TéléDiffusion de France broadcast the ALS162 time signal, provided by LNE-SYRTE[1] and LNE-LTFB time laboratories under ANFR (state body for radio frequencies) responsibility, from the Allouis longwave transmitter at 162 kHz, with a power of 800 kW.

The signal transmission is almost continuous, but there is a regularly scheduled interruption for maintenance and tests every Tuesday from 08:00 to 12:00.

[3] The transmitter building contains two caesium atomic clocks which are used to generate the time signal and which are monitored through the SYREF system and GPS common-view measurements, to align with the official French UTC(OP) time scale.

[4] The monitoring of the ALS162 signal is jointly conducted by LNE-SYRTE, LNE-LTFB and the trade body France Horlogerie and measurement results are published in real time.

[1] Monthly monitoring bulletins, like H 649 of the ALS162 signal regarding January 2022 measurements, show if the exactitude goals were met.

The call sign ALS162 stands for ALS = Allouis transmitter, 162 = frequency: 162 kHz.

[2][11][12][13] TéléDiffusion de France (TDF) uses an amplitude modulated longwave transmitter station.

The binary encoding of date and time data during seconds 15 through 18 and 20 through 59 is identical to that of DCF77; the numbers of the minute, hour, day of the month, day of the week, month and year are transmitted each minute from the 21st to the 58th second, in accordance with the French legal time scale.

As extensions to the DCF77 code, bit 14 is set during public holidays (14 July, Christmas, etc.

But the second marker (and data bit) is always preceded by 100 ms without any phase modulation.