On 12/6/2024 8:27 AM, Steve Sykes via time-nuts wrote:

Steve, historically the original LORAN was somewhere in the LF range
around 1.8 MHz, post WWII.  eLoran was at 100 kHz.  It would depend on
the age of your receiver, but I'd hazard a wild guess it's not of use now.

Dan - ac6ao

Yes, the eLoran signal is backward compatible.  Older receivers ignore
the 9th pulse added in eLoran.

73,

David N1HAC

On 12/6/24 11:27 AM, Steve Sykes via time-nuts wrote:

Steve several answers. Your receiver will detect the signals if it can hear
them.
My experience with a LORAN C whip and preamp never has detected the signal.
The whip just picks up far too much local noise even though its 150' from
the house in the woods.
Here is the real catcher.
Most navigation devices depended on 3 loran stations. A master and 2
secondaries.
None of the stations is transmitting the master 10 pulse. They all appear
as secondaries and are sending 9 pulses.
A secondary was 8 pulses. A ninth was added that carries the data.
The austrons (Timing and frequency receivers) work because they only look
for 1 station. A Master or secondary.
I am using a 10' square loop and preamp tuned for 60 KHz and simply getting
away with it. Pretty good for 2400 miles.
The 4' loop I have just brought in. Its simply not behaving well. But I
expect to get it corrected and that will be the eLORAN antenna.
The loops are great because they null a lot of the noise out.
Paul
WB8TSL

On Fri, Dec 6, 2024 at 2:06 PM Steve Sykes via time-nuts <
time-nuts@lists.febo.com> wrote:

The original eLoran, called "euroFix" was developed in NL for the NELS chain.

It shifted two pulses in the original code one microsecond, but
always balanced, so one would move earlier and the other later, so
the average of the 3rd zero-crossings remained the same, but with
almost unmeasurable worse S/N.

I've attached a picture of it.  If not for euroFix, there would be
8 dots in a straight line, but the modulation causes them to
wander sideways.  The difference in S/N is the distance between the
extreme two points in the lower left corner.

(This was using Dave Mill's original ISA-board computerrized Loran-C
receiver.)

But thinking more about it:

Why do they still bother to keep compatibility at this point ?

I get that they are reusing the old transmitters, so the pulses are
a given, and it's limited how much you can change, for reasons
of spectrum compliance,

But for instance the sign-imbalance in code causes Loran-C to be
more sensitive to noise than it needs to be, why not fix that ?

With modern CPU based receivers, and nobody is ever going to build
anything but, only the first pulse needs to have a defined sign,
the rest can be put to work for modulation and spectrum management.

--
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phk@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.

Dan Rae via time-nuts writes:

Loran-A and -B were indeed LF, but unless the mentioned receiver is WWII
vintage, it is almost guaranteed to be a Loran-C receiver, which is at 100kHz.

eLoran is 1990'ies and later attempt to augment Loran-C with a
data-channel, to make it more competitive with GPS.

Loran-D was a 16 pulse "tactical Loran-C" proposed during the Vietnam
War, it was supposed to run at higher frequency than Loran-C to keep
X-mitter antenna size workable, but no specific frequency was ever
settled on.

--
Poul-Henning Kamp      | UNIX since Zilog Zeus 3.20
phk@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.

Hi

Your receiver is designed for navigation. It’s Loran-C (and not Loran-A) so it does run at 100 KHz.

The gotcha is that for navigation, the stations operated in “chains”. You had a master and a set of slaves.
In order to navigate, you locked on to the master and then looked at relative data from the slaves.

As eLoran is currently being operated, there is no “master”. They all appear to be operating as slaves.
Without a master your device has nothing to lock on to. Best bet. it will just sit there being very confused.

Bob

Hi Poul:

I thought just before LORAN-C was turned off they had atomic clocks at each station rather than have the slave station
timing determined by the chain master station.
That would allow using each transmitter, like a GPS receiver uses each satellite, independently of each other.  So, you
can get a position fix using two or more stations, even if they are from different chains.

--
Have Fun,

Brooke Clarke
https://www.PRC68.com
axioms:

1. The extent to which you can fix or improve something will be limited by how well you understand how it works.
2. Everybody, with no exceptions, holds false beliefs.

-------- Original Message --------

Brooke Clarke via time-nuts writes:

Warner is the best person to talk about that, because he was involved in the last
control system upgrade.  (My understanding is that the Cs's were steered to GPS.)

You could always do that, if your receiver was advanced enough.

The question was what your precision would be like.

My understanding is that GPS-steering the stations was also hoped to improve that aspect.

--
Poul-Henning Kamp      | UNIX since Zilog Zeus 3.20
phk@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.

I believe the stations all had the 3 Cesiums.
But that said (I am not a navi-guesser) two stations leave ambiguity in
position as I recall.
The third eliminates it. The reason for 3 Cesiums at many stations is that
the stations were dual rated. A station worked in two or more different
chains so might be a Master.
Here is the funny thing, URSA-NAV made a statement long ago that I
remember. You could locate position with 1 station.
Never made sense to me but what they were doing with eLORAN and higher
resolution perhaps does allow that.
I'll snip a bit of a log and attach it later today to share.
Paul

On Sat, Dec 7, 2024 at 1:53 AM Poul-Henning Kamp via time-nuts <
time-nuts@lists.febo.com> wrote: