Hello group. I hope I am not blowing this but I think it was maybe Bruce who made a comment about only a carrier being heard on 162 kHz. The signal will at first sound just like a carrier with no modulation but if you narrow down the receiver BW and listen carefully you can hear slight variations.I went ahead and made a quick 1+ minute recording of TDF on 162 kHz and I spread out the horizontal span to almost the maximum I can do on this SDR. I also sped up the waterfall display so it is easier to see variations on that carrier.
The variations are simply binary data modulating that carrier. If you look close you can see the individual bits. What is neat is the pause right at the top of each minute. I hope this helps explain why you do no hear any modulation (even though the carrier really is being modulated by digital data). If you like I can post a video where I have decoded the digital data and can see where TDF is transmitting the exact date and time like our WWVB. 73 Gedas W8BYA
www.youtube.com/shorts/105yvYaEmX8