{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/102897"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/102897","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"The Eltro","abstract":"In the world of audio signal processing, before the digital era, there was a variety of analog samplers that could pitch-shift and time-compress audio signals on magnetic tape. In all cases, the essence of these devices depended not on one, but typically four tape heads, uniformly placed along a circular drum. By varying the speed of the tape and the rotational speed of the drum, the relative head-to-tape speed could be manipulated, in ways not previously possible, in order to achieve analog pitch-shifting and time-compression of the signal. The idea of a rotating drum having multiple tape heads dates back to as early as the 1920s. But it wasn’t until 1954 that the ball actually started rolling, when G. Fairbanks, W. Everitt, and R. Jaeger built a working machine, with a rotating drum at its core, for pitch-shifting and time-compressing tape signals, and perhaps more importantly, formally explained its inner workings. There were others, thinking in parallel on similar devices, but it was the work of Fairbanks, Everitt and Jaeger that really stood out. Some years later, in the 1960s, along came the Eltro Information Rate Changer, perhaps the most celebrated of these largely forgotten analog samplers. The Eltro was primarily used in the advertising industry to adjust the time duration of an audio signal whenever the accompanying film needed to run at a different rate so that a commercial could fit into the standard 30 or 60 second time slots. If, for example, a commercial film needed to run faster, and the audio signal were simply sped up by the same amount, we’d get the familiar “chipmunk” effect, where all of the signal frequencies have been shifted up by an amount corresponding to the increased tape speed. The Eltro got around this problem by preserving the signal’s frequency information while compressing or expanding its time duration. The most famous usage of the Eltro, however, was not for time compression, but for pitch-shifting the dying voice of HAL9000 in Stanley Kubrik’s “2001: A Space Odyssey”. In the late 1960s and early 1970s, when computers were finally catching up with DSP theory, naturally, pitch-shifting and time-compression of audio, particularly speech signals, was of great interest. Foulke, in 1970, and Lee, in 1972, were the first to digitally implement the rotating head tape recorder, primarily motivated by reducing the number of bits required to convey the same amount of information, or compression, in the modern sense of the word. Sadly, along with the others of its kind, this is when the Eltro got away. As a form of DSP archaeology, I would like to bring it back, in digital form, if for no other purpose than the pure enjoyment of hearing it once more. For my research, I will formalize the signal processing theory necessary to create an algorithm, which, in the digital domain, will faithfully emulate the Eltro Information Rate Changer. I will first find a continuous, closed-form equation that governs the positions of the four tape heads along the tape, as measured from the tape’s beginning, as a function of one independent variable, time. I will then discretize the equation, and in the process develop the algorithm necessary for a faithful emulation of the original, analog Eltro. In addition to developing a theoretical framework and efficient algorithm, I intend to implement the system physically in the form of a stand-alone, embedded DSP device.","abstract_html":"In the world of audio signal processing, before the digital era, there was a variety of analog samplers that could pitch-shift and time-compress audio signals on magnetic tape. In all cases, the essence of these devices depended not on one, but typically four tape heads, uniformly placed along a circular drum. By varying the speed of the tape and the rotational speed of the drum, the relative head-to-tape speed could be manipulated, in ways not previously possible, in order to achieve analog pitch-shifting and time-compression of the signal. The idea of a rotating drum having multiple tape heads dates back to as early as the 1920s. But it wasn’t until 1954 that the ball actually started rolling, when G. Fairbanks, W. Everitt, and R. Jaeger built a working machine, with a rotating drum at its core, for pitch-shifting and time-compressing tape signals, and perhaps more importantly, formally explained its inner workings. There were others, thinking in parallel on similar devices, but it was the work of Fairbanks, Everitt and Jaeger that really stood out. Some years later, in the 1960s, along came the Eltro Information Rate Changer, perhaps the most celebrated of these largely forgotten analog samplers. The Eltro was primarily used in the advertising industry to adjust the time duration of an audio signal whenever the accompanying film needed to run at a different rate so that a commercial could fit into the standard 30 or 60 second time slots. If, for example, a commercial film needed to run faster, and the audio signal were simply sped up by the same amount, we’d get the familiar “chipmunk” effect, where all of the signal frequencies have been shifted up by an amount corresponding to the increased tape speed. The Eltro got around this problem by preserving the signal’s frequency information while compressing or expanding its time duration. The most famous usage of the Eltro, however, was not for time compression, but for pitch-shifting the dying voice of HAL9000 in Stanley Kubrik’s “2001: A Space Odyssey”. In the late 1960s and early 1970s, when computers were finally