Wednesday, September 26, 2018

Spotting Tonga in the Afternoon

Tonga Broacasting Commission, A3Z, recently extended their broadcasting schedule to 24 hours. In Kongsfjord, the station has been a frequent guest on 1017 kHz early in the day for many years. However, it requires good conditions to come that early at this time of the autumn, and this year in particular the early hours have been eerily silent.

Today, the 10-kW transmitter  with its roughly +5 Hz offset was noted with a weak carrier at 11:30 UTC, and snippets of audio at 12:30. The Jaguar spectrum followed the signal at  mostly very low levels throughout the day. Then, prior to 17:00 the signal suddenly increased significantly. At the full hour their BBC World Service news bulletin was indeed very strong, and dominating over the usually strong Asian stations on 1017. Was I surprised? Very! Then a few minutes after, the signal started to fade, and eventually disappeared.

But Tonga sunrise today was at 17:38, and pre-sunrise signal enhancement is a well known phenomenon especially among radio amateurs. So a peak like that is really what you might expect, or at least hope for.

Curious if this was a one-day only event, I scrolled back the Jaguar spectrum a few days. And yes, although weaker due to propagation, the Tonga signal had the same characteristics several days back.

Below is the 1017 spectrum from 11:00 to almost 18:00 UTC, showing the Tonga signal level from fade in to fade out.

And to give you a perspective of Tonga in relation to Kongsfjord, and more importantly, the sunrise, see below.

But this "news" about a late Tonga peak might not be news at all. According to the Pacific-Asian Log, the previous sign-on time for Tonga was 16:50. So, we should have noted the signal before they went 24 hours. But since they were so "easy" to hear before close-down, we never bothered to check, did we. Or maybe someone did?

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