[time-nuts] LORAN-C

John Ackermann N8UR jra at febo.com
Mon Nov 12 19:10:23 EST 2007


For what it's worth, I've never felt that the frequency error display on
the 2100 series was all that reliable, even when you use the longest
averaging time.  When I've used LORAN for frequency measurement, I hook
an A/D on the strip recorder output and monitor the phase with that for
a day or three.  That yields pretty good results.

By the way -- if you live near AM BCB stations, I tracked down a diurnal
phase shift when I realized that it matched the time that the strongest
station shifted its antenna from daytime to nighttime pattern, and vice
versa.  Apparently the BCB signal was overloading the front end, and the
change in power when the pattern shifted (about 3 dB) changed the
operating condition of the amp, and thereby changed the phase delay.
Putting an LPF in front of the antenna connector solved that problem.

John
----

wa1zms at att.net said the following on 11/12/2007 07:01 PM:
> ); SAEximRunCond expanded to false
> Errors-To: time-nuts-bounces+jra=fluffles.febo.com at febo.com RETRY
> 
> Stan's comments below about his noted errors between
> LORAN & GPS that range from E10 to E13 each day remind me
> of the similar errors that I have observed.
> 
> I had originally attributed them to ground-wave vs. sky-wave
> propagation on the LORAN side. But I know that the LORAN
> system encoding is intended to be resistant to such propagation
> situations.
> 
> I have not made the effort to fully quantify my particular
> measurements. But I do routinely observe my Austron 2100F
> showing an almost diurnal change in displayed error when
> using it as the measurement system against an HP-5061 or Z3801A.
> 
> Can someone confirm that the E10 to E13 errors are typical
> of the 2100F? And what ultimate long-term stability have others
> been able to achieve using LORAN as a reference?
> 
> Thanks in advance,
> -Brian, WA1ZMS
> 
> 
> 
> -----Original Message-----
> <snip>
> I have gotten a 4 parts in E13 comparison between the LORAN-C and the
> GPS disciplined oscillator,
> at least for a short time, multiple times a day.
> Most readings are between E10 an E13 comparing the GPS DO and the
> Loran-C RX.
> probably bouncing due to the propagation paths and propagation
> perturbations.
> <snip>
> 
> Stan, W1LE   FN41sr  Cape Cod
> 
> 
> 
> 
> 
> 
> nnovotney at cinci.rr.com wrote:
> 
>> Hello:
>>
>> My different types of equipment (scope, freq cntr, spec analyzer, etc)
> never seem to be right on the money, so I decided to run them all off a
> commnon exact 10MHz rubidium source.
>> I got an FE-5680A  (was on a chopped off ckt board-whcih is apparently part
> of some motorola system pcb)..I hooked pin 1 to +15V & pins 2 to gns ...but
> nothing came out any of the other pins?!??  Where is the output?  Do I need
> another cxonnection?  I read you might need to apply +5v, but  don't want to
> try unless I know what I'm doing.  How do you determine what option your
> unit has?  It looks like about 60 options are possible!!  By the way, with
> my spec analyzer probe nearby I am sniffing the 6.834xx GHz signal-so the Rb
> is in there doing its thing.
>> As a second note, as I read around here, it seems (to my understanding)
> that the Rb osc is not exact--that in fact it needs calibrated!!  Well, I
> dont't want to cal it --I bought this "atomic clock"  to let me cal all of
> my various xtal oscilators.  How on earth shall I cal this thing?  If I
> don't cal, how far off is it?  Can i count on 9 digits of accuracy with "no
> cal"
>> a
>> thanks for your hints & direction....I think I'll enjoy this group & hope
> to make some contibutions once I get going.
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>>
> 
> 
> 
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