catching up with DSP theory, naturally, pitch-shifting and time-compression of audio, particularly speech signals, was of great interest. Foulke, in 1970, and Lee, in 1972, were the first to digitally implement the rotating head tape recorder, primarily motivated by reducing the number of bits required to convey the same amount of information, or compression, in the modern sense of the word. Sadly, along with the others of its kind, this is when the Eltro got away. As a form of DSP archaeology, I would like to bring it back, in digital form, if for no other purpose than the pure enjoyment of hearing it once more. For my research, I will formalize the signal processing theory necessary to create an algorithm, which, in the digital domain, will faithfully emulate the Eltro Information Rate Changer. I will first find a continuous, closed-form equation that governs the positions of the four tape heads along the tape, as measured from the tape’s beginning, as a function of one independent variable, time. I will then discretize the equation, and in the process develop the algorithm necessary for a faithful emulation of the original, analog Eltro. In addition to developing a theoretical framework and efficient algorithm, I intend to implement the system physically in the form of a stand-alone, embedded DSP device.","abstract_has_math":false,"creators":["Sconza, Justin"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Electrical & Computer Engr","degree_department":null,"school":null,"contributors":["Haken, Lippold","Jones, Douglas L."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2019,"date_issued":"2019-02-08T18:39:42Z","date_published":"2019-02-08T18:39:42Z","updated_at":"2026-07-22T22:24:42Z","subjects":["pitch shifting","time compression"],"languages":["en"],"rights":["Copyright 2018 Justin Sconza"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/102897","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Haken, Lippold","Jones, Douglas L."]},{"key":"dc:creator","label":"Author","values":["Sconza, Justin"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2019-02-08T18:39:42Z","2021-02-09T10:15:38Z","2018-10-16","2018-12"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Electrical & Computer Engr"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["pitch shifting","time compression"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2018 Justin Sconza"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/102897"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["In the world of audio signal processing, before the digital era, there was a variety of analog samplers that could pitch-shift and time-compress audio signals on magnetic tape. In all cases, the essence of these devices depended not on one, but typically four tape heads, uniformly placed along a circular drum. By varying the speed of the tape and the rotational speed of the drum, the relative head-to-tape speed could be manipulated, in ways not previously possible, in order to achieve analog pitch-shifting and time-compression of the signal. The idea of a rotating drum having multiple tape heads dates back to as early as the 1920s. But it wasn’t until 1954 that the ball actually started rolling, when G. Fairbanks, W. Everitt, and R. Jaeger built a working machine, with a rotating drum at its core, for pitch-shifting and time-compressing tape signals, and perhaps more importantly, formally explained its inner workings. There were others, thinking in parallel on similar devices, but it was the work of Fairbanks, Everitt and Jaeger that really stood out. Some years later, in the 1960s, along came the Eltro Information Rate Changer, perhaps the most celebrated of these largely forgotten analog samplers. The Eltro was primarily used in the advertising industry to adjust the time duration of an audio signal whenever the accompanying film needed to run at a different rate so that a commercial could fit into the standard 30 or 60 second time slots. If, for example, a commercial film needed to run faster, and the audio signal were simply sped up by the same amount, we’d get the familiar “chipmunk” effect, where all of the signal frequencies have been shifted up by an amount corresponding to the increased tape speed. The Eltro got around this problem by preserving the signal’s frequency information while compressing or expanding its time duration. The most famous usage of the Eltro, however, was not for time compression, but for pitch-shifting the dying voice of HAL9000 in Stanley Kubrik’s “2001: A Space Odyssey”. In the late 1960s and early 1970s, when computers were finally catching up with DSP theory, naturally, pitch-shifting and time-compression of audio, particularly speech signals, was of great interest. Foulke, in 1970, and Lee, in 1972, were the first to digitally implement the rotating head tape recorder, primarily motivated by reducing the number of bits required to convey the same amount of information, or compression, in the modern sense of the word. Sadly, along with the others of its kind, this is when the Eltro got away. As a form of DSP archaeology, I would like to bring it back, in digital form, if for no other purpose than the pure enjoyment of hearing it once more. For my research, I will formalize the signal processing theory necessary to create an algorithm, which, in the digital domain, will faithfully emulate the Eltro Information Rate Changer. I will first find a continuous, closed-form equation that governs the positions of the four tape heads along the tape, as measured from the tape’s beginning, as a function of one independent variable, time. I will then discretize the equation, and in the process develop the algorithm necessary for a faithful emulation of the original, analog Eltro. In addition to developing a theoretical framework and efficient algorithm, I intend to implement the system physically in the form of a stand-alone, embedded DSP device.","Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2020-12-01","The student, Justin Sconza, accepted the attached license on 2018-10-15 at 14:04.","The student, Justin Sconza, submitted this Thesis for approval on 2018-10-15 at 14:11.","This Thesis was approved for publication on 2018-10-16 at 12:41.","DSpace SAF Submission Ingestion Package generated from Vireo submission #13032 on 2019-02-08 at 11:38:12","Made available in DSpace on 2019-02-08T18:39:42Z (GMT). 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In all cases, the essence of these devices depended not on one, but typically four tape heads, uniformly placed along a circular drum. By varying the speed of the tape and the rotational speed of the drum, the relative head-to-tape speed could be manipulated, in ways not previously possible, in order to achieve analog pitch-shifting and time-compression of the signal. The idea of a rotating drum having multiple tape heads dates back to as early as the 1920s. But it wasn’t until 1954 that the ball actually started rolling, when G. Fairbanks, W. Everitt, and R. Jaeger built a working machine, with a rotating drum at its core, for pitch-shifting and time-compressing tape signals, and perhaps more importantly, formally explained its inner workings. There were others, thinking in parallel on similar devices, but it was the work of Fairbanks, Everitt and Jaeger that really stood out. Some years later, in the 1960s, along came the Eltro Information Rate Changer, perhaps the most celebrated of these largely forgotten analog samplers. The Eltro was primarily used in the advertising industry to adjust the time duration of an audio signal whenever the accompanying film needed to run at a different rate so that a commercial could fit into the standard 30 or 60 second time slots. If, for example, a commercial film needed to run faster, and the audio signal were simply sped up by the same amount, we’d get the familiar “chipmunk” effect, where all of the signal frequencies have been shifted up by an amount corresponding to the increased tape speed. The Eltro got around this problem by preserving the signal’s frequency information while compressing or expanding its time duration. The most famous usage of the Eltro, however, was not for time compression, but for pitch-shifting the dying voice of HAL9000 in Stanley Kubrik’s “2001: A Space Odyssey”. In the late 1960s and early 1970s, when computers were finally catching up with DSP theory, naturally, pitch-shifting and time-compression of audio, particularly speech signals, was of great interest. Foulke, in 1970, and Lee, in 1972, were the first to digitally implement the rotating head tape recorder, primarily motivated by reducing the number of bits required to convey the same amount of information, or compression, in the modern sense of the word. Sadly, along with the others of its kind, this is when the Eltro got away. As a form of DSP archaeology, I would like to bring it back, in digital form, if for no other purpose than the pure enjoyment of hearing it once more. For my research, I will formalize the signal processing theory necessary to create an algorithm, which, in the digital domain, will faithfully emulate the Eltro Information Rate Changer. I will first find a continuous, closed-form equation that governs the positions of the four tape heads along the tape, as measured from the tape’s beginning, as a function of one independent variable, time. I will then discretize the equation, and in the process develop the algorithm necessary for a faithful emulation of the original, analog Eltro. In addition to developing a theoretical framework and efficient algorithm, I intend to implement the system physically in the form of a stand-alone, embedded DSP device.","Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2020-12-01","The student, Justin Sconza, accepted the attached license on 2018-10-15 at 14:04.","The student, Justin Sconza, submitted this Thesis for approval on 2018-10-15 at 14:11.","This Thesis was approved for publication on 2018-10-16 at 12:41.","DSpace SAF Submission Ingestion Package generated from Vireo submission #13032 on 2019-02-08 at 11:38:12","Made available in DSpace on 2019-02-08T18:39:42Z (GMT). No. of bitstreams: 2 SCONZA-THESIS-2018.pdf: 14189950 bytes, checksum: 9e0a36c1224a7423c25155c2c68a8bf5 (MD5) LICENSE.txt: 4210 bytes, checksum: 80c5870be6659799ba0bf7f0c46ccaeb (MD5) Previous issue date: 2018-10-16","Embargo set by: Seth Robbins for item 109923 Lift date: 2021-02-08T18:40:00Z Reason: Author requested closed access (OA after 2yrs) in Vireo ETD system","Embargo set by: Seth Robbins for item 109923 Lift date: 2021-02-08T18:42:23Z Reason: Author requested closed access (OA after 2yrs) in Vireo ETD system","Embargo set by: Seth Robbins for item 109923 Lift date: 2021-02-08T18:43:54Z Reason: Author requested closed access (OA after 2yrs) in Vireo ETD system","Embargo set by: Seth Robbins for item 109923 Lift date: 2021-02-08T18:44:50Z Reason: Author requested closed access (OA after 2yrs) in Vireo ETD system","Limited Restriction Lifted for Item 109923 on 2021-02-09T10:15:38Z."],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/102897"],"dc:language":["en"],"dc:rights":["Copyright 2018 Justin Sconza"],"dc:subject":["pitch shifting","time compression"],"dc:title":["The Eltro"],"dc:type":["text"],"thesis:degree_discipline":["Electrical & Computer Engr"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["M.S."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:24:42Z"}