--- In [email protected], "wb6ymh" <freebsd...@...> wrote: > > Bob, you might consider picking up a rubidium frequency standard, they > are <$100 on ebay. In fact there's a $77 buy it now listing > with free shipping at the moment: > http://cgi.ebay.com/10MHZ-EFRATOM-LPRO-101-Rubidium-Frequency-Standard-DHL_W0QQitemZ270442620847QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3ef7a2e7af&_trksid=p3286.c0.m14 > > You'll need a heatsink and a 24 volts power supply. A GPS locked > standard would be ultimate, but they are more like $300. > > 73's Skip WB6YMH
I take it back, GPS standards have come WAY down in price since the last time I looked. Here's one for $120... hmmm... tempting... http://cgi.ebay.com/Thunderbolt-PRECISION-GPS-10mhz-FREQUENCY-TIME-Standard_W0QQitemZ180399458965QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item2a00a54a95&_trksid=p3286.c0.m14 73's Skip WB6YMH > > --- In [email protected], no6b@ wrote: > > > > At 9/5/2009 21:20, you wrote: > > > > OK, now that NTSC video is gone, so are my handy local video > > > > carriers that > > > > I used to use to check the frequency accuracy of my signal > > > > generators. However, I understand that there are pilot > > > > carriers buried > > > > within the 8VSB DTV signals that can be used for the same purpose. A > > > > couple of Google searches revealed that DTV ch. 7 is supposed > > > > to have a > > > > pilot at 174.310 MHz. Putting my old FM-10 on 174.310 & > > > > listening to the > > > > beat signal on my R-100, I heard a heterodyne of ~500 Hz. I > > > > thought that > > > > error was a bit high, so checked a few other DTV pilots (186.310 & > > > > 198.310). Interestingly, they were off by the same amount. I > > > > moved the > > > > FM-10 to 15 MHz & checked it against WWVH; heterodyne was > > > > ~1.5 Hz, equating > > > > to ~18 Hz @ 180 MHz, not ~500 Hz. My best guess is that the > > > > ATSC pilots > > > > are actually 309.450 kHz above the bottom of each channel, > > > > and the 310 kHz > > > > reference is an approximation. > > > > > > > > Can anyone confirm the above? > > > > > > > > Bob NO6B > > > > > >You're trying to make it easier than it is Bob :-) > > > > > >Normally it would be 309.440559 kHz above the bottom of the channel. > > >That's > > >a real big "normally". > > > > OK, thanks. Well as long as they don't change with the seasons... > > > > I took a closer look at chs. 7, 9, 11 & 13 today. I see 7 at 174.309450, 9 > > at 186.309441, 11 at 198.309730 & 13 at 210.309716. Since the errors > > between the frequencies are not linear, I suspect that they're either some > > exceptions to the normal freq., or possibly just loose freq. tolerances. > > > > Bob NO6B > > >
