangement for synchronization of telegraph apparatus that print lines of text characters decomposed into pixels
699712	DE	1933	Dr.-Ing. Rudolf Hell	Siemens & Halske AG	Anordnung zur Gleichlaufregelung von Telegrafiegeräten, bei denen die Schriftzeichen in Bildpunkte zerlegt aufgezeichnet werden	Device for the synchronization of telegraphy machines that print text characters decomposed into pixels [addition to patent 658527]
2113429	US	1934	Dr.-Ing. Rudolf Hell	Siemens & Halske AG	-	Arrangement for synchronizing of telegraph apparatus
146320	OE	1934	Rudolf Hell	Siemens & Halske AG	Verfahren und Anordnung zur Gleichlaufregelung von Telegraphenapparaten	Method and device for synchronization of telegraph apparatus
698550	RP	1935	Dr.-Ing. Rudolf Hell	Dr.-Ing. Rudolf Hell	Anordnung zur Aufzeichnung von Schriftzeichen, die durch Bildelementen entsprechende Impulsreihen durch ein Magnetsystem und eine umlaufende Schreibspindel übertragen und deren Linien aus gleichlangen, parallel zur Auzeichnungsrichtung verlaufenden Strichen zusammengesetzt werden	Device for recording characters, decomposed into pixel impulses, with a magnet-system and turning printer spindle, as lines made up of same-length strokes parallel to the printing direction
710253	RP	1936	Dr.-Ing. Rudolf Hell	Dr.-Ing. Rudolf Hell	Anordnung zur Start-Stop-Synchronisierung von Bildübertragungsgeräten, Ferndruckern und Fernschreibern, bei denen die einzelnen Zeichen durch Impulse übertragen werden	Device for start-stop sync of fax machines and teleprinters in which characters are transmitted as pulses
683628	DE	1936	Dr.-Ing. Rudolf Hell	Dr.-Ing. Rudolf Hell	Druckhammer für Bildübertragungsgeräte und Fernschreiber	Print hammer for image transmitting devices and tele-writers
150113	OE	1936	Dr.-Ing. Rudolf Hell, Dipl-Ing. Horst Rassow	Siemens & Halske AG	Sendeeinrichtung für Faksimiletelegraphen	Sending device for facsimile telegraphs
668102	DE	1936	Dr.-Ing. Rudolf Hell	Dr.-Ing. Rudolf Hell	Schreibsystem zur Registrierung von Morsezeichen, Schriftzeichen und Bildpunkten	Printing system for Morse characters, text characters and pixels
155198	AT	1937	Max Dreßler, Dr.-Ing. Rudolf Hell, Dipl-Ing. Horst Rassow, Willy Skawran	Siemens & Halske AG	Verfahren und Vorrichtung zur Synchronisierung von Bildübertragungsgeräten, Ferndruckern und Fernschreibern	Method and device for synchronization of image transmitting devices, tele-printers and tele-writers
757304	RP	1937	Dr.-Ing. Rudolf Hell	Dr.-Ing. Rudolf Hell	Anordnung zur Herstellung des Gleichlaufs von Fernschreibern	Device for establishing synchronization of tele-writers [single motor for sender and printer]
694437	DE	1938	Dipl.-Ing. Dr.-Ing. Rudolf Hell	Dr.-Ing. Rudolf Hell	Schreiber für Morsezeichen und Bildtelegrafenimpulse	Printer for Morse characters and image telegraphy pulses
707536	DE	1939	Dr.-Ing. Rudolf Hell	Dr.-Ing. Rudolf Hell	Schreiber für Morsezeichen und Bildtelegrafenimpulse	Printer for Morse characters and image telegraphy pulses
739880	DE	1939	Dr.-Ing. Rudolf Hell, Walter Ay	Dr.-Ing. Rudolf Hell	Verfahren zur Übertragung von Schriftzeichen, die in Bildpunkte aufgelöst auf einer Sendewalze aufgetragen sind	Method for transmission of text characters tat are decomposed into pixels and arranged onto a sending drum
741784	RP	1939	Dr.-Ing. Rudolf Hell	Siemens & Halske AG	Fernschreiber, bei denen die Zeichen durch umlaufende, zu beginn jeder Abtast- bzw. Aufzeichenlinie ankuppelbare Organe gegeben und durch eine dauernd umlaufende, mit dem Geberantrieb synchrone oder annähernd synchrone Schreibspindel aufgezeichnet werden	Teleprinter with single synchronous motor for sender and printer
513715	RP	1939	Dr.-Ing. Rudolf Hell	Dr.-Ing. Rudolf Hell	Fernschreiber mit einer an einem Hebel angeordneten Farbrolle	Teleprinter with a lever-mounted inkroller [spring-loaded]
1487291	RP	1940	Dr.-Ing. Rudolf Hell	Dr.-Ing. Rudolf Hell	Anordnung für Fernschreiber mit einer unmittelbar mit einem Motor gekuppelten Schreibspindel	Arrangement for teleprinters with a direct-drive printer-spindle [flexible, torsionally-stiff link]
2335410	US	1940	Rudolf Hell	Rudolf Hell	-	Method of transmitting characters by means of revolving drums
2356584	US	1940	Rudolf Hell	Rudolf Hell	Verfahren zur sichtbaren Registrierung von elektrischen oder magnetischen Impulsen	Recording spindle
839368	BD	1948	Dr.-Ing. Rudolf Hell	Dr.-Ing. Rudolf Hell	Facsimile printing telegraph system and apparatus	Method for printing electrical or magnetic pulses [Hell- or Morse printer with magnetic ink; with tape-recorder read head]
866052	BD	1948	Dr.-Ing. Rudolf Hell	Siemens & Halske AG.	Blattschreiber nach dem Hell-System	Page/sheet printer according to the Hell-system
848970	BD	1948	Dr.-Ing. Rudolf Hell	Siemens & Halske AG.	Blattschreiber für Hellempfang	Sheet/page printer for Hell reception
