7.5 NABU: THE NABU NETWORK
Ottawa Cablevision is currently offering the facilities of its network (90,000 subscribers) as the beta-site host for the NABU Manufacturing Corporation’s computer data and software broadcasting field trial of “The NABU Network”. NABU was incorporated in 1981 specifically to enter this particular field. Approximately 100 households and one school are taking part in the present field trial which features, besides games, the downloading of MIT’s educational programming language LOGO.
The home terminal is capable of being augmented by the addition of a printer and disk drives to function as a personal computer. Digital Research Incorporated’s popular disc operating system CP/M and the scientific applications programming language Pascal are both to be made available via the network for users requiring applications beyond simple computer game levels. NABU is unique in employing the highest data rate (6.3 Mbps) of any CATV network data downstreaming system. Offset quadrature phase shift keying (OQPSK) modulation is used to achieve this rate on a carrier that is 10 dB lower in power than a conventional cable video carrier. Since the NABU carrier is centered within a standard 6 MHz channel, it is capable of generating composite beat products outside the normal pattern dictated by regular video carrier spacing. The lower carrier power level helps to mitigate the effect of this potential non-linear distortion.
The sketch below illustrates the configuration employed by NABU in the Ottawa Cablevision field trial:
Thanks to the efforts of technology enthusiast Grizzly Adams, we now have an amazing document from 1983 which the above information was sourced from, specifically page 66 (page 76 in the PDF).
Download the full source document:
- Cable Data Communicatons Systems 1983, Department of Communications, Ottawa, Canada – PDF (10.77 MB)
If you have any historical documentation about the NABU, we would love to add it to our archives, so please get in touch with us.