CBC-SRC North / Radio-Canada / Radio One
Audibility Improvement Proposal
Canada's rural and northern populations are for the most part not fully served by AM & FM radio stations during daytime hours.
CBC North runs an extensive AM / FM and TV network for northern Canadian residents. Yet there are still millions of square kilometers that the CBC-SRC will never be able to reach with its current broadcast network.
Lack of access to an information radio service in Canada's remote regions increases the demands on expensive to deliver federal and provincial services. Poor delivery of basic government services has led to a negative relationship between northern and rural residents and Canada's southern urban population.
In a matter of speaking CBC-SRC has failed to meet the news and information needs of all northern and rural residents. The mandate to serve these residents has been in place since the 1970s. This mandate is to provide a basic information radio service to all of Canada's regions.
Most of Canada's populated remote areas can be reached cost effectively with two shortwave transmission sites. Shortwave is an ideal media for delivering radio programming to remote regions during morning, daytime and evening hours. The proposal before you is for a transmitter site in British Columbia that could serve western and northern Canada and a transmitter site in Newfoundland that can reach Labrador, Northern Quebec and regions in the high arctic that are poorly reached by the BC transmitter site.
EEZ: Exclusive Economic Zone (includes "Home Waters" and ocean up to 200 km or Continental Shelf)
DRM: Digital Radio Mondial, the Digital Audio Broadcasting system for Shortwave and Mediumwave
SW: Shortwave (3.5 mhz to 25 mhz)
MW: AM band (550 kHz to 1700 kHz)
LPH: Horizontal Log Periodic antenna, technically a kind of fractal antenna with broadband performance
It is assumed that all shortwave transmitters will be fully DRM compatible, but should be configurable to broadcast in analog mode within 2 hours.
- DRM allows for digital audio broadcasting over very long distances and poor reception conditions, with FM radio audio quality independent of propagation conditions.
- DRM possesses data transmission capabilities that allow for the transmission of the text and graphic contents of the CBC-SRC websites.
- DRM also allows for secure military messaging and other data services, making it possible for this special CBC-SRC radio network to carry training and emergency messages for Canadian Forces within Canada's EEZ.
- This proposal requires using 1 x 50 kw DRM SW transmitters (if just the BC part of the proposal is adopted), it is assured that a 10 kw analog spare transmitter would also be included -- to allow for maintenance and repair of the primary transmitter.
- This proposal -- in its alternate form requires using 3 x 20 kw DRM SW transmitters.
- The two DRM transmitters would be expected to run around 16 hours a day equaling at 112 hour transmission week.
- A transmitter running 24 hours per day would run for 168 hours per week, thus (112/168) = 60% the cost of 24 hour service.
- In cases of national emergency, the network could run 168 hours a week with 5 different voice only audio streams.
It is not expected that a new frequency allocation for this shortwave service, as the CBC-SRC is already using three shortwave frequencies (http://www.cbc.ca/frequency/shortwave.html).
- Canada needs to make a uniform national allocation of 40 kHz for domestic shortwave broadcasting within the 49 m and 41 m bands, via the High Frequency Coordination Council (HFCC).
- It is assumed that 20 kHz per band will be adequate, as each analog shortwave allocation is 5 kHz and a digital mode (DRM) allocation is 10 kHz..
- This allocation would be made for use by all domestic shortwave broadcasters in Canada, greatly simplifying the current ad-hoc system.
Important Technical & Transmission Issues
Shortwave broadcasting technical issues
- Water [in the immediate vicinity of a shortwave transmission site] as well as saturated ground or so called wet ground are highly reflective of RF energy in the 100 kHz to 25 MHz range. On SW frequencies below 10 MHz, the reflectivity is similar to that of MW (AM band).
- Wet ground reflectivity decreases local skywave losses in the 100 km radius around the transmission antenna.
- The skywave signal will have more power before it is reflected off the ionosphere to its primary and secondary target areas, where wet ground is available at the transmitter site.
- Transmitter output power can be lowered by placing transmitter sites near lakes, wetlands or the ocean. This saves in the long term running costs of the broadcasting networks.
Antenna directivity issues that affect all broadcasting locationsHorizontal Log Periodic (LPH) antennas are best suited for domestic shortwave transmission.
General propagation issues
- LPH reception is optimal over signal paths of ~400 km to ~1200 km from the transmitter site.
- LPH antennas are simple to build and maintain, there are no moving parts.
- LPH antennas are durable under severe weather conditions.
- LPH transmission systems typically send most of the broadcast energy into the ionosphere at angles of 30º to 50º making long path propagation less probable.
- Long path propagation needs to be avoided, as it would be unreasonable for a domestic Canadian broadcaster to purposefully engage in international broadcasting.
- Further antenna optimization is needed to increase signal strength in Canada, as the LPH transmission system specified has only been through limited system optimization.
- With two or three frequencies transmitted from opposite ends of the nation, one frequency will always be usable -- no matter how upset the ionosphere is at high latitudes. The same geomagnetic effects that generate "Northern Lights" hinder shortwave propagation and separate transmission sites aid in audibility.