816422	BD	1948	Dr.-Ing. Rudolf Hell	Dr.-Ing. Rudolf Hell	Anordnung zum Anlassen und Anhalten von Hellschreibern und ähnlichen Telegraphiegeräten	Device for starting and stopping of Hellschreibers and similar telegraphy machines [remote control]
825277	BD	1948	Dr.-Ing. Rudolf Hell	Siemens & Halske AG.	Blattschreiber nach dem System des Hellschreibers	Hellschreiber sheet/page printer
832444	BD	1949	Dr.-Ing. Rudolf Hell	Siemens & Halske AG.	Verfahren zur Übertragung von Schriftzeichen nach dem Hell-System mittels Blattschreiber	Method for the transmission of characters with a page/sheet printer, per the Hell system
838322	BD	1949	Dr.-Ing. Rudolf Hell	Siemens & Halske AG.	Verfahren zur Übertragung von Schriftzeichen	Method for the transmission of characters [page/sheet printer]
803577	BD	1949	Dr.-Ing. Rudolf Hell	Dr.-Ing. Rudolf Hell	Elektrischer Fliehkraftregler	Electrical centrifugal governor
838765	BD	1949	Dr.-Ing. Rudolf Hell, Dipl.-Ing. Heinz Taudt	Siemens & Halske AG.	Verfahren und Einrichtung zur Gleichlaufregelung von Empfangsanordnungen für Schriftzeichen-Übertragung nach dem Hell-System	Method and device for the synchronization of receivers for character transmission per the Hell system
847024	BD	1949	Dr.-Ing. Rudolf Hell	Siemens & Halske AG.	Blattschreiber für die Aufzeichnung von Schriftzeiche	Page/sheet printer for the recording of characters
851826	BD	1949	Dr.-Ing. Rudolf Hell, Dipl.-Ing. Heinz Taudt	Siemens & Halske AG.	Einrichtung zur Gleichlaufregelung von Empfangsanordnungen für Schriftzeichen nach dem Hell-System	Device for the synchronization of receivers for character transmission per the Hell system
863358	BD	1949	Dr.-Ing. Rudolf Hell	Siemens & Halske AG.	Verfahren und Einrichtung zum Synchronisieren der Sende- und Empfangsanlage für Schriftzeichenübertragungen nach einem Abtastverfahren	Method and device for the synchronization of sending and receiving equipment for the transmission of characters using a scanning method [derives sync info from blank top & bottom line of Hell-characters
9699210	BD	1949	Dr.-Ing. Rudolf Hell	Fa. Dr.-Ing. Rudolf Hell	Vorrichtung zum Aussenden von in Bildelemente zerlegten Schriftzeichen nach dem Hell-System mittels Impulsfolgen	Device for the transmission with pulse sequences of characters that have been decomposed into pixels per the Hell-system.
290749	CH	1949	-	Siemens & Halske AG.	Verfahren und Anordnung zur Übertragung von Schriftzeichen	Method and system for the transmission of characters
880318	BD	1949	Dr.-Ing. Rudolf Hell, Dr.-Ing. Rudolf Zimmermann	Siemens & Halske AG.	Verfahren zur Übertragung von Schriftzeichen nach dem Hell-System	Method for transmission of text characters with the Hell-system
856605	BD	1950	Dr.-Ing. Rudolf Hell	Siemens & Halske AG.	Anordnung für Fernschreiber mit Kontaktwalzen, bei denen durch Druck einer Taste eine Sperrvorrichtung betätigt wird	Arrangement for teleprinters with contact-drum, in which a lock-out mechanism is engaged when a key is pushed
856606	BD	1950	Dr.-Ing. Rudolf Hell	Siemens & Halske AG.	Verfahren und Einrichtung zur Synchronisierung von Hell-Schreibern	Method and device for the synchronization of Hellschreibers [using separate pulses]
2656240	US	1950	Rudolf Hell	Siemens & Halske AG.	-	Recording apparatus for the reception of message characters [Hell page printer]
872515	BD	1950	Dr.-Ing. Rudolf Hell	Siemens & Halske AG.	Faksimile-Schreiber für Schriftzeichenübertragung mit baulicher Vereinigung des Schreibsystems, des Antriebsmotors und des für den Betrieb des Schreib-systems erforderlichen Verstärkers	Fax-printer for character transmisison, with integration of the printer-head, motor, and printer-amplifier [looks like Presse-Hell printer, with simple record-player motor with centrifugal regulator]
2658106	US	1950	Rudolf Hell	Siemens & Halske AG	-	Facsimile Printing Telegraph System
2674654	US	1950	Rudolf Hell	Siemens & Halske AG	-	Apparatus for synchronizing facsimile printers  [for spindle printer, using uniformly distributed sync-pixel pulses]
853005	BD	1950	Dr.-Ing. Rudolf Hell	Dr.-Ing. Rudolf Hell.	Fernschreib-Empfangseinrichtung für elektrische Impulsübertragung vorzugsweise nach dem Fünfer- oder Siebener-Alphabet	Teleprinter for elektrical pulse transmission, preferably 5- or 7-bit code [CRT-based bit pattern display for 5- or 7-bit codes]
2731322	US	1950	Rudolf Hell	Rudolf Hell	-	Recording devices [variants of spindle and paper tape]
855876	BD	1951	Dr.-Ing. Rudolf Hell	Dr.-Ing. Rudolf Hell	Anordung zur geheimen telegraphischen Nachrichtenübermittlung mittels Hellschreiber	Device for secret telegraphic message transmission with Hellschreiber [crypto]
866052	BD	1952	Dr.-Ing. Rudolf Hell	Siemens & Halske AG	Blattschreiber nach dem Hell System	Page printer per the Hell system
