GPS Selective Availability. Is it On or Off?
My understanding is that Selective Availability was turned off. Is that True?
I Have an AUTEC Frequency Standard w/Rubidium Oscilator which is Disciplined by a GPS Receiver.
I notice during initial Disciplining that once every 75 seconds (exactly 75 Seconds) it get two consecutive readings that are way out of spec. Thus I wonder whether this might be selective availability at work.
Thanks
Don Mimlitch
donmeis@yahoo.com
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From: Don Mimlitch donmeis@yahoo.com
Subject: [time-nuts] GPS Selective Availability. Is it On or Off?
Date: Sun, 12 Mar 2006 09:23:36 -0800 (PST)
Message-ID: 20060312172336.82486.qmail@web33609.mail.mud.yahoo.com
My understanding is that Selective Availability was turned off. Is that True?
Yes. The Anti-Spoofing (AS) is however still enabled.
I Have an AUTEC Frequency Standard w/Rubidium Oscilator which is Disciplined by a GPS Receiver.
I notice during initial Disciplining that once every 75 seconds (exactly 75 Seconds) it get two consecutive readings that are way out of spec. Thus I wonder whether this might be selective availability at work.
I would look for other sources, probably much more local than the GPS setup.
Cheers,
Magnus
SA was turned off to allow the troops in Desert Storm to use
civilian GPS units (there was a critical shortage of military
P-band units)
It has never been turned on since.
-Chuck Harris
Don Mimlitch wrote:
My understanding is that Selective Availability was turned off. Is that True?
I Have an AUTEC Frequency Standard w/Rubidium Oscilator which is Disciplined by a GPS Receiver.
I notice during initial Disciplining that once every 75 seconds (exactly 75 Seconds) it get two consecutive readings
that are way out of spec. Thus I wonder whether this might be selective availability at work.
Thanks Don Mimlitch donmeis@yahoo.com
--------------------------------- Relax. Yahoo! Mail virus scanning helps detect nasty viruses!
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On Sun, 12 Mar 2006 12:36:12 -0500, Chuck Harris cfharris@erols.com
wrote:
SA was turned off to allow the troops in Desert Storm to use
civilian GPS units (there was a critical shortage of military
P-band units)
It has never been turned on since.
-Chuck Harris
Where did you get that notion? Desert Stom was 1991, wasn't it? What
happened in 2000, like this web page mentions?
http://www.cycc.org.uk/news/gpssa.htm
From: Rex rexa@sonic.net
Subject: Re: [time-nuts] GPS Selective Availability. Is it On or Off?
Date: Sun, 12 Mar 2006 09:58:25 -0800
Message-ID: 21o812lqml7dl24s3ijbnf2kcj1tkh480o@4ax.com
On Sun, 12 Mar 2006 12:36:12 -0500, Chuck Harris cfharris@erols.com
wrote:
SA was turned off to allow the troops in Desert Storm to use
civilian GPS units (there was a critical shortage of military
P-band units)
It has never been turned on since.
-Chuck Harris
Where did you get that notion? Desert Stom was 1991, wasn't it? What
happened in 2000, like this web page mentions?
http://www.cycc.org.uk/news/gpssa.htm
The SA was enabled again after Desert Storm, and it was not until the
presidential order that it was turned off again for a longer period of time.
See this page if you don't beleive me:
http://www.leapsecond.com/pages/saoff/
Cheers,
Magnus
SA was turned off in May 2000, and has stayed off since. The US Mil have
other ways of denying access to C/A on a local basis, rather than the global
degradation that S/A gave. The main reason for this is that US MIL have
mandated that all future procurement of GPS will be using SAASM Direct P/Y
hardware. This equipment has enhanced black key security features to the
existing P/Y hardware, plus the ability to acquire without the need for C/A
(C/A was designed originally as purely the coarse clock to enable P code).
Now, in times of conflict, all they need do is deny C/A in that area. The
new hardware can run without C/A, come up cold without C/A, but the enemy
and anyone in that geographic area is denied service.
This info is in the public domain. FEI-Zyfer (formerly Odetics)
www.fei-zyfer.com whom I used to work for manufacture SAASM GPS timing
products.
Rob K
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Magnus Danielson
Sent: 12 March 2006 18:58
To: time-nuts@febo.com; rexa@sonic.net
Subject: Re: [time-nuts] GPS Selective Availability. Is it On or Off?
From: Rex rexa@sonic.net
Subject: Re: [time-nuts] GPS Selective Availability. Is it On or Off?
Date: Sun, 12 Mar 2006 09:58:25 -0800
Message-ID: 21o812lqml7dl24s3ijbnf2kcj1tkh480o@4ax.com
On Sun, 12 Mar 2006 12:36:12 -0500, Chuck Harris cfharris@erols.com
wrote:
SA was turned off to allow the troops in Desert Storm to use civilian
GPS units (there was a critical shortage of military P-band units)
It has never been turned on since.
-Chuck Harris
Where did you get that notion? Desert Stom was 1991, wasn't it? What
happened in 2000, like this web page mentions?
http://www.cycc.org.uk/news/gpssa.htm
The SA was enabled again after Desert Storm, and it was not until the
presidential order that it was turned off again for a longer period of time.
See this page if you don't beleive me:
http://www.leapsecond.com/pages/saoff/
Cheers,
Magnus
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In message: 44145C0C.10100@erols.com
Chuck Harris cfharris@erols.com writes:
: SA was turned off to allow the troops in Desert Storm to use
: civilian GPS units (there was a critical shortage of military
: P-band units)
:
: It has never been turned on since.
Desert Storm was 1991. SA was turned off in 2000 upon a Presidential
directive from Clinton.
Warner
Rex wrote:
On Sun, 12 Mar 2006 12:36:12 -0500, Chuck Harris cfharris@erols.com
wrote:
SA was turned off to allow the troops in Desert Storm to use
civilian GPS units (there was a critical shortage of military
P-band units)
It has never been turned on since.
-Chuck Harris
Where did you get that notion? Desert Stom was 1991, wasn't it? What
happened in 2000, like this web page mentions?
http://www.cycc.org.uk/news/gpssa.htm
I got the notion that it was turned off during Desert Storm,
by virtue of being involved in the e-warfare effort that lead
up to, and followed the event.
I haven't been paying much attention since. I knew that they
had intended to turn SA back on after production of the p-code
units was up to speed, but I hadn't heard whether or not they
did.
-Chuck Harris