Western Canada "Coverage Gap" Elimination Proposal
The CHU time station is Canada's domestic
shortwave time signal station. CHU existed long before the Internet and
satellite navigation systems that also provide time signals. CHU itself
provides most of the
time services (but not frequency services) of equal quality to WWV
& WWVB
(Bolder, Colorado) and WWVH (Kauai, Hawaii).
However, the usefulness of
CHU decreases as one moves farther and
farther away from Ontario and Quebec.
CHU reception in the high Arctic may be as problematic as
reception in Western Canada. What with other Artic nations making new
claims on
Arctic resources, there is a territorial imperative to provide services
to this region.
The CHU station is currently located 15 km southwest of Ottawa.
Three frequencies are used are :
3330 kHz, 7850 kHz and 14670
kHz.
Individual
vertical
[dipole] antennas are used for each frequency. The transmission mode is
(Compatible) Upper Single Sideband with carrier re-inserted. This
provides time
signal service without specifically requiring a special SSB radio. A
talking clock
using digitally recorded voices makes the announcements. All
transmitters run at 3 kw of power, equaling about 5 kw of power if
traditional Amplitude Modulation were used.
Current problems with CHU that need to be addressed
National
sovereignty
WWV, WWVB and WWVH should not be
considered as
viable replacements for Western Canada as there are still technological
problems with their IRIG Time Signaling data structures.
Beyond the 250 km strip of habitation in
southern Canada, WWV and WWVH provide poor signals.
Most modest geophysical storms can render
WWV reception useless (on all frequencies) in approximately 30% of
Canada's EEZ, and 70% of its landmass.
Shortwave propagation
studies suggest that the
transmitter of 20 kw power should be able to reach the high arctic as
well as provide substantial day to day redundancy with the US WWV Time
Station.
Quality of Service
Regulatory
Broadcast
The current CHU IRIG Signaling
structure
does not
indicate the transmitter coordinates thereby making reverse VOACAP time
delay
calculations very complicated and ambiguous.
CHU reception in Western Canada
(West of Manitoba) and the Arctic (North of 55º Latitude) is
generally poor year round on all frequencies.
Mild to moderate geomagnetic storms
make
CHU
inaccessible on all frequencies in Western Canada.
Atlantic
Canada has CHU reception problems similar to Western Canada.
CHU can deliver other kinds of important scientific
and governmental
messaging services. With some partial reorganization of CHU's legal
status it could be possible to make its services self funding.
It
may be
advisable to use frequencies ~10 kHz above or below CHU's current
frequencies.
It
may be advisable
initially to make the BC site a 7
MHz transmission site only.
14 MHz frequency support (daytime only) should
be implemented.
The DRM transmission mode option
must be considered for this kind of utility signal broadcasting.
Upgrading CHU's Ottawa transmitters
to 10 kw will not universally fix coverage and reliability problems in
Western Canada.
This CHU coverage proposal is to
enhance
reception in the ITU CIRAF Zones: 02, 03, 06NW.
This
proposal can be optimized for Atlantic Canada on a smaller scale
using a different frequency and lower power levels probably 5 kw.
Propagation
Cost Minimization
Digital Audio Broadcasting
The "ionospheric path delay" that is inherent in
shortwave propagation
makes using CHU's time signals problematic in Western Canada.
The NRC
has openly acknowledged the 'path delay' problem for decades: "for all
distant users of CHU, the dominant source of time error
comes from the radio wave path reflecting off the ionosphere as the
radio signal travels from the transmitter".
Having 2 or 3 separate national sites dedicated to
the
transmission of shortwave time signals is a good idea. Canada's
landmass and EEZ size dictates this.
A "Stratum 0" time server can be
cobbled together with spare components that are floating around Western
Canada.
Using a 20 kw transmitter to cover Western Canada on
all frequencies is not obligatory, as
10 kw may suffice for 14 MHz band.
A DRM based time server system may
be 2 or 3 times cheaper than replicating CHU's IRIG analog time server
systems.
An ultrastable transmitter frequency should not be a
design goal, but a future option.
Digital Radio Mondial (DRM) has a globally agreed
upon transmission system that can already transmit time signal packets
with accuracy and resolution and equal to CHU's.
DRM offers more options, including the ability to
design custom services like alternate time service.
DRM can transmit geophysical alerts, websites, etc
... it is a very flexible digital transmission medium.
DRM does not require an ultrastable transmitter
frequency to operate effectively with respect to 3 hop data
transmission.
How
can this infrastructure project be implemented?
In order to be able to
build and
maintain this infrastructure project a series of Public-Private
Partnerships (PPP)
are needed.
All NRC Time Stations (be they on shortwave, longwave
or via any other delivery medium) should all be converted to "Public
Trust" entities.
As Public Trust entities they would be better protected from closure
due to "Year-to-Year" Federal Government funding issues. This legal
status should be viewed as separate from their existence as entities
that are either directly government funded or PPP funded.
Here is how a PPP could be
constructed for this kind of
project
Project design : University of British Columbia (UBC)
All work could easily be done by Graduate or
Undergraduate students were appropriate, with departmental oversight
and certification. Technically this is the construction of a scientific
instrument.
Project daily maintenance : Thompson Rivers University
Project seasonal maintenance : University of British
Columbia & National Research Council
Project regulatory issues : National Research Council (ITU
Frequency, ITU Status, Electricity 50%, Plant & Equipment 50%)
Cost sharing (suggested)
UBC : 20% (50% of Seasonal Maintenance and Design Costs)
TRU : 20% (50% of Electricity Costs and 50% of Daly
Maintenance Costs)
NRC : 60%
Proposed
"CHU-2"
Transmitter Site British Columbia
Note that CHU Ottawa's change to
7850 kHz does not affect
the calculations below substantially. The
antenna type chosen below is very broadband and delivers similar
performance from 6.0 MHz to 8.0 MHz. This design has a 350 kHz
tolerance range where electromagnetic and electrodynamic behavior are
essentially invariant under normal conditions.