939159	BD	1955	Dr.-Ing. Rudolf Hell	Fa. Dr.-Ing. Rudolf Hell	Verfahren zur Übertragung von mit einer Schreibmaschine auf einen bandförmigen Schriftträger gedruckten Schriftzeichen durch photoelektrische Abtastung der Schriftzeichen nach dem Hell-System	Method for the transmission of characters printed onto tape medium, with photoelectrical scanning of the characters per the Hell system
2843670	US	1955	Rudolf Hell, Hans Daudt	Siemens & Halske AG	-	Device for electro-mechanically recording telegraphic impulses
2853551	US	1956	Rudolf Hell	Dr.-Ing. Rudolf Hell KG	-	Page printer facsimile receiver
2938948	US	1958	Rudolf Hell	Dr.-Ing. Rudolf Hell KG	-	Form-printing facsimile receiver
378940	CH	1959	Dr.-Ing. Rudolf Hell	Fa. Dr.-Ing. Rudolf Hell	Verfahren und Vorrichtung zur Übertragung von Schriftzeichen, die entsprechend dem Hell-Code oder einem diesem ähnlichen Code in Bildelemente zerlegt sind, und zu deren Aufzeichnung mittels Blattschreibers im Faksimileverfahren	Method and device for the transmission of characters that have been decomposed into pixels per the Hell-code or similar code, and for their recording with a facsimile method on a page/sheet printer

Patent office abbreviations:
 OE = Österreichisches Patentamt
 AT = Deutsches Reich, Reichspatentamt, Zweigstelle Österreich
 DE = Deutsches Reich, Reichspatentamt
 RP = Reichspatentamt
 DP = Deutsches Patentamt
 BD = Bundesrepublik Deutschland, Deutsches Patentamt
 US = United States Patent Office
 CH = Swiss Patent Office (Schweizerische Eidgenossenschaft - Eidgenossisches Amt für geistiges Eigentum)

Patent sources:

• DEPATISnet, the on-line public database of the Deutsches Patent- und Markenamt (DPMA, German Patent and Trademark Office)
• PATFT, the on-line public database of the United States Patent and Trademark Office.

Interesting development and patent activities in this same area are by Ernst Eduard Kleinschmidt, a German-born US immigrant. During the period 1915-1920 he developed electromechanical printing telegraphs with Charles Krum. Their improved synchronization method was used in the "Springschreiber" ("start-stop teleprinter"). It was licensed to the C. Lorenz company of Berlin-Tempelhof in 1926, and equipment was sold directly to the Deutsche Reichspost that same year. Siemens-Halske developed similar machines that avoided that Kleinschmidt patent (e.g., Blattschreiber "T typ 37"), as did the Creed Co. in the UK.

The Kleinschmidt patent listed below was filed August 1930, well after Hell's original patent filed April 1929. It also includes a double-helix printer spindle and a (notched) character code drum, though the construction is more complex. Kleinschmidt is behind the development of Teletype Corp. Model 17 teleprinter, which appears functionally to be a copy of the Hell Feldfernschreiber.

Patent number	Patent office	Year	Inventor(s)	Patent owner(s)	Title (original)	Title (translated)
2046328	US	1930	E.E. and E.F. Kleinschmidt	Teletype Corp.	Facsimile Printing Telegraph System and Apparatus	-

The C. Lorenz company also obtained patents regarding the decomposition of text characters into pixels. The three patents listed below are basically identical, but filed and obtained in different countries.

Patent number	Patent office	Year	Inventor(s)	Patent owner(s)	Title (original)	Title (translated)
153370	OE	1935	-	C. Lorenz AG	Verfahren zur elektrischen Übertragung von Schriftzeichen, die nach Art der Bildtelegraphie in Einzelzeichen aufgelöst sind (Bildschreiber)	Method for the electrical transmission of characters that have been decomposed into pixels per image telegraphy (image printer)
196491	CH	1936	-	C. Lorenz AG	Verfahren zur elektrischen Übertragung von Schriftzeichen, die nach Art der Bildtelegraphie in Einzelzeichen aufgelöst sind.	Method for the electrical transmission of characters that have been decomposed into pixels per image telegraphy
744883	DE	1935	-	C. Lorenz AG	Verfahren zur elektrischen Übertragung von Schriftzeichen, die nach Art der Bildtelegraphie in Einzelzeichen aufgelöst sind	Method for the electrical transmission of characters that have been decomposed into pixels per image telegraphy

Towards the end of WWII, the Allies began a massive, systematic search for and capture of German “war secrets” technology, scientific knowledge and industrial know-how. Upon the German surrender, as part of war reparations, this was expanded with confiscation of all existing (and new) German intellectual property, and of all associated rights (e.g., patents) in Germany and abroad. Companies in Allied countries, and others considering themselves as such, were given access to much of the records and material, as well as to factories and research institutes in occupied Germany, either for free or for a symbolic fee. In many cases, they found technology that was years or decades ahead of “Allied” technology. This official grab lasted for at least two years. Ref. 34, 35.

