When you hear hfgcs echo, it's more likely due to several tx sites simulkeying around the world than an actual long delayed echo. Not that it can't happen tho.
that was my first thought also, that Gander may use a second TX located in another area for coverage reasons, there are many HF communication stations that do this.
bingo! these two comments are right on the mark.
I made a post to the UDXF groups.io list and got some very interesting replies. One knowledgeable individual had all the details and our own Chris S made a comment which provided some additional collaborative evidence.
quote
Well, after some analysis by others on another list, it turns out that I mistaken in my observation that what I heard was a delayed echo.
<quote - my reply on first and another post below>
I checked the most recent Industry Canada frequency list and you are correct - Iqaluit and Cambridge Bay are still listed as remote TX sites on that frequency (listed as TX 11.2804 MHz which makes it a bit of challenge to search for). And Chris S estimation of "a delay of about 46,500 miles" all fits as well.
So, what I heard was in fact more an interesting bit of propagation where I was clearing hearing both Gander and either their remote transmitter in Iqaluit or Cambridge Bay and the remote transmission had a delay due to relay through a geosat.
Not what I thought but still pretty interesting non the less.
cheers, Graham near Ottawa Canada
On 2018-07-28 16:45, wrote:
<blockquote>
At last check (when I retired from ATC electronics in Canada in mid-2016) Gander had the NAT-D family of frequencies at Cambridge Bay, Iqaluit and if memory serves at Gander NL. The two remote locations are fed via satellite links, and the satellites in geosynchronous orbit are about 22500 miles up so your round-trip calculation of 46000 miles is very accurate. A delay of half a second would not be unreasonable when multiple sites are selected for transmit at QX IFSS. Also, and this may have changed since, the feed to/from YQX actually went to North Bay Ontario then to Telesat for uplinking as Arctic Radio was always at YYB FIC until it was amalgamated into QX IFSS nearly 10 years ago, so additional delay can certainly exist in that process. As to why you heard the echo clearly then it faded may be more to do with changing conditions preventing you from hearing multiple sites continuously. Cheers
<end quote>
</blockquote>
And as I said - an interesting bit of propagation but not what I at first thought it was.cheers, Graham
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