Gap Filler Detail

1959 – National Archives of Canada

SECRET

S950-113-2(EinC)

MEMORANDUM

15 Jun 59

Ref CCE Memo 10-36-80/5 (JDPG) 23 Apr 59

ATSC

Gap Filler Radar (FPS-18) - Interference

The following 15 gap filler stations have been checked for interference with other communications facilities known to exist in the areas:

C16B - Atikokan
C15A - Nipigon
C15B - Silver Falls
C9C - Elliot Lake
C119B - Chapleau
C3c - Algonquin Park *
C4B - NObel
C4A - Buck Horn
C2B - La Macaza
C1A - Grand Fond *
C6A - St Cecil
C5E - St Cleophas
C5A - Scotch Settlement *
C11A - New Yarmouth
C5B - Todd Mountain

The information concerning the communications facilities was obtained from the following sources:

  1. The Trans-Canada Telephone System - Catalogue of Microwave Relay Stations

  2. Quebec Hydro Microwave System Listings

  3. Canadian National and Canadian Pacific Microwave System Listings

  4. Department of Transport Frequency Charts - (Coded "A" to "J" inclusive).

  5. Verbal data supplied from Commercial Carrier Companies.

The criteria used for the analysis was based on the following assumptions:

  1. Interference below 2080 mcs is not expected because the FPS-18 waveguide cutoff occurs at this frequency.

  2. The FPS-18, because of its basic design, (Klystron operation) can be expected to produce an insignificant amount of spurious radiation and therefore only interference from harmonics and from spectrum splatter has been considered. (The FPS-18 spurious and harmonic frequency tests have not yet been carried out. However the test results for the FPS-20 provides support for this assumption).

The fourth harmonic of the Gap Fillers falls directly in the frequency band of the proposed Bell Telephone TJ microwave short haul equipment. However, because Bell have been unable to advise when and where this equipment will be installed TJ has not been considered.

Based on the above all of the above sites are considered satisfactory with exception of the following for the reasons indiated:-

  1. C3C - Algonquin Park

    NRC (Radio Physics Laboratory) are installing or, are planning to install a radio telescope in the general area (Lat 45º 35', Long 78º 03' approx) and radar interference from this gap filler could seriously affect its operation. NRC have been advised of this proposed radar site but it is recommended that this matter be resolved with them before any work is started. Otherwise, this station is considered satisfactory.

  2. C5A - Scotch Settlement

    This site is co-located with a New Brunswick Telephone microwave station (now under construction) and with a local highway patrol microwave station. If resiting is impossible or very difficult special precautions may reduce the interference.

  3. C1A - Grand Fond

    This site is co-located with a Quebec Hydro microwave system. The same remarks as indicated in (b) above also apply

As additional information becomes available, it may be necessary to amend this report. You will be notified immediately of any change in status.

A report on the remaining gap filler sites will be submitted later.

(HJ VonBaeyer) Dr.
EinC
6-8632