CHU Time Station

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 Arctic 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
  • 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.
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.
    • Antennas: UBC Electrical Engineering (EE)
    • Transmitter Buildings & Facilities : UBC Architecture
    • Non-transmitter Equipment : UBC EE or Physics
  • 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 "Day to Day" 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 not subject to significant pattern distortion (-/+ 500 kHz).

The proposed antenna will still deliver nearly identical performance from 6.0 MHz to 8.0 MHz, the only differential being changes in propagation beyond the antenna.

CHU2 coverage area Western Canada {DBU}

Proposed CHU directional antenna system

Proposed Log Periodic Horizontal antenna for optimal coverage

Technical Reference

CHU Proposal

Document Revision History
Max Power

10 JAN 2006

Last Revised
21 MAY 2010