TDF 162 kHz power test, November 2019

Pieter-Tjerk de Boer, PA3FWM

From November 12 till 14 2019, the ANFR (Agence nationale des fréquences) did a test with their 162 kHz transmitter, running it at 800 instead of 1100 kW; see Nowadays, this transmitter only transmits a timecode; see here.

Below are two plots of the received signal strength in in Enschede, the Netherlands during part of these days. Vertical axis is relative power in dB; carrier power has been averaged over 1-second intervals and plotted as dots. Horizontal axis is UTC time. Note that a reduction from 1100 kW to 800 kW is a change of 1.38 dB.

The first graph shows the start of the Tuesday maintenance interval shortly after 8 o'clock local time, blue line. It seems they briefly tried various power levels before shutting down the transmitter completely for a couple of hours.
[received signal strength around 07 UTC]

The second graph shows the power around 12:00 local time, which was announced to be the start and end time of the test on November 12 and 14.
[received signal strength around 11 UTC]

On Tuesday November 12 (blue line), we see the signal reappear after the maintenance window around 10:38 UTC (11:38 local); it is some 4 dB stronger than before, but that may well be due to propagation variations, not to a power change.

On Wednesday and Thursday, the signal is briefly interrupted at exactly 11:00 UTC (12:00 local). Around this interruption, the power increases by 1.2 dB on Wednesday (green line), not on Thursday (yellow line).

So it looks as if the test was ended one day earlier than announced.
Also, it is quite notable that variations due to propagation, even during daytime, are more than 1.3 dB, at least at this location; so one can wonder whether a 1.3 dB reduction can make a significant difference for a practical user (but of course it does save 300 kW of electricity).

Text and pictures on this page are copyright 2019, P.T. de Boer, .
Republication is only allowed with my explicit permission.