The Foundations of DRTE
(F.T. Davies)

A Brief History of CRC
(Nelms, Hindson)

The Early Days
(John Keys)

CRC's Pioneers


Bits and Pieces


The Alouette Program
The ANIK B Projects
David Florida Laboratory
Defence Communications
Detection Systems
The DRTE Computer
Doppler Navigation
HF Radio Resarch
The ISIS Program
Janet - Meteor Burst Communications
Microwave Fuze
Mobile Radio Data Systems
Prince Albert Radar Lab.
Radar Research
Radio Propagation Studies
Radio Warfare
Search and Rescue Satellite
Solid State Devices
Sounding Rockets
Trail Radio


John Barry - Doppler Navigation
John Belrose - The Early Years
Bert Blevis - The Role of the Ionosphere and Satellite Communications in Canadian Development
Bert Blevis - The Implications of Satellite Technology for Television Broadcasting in Canada
Richard Cobbold - A Short Biography of Norman Moody
Peter Forsyth - the Janet Project
Del Hansen - The RPL Mobile Observatory
Del Hansen - The Prince Albert Radar Laboratory 1958-1963
LeRoy Nelms - DRTE and Canada's Leap into Space
Gerald Poaps' Scrapbook
Radio Research in the Early Years
John Wilson - RPL as I Recall It, 1951-1956



Annual Reports






View of Telidon equipment, including telephone, modem, television set and decoder with keypad.
Photo CRC 79-38981.

CRC employee using a Telidon terminal.
Photo CRC 76-33297.

Photograph of J.E. Colbert family using Telidon.
Photo CRC 79-38493.

Photograph of Telidon screen graphics, displaying Telidon screen logo.
Photo CRC 82-7675.

The Telidon program began officially on August 15, 1978 and ended on March 31, 1985.

  • To promote development of a national videotex infrastructure through appropriate standards, regulations and technology.
  • To encourage the creation of a viable Telidon industry producing hardware, software, systems and services.
  • To encourage joint government-industry research and development, product development, promotional activity and support market trials and operational systems.

Herb Bown is widely considered the "Father" of Telidon. Others team members included C.D. O'Brien, Bill Sawchuck, J.R. Storey and Bob Warburton. In 1966, there were very few people with experience in computer-aided design (CAD). Consequently, there was lots of room for innovation. By 1967, Herb Bown was blazing new ground by incorporating plotting capabilities into the CAD programs that he had developed so that the results of the computer's calculation could be plotted on paper as they were performed. However, as computer graphics emerged as a discipline in its own right, research began on sophisticated systems that would permit pictures of structures and circuits to be displayed on cathode ray tubes and then manipulated like text or numerals. The objective was to create flexible work stations that would permit designers to draw and manipulate circuits and spacecraft on screens and display information from satellites, computers and human operators in both graphical and numeric form. Over the next several years, Herb Bown made a number of important contributions to this work by developing advanced graphics programs that found application in interactive visual communications systems. It was this work that led to Telidon.

From 1970, effort was concentrated into building hardware and software to advance Canadian capabilities in this interactive graphics area. This research led initially to a new interactive programming language (IGPL) and to a preliminary definition of picture description instructions (PDIs). Both the hardware and various communication protocols involving PDIs evolved to the point where the Telidon terminal contained its own intelligence. The developers felt it would be inappropriate to design a picture coding scheme that was tied to a particular display technology. As a result, they defined a terminal-independent alpha geometric PDI coding scheme.

In 1975, the CRC gave a contract to Norpak Limited to develop an interactive colour display technology, based on CRC's previous work. This contract led to further work between CRC and Norpak to develop specialized terminals and other colour display systems. By the end of 1977, the CRC research on interactive graphics systems resulted in three patent applications: one for a touch sensitive input mechanism for computerized graphics displays; one for a new interactive visual communication system; and the last for a new interactive graphics programming language.

Telidon was the specific name given to an information system capable of operating in either a one-way teletext or two-way videotex mode and had superior graphics for its time. Teletext is a one-way information delivery system designed to make use of the spare signal carrying capacity in existing television broadcasting channels. It can present from 100 to 300 pages or screens of information. Meanwhile, videotex is an information delivery system that makes use of the telephone for two-way telecommunications. It may also be linked into two-way cable TV or hybrid cable TV/telephone system. Electronic mail can also be used. Both are public-accessed, information retrieval services, but videotex is interactive, whereas teletext is not. The Telidon terminal consists of a modified television receiver or terminal screen (computer), a videotex decoder and display generator and a modem or cable connection. Users would access information available from an information provider (eg. Infomart). Users were provided with teleshopping, business services, telebanking, news, community bulletins, information on travel, film, sports, theatre, government, education, agriculture and stocks, as well as a variety of other services.

