Empathy List Archives

BC

Bob Camp

Thu, Mar 8, 2012 5:02 PM

Hi

If they are backing up GPS for telcom, then CDMA timing is the most likely
target. That gets them to 10 us max and < 1 us typical. Of course somebody
would have to buy the gear to actually use it to do any good... (yes I
could and have gone on and on about that topic).

Bob

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Poul-Henning Kamp
Sent: Thursday, March 08, 2012 2:58 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Loran in the US

Has anybody asked them how good time&freq they're trying to deliver ?

I would assume that they are aiming for a backup for GPS in
telecom-GPSDO context.

If so, frequency stability is priority number one and time is
probably just "better than 100msec" or so

--
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.

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Hi If they are backing up GPS for telcom, then CDMA timing is the most likely target. That gets them to 10 us max and < 1 us typical. Of course somebody would have to buy the gear to actually *use* it to do any good... (yes I could and have gone on and on about that topic). Bob -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Poul-Henning Kamp Sent: Thursday, March 08, 2012 2:58 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Loran in the US Has anybody asked them how good time&freq they're trying to deliver ? I would assume that they are aiming for a backup for GPS in telecom-GPSDO context. If so, frequency stability is priority number one and time is probably just "better than 100msec" or so -- 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. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.

PK

Poul-Henning Kamp

Thu, Mar 8, 2012 10:09 PM

In message D20D95B53D5C40F5ACA05DF98FDB9F08@vectron.com, "Bob Camp" writes:

If they are backing up GPS for telcom, then CDMA timing is the most likely
target. That gets them to 10 us max and < 1 us typical. Of course somebody
would have to buy the gear to actually use it to do any good... (yes I
could and have gone on and on about that topic).

Well, they do actually regulate telecoms, so they may simply be told that
it will be a condition for their licenses.

That happened with respect to power backups for cellular towers
after Katrina showed the inadequacy of 3 hours lead-acid backup.

--
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.

In message <D20D95B53D5C40F5ACA05DF98FDB9F08@vectron.com>, "Bob Camp" writes: >If they are backing up GPS for telcom, then CDMA timing is the most likely >target. That gets them to 10 us max and < 1 us typical. Of course somebody >would have to buy the gear to actually *use* it to do any good... (yes I >could and have gone on and on about that topic). Well, they do actually regulate telecoms, so they may simply be told that it will be a condition for their licenses. That happened with respect to power backups for cellular towers after Katrina showed the inadequacy of 3 hours lead-acid backup. -- 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.

BC

Bob Camp

Thu, Mar 8, 2012 10:21 PM

Hi

Should be very interesting to watch if they try to legislate something
like that...

Bob

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Poul-Henning Kamp
Sent: Thursday, March 08, 2012 5:10 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Loran in the US

In message D20D95B53D5C40F5ACA05DF98FDB9F08@vectron.com, "Bob Camp"
writes:

If they are backing up GPS for telcom, then CDMA timing is the most likely
target. That gets them to 10 us max and < 1 us typical. Of course somebody
would have to buy the gear to actually use it to do any good... (yes I
could and have gone on and on about that topic).

Well, they do actually regulate telecoms, so they may simply be told that
it will be a condition for their licenses.

That happened with respect to power backups for cellular towers
after Katrina showed the inadequacy of 3 hours lead-acid backup.

--
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.

time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Hi Should be *very* interesting to watch if they try to legislate something like that... Bob -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Poul-Henning Kamp Sent: Thursday, March 08, 2012 5:10 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Loran in the US In message <D20D95B53D5C40F5ACA05DF98FDB9F08@vectron.com>, "Bob Camp" writes: >If they are backing up GPS for telcom, then CDMA timing is the most likely >target. That gets them to 10 us max and < 1 us typical. Of course somebody >would have to buy the gear to actually *use* it to do any good... (yes I >could and have gone on and on about that topic). Well, they do actually regulate telecoms, so they may simply be told that it will be a condition for their licenses. That happened with respect to power backups for cellular towers after Katrina showed the inadequacy of 3 hours lead-acid backup. -- 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. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.

MD

Magnus Danielson

Thu, Mar 8, 2012 10:27 PM

On 03/08/2012 11:21 PM, Bob Camp wrote:

Hi

Should be very interesting to watch if they try to legislate something
like that...

