[time-nuts] [Fwd: Re: Simulating LORAN-A GRI Timing Generator]
paulswedb at gmail.com
Sat Jan 8 15:43:25 UTC 2011
So if I read the excel correctly you only actually need 1 system.
Say H0 is the master then the delays for H1-X is how far away from the
master the pulse would be. More importantly you would only need 2 other of
the Hs to create a navigational fix.
Is this a correct interpretation?
Have to go dig out of the snow.
On Sat, Jan 8, 2011 at 10:35 AM, Magnus Danielson <
magnus at rubidium.dyndns.org> wrote:
> On 08/01/11 16:08, J. Forster wrote:
>> Pondering some more on this, doing some calculations (spread-sheets) the
>> actual scheme emerge... the range of 0 to 7 is not selected by accident.
> I had essentially the same spread sheet...
> However, how would you be able to achieve simplicity of design by being
> true to the PRI/PRR given or to what seems like reasonable counter based
> solution. Notice that the ARN-4 has a "Crystal phasing" control to adjust
> the crystal frequency of the receiver so that the receiver will align up to
> the actual rate of the master station.
> I think the PRI/PRR given is a presentation simplification rather than true
> numbers. Considering that absolute frequency was not a requirement, the
> repetition rate of the master needs to be sufficiently stable for
> distinction of station and the receiver to make stable reading, in presence
> of other stations.
> That LORAN-C uses GRI indications with repetition rate in microseconds, and
> fairly even such numbers as well, is another hint.
> Thus, I view the PRI/PRR ratios as approximations at best, a matter of
> presentation rather than actual nominal rates.
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