Like I mentioned in a precedent message
(answering Magnus) I'm seeing some temp
effects on my GPS module, see this message:
http://www.febo.com/pipermail/time-nuts/2012-December/073310.html
In this graph there are the FE5680 voltages
and temperatures, and the temperature sensed
on the PCB near th
Hi
The GPS does an estimate against the local crystal frequency. It generates the
PPS off of it's estimate. The less often it updates the estimate the more odd
things you see as the crystal drifts.
Of course, the crystal can have trouble all it's own. If the crystal has a
rapid rate of freque
Yes, we have yet another proof that the oscillator in (cheap?) GPS
receivers can be a source of troubles... shall we start to design Ovenized
GPS Receivers (OGPR) too? Or ovens for GPS receivers.
On Fri, Dec 28, 2012 at 11:35 PM, Bob Camp wrote:
> Hi
>
> The GPS does an estimate against the loca
On 28/12/12 23:35, Bob Camp wrote:
Hi
The GPS does an estimate against the local crystal frequency. It generates the
PPS off of it's estimate. The less often it updates the estimate the more odd
things you see as the crystal drifts.
A typical GPS off the shelf solves the position solution ev
Hi
…. except… A navigation GPS doesn't care much about the time solution. Updating
the location is a much higher priority than updating the time. The typical
"solution" is to let the time estimate coast for a while and update it much
less often than the location.
Bob
On Dec 28, 2012, at 7:18
Bob,
That is simply not accurate - if the solution rate is 1/second, then all
parameters are solved in that time frame. There are 4 indpendent variables
and minimal processing power is required to solve all four equations.
Although I am not very familiar with commercial receivers, that is what
happ
Hi
Indeed the solution is done once per second or so. In the solution they weight
the significance of position versus time. If you accept a larger time error in
the solution, you can come up with a smaller location error. Is that a bit of
mathematical sleight of hand? - of course it is. Can yo
Fabio,
Happens in all the GPS receivers we have tested here. The difference between
receivers is how fast they can recognize this error and how fast they can
re-aquire once they shut off the 1PPS output due to tcxo instability.
There was a recent thread here about effects of adding a fan to a Z
On 12/28/12 9:14 PM, Michael Perrett wrote:
Bob,
That is simply not accurate - if the solution rate is 1/second, then all
parameters are solved in that time frame. There are 4 indpendent variables
and minimal processing power is required to solve all four equations.
Although I am not very familia
On Sat, 29 Dec 2012 12:18:56 -0800, Said Jackson
wrote:
>Fabio,
>
>Happens in all the GPS receivers we have tested here. The difference between
>receivers is how fast they can recognize this error and how fast they can
>re-aquire once they shut off the 1PPS output due to tcxo instability.
>
>Th
Hi,
> On 12/28/12 9:14 PM, Michael Perrett wrote:
>> Bob,
>> That is simply not accurate - if the solution rate is 1/second, then all
>> parameters are solved in that time frame. There are 4 indpendent
>> variables
>> and minimal processing power is required to solve all four equations.
>> Althoug
Hi Bob,
I am curious about