REFERENCES

• Ref. 1: "Die Entwicklung des Hell-Schreibers" by the inventor himself: Rudolf Hell; pp. 2-11 in "Hell - Technische Mitteilungen der Firma Dr.-Ing. Rudolf Hell - Gerätentwicklungen aus den Jahren 1929-1939", Nr. 1, May 1940.
• Ref. 2: p. 388-389 in "Decrypted Secrets: Methods and Maxims of Cryptology", by F. L. Bauer, Springer Verlag, 2002, 473 pp.
• Ref. 3: p. 23 in "Some historical and technical aspects of radio navigation, in Germany, over the period 1907 to 1945", by A.O. Bauer, PAØAOB, 28 pp.
• Ref. 4: p. 13, 18 in "Blitz!: Germany's Arado Ar 234 Jet Bomber", by J.R. Smith, E.J. Creek, Merriam Press, 1997.
• Ref. 5: "Hitlers letzte Maschinen" chapter 2.17 in "Codeknacker gegen Codemacher - Die faszinierende Geschichte der Verschlüsselung", by K. Schmeh, W3L Verlag, 2nd edition, 2007, 414 pp.
• Ref. 6: "Der SH-Feldschreiber", Siemens-Halske AG, Berlin-Siemensstadt, SH 7535. 1.2.39. TT1., 11 pp. (courtesy Siemens Corporate Archives, München).
• Ref. 7: "Dr.-Ing. Rudolf Hell: Der Jahrhundert-Ingenieur im Spiegelbild des Zeitgeschehens. Sein beispielhaftes Wirken" ["Dr.-Ing. Rudolf Hell: engineer of the century. His exemplary contributions"], Boris Fuchs and Christian Onnasch, Edition Braus, Wachter Verlag, 2005, ISBN 3-89904-163-1, 280 pp.
• Ref. 8: "My collaboration with Don Knuth and my font design work", Hermann Zapf, TUGboat (Communications of the TeX Users Group), Vol. 0, 2000, No. 0, pp. 26-30.
• Ref. 9: "Oral-History: Nobutoshi Kihara" (interview with Sony engineer), IEEE Global History Network, People and Organizations, January 2009.
• Ref. 10: "Siemens A.G. Business Information, Profile, and History", Company Profiles Vol. 76.
• Ref. 11: "Historical German contributions to physics and applications of electromagnetic oscillations and waves", by Manfred Thumm, Chapter 11 in "History of Wireless", Wiley-IEEE Press, 2006.
• Ref. 12: "Siemens und die Siemensstadt - Ein Standort im Wandel der Zeit", Siemens AG, Berlin 1999.
• Ref. 13: "Siemens: Wiederaufbau in Berlin-Siemensstadt, Investierungen 1945 -1952", Büxenstein, 1952, 56 pp.
• Ref. 14: "Die Siemensstadt: Geschichte und Architektur eines Industriestandortes", Wolfgang Ribbe and Wolfgang Schäche, Ernst & Sohn, 1985, 876 pp., ISBN 3433010234.
• Ref. 15: "160 years of Siemens", Wilfried Feldenkirchen, special edition of SiemensWorld, October 2007, 4 pp.
• Ref. 17: "Radiokatalog Band 1", by Ernst Erb, M+K Computer Verlag AG, 1^st ed.,1998, 400 pp, ISBN-10: 3907007212.
• Ref. 18: "Rundfunkindustrie in Dresden - Radio Mende und Funkwerk Dresden", Waldemar Ueberfuhr, March 2007, 3 pp.; Appendix 5.1.1 to "VEB Robotron-Meßelektronik "Otto Schön" Dresden".
• Ref. 19: "Wegbereiter der Nachrichtentechnik", G. Weinreich, Deutsche Telekom Unterrichtsblätter, Jg. 53, Nr. 1, January 2000, pp. 32-36.
• Ref. 20: "Die Entwicklung des Bildfunks", Funk (Wochenschrift des Funkwesens), Weidmannsche Buchh., 1926, Heft 17, p. 131.
• Ref. 21: "Rudolf Hell war ein genialer Erfinder", Gottfried North, in "DAS ARCHIV - Magazin für Kommunikationsgeschichte, Deutsche Gesellschaft für Post- und Telekommunikationsgeschichte e.V.", 2003, Band 2, pp. 96 – 97.
• Ref. 22: "Rudolf Hell zum 100. Geburtstag - Das Jahrhundert entscheidend mitgeprägt", Festschrift der Heidelberger Druck AG zum 100. Geburtstag von Dr. Rudolf Hell, 21 December 2001, 16 pp.
• Ref. 23: "Lebensdaten und Ehrungen Dr. Rudolf Hell", Archiv Schierling 2001.
• Ref. 24: "Laudatio auf Dr.-Ing., Dr.-Ing. E.h. Rudolf Hell zum 100. Geburtstag", Boris Fuchs, Frankenthal, Archiv Schierling 2001.
• Ref. 25: "Hell-Schreiben - Dr. Hell wird 85 Jahre alt", Thomas Beiderwieden (DG9YAG), cq-DL, 1989, nr. 2, p. 120.
