[time-nuts] 60 KHz Receiver

[WB6BNQ]

Poul,

Please explain to me how spread spectrum would enhance any process of frequency or
time recovery ?

I just do not see it.

The reason for the spread spectrum used with the GPS is because all of the Birds
are in the same base frequency.  Thus the spreading codes allow for distinction
between the different signals.

At 100 kHz the system bandwidth is very, very limited compared to the very wide
spectrum of the GPS.  Stepping up into the HF area brings in the sky wave
propagation issues.

The whole purpose of suggesting an amateur approach is to utilize the large base of
existing LORAN receivers as someone pointed out.  However, as the number of people
needing such a service is quite small it does not make economical sense, as the
cost would certainly be prohibitive.  The only feasible way would be to have many
lower power 100 kHz transmitters and there are just not enough people around to
construct, install and maintain such an operation; not to mention the licensing
issues.

Besides, you would achieve nothing above what is already provided by operations
such as the 60 kHz WWVB and similar in other countries.  So I see it as a pie in
the sky nice idea but no cigar.

Bill....WB6BNQ


Poul-Henning Kamp wrote:

> In message <63077.12.6.201.2.1286310871.squirrel at popaccts.quikus.com>, "J. Fors
> ter" writes:
>
> >That's why I think an amateur timing LORAN network might be quite
> >feasable. Imagine a dozen 1 KW PEP A-LORAN stations with Rb and GPS
> >scattered around the US. There is no reason why a single transmitter could
> >not spoof a whole chain as it would not be used for navigation.
>
> Why try to emulate technology from WWII ?
>
> I would find it much more interesting to invent a good spread-spectrum
> modulation, and see if we could do world wide time-transmission with
> just a single 1W tranmistter per continent, which could be received
> with a simple down-converter frontend and a soundcard.
>
> Poul-Henning
>
> --
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
>
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