- Canada's average length of ~1.55 skywave hops (for frequencies around 10 MHz (±3.5 MHz) , via the ionosphere at 300 to 350 km) makes the two-antenna site transmission system workable.
Radio Canada / CBC Radio
Audibility Improvement Program (specifications)
- Masset, BC allows for an all water path for the first ionospheric hop.
- A near "all water path" (with respect to signal reflection into the nearby sea into the ionosphere) allows a 50 kw transmitter to be used as opposed to a 100 kw transmitter. This means a 50% power savings from the 1st day of transmitter operation.
- Masset also possesses other local environmental conditions that are optimal for obtaining greatest HF reflectivity, like uniformly "wet" ground soils.
- The same variables and constraints that make Masset, BC optimal as a shortwave transmission site are not unique on the BC coast -- other slightly less optimal sites do exist.
- It must be taken into account that conditions beyond the control of CBC-SRC may render Masset unavailable (or unusable) for high power HF broadcasting.
- A 2nd identical LPH antenna targeted at the USA, for emergency (or lease) use by Radio Canada International (RCI) should be considered as part of the overall proposal. This allows for RCI to schedule more maintenance on its Sackville Relay station transmission system targeting the Americas.
- A 3rd identical LPH antenna targeted at Australia / NZ & Pacific Islands could also be considered as an option for RCI use. This would allow the transmitter to run a 168 hours / week, but require it change to a 3rd or 4th frequency. There are no legal constraints against CBC-SRC leasing out transmission facilities to RCI for international broadcasting, as long as CBC-SRC itself does not engage in international broadcasting.
- Antenna elevation: 200 m above sea level, related to tsunami safety reasons.
- ITU CIRAF Zone Coverage: 02, 03, 06NW.
- Is this location optimal: nearly so -- it is possible to use "Twilight Immunity" (a form of DX Grayline frequency and skywave launch angle techniques) thus allowing listeners in the Eastern Time Zone to be reached similarly to how RFE/RL was able to reach listeners in Russia from its transmission facility in Gloria, Portugal (as well as Playa De Pals, Spain).
Newfoundland & Labrador
- The Newfoundland transmitter location was chosen using the same variables and constraints as the Masset site.
- Sea ice is a poor HF reflection medium. Signal strength may seasonally vary based on the amount of land and sea ice zone surrounding the transmitter site. I do not expect gross signal attenuation because of the effects of sea ice, but a mid-Winter loss of 0.5 db is to be expected. This attenuation affect can be minimized by optimal frequency choices during the winter season.
- Coverage of the US New England region was unavoidable with the chosen LPH antenna and transmission site. As US shortwave listening decreases, and as fewer international broadcasters target the US this accidental coverage should not prove to be an issue. Excellent signals are available to New York City, Washington, DC and Boston, MA -- not necessarily a design defect.
- Antenna elevation is recommended to be some 60 m above sea level. Newfoundland & Labrador has an overall lower elevation than the Queen Charlotte Islands (or Vancouver Island), but a lower tsunami risk.
- A 2nd antenna aimed at the Eastern US should be considered as a backup for RCI. RCI could extend its shortwave service to geopolitically important Eastern US using the 2nd antenna.
- A 3rd antenna aimed at Western Europe could be considered as a backup for RCI. I do not believe that it is geopolitically necessary to cover Western Europe with such marginal signals as local MW and LW transmitters in Europe are available for lease allowing a larger audience to be reached in that way.
- If the third antenna were aimed at the North Atlantic Sea â€“ it could be used to transmit Canadian Forces Radio during NATO exercises.
- If a 10 kw analogue SW transmitter is available as a spare at the transmission site, listeners will only notice weaker signals during select times of the day â€“ and more than one antenna could be used.
- ITU CIRAF Zones : 04, 09, 08NE.
- Manitoba, due to its central location and proximity to the inland waters of Hudson's Bay -- makes it a strategic location to supply secondary propagation path coverage to the Arctic.
- Sea ice is a poor HF reflection medium. Signal strength may seasonally vary based on the amount of land and sea ice zone surrounding the transmitter site. Gross signal attenuation is not expected because of the effects of sea ice, but a mid-Winter loss of 0.5 db is to be expected. This attenuation affect can be minimized by optimal frequency choices during the winter season.
- Marginal coverage of the US Great Lakes region is unavoidable with the chosen LPH antenna and transmission site.
- As US shortwave listening decreases, and as fewer international broadcasters target the US this accidental coverage should not prove to be an issue.
- Reasonable signals from this transmitter site are available to Chicago, Illinois and Saint.Paul, Minnesota.
- CIRAF Zones: 03, 07 NE, 07 NW
These computations do not represent a finalized transmission system.
The frequency and antenna types may need to be slightly or significantly altered to fully achieve the goal of covering 98% of Canada's land mass (and 90%+ of its EEZ) with a reliable shortwave service from two (or possibly three) transmitter sites.
This proposal is only optimal for about 90% landmass and 80% of its EEZ.