• Ref. 26: "Hell-FAX", Jörg Schlemminger (DB4LM), cq-DL, 1987, nr. 3, p. 182.
• Ref. 27: "Gutenberg-Preis der Stadt Mainz und der Gutenberg-Gesellschaft verliehen an Rudolf Hell am 25. Juni 1977", Reihe: Kleiner Druck der Gutenberg-Gesellschaft, Nr. 104, Gutenberg-Gesellschaft, 1978, 32 pp., ISBN-10: 3775521046 (here: only pp. 14-32: speeches by Prof. H. Zapf and Rudolf Hell) (in German).
• Ref. 28: "Transmission and reception of Photoradiograms" [fax technology and history], R. H. Ranger, Proceedings of the Institute of Radio Engineers (IRE), Vol. 14, No. 2, April 1926, pp. 161-180.
• Ref. 29: "Der Betrieb von Siemens-Hell-Schreibern auf Hochspannungsleitungen im Elektrizitätswerk-Nachrichtendienst" [operating Hellschreibers over 60 kV and 100 kV power lines], Fernmeldetechnik, Siemens & Halske, Berlin-Siemensstadt, 1939, SH. 7802, 1,5 9. 39, 4 pp.
• Ref. 31: "Enigma", [incl. PA0AOB Hellschreiber] D.W. Rollema (PA0SE), Wireless World, Vol. 89, Nr. 1569, June 1983, p. 49-54.
• Ref. 32: "The Tiltman Break", F.L. Bauer, Appendix 5, pp. 370, 371 in "Colossus: the secrets of Bletchley Park's codebraking computers", B. Jack Copeland (ed.), Oxford University Press, 2006, ISBN 019284055X, 462 pp.
• Ref. 33: "Die Fernmeldetechnik als Hilfe bei der Rationalisierung der Eisenbahn", W. Leitenberger [Hellschreiber use in German railroad system is described in Section 3: "Modernisierung des Eisenbahnbetriebes"], ETR: Eisenbahntechnische Rundschau, Nr. 4, April 1966, pp. 139-146.
• Ref. 34: "Science Technology and Reparations: Exploitation and Plunder in Postwar Germany", John Gimbel, Stanford University Press, 1990, 280 pp., ISBN/ISSN: 0804717613. [pdf] See note 1.
• Ref. 35: "Secrets By The Thousands", C. Lester Walker, Harper's Magazine, October 1946, pp. 329-336.
• Ref. 36: "A.E.G. avoids the bombs in WW II", in Chapter 3 of "Wall Street and the Rise of Adolf Hitler", Antony C. Sutton, Buccaneer Books, 1999, 224 pp, ISBN: 1568497261.
• Ref. 37: p. 121 and p. 127 in "Die deutschen Funklenkverfahren bis 1945", Fritz Trenkle, AEG-Telefunken AG, 1982, 216 pp., ISBN 3870871334.
• Ref. 38: "Ein Firmenbild wird zerlegt - Eine Visitenkarte der Dr.-Ing. Rudolf Hell GmbH - Scanning of an image".
• Ref. 39: "p. 4 in "Im Prinzip ganz einfach - Bild und Schrift mit Hell-Technik".
• Ref. 40: "Catholic school shuns pupil called Hell", The Times, 10 July 2007.
• Ref. 41: "The Siemens Company; its historical role in the progress of electrical engineering with chronological table 1847-1977", S. von Weiher, H. Goetzeler, Siemens, 1977, 183 pp.
• Ref. 42: "Die Siemensstadt; Geschichte und Architektur eines Industriestandortes", Wolfgang Ribbe, Wolfgang Schäche, Ernst Verlag, 1985, 876 pp., ISBN 3-433-01023-4.
• Ref. 43: "Max Dieckmann: Gründer des Forschungs-Standortes Oberpfaffenhofen Überblick über seine wissenschaftlichen Aktivitäten", Rudolf Schmid, 06 Nov. 2007, 13 pp. presentation.
• Ref. 44: selected patents
• Ref. 44A: "Verfahren zur Übertragung von Schriftzeichen und Strichzeichnungen unter Benutzung der Kathodenstrahlröhre" [Method for the transmission of letters and line drawings, using a cathode-ray tube], Max Dieckmann, Gustav Glage, Kaiserliches Patentamt Patentschrift Nr. 190102, filed 12 September 1906, awarded 9 September 1907. Demonstrated in 1907 with a 3x3 cm image, 20 image lines, 10 Hz image update rate!
• Ref. 44B: "Anordnung zur Abtastung von Schriftzeichen für Bilduebertragungszwecke mittels engbenachbarter leitender Stifte" [Arrangement for scanning characters by means of closely space styli, for the purpose of image transmission], Reichspatentamt Patentschrift Nr. 520466, Dr. Max Dieckmann, filed 24 March 1929.
• Ref. 44C: "Walzensteuerung fürr elektrische Kopiertelegraphenempfaenger mit Gleichtrittregelung und Aufzeichnung der Schriftzeichen in einer Wendellinie auf die mit Papier bespannte Walze mittels einer Schreibspitze" [Control with synchonization, of a drum for electrical telecopying receivers, and spiral recording of characters onto a paper-covered drum, using a printing tip], Reichspatentamt Patentschrift Nr. 461947, Dr. Max Dieckmann, filed 9 Juni 1926.
