From The RadioReference Wiki
Line A Description
A line spanning from Washington State to Maine which approximates the border between the United States and Canada. The exact position of the line with respect to the border varies, however in most places it is about 75 miles/ 120 km from the border. The line was established in the Terrestrial Radiocommunication Agreements and Arrangements treaty of 1965, titled "Telecommunication: Coordination and Use of Radio Frequencies Above 30 Megacycles per Second."
Lines B, C, and D
Line A is complemented by Line B, which is a similar line within Canada. Stations south of Line B must coordinate with the United States, as well.
A Line C exists in Alaska and a complementary Line D exists in Canada bordering Alaska. Due to sparse population, Line C issues present less frequently.
Applications from stations which operate in Part 90 (business and public safety) are sent by the FCC to Industry Canada for review against their Technical and Administrative Frequency List (TAFL) database records. If the proposed application's -148 dBW signal signal (for VHF, -146 dBW for UHF) touches a Canadian licensee, a "NOTICE OF RETURN FOR CANADIAN OBJECTIONS" is generated. Although the treaty does not specify any particular vetting methodology, the algorithm used to determine this return is roughly based on Longley-Rice F(50,10) at -118 dBm for VHF and -116 dBm for UHF (which is equal to -148 dBW/-146 dBW) at the height of the listed receiver antenna. If the objection references an area of operation, the area usually refers to signal incursion into a 50 km radius from the point coordinate referenced. The typical model which approximates this incursion uses a 3m antenna elevation for the propagation model. Any incursion at the receiver antenna or within the area of operation specified, even if it is compliant to what would be accepted U.S. frequency coordination practices, is grounds for return.
Canadian Objection Letter
The Canadian objection letter usually states that harmful interference is anticipated ("HIA") and provides specific information against which the proposed system may be disputed. The dispute might be settled by providing a detailed engineering study indicating the signal does not impinge on Canadian operations. The engineering study may, however, indicate that the proposed system will impinge on Canadian operations, thus requiring the selection of another frequency, reduction in power, selection of antenna patterns which "protect" (or harshly notch radiation in the direction of) the Canadian station noted, or reduction in height above average terrain. On-air testing may be arranged if both parties remain at an impasse, but only after other methods have been exhausted.
Industry Canada TAFL Database
The Industry Canada TAFL database contains information which has been protected for Canadian national security reasons. This information is unavailable through Industry Canada's search features. It is, therefore, possible to receive a Canadian objection with no specific information provided by the FCC, or on a frequency that otherwise appears to be "clear" between Lines A and B. These objections are based on harmful interference anticipated to the protected operations. Depending on province, the amount of redacted information may be between 20 - 35% of the database content, making system implementation north of Line A extremely difficult due to the element of chance and uncertainty of available resources. If a frequency north of Line A seems clear, it's probably clear for a reason.
Accepting Secondary Status
If all attempts to justify implementation fail Industry Canada review and appeal, the potential licensee may accept secondary status and a power level not greater than 5 Watts output/5 Watts effective radiated power. Often, this power level is unsatisfactory for the proposed use. It is wise to not procure VHF or UHF systems, particularly those of significant expense, without first insuring that uncontested resources are available within the required area. Given the element of uncertainty from redacted data, a salesperson or consultant typically cannot make those assurances without going through the application process and receiving official responses to the affirmative first. Caveat emptor.
Strategies for Successful Procurement of Resource
- NEVER buy a new system north of Line A without having obtained an FCC license first. The process of doing so may require in excess of a year of exchanges between the FCC and Industry Canada, and returns to other parties. Therefore, budgeting time is as much a necessity as budgeting finance. No third party is capable of making assurances of getting the resources necessary to build, as the process mimics informed trial and error. The only such assurance is a license-in-hand.
- Deliberately map out the areas where coverage is absolutely necessary. Use low effective radiated power and engineered radiation patterns to minimize signal toward Canada and direct the energy into the required coverage area. In some cases, a lack of geographic opposition will result in areas painted by signal into Canada regardless of how much power may be reduced. High power out to the horizon from a mountaintop is generally not an option.
- Do not state an area of operation that is uncharacteristic of the actual served jurisdiction plus a modest buffer region around it. For example, if the jurisdiction requiring coverage is 2 square miles, do not state that the mobile area of operation is 40 km. Unfortunately, the definition of an area of operation is also a triggering point for 90.205 ("Safe Harbor") effective radiated power reductions, as well.
- For VHF, Canada has not narrowbanded and typically remains channelized on 15 kHz channel centers using 16K0 emissions. When a frequency with a 7.5 kHz channel center is proposed in the US, it is considered to be co-channel to the immediate adjacent lower 15 kHz channel center AND the immediate adjacent upper 15 kHz channel center, BOTH.
- If a frequency appears to be clear, it's likely clear because it's protecting a redacted Canadian concern. Selecting a frequency that has other users north of Line A will have a greater chance of successful licensing.
- Use frequency resources in a responsible, non-consumptive manner.
- Cooperate with other US licensees and applicants in effective sharing of finite frequency resources in "interference-limited" configurations. This usually requires constructing systems to tolerate additional degrees of interference from other systems (all frequencies below 470 MHz are considered to be "shared use" unless there is FB8 exclusivity), and cooperating with others in allowing for concurrence measures.
- Consider deployment of systems within frequency bands where international planning has taken place. These are typically higher-frequency systems which may require additional sites to achieve performance due to propagation characteristics. While the expense of such deployment may be higher, the cost:benefit ratio is offset by what may be peril of not being able to procure clear and necessary amount of resource in lower frequency bands.
- - (FCC) ...guidance to ...applicants seeking VHF and UHF frequencies along the U.S. - Canada Border
- - Telecommunication: Coordination and Use of Radio Frequencies Above 30 Megacycles per Second