Indeed.

There are different telecom needs. CDMA isn't everything.

SDH/SONET goes under G.811, meaning within 1E-11 in frequency.
GSM should be within +/- 50 ppb, but long-term should be like SDH/SONET.
etc. etc.

Cheers,
Magnus

Bob

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Poul-Henning Kamp
Sent: Thursday, March 08, 2012 5:10 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Loran in the US

In messageD20D95B53D5C40F5ACA05DF98FDB9F08@vectron.com, "Bob Camp"
writes:

If they are backing up GPS for telcom, then CDMA timing is the most likely
target. That gets them to 10 us max and< 1 us typical. Of course somebody
would have to buy the gear to actually use it to do any good... (yes I
could and have gone on and on about that topic).

Well, they do actually regulate telecoms, so they may simply be told that
it will be a condition for their licenses.

That happened with respect to power backups for cellular towers
after Katrina showed the inadequacy of 3 hours lead-acid backup.

On 03/08/2012 11:21 PM, Bob Camp wrote: > Hi > > Should be *very* interesting to watch if they try to legislate something > like that... Indeed. There are different telecom needs. CDMA isn't everything. SDH/SONET goes under G.811, meaning within 1E-11 in frequency. GSM should be within +/- 50 ppb, but long-term should be like SDH/SONET. etc. etc. Cheers, Magnus > Bob > > -----Original Message----- > From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On > Behalf Of Poul-Henning Kamp > Sent: Thursday, March 08, 2012 5:10 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Loran in the US > > In message<D20D95B53D5C40F5ACA05DF98FDB9F08@vectron.com>, "Bob Camp" > writes: > >> If they are backing up GPS for telcom, then CDMA timing is the most likely >> target. That gets them to 10 us max and< 1 us typical. Of course somebody >> would have to buy the gear to actually *use* it to do any good... (yes I >> could and have gone on and on about that topic). > > Well, they do actually regulate telecoms, so they may simply be told that > it will be a condition for their licenses. > > That happened with respect to power backups for cellular towers > after Katrina showed the inadequacy of 3 hours lead-acid backup. >

BC

Bob Camp

Thu, Mar 8, 2012 11:16 PM

Hi

SDH/SONET generally is line timed rather than GPS locked. It's ultimate authority is the Stratum 1 above it... With CDMA framing, GPS time is actually the ultimate authority. With GSM (as with the CDMA carrier frequency) a free running oscillator is generally "good enough".

Bob

On Mar 8, 2012, at 5:27 PM, Magnus Danielson magnus@rubidium.dyndns.org wrote:

On 03/08/2012 11:21 PM, Bob Camp wrote:

Hi

Should be very interesting to watch if they try to legislate something
like that...

Indeed.

There are different telecom needs. CDMA isn't everything.

SDH/SONET goes under G.811, meaning within 1E-11 in frequency.
GSM should be within +/- 50 ppb, but long-term should be like SDH/SONET.
etc. etc.

Cheers,
Magnus

Bob

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Poul-Henning Kamp
Sent: Thursday, March 08, 2012 5:10 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Loran in the US

In messageD20D95B53D5C40F5ACA05DF98FDB9F08@vectron.com, "Bob Camp"
writes:

If they are backing up GPS for telcom, then CDMA timing is the most likely
target. That gets them to 10 us max and< 1 us typical. Of course somebody
would have to buy the gear to actually use it to do any good... (yes I
could and have gone on and on about that topic).

Well, they do actually regulate telecoms, so they may simply be told that
it will be a condition for their licenses.

That happened with respect to power backups for cellular towers
after Katrina showed the inadequacy of 3 hours lead-acid backup.