• Ref. 45: "A narrative bibliography of radio facsimile", Callahan, J.L., pp. 112-128 in "Radio facsimile - Volume 1", Goldsmith, A.N., Van Dyck, A.F., Horn, C.W., Morris, R.M., Galvin, L. (eds.), RCA Institutes Technical Press, 1938, 353 pp.
• Ref. 46: "Aus der Geschichte des Hauses Siemens - 40 Jahre S&H-Zeichen", Siemens-Zeitschrift, Band 18, Heft 10/11, October/November 1938, p. 497.
• Ref. 47: "Reuters' Wireless Services", W. West, The Post Office Electrical Engineers’ Journal, Vol. 39, July 1946, pp. 48-52. [incomplete file]
• Ref. 48: "Aus der Rüstung des Dritten Reiches (Das Heereswaffenamt 1938-1945); ein authentischer Bericht des letzten Chefs des Heereswaffenamtes", General Emil Leeb (last chief of the Heereswaffenamt), Wehrtechnische Monatshefte (Zeitschrift für Wehrtechnik, Wehrindustrie und Wehrwirtschaft, Deutsche Gesellschaft für Wehrtechnik), Beiheft 4, May 1958,70 pp. [62 MB !]
• Ref. 49: "Werner-von Siemens-Ring-Verleihung 1978, Rudolf Hell", Stiftung Werner-von-Siemens-Ring, Berlin, 1980.
• Ref. 50: "Technik für uns alle" part 1-7, Wolf Rustmeier, Hell company magazine, March 1981 - May 1982.
• Ref. 51: "Gestorben - Rudolf Hell, 100", obituary in "Der Spiegel", Nr. 12, 2002, 18 March 2002, p. 246.
• Ref. 52: "Lorenz and Colossus" [military cryptography], A.E. Sale, Proc. of the 13^th IEEE Computer Security Foundations Workshop, (CSFW-13), 2000, pp. 216-222.
• Ref. 53: "Hochfrequenz-Nachrichtentrechnik für Elektrizitätswerke" [HF communication for power plants], Gerhard Dreßler
• Ref. 53A: pp. 65-66 in the 1941 edition, Springer Verlag
• Ref. 53B: pp. 94-96, 162, 163, 170-172  in the 2^nd ed., Heinrich-Karl Podszeck, Springer Verlag, 1952, 183 pp.
• Ref. 54: "Neue Stufe der Nachrichtenübermittlung. Der Hellschreiber wird den Sprechfunk ersetzen", p. 261, 262 in "Der Zeitungs-Verlag: Fachblatt für das gesamte Pressewesen", Vol. 40, Nr. 17, 29 April 1939.
• Ref. 55: "The awful German language", Appendix D of "A Tramp Abroad" by Mark Twain, 1880.
• Ref. 56: "Rudolf Hell 65 years old", in "NTZ-Communications journal" (NTZ-CJ), No. 3, 1967, p. 146.
• Ref. 57: "Die Firmenneugründung der Firma Dr. Ing. Rudolf Hell GmbH in Kiel 1947 - Interview zwischen Christian Sütel und Christian Onnasch, gehalten am 1. September 2001", 12 pp.; source: Hell Verein, Kiel
• Ref. 58: "Siemens liefert größte Lichtsetzanlage and das Berliner Satz-Rechen-Zentrum Hartmann + Heenemenna KG", in "Neues aus Forschung, Industrie und Wirtschaft", in "Frequenz - Zeitschrift für Schwingungs- und Schwachstromtechnik", Bd. 26, Nr. 1, January 1972, p. 28.
• Ref. 59: p. 387 in "Faksimiletechnik", §10 (pp. 381-392) of "Fernschreibtechnik", Fritz Schiweck, Band 9 of "Lehrbücher der Feinwerktechnik", 4^th ed., 1962, C. F. Winter, 894 pp.
• Ref. 60: "Hell, Rudolf", Herbert Goetzeler, pp. 76-77 in "Männer der Funktechnik – eine Sammlung von 70 Lebenswerken deutscher Pioniere der Funktechnik (drahtlose Telegrafie, Radar, Rundfunk und Fernsehen)", Sigfrid von Weiher (ed.), VDE-Verlag,1983, ISBN 3-8007-1314-4.
• Ref. 61: radio licenses
• Ref. 61A: p. 6 in "Rufzeichenliste der von der deutschen Reichspost genehmigten privaten Versuchsfunkanlagen mit Fernstrahlung (einschl. der versuchsanlagen der DRP)", Reichspostzentralamt, Belin-Tempelhof, 1 May 1935, 12 pp. Source: "Funk in Braunschweig - Die ersten Anfänge" page of the website of Radioclub Braunschweig - Dr.-Ing E. Viehl.
• Ref. 61B: p. 6 in "Rufzeichenliste", 1938, 22 pp. Same source as ref. 61a.
• Ref. 61C: "Liste der Kreigsfunkgenehmigungsinhaber (Stand 25. August 1944)"
• Ref. 62: "Antenne und Erde", Hanns Günther and Rudolf Hell, 1926; reprinted in 1994 by Wilhelm Herbst Verlag, 336 pages, ISBN 3-923-925-54-9.
• Ref. 63: "Geschichte des Amateurfunk und die rechtlichen Grundlagen" on the website of the DARC.
• Ref. 64: "DASD-CQ various"
• Ref. 65: "Rudolf Hell 1901 bis 2002", p. 34 in "Glückwunsch, Dipl.-Ing.! Ein Gutesiegel made in Germany wird 111 Jahre alt", Ernst M. Schmachtenberger (ed.), TU9 Die Allianz der führenden Technischen Universitäten in Deutschland, 2010, 82 pp., ISBN 978-3-00-032050-7.
• Ref. 66: "Umbruch in der Medienwelt: der Erfinder Rudolf Hell Der Erfinder Rudolf Hell", F. Gnegel, in "Das Archiv. Magazin für Post- und Telekommunikationsgeschichte", 2009, Heft 2, pp. 65-70. See note 1.
• Ref. 67: "Rudolf Hell 75 Jahre", pp. 1-4 in "für uns alle - Werkzeitschrift der Dr.-Ing. Rudolf Hell GmbH", Nr. 39, 10 January 1977.
• Ref. 68: "Dr. Hell zum 80. Geburtstag", pp. 1-5 in "für uns alle - Werkzeitschrift der Dr.-Ing. Rudolf Hell GmbH", Nr. 70, 19 December 1981.
• Ref. 69: p. 197-199 in "Blitz & Anker: Informationstechnik - Geschichte und Hintergründe, Volume 1", Joachim Beckh, BoD GmbH, 2005, 560 pp.
• Ref. 70: p. 1 in "Signal + Draht: Zeitschrift für das Signal- und Fernmeldewesen der Eisenbahnen", Nr. 11/12, November 1968.
• Ref. 71: Siemens-Hell-Fax, Kleinfax KF 108
• Ref. 71A: "Faksimileschreiber Siemens-Hell-Fax KF 108 - Beschreibung und Bedienungsanleitung", Fs Bs und Ba 1253/8, Siemens Fernschreibtechnik, Siemens & Halske A.G., Wernerwerk für Telegrafen- und Signaltechnik, November 1960, 63 pp.
• Ref. 71B: "Ricetrasmettori per facsimile SIEMENS HELL KF108" [incl. 2 page schematic], Franco Fanti (I4LCF), in "CQ elettronica", Nr. 2, February 1974, pp. 222-228       [pdf]
• Ref. 71C: p. 113 in "Fernkopierer", Adalbert Kukan, in "Kultur und Technik", December 2012, pp.  112-115
• Ref. 72: "Exportweltmeister für Ideen - In Deutschland erfunden, in Japan gebaut" [World champion in export of ideas - invented in Germany, built in Japan], Klaus-Peter Kerbusk, SPIEGEL SPECIAL "Made in Germany - Wie die deutsche Wirtschaft durch die Globalisierung gewinnt", Nr.5/2008, 158 pp. Spiegel Online 18-Nov-2009. [pdf]
• Ref. 73: "50 Jahre Polizeifunk - Geschichte des Funkwesens der Sicherheitsbehörden", Alfred Samlowski (ed.), Polizei Technik Verkehr (publ.), 1970, 100 pp.
• Ref. 74: "Der DVL-Hell-Eisensucher", K. Bär, pp. 50-52 in "Hell - Technische Mitteilungen der Firma Dr.-Ing. Rudolf Hell - Gerätentwicklungen aus den Jahren 1929-1939", Nr. 1, May 1940.
• Ref. 75: p. 337 in "Blitz & Anker: Informationstechnik - Geschichte und Hintergründe, Volume 1", Joachim Beckh, BoD GmbH, 2005, 560 pp.
• Ref. 76: "Faksimileschreiber Siemens-Hell-Fax KF 108 - Beschreibung und Bedienungsanleitung", Siemens Fernschreibtechnik, Fs Bs und Ba 1233/B, Siemens & Halske AG, Wernerwerk für Telegrafen- und Signaltechnik, November 1960, 63 pp.
• Ref. 77: "BILDFUNK - Anleitung zum Selbstbau eines Bildempfängers", Vol. 21 of "Die Radio-Reihe", R.C. Schmidt Verlag (publ.), 1927, 114 pp. Source: nvhrbiblio.nl, retrieved 2 October 2020.
• Ref. 78: "Die Selbstherstellung eines Funkbild-Empfangsgerätes" [build your own fax receiver-printer], Rudolf Hell, in "Funk", Wochenschrift des Funkwesens, Weidmannsche Buchhandlung, 1926, 6 pp.
• Ref. 79: "Direktzeigendes funkentelegraphisches Peilverfahren" ["Direct-indicating radio-telegraphy direction finding"], 1929, 10 pp., Krayn Verlag, Berlin, Hochschulschrift, 1928 doctoral dissertation at Technische Hochschule München.
• An article with the same title by Rodulf Hell  appeared in "Jahrbuch der drahtlosen Telegraphie und Telephonie - Zeitschrift für Hochfrequenztechnik", Vol. 33, No. 4, April 1929, pp. 138-145.
• Ref. 80: Personal correspondence with J. Vingard, December 2014.
• Ref. 81: p. 421 in "Demontagen in der Sowjetischen Besatzungszone und in Berlin 1945 bis 1948 - Sachthematisches Inventar", Klaus Neitmann (ed.), Jochen Laufer (ed.), Klaus Jochen Arnold, Brandenburgisches Landeshauptarchiv, Zentrum für Zeithistorische Forschung, Potsdam 2007, 467 pp.
• Ref. 82: p. 282 in "Early Developments in Rocket and Spacecraft Performance, Guidance, and Instrumentation"", Ernst A. Steinhoff, in "Smithsonian Annals of Flight", Nr. 10, "First Steps Towards Space", Frederick Durant, George James (eds.), Smithsonian Institution Press, 1974, 307 pp.
