Archived—Report on AM Broadcasting Possibilities in The Greater Toronto Area
Appendix 1 – Letter from Gordon Elder on sharing Toronto Island sites
Elder Engineering Inc.
P.O. Box 10, King City, Ontario
Broadcast and Communications Consultants
Area Code: 905
February 26, 2001
Mr. Douglas Forde
AM Broadcast Engineering
300 Slater Street
Ottawa, Ontario K1A 0C8
Subject: Sharing an AM Transmitting Site, on Toronto Island
This follows CRTC P.N. 2001–10 of January 31, 2001, concerning engineering requirements to increase the diversity of ethnic programming in the GTA and specifically AM radio, which is discussed in paragraph 56.
As you know, I became very familiar with the island sites in 1960, as CKEY's consultant for their facilities at Gibraltar Point. Later, we designed and commissioned CHWO and CJMR's jointly owned seven tower shared array, on the mainland. It operates on 1250 and 320 kHz in Oakville.
CHIN's 1540 kHz array is immediately SSW of CHKT's on 1430 kHz. All eleven ATU's have filters to avoid reradiating and distorting the adjacent station's pattern.
The following are only preliminary comments. A detailed design, SC-5 analysis at the school, capital cost estimates, including for freight and installation, negotiations with the licensee and the City of Toronto, would be essential. The three frequencies under consideration and their approximate NL's are:
|kHz||Approximate NL (mV/m)|
The night pattern on 1500 kHz would require suppression to very low radiation levels, over the 225° arc from east to northwest, in order to protect WTOP and KSTP's skywave service. A special array design would be necessary. In our opinion, sharing either CHIN's or CHKT's site and all or part of their array, would not be feasible, due to the severe constraints and complications. Neither would a suitable separate Island or adjacent lakefront site be available for a 1500 kHz station, due to Toronto's current land use leasing restrictions and prudent avoidance policies.
1470 kHz has a lower night limit, but its daytime service to Mississauga would be poorer then 1480 kHz's, in order to protect CJOY, Guelph. If either of these frequencies was selected and the assignment co-sited with CHIN, the field intensifies at CHKT's array would be much stronger than would occur at CHIN's, if it was co-sited with CHKT. Therefore, less tower reradiation and filter suppression would be required, if the new 1470 or 1480 kHz station shared CHKT's array.
This concept is technically feasible, but perhaps not economically feasible. Complex design details are involved, which may reduce the system's reliability. For example, the small difference in frequency of approximately only 3% or 40–50 kHz, would require excellent filter-combiner design techniques. Additional coaxial cables, larger ATU huts and additiooal floor space for the new transmitter and phasor would be required. For these reasons, CHKT's licensee – Fairchild Radio, may be reluctant to share its transmitting site and array, especially with a potential competitor.
The site sharing difficulties would depend upon the applicant's desired service area, power and antenna pattern requirements, of course.
At your discretion, part or all of this letter may be submitted to IC and/or CRTC. if desired or required.
Yours very truly,
- Date modified: