CANADIAN
DIGITAL TELEVISION
¨ Why
has CDTV built an experimental digital TV transmitter?
Canadian
broadcasters will soon start building their own DTV transmitters. They require practical information about how such
facilities should be planned and operated. Moreover,
the service assumptions applied during the development of Canada’s channel allotment
plan need to be verified by practical measurements and observations. At present, CDTV operates the only DTV transmitter
in Canada.
¨ What
are the specific test plans?
The
facilities are intended to be used for:
· Verifying
DTV coverage prediction methods;
· Assessing
DTV coverage at the fringe of the service area and under difficult receiving conditions;
· Assessing
the quality of DTV reception in the urban and most populous areas, where reception with an
indoor antenna is prevalent.
· Comparing
the coverage and service reliability of the DTV facilities versus the co-sited NTSC
facilities;
· Assessing
various techniques for re-broadcasting DTV signals.
· Assessing
reception and modulation conversion of the off-air 8-VSB DTV signals by cable, MDS and DTH
satellite distribution undertakings;
· Experimenting
with the transmission of multiple standard-definition (SD) and single high-definition (HD)
video signals, combined with audio and possibly auxiliary data services.
· Possible
public demonstrations of both SD and HD DTV signals.
¨ Who
is doing the testing?
The
majority of the testing is being carried out by the Broadcast Technologies Research Branch
of the Communications Research Centre (CRC), under a contract issued by Industry Canada. Signals from this facility may also be used by
others (e.g. cable, MDS and DTH services) to experiment with signal
pick-up and carriage.
¨ What
transmission facilities has CDTV built?
The
DTV transmitting facilities assembled by CDTV are similar to those constructed by
broadcasters in the USA. Equipment is
professional-grade and of high quality. The
facilities are located at the Rogers Broadcasting Ltd tower site near Manotick, ON. The signal from the DTV transmitter has been
combined into an existing antenna, currently used for NTSC service on Channel 65 by
CITY-TV-3.
¨ What
TV channel is being used?
The
transmitter operates on Channel 67 (788-794 MHz), a DTV allotment for Ottawa, ON, listed
in the Canadian TV Allotment Plan.
¨ What
are the operating parameters?
The
antenna consists of an 8-bay panel array using four RFS Broadcast UHF-TV panels per bay. The antenna is nominally omnidirectional but in
fact has a slight horizontal gain variation of ±1.7 dB.
The RMS vertical gain of the antenna is 13.8 dBd.
A 2.5 kW Larcan solid state, air-cooled Channel 67 DTV transmitter is being fed to
the antenna through the existing CITY-TV-3 constant impedance filter, acting as a
combiner. The maximum ERP of the facility is
44.2 kW and the average (RMS) ERP is 29.9 kW. The
antenna EHAAT is 215.4m.
¨ Over
what range can the signals be received?
Off-air
reception of the DTV signals should be possible within the existing Grade B service
contour of CITY-TV-3, or a radius of about 70-80 km.
¨ What
type of DTV signal is being transmitted?
At
present, the system transmits mainly an 8-VSB signal, complying with Canada’s
transmission standard for DTV (ATSC A/53). Input
to the transmitter will be SMPTE 310M, 19.39 Mb/s transport layer. Other test signals may be transmitted from time to
time, as required.
¨ How
long will this facility be in operation?
At
present, 18-24 months of experimental transmissions are planned.
¨ Where
can I get more information:
Please
contact: Wayne
A. Stacey, P.Eng.
Vice-Chairman,
CDTV Technical Working Group
c/o
Stacey, Lawson Associates Ltd.
5-1420
Youville Drive, Ottawa ON K1C 7B3
Tel
(613) 830-6985
E-Mail:
wstacey@stalaw.com
2021-02-16