Yes, that is what they are doing. A given Doppler shift corresponds to a certain "ring" on the Earth's surface. Each Hertz of Soppler shift corresponds to a certain number of miles on the radius of the ring.
At 1.6GHz one part per billion is 1.6Hz. 175Hz of shift gives something like a 2,400 mile radius ring. On Wed, Aug 20, 2014 at 8:47 AM, Joe Leikhim <[email protected]> wrote: > The L Band uplink was reported to be transmitting at around 1.6435/ghz. > / > Assuming, we actually knew what the tolerance of the OCXO (If it is an > OCXO) was under the environment of the mishap, and assuming it /was/ 10ppm > for example. The error would be (1,650 X1,000,000) * 10ppm or _16,500 hz_. > I think we can discount the error being that large, but could still > rationalize it being a significant portion of the reported BFO value./ > / > Also the ground track is unknown, they are attempting to reconstruct the > ground track from the BFO (Burst Frequency Offset "Doppler") and from the > BTO (timing pings) the BTO supposedly offers range information, hence the > concentric rings corresponding to pings._ > > _ > > _Chris Alb__ertson wrote:_ > > > "The total Doppler in this case is on the order of 100 Hz. The tiny > frequency shifts of an out of spec OCXO is just to small to measure. > The data says at UTC 18:30 the shift was in the mid range and was > about 175Hz. Assume the OCXO drifts 10 parts per million. That > is a lot for an OCXO. But maybe the effect is only about 50 feet on > the ground. > > The OCXO error of even 1E-5 is just not very important as it does not > move the aircrafts ground track enough to matter." > > > -- > Joe Leikhim > > > Leikhim and Associates > > Communications Consultants > > Oviedo, Florida > > [email protected] > > 407-982-0446 > > WWW.LEIKHIM.COM > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. -- Chris Albertson Redondo Beach, California _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