The first Telidon terminal had a public demonstration on August 15, 1978 and the Department of Communications announced its first four-year Telidon development program. Under this program, the DOC planned a number of ways to encourage the private sector and government agencies to utilize Telidon technology. These included field trials and public demonstrations of the technology to the Canadian private sector, foreign firms and negotiations, lobbying in the videotex standards negotiation, international marketing efforts and the formulation of policies to deal with social and political effects of the new technology.

The role of the government was meant to be that of a catalyst, to assemble the various elements of the Telidon industry into a working industrial infrastructure under a common Telidon standard. The main purpose was to encourage the transfer of this government-developed technology to Canadian industry and business. The means to the end was financial support of the Telidon field trials. To support the field trials, the DOC purchased user terminals which were then lent to the organization developing the trial. In some cases, the department also lent its central computing facilities. The DOC stimulated the testing of Telidon applications using a wide variety of transmission media ranging from telephone wires and cable television to new media such as direct broadcast satellite and optical fibres.

In 1983, AT&T, Bell System and the DOC augmented the picture description instructions which had been published by the Canadian government. This led to the formation of a new protocol by the name of North American Presentation Level Protocol Syntax (NAPLPS). The standard was a coding format for exchanging graphical information which is analogous to and potentially as ubiquitous as the ASCII code for exchanging textual information electronically.

Much of the industry activity was implemented because of government support. Over 200 companies were involved in the government's Telidon program. The videotex/teletext trial activity was undertaken by six major groups: telephone companies (i.e. BC Tel, Alberta Government Telephone, Bell Canada, Saskatchewan Telephone, Manitoba Telephone and New Brunswick Telephone); cable companies (i.e. Telecable, Videotron and Canadian Cable Systems); broadcasters (i.e. Ontario Education Communication Authority (OECA) and the CBC); system suppliers (i.e. Infomart and government Cantel service); information provider companies; and the Department of Communications.

The largest suppliers of terminals were Electrohome, Norpak and Microtel. One of the fundamental problems which emerged in the hardware industry with respect to commercial development was the high price of these systems, which ranged between $1,800 and $2,500. During the early development period, hardware manufacturers felt that the demand would drive down terminal prices to the point where, ideally, they would be selling for less than $600. However, results from field trials indicated that terminal prices were likely to remain out of the range of most mass market buyers. In addition, the field trials indicated that while people were interested in the technology, they were disappointed by the size of the database and available software. The trials indicated it would take not tens of thousands, but hundreds of thousands of pages to reach a level of satisfaction. Also, the field trial indicated that technical improvements were required. The program of field trials officially ended on March 31, 1985.

The Telidon program had originally been directed towards developing an industry geared towards mass market use. This objective was not reached, as the field trials clearly indicated that the Telidon technology was better geared to specific markets with special requirements. Telidon- related technology was used in a variety of ways throughout government departments and agencies for many years. In addition, a significant contract was undertaken with IDON Corporation which made use of Telidon-related technology to develop a communications system technique for speech-impaired children, using Bliss symbols.

One of the most significant and unusual videotex projects undertaken, took place in the Pan-Arctic in July 1983. The occasion was the Third General Assembly of the Inuit Circumpolar Conference held in Frobisher Bay on Baffin Island in the Canadian Arctic. The conference was distinguished by the spectacular use of Telidon to overcome the horrendous communication and information problems. For the Assembly, a multilingual data base was established in Novatex service host computer at Teleglobe Canada's facility in Toronto. This contained NAPLPS pages in English, French, Danish, Inuktitut, Greenlandic, Labradorian, Inupiag, Yupik and Western Arctic. The Telidon user terminals were supplied by AEL Microtel and sixteen were located at various sites in Frobisher Bay, with others in Vancouver, British Columbia; Washington D.C.; Copenhagen, Denmark; Anchorage, Bethel and Barrow, Alaska; Nuuk, Greenland, as well as other northern communities. Communication facilities were provided by Bell Canada, Teleglobe, Greenland Telecommunications and the Danish Post and Telegraph. The page creation terminals were supplied by Cableshare Limited.


Booth, Peter and Wills, Russel. Teletext and Videotex: A Canadian Perspective. Vancouver; Wescom Communications, 1985.
Bown, H.G., O'Brien, C.D., Sawchuck, W. , and Storey J.R. A General Description of Telidon: A Canadian Proposal for Videotex Systems.CRC Technical Note No. 697-E. Ottawa; Department of Communications, December 1978
Parkhill, Douglas F. The Beginning of a Beginning. Ottawa; Department of Communications, 1987.

Page created on August 8, 1996 by Cynthia Boyko
Last updated on October 14, 1997 by Cynthia Boyko
Copyright © Friends of CRC, 1997.