time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Hi SDH/SONET generally is line timed rather than GPS locked. It's ultimate authority is the Stratum 1 above it... With CDMA framing, GPS time is actually the ultimate authority. With GSM (as with the CDMA carrier frequency) a free running oscillator is generally "good enough". Bob On Mar 8, 2012, at 5:27 PM, Magnus Danielson <magnus@rubidium.dyndns.org> wrote: > On 03/08/2012 11:21 PM, Bob Camp wrote: >> Hi >> >> Should be *very* interesting to watch if they try to legislate something >> like that... > > Indeed. > > There are different telecom needs. CDMA isn't everything. > > SDH/SONET goes under G.811, meaning within 1E-11 in frequency. > GSM should be within +/- 50 ppb, but long-term should be like SDH/SONET. > etc. etc. > > Cheers, > Magnus > >> Bob >> >> -----Original Message----- >> From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On >> Behalf Of Poul-Henning Kamp >> Sent: Thursday, March 08, 2012 5:10 PM >> To: Discussion of precise time and frequency measurement >> Subject: Re: [time-nuts] Loran in the US >> >> In message<D20D95B53D5C40F5ACA05DF98FDB9F08@vectron.com>, "Bob Camp" >> writes: >> >>> If they are backing up GPS for telcom, then CDMA timing is the most likely >>> target. That gets them to 10 us max and< 1 us typical. Of course somebody >>> would have to buy the gear to actually *use* it to do any good... (yes I >>> could and have gone on and on about that topic). >> >> Well, they do actually regulate telecoms, so they may simply be told that >> it will be a condition for their licenses. >> >> That happened with respect to power backups for cellular towers >> after Katrina showed the inadequacy of 3 hours lead-acid backup. >> > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there.

MD

Magnus Danielson

Thu, Mar 8, 2012 11:36 PM

On 03/09/2012 12:16 AM, Bob Camp wrote:

Hi

SDH/SONET generally is line timed rather than GPS locked. It's ultimate authority is the Stratum 1 above it...

Yes, but GPS/LORAN can be used to build holdover synchronisation, and
verify the local cesiums.

Stratum 1 is the ANSI T1.101 name, also known as PRC in SDH, which is
ITU-T G.811.

Cheers,
Magnus

On 03/09/2012 12:16 AM, Bob Camp wrote: > Hi > > SDH/SONET generally is line timed rather than GPS locked. It's ultimate authority is the Stratum 1 above it... Yes, but GPS/LORAN can be used to build holdover synchronisation, and verify the local cesiums. Stratum 1 is the ANSI T1.101 name, also known as PRC in SDH, which is ITU-T G.811. Cheers, Magnus

BC

Bob Camp

Fri, Mar 9, 2012 1:45 AM

Hi

Indeed, you can use GPS for a lot of things. You pretty much must use it for CDMA.

Bob

On Mar 8, 2012, at 6:36 PM, Magnus Danielson magnus@rubidium.dyndns.org wrote:

On 03/09/2012 12:16 AM, Bob Camp wrote:

Hi

SDH/SONET generally is line timed rather than GPS locked. It's ultimate authority is the Stratum 1 above it...

Yes, but GPS/LORAN can be used to build holdover synchronisation, and verify the local cesiums.

Stratum 1 is the ANSI T1.101 name, also known as PRC in SDH, which is ITU-T G.811.

Cheers,
Magnus

time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Hi Indeed, you *can* use GPS for a lot of things. You pretty much *must* use it for CDMA. Bob On Mar 8, 2012, at 6:36 PM, Magnus Danielson <magnus@rubidium.dyndns.org> wrote: > On 03/09/2012 12:16 AM, Bob Camp wrote: >> Hi >> >> SDH/SONET generally is line timed rather than GPS locked. It's ultimate authority is the Stratum 1 above it... > > Yes, but GPS/LORAN can be used to build holdover synchronisation, and verify the local cesiums. > > Stratum 1 is the ANSI T1.101 name, also known as PRC in SDH, which is ITU-T G.811. > > Cheers, > Magnus > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there.

DF

Dennis Ferguson

Fri, Mar 9, 2012 2:17 AM

On 8 Mar, 2012, at 02:58 , Poul-Henning Kamp wrote:

Has anybody asked them how good time&freq they're trying to deliver ?

I would assume that they are aiming for a backup for GPS in
telecom-GPSDO context.

If so, frequency stability is priority number one and time is
probably just "better than 100msec" or so

I could swear I saw something that said "50 ns", though I can
no longer find it and that sounds like science fiction. I note,
though, that the Federal Register publication for the project,
here:

http://www.gpo.gov/fdsys/pkg/FR-2012-01-11/html/2012-307.htm

indicates they aren't just looking at Loran by itself. The
MF dGPS bands and 500 kHz are also included in whatever they
are doing.

