[time-nuts] 60 KHz Receiver

J. Forster jfor at quik.com
Tue Oct 5 22:24:55 UTC 2010


The localized LORAN is not that hard, IMO:

Many TNs have GPS & Rbs.
At least one simulator has been built.
RF amps are easily available (ENI) for 100W pulse at 100 KHz.
Home Depot has 250' rolls of #14 THHN.

FWIW,

-John

============

> 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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