well, they don't have the Chroma subcarrier, nor the 3.58..., nor the 4.5 MHz audio subcarrier. Yeah, they do have pilot tones, which should be stable-ish.  On Thu, 27 Mar 2025 12:28:25 -0500, Dana Whitlow via time-nuts <time-nuts@lists.febo.com> wrote: Correction to Jim's statement that DTV signals do not have subcarriers: ATSC 1.0: There is a continuous pilot carrier near the bottom end of the overall spectrum. ATSC 3.0: There are pilot tones all over the place. While most would be very difficult to use, two of them (one at the bottom and one at the top) are easy to use. Each is interrupted *very briefly* at a rate of 4X per second, and a clean uninterrupted tone can be obtained by merely selecting that clean carrier with a BPF narrow enough to block the sidebands. Caveat: these tones track variations in the transmitting station's RF frequency. For the two stations within indoor dipole receiving range of my home, I see frequency variations in the neighborhood of 50 mHz (that's *milli*-Hz) P-P. Both stations (KMYS & KPXL) operate at roughly 500 MHz regime, and had roughly comparable stability, although their detailed waveforms differed. I think this could offer insight into the nature of their frequency references. Dana Kerrville, TX variations of On Thu, Mar 27, 2025 at 11:59 AM Jim Lux via time-nuts < time-nuts@lists.febo.com> wrote: > > > > > If for no other reason than broadcast TV is now all digital, so there's no > color burst or subcarrier to measure. > The transmitted frequency might be fairly accurate (so they can do > multiple transmitters on the same frequency - to a receiver, it just looks > like multipath, and it uses a RAKE receiver to deal with it). > But that probably wouldn't give you "time". > > > > On Wed, 26 Mar 2025 11:17:32 -0700, Richard Karlquist via time-nuts < > time-nuts@lists.febo.com> wrote: > > In the 1980's when I worked for HP Santa Clara Division, they had three > dedicated 5061A high performance option cesiums that were steered by > Loran C signals. My boss would brag that this was the most accurate > clock on the West Coast. This was called the "House Standard" and was > distributed throughout the plant. They had a setup to measure the > chroma carrier of various local TV stations, and they could tell them by > how much their Rb clock was in error. (I believe the TV stations moved > on from that paradigm many years ago, so you can't use your TV for a > frequency reference any more). > > --- > Rick Karlquist > N6RK > > On 2025-03-26 01:50, john.haine--- via time-nuts wrote: > > > Geoff, I'm not sure where you are located but in Europe there is of > course the DCF77 signal from Mainflingen at 77.5 kHz and the MSF signal at > 60 kHz from Anthorn (UK). I am fairly certain that there are still products > around that use these to derive a stable frequency and time source, and > there have been a number of amateur projects published. With the growing > concerns over GNSS jamming and spoofing there's increasing interest in > e-LORAN at 100 kHz for PNT, there is a > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com > > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe send an email to time-nuts-leave@lists.febo.com