Dennis Ferguson

On 8 Mar, 2012, at 02:58 , Poul-Henning Kamp wrote: > Has anybody asked them how good time&freq they're trying to deliver ? > > I would assume that they are aiming for a backup for GPS in > telecom-GPSDO context. > > If so, frequency stability is priority number one and time is > probably just "better than 100msec" or so I could swear I saw something that said "50 ns", though I can no longer find it and that sounds like science fiction. I note, though, that the Federal Register publication for the project, here: http://www.gpo.gov/fdsys/pkg/FR-2012-01-11/html/2012-307.htm indicates they aren't just looking at Loran by itself. The MF dGPS bands and 500 kHz are also included in whatever they are doing. Dennis Ferguson

PK

Poul-Henning Kamp

Fri, Mar 9, 2012 8:16 AM

In message 9D1DABC0-AE63-4FB5-AD7D-D8C42F9FDE06@gmail.com, Dennis Ferguson wr
ites:

If so, frequency stability is priority number one and time is
probably just "better than 100msec" or so

I could swear I saw something that said "50 ns", though I can

You can almost do that with loran, if you know your l/l coords.

indicates they aren't just looking at Loran by itself. The
MF dGPS bands and 500 kHz are also included in whatever they
are doing.

Which indicates to me that they are pretty damn serious, and not
just catering to some recently discovered VIP Loran-C users.

I'd be very surprised if LightSquared nuking GPS reliability doesn't
have something to do with this.

--
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.

In message <9D1DABC0-AE63-4FB5-AD7D-D8C42F9FDE06@gmail.com>, Dennis Ferguson wr ites: >> If so, frequency stability is priority number one and time is >> probably just "better than 100msec" or so > >I could swear I saw something that said "50 ns", though I can You can _almost_ do that with loran, if you know your l/l coords. >indicates they aren't just looking at Loran by itself. The >MF dGPS bands and 500 kHz are also included in whatever they >are doing. Which indicates to me that they are pretty damn serious, and not just catering to some recently discovered VIP Loran-C users. I'd be very surprised if LightSquared nuking GPS reliability doesn't have something to do with this. -- 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.

BC

Bob Camp

Fri, Mar 9, 2012 5:20 PM

Hi

A lot depends on weather it's 50 ns right out of the spout (1 second samples
or what ever) or if it's a couple day average. There are a number of odd
things that happen with the sunrise and sunset.

Bob

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Poul-Henning Kamp
Sent: Friday, March 09, 2012 3:16 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Loran in the US

In message 9D1DABC0-AE63-4FB5-AD7D-D8C42F9FDE06@gmail.com, Dennis Ferguson
wr
ites:

If so, frequency stability is priority number one and time is
probably just "better than 100msec" or so

I could swear I saw something that said "50 ns", though I can

You can almost do that with loran, if you know your l/l coords.

indicates they aren't just looking at Loran by itself. The
MF dGPS bands and 500 kHz are also included in whatever they
are doing.

Which indicates to me that they are pretty damn serious, and not
just catering to some recently discovered VIP Loran-C users.

I'd be very surprised if LightSquared nuking GPS reliability doesn't
have something to do with this.

--
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.

time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Hi A lot depends on weather it's 50 ns right out of the spout (1 second samples or what ever) or if it's a couple day average. There are a number of odd things that happen with the sunrise and sunset. Bob -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Poul-Henning Kamp Sent: Friday, March 09, 2012 3:16 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Loran in the US In message <9D1DABC0-AE63-4FB5-AD7D-D8C42F9FDE06@gmail.com>, Dennis Ferguson wr ites: >> If so, frequency stability is priority number one and time is >> probably just "better than 100msec" or so > >I could swear I saw something that said "50 ns", though I can You can _almost_ do that with loran, if you know your l/l coords. >indicates they aren't just looking at Loran by itself. The >MF dGPS bands and 500 kHz are also included in whatever they >are doing. Which indicates to me that they are pretty damn serious, and not just catering to some recently discovered VIP Loran-C users. I'd be very surprised if LightSquared nuking GPS reliability doesn't have something to do with this. -- 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. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.

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Questions about Austron 5000 Loran C receiver