[amsat-bb] Re: GPS Time observation

jmfranke jmfranke at cox.net
Thu Feb 2 12:44:11 PST 2012


The difference between GPS time and UTC is adjusted as necessary. The 
adjustments come in the form of leap seconds and are added when needed at 
the end of June or December. The difference between GPS time and UTC is 
currently 15 seconds. There will be a leap second added this coming June 30. 
What is being seen is the casual user GPS receiver software does not put a 
high priority on time display.

John  WA4WDL

--------------------------------------------------
From: "Jim Jerzycke" <kq6ea at verizon.net>
Sent: Thursday, February 02, 2012 3:18 PM
To: <amsat-bb at amsat.org>
Subject: [amsat-bb] Re: GPS Time observation

> I think this has something to do with "GPS Time" vs "Earth Time".
>
> IIRC, GPS time doesn't take into account the Leap Seconds that have been 
> added to Earth time since the first GPS satellites have been launched. I 
> think some of the newer receivers can compensate for this, but I'm not 
> sure.
>
> It's been about 14 years since I last worked in the GPS industry, and I'm 
> a bit rusty on all the new stuff!
>
> 73, Jim  KQ6EA
>
> On 02/02/2012 04:57 PM, George and Cheryl Abbott wrote:
>> I'm not sure about GPS,but I have noticed that the clock on our cable box 
>> is off by up to 4 seconds at times.Customer service was not aware or 
>> concerned when I let them know.
>>
>> -----Original Message----- From: Vince Fiscus, KB7ADL
>> Sent: Thursday, February 02, 2012 10:28 AM
>> To: amsat-bb at amsat.org
>> Subject: [amsat-bb] GPS Time observation
>>
>>
>> I have an old GPS unit, a Magellan explorist 210.  It's fairly accurate
>> determining position. After it has acquired about eight to ten satellites
>> the position error averages between 20 to 35 feet.   Now the question, 
>> the
>> other day I was looking at one of the information pages the unit can
>> display and on it, it gives the time in UTC. Just for fun I thought I 
>> would
>> see how close the time was to WWV.  I was surprised to see the unit was
>> between one to four seconds off over various tests compared to WWV.  IS
>> this typical of all GPS units or do some display the time of day more
>> accurately?
>>
>> KB7ADL
>>
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>
> _______________________________________________
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