[time-nuts] L1 and L2 frequencies

Li Ang lllaaa at gmail.com
Fri Jan 16 07:58:14 EST 2015


Hi
  I have a question about the GPS antenna. Since the GPS signal strength on
the ground is about 20db lower than the thermal noise, does the gain of
antenna matter?

2015-01-16 7:01 GMT+08:00 "Björn Gabrielsson" <bg at lysator.liu.se>:

> Magnus,
>
> >>> If civilian receivers where to implement L2C and L5 which now is
> >>> becoming common, they would gain quite a bit of precision in a similar
> >>> fashion. For car navigation, the GPS would know which lane you are in.
> >>
> >> There ARE civilian receivers doing this, and has been for quite some
> >> years. And its not from only a few vendors - all the big ones have it -
> >> Trimble, Novatel, Topcon, Javad, Leica, Septentrio and a few more. There
> >> are now receivers tracking "GPS L1/L2/L2C/L5, Galileo
> >> E1/E5A/E5B/AltBoc/E6, GLONASS L1/L2/L3, BeiDou B1/B2/B3, QZSS L1/L2/L5"
> >>
> >> The price exceeds my home hobby budget, but so does a replacement
> >> CS-tube
> >> a factory new OCXO based GPSDO and many other things you can sometime
> >> find
> >> at reasonable cost used/recycled.
> >
> > I naturally meant with a reasonable price-tag, sorry for being sloppy on
> > that detail, and I do know that there is vendors for those signals.
> >
> > If we had dual or triple frequency receivers below 500 USD things would
> > start to be interesting. If high-volume kits would be just twice as
> > expensive, it would be possible to consider for more luxury models.
>
> Receiver with 24 universal channels each of GPS L1/L2/L2C/L5 is cheaper
> than a entry level TCXO-based 19" GPSDO (M300GPS @ Dustin). And about the
> same price as a modern Loran receiver. What is a reasonable commercial
> price?
>
>  But yes, multi frequency GNSS is much more expensive than the Oncore,
> Ublox traditionally used in a GPSDO. Is the performance gain worth the
> cost? Certainly not for all but a few.
>
> On the oscillator side, we consider everything from XO, TCXO, OCXO, DOCXO,
> to devar based designs - BVAs and others, and rubidiums, cesiums and
> Masers. What are reasonable price-tags for oscillators compared to various
> time transfer capable receiver?
>
> --
>
>      Björn
>
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