• Ref. 83: "Express-News Scores 'First' With Electronic Color Plates" [first color Klischograph in US], San Antonio Express and News (newspaper), 10 June 1961, p. 15.
• Ref. 84: "100 Prozent Siemens", p. 2 in "für uns alle - Werkzeitschrift der Dr.Ing. Rudolf Hell GmbH", Nr. 63, 17 March 1981. Source: Hell Verein Kiel.
• Ref. 85: p. 20 in "Ein Firmenbild wird zerlegt - Scanning of an image" [pdf], p. 2 in "für uns alle - Werkzeitschrift der Dr.Ing. Rudolf Hell GmbH", Nr. 63, 17 March 1981. Source: Hell Verein Kiel.
• Ref. 86: "Das Hell-Jahrhundert" [The Hell Century], Lothar Deckert, 2006, Schmidt & Klaunig (publ. & printing), ISBN 9783-8831-2367-7, 182 pp. [24 MB]. Source: Verein der Freunde und Förderer Technische Sammlung Dr.-Ing. Rudolf Hell in Kiel e.V; accessed 6 March 2019.
• Ref. 87: Fritz Karl Preikschat's 7-stylus 35-dot matrix teletype writer
• Ref. 87A: "Umschalteinrichtung für Fernschreiber, bei dem die Schriftzeichen in Rasterpunkte zerlegt sind" ["switching unit for teleprinters where characters are decomposed into pixels"], Fritz Karl Preikschat / Telefonbau und Normalzeit G.m.b.H., Deutsches Patentamt, Patent nr. 1006007B, application 29 July 1952, awarded 11 April 1957, 3 pp.
• Ref. 87B: "Schreibkopf für Rasterbildfernschreibmaschinen" ["printer head for dot-matrix teleprinters"], Fritz Karl Preikschat / Telefonbau und Normalzeit G.m.b.H., Deutsches Patentamt, Patent nr. 1019694, application 29 July 1952, awarded 21 November 1957, 3 pp.
• Ref. 87C: Photos of Fritz Karl Preitschat's dot matrix teletypewriter prototype, as shown to the General Mills company and the Deutsche Bundespost in 1957. Source: wikipedia.org, accessed 3-July-2019.
• Ref. 87D: "Letter of Telefonbau und Normalzeit G.m.b.H. to Mr. Fritz Preikschat / Vertrag zwischen der Firma Telefonbau und Normalzeit G.m.b.H. und Herrn Fritz Preikschat" [contract regarding use of patent rights], 31 May 1957, 8 pp. Source: wikipedia.org, accessed 3-July-2019.
• Ref. 87E: "Description, principles of operation, the circuit diagram, conclusion", F.K. Preikschat, 15 September 1961, 13 pp. Source: wikipedia.org, accessed 3-July-2019.
• Ref. 87F: "Facsimile transponder development" [optical scanner + Preitschat printer], Boeing Company, 6 February 1967, 29 pp. Source: wikipedia.org, accessed 3-July-2019.
• Ref. 88: US National Security Agency (NSA) - Correspondence, Memoranda, and Personnel File Records; Friedman Documents:
• Ref. 88A: "Hagelin Letter to Friedman; Update on Bo; Comments on Dr. Rudolf Hell", 24 April 1956, 1 p.,Declassified NSA Document ID A2263167; retrieved 9 July 2019. [pdf]
• Ref. 88B: "Friedman Letter to Hagelin; Meeting with Dr. Hell", 4 May 1956, 2 pp., Declassified NSA Document ID A2263168; retrieved 9 July 2019. [pdf]
• Ref. 88C: "Hagelin Letter to Friedman; Spending Time with the Hells; Article In Encyclopedia", 24 July 1956, 1 p., Declassified NSA Document ID A2263175; retrieved 9 July 2019. [pdf]
• Ref. 89: "Dr. ing. Rudolf Hell - Einrichtung von Baracken für 108 Personen in Teltow bei Berlin, Westseite Warthestraße" ["Establishment of baracks for 108 persons in Berlin-Teltow, west side of Warthestrasse street], [file size 31 MB], p. 555-604 in "Lager- und Barackenbauten in Berlin für einzelne Unternehmen und Institutionen (alphabetische sortiert, mit Bauplänen) ["Construction of warehouses and baracks of individual companies and institutions in Berlin"], 1941-1944", Vol. 17 "Alphabetische Folge Ha-He", 714 pp. Content: period summer-1942 / spring-1943, correspondence regarding contruction permit applications, supported by the Oberkommando der Kriegsmarine, site layout (adjacent to the newly constructed Hell military company), cost projections (60k Reichsmark ≈ 336k US$ and ≈ 311k € in 2016), baracks for German workers & Luftwaffe personnel for expediting equipment production, baracks provided by the Oberkommando des Heeres.
• Source: BArch file nr. (Signatur) R 4606/4895, used in accordance with "Erstinformation für Ihren Besuch im Bundesarchiv in Freiburg, Stand Juni 2016".
• Ref. 230Z: "Zielfluggeräte nach ‟Dieckmann-Hell‟" [Dieckmann-Hell airplane radio direction finding systems; Luftwaffe ZVG 15 / 16 / 17 Z, FuG 141], Werner Thote, in "Radiobote", Vol. 13, Nr. 76, September-October 2018, pp. 14-19. Source: radiobote.at.

Note 1: due to copyright reasons, this file is in a password-protected directory. Contact me if you need access for research or personal study purposes.