David, That is correct, the signal is delayed by at least the run length as well. We had to tweak the ublox parameters on our GPSDOs for a particular data center application that used a re-radiator to make it work as the default ublox parameters would get the unit confused due to residual multipath etc.
This is the type of obscure real-world firmware fine-tuning that separates the boys from the men... One may never need it, but it's good to know its there. Bye, Said On Apr 12, 2012, at 8:11, David McGaw <[email protected]> wrote: > The time/position fix would be from the location of the receiving antenna of > the repeater, degraded only by noise. > > This should work if both antennas have good back-side rejection (choke-rings > are particularly good for this but perhaps any good timing antenna could meet > this), the re-transmitting antenna is close to being directly under the > receiving antenna, and the system gain is low enough. The problem I would > see in a room that is not fully shielded is interference between the direct > and retransmitted signals at the receiver under test. > > David N1HAC > > On 4/12/12 10:17 AM, MailLists wrote: >> GPS being extremely time-dependent, any delay introduced will affect >> positioning precision. Also, the signal is too weak for such an >> amplification/echo cancelling signal chain. >> Passive relaying, or using at most a simple amplifier with low enough gain, >> and short signal delay, remain the only feasible concepts. >> >> On 4/12/2012 4:48 PM, Azelio Boriani wrote: >>> Passive UHF TV repeaters were in use in Italy too. Nowadays, for the DVB-T >>> TV, active gap-fillers are used instead. Active gap-fillers are >>> same-channel repeaters with the necessary, sophisticated echo suppression >>> technique. We have developed our echo suppression signal processor on a >>> Xilinx Virtex5 FPGA: maybe something similar may be done for the GPS CDMA. >>> >>> On Thu, Apr 12, 2012 at 3:29 PM, Alan Melia<[email protected]>wrote: >>> >>>> If the isolation is good and the "clear view" signal is reasonably strong, >>>> the passive system works well in hangers, metalclad warehouses, ferry lorry >>>> decks. >>>> The passive system in the UK used to be refered to as the "Matlock >>>> Repeater". >>>> >>>> Alan >>>> G3NYK >>>> >>>> ----- Original Message ----- >>>> From: "Michael Baker"<[email protected]> >>>> To:<[email protected]> >>>> Sent: Thursday, April 12, 2012 2:05 PM >>>> Subject: [time-nuts] Re-radiating a GPS signal...?? >>>> >>>> >>>>> Time-nutters-- >>>>> >>>>> So-- How do GPS signal re-radiators work? >>>>> >>>>> How do you place a GPS antenna on top of a building, >>>>> pick up the signal with an LNA, amplify it to re-transmit >>>>> on an inside antenna without the amplified re-transmitted >>>>> signal getting back into the roof-top receiving antenna? >>>>> >>>>> I can see circumstances where a huge metal building >>>>> (aircraft hangar?) might provide enough isolation to >>>>> prevent problems, but in many cases I wonder about it... >>>>> ---------------------------- >>>>> >>>>> As an aside note-- I recall seeing, many years ago, a totally >>>>> passive TV signal repeater on top of a tall hill in mountainous >>>>> territory relaying a TV station signal to some homes in a valley >>>>> just below. The passive repeater consisted of an array of >>>>> high-gain UHF yagis pointing to the 40 mile distant TV station tower. >>>>> The yagi array was coupled to another set of high-gain yagi >>>>> antennas pointing down to the homesites in the valley. I was >>>>> told that it worked pretty well. >>>>> >>>>> Mike Baker >>>>> ---------------------- >>>>> >>>>> _______________________________________________ >>>>> 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. >>>> >>>> >>>> _______________________________________________ >>>> 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. >>>> >>> _______________________________________________ >>> 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. >> >> _______________________________________________ >> 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. > > _______________________________________________ > 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. _______________________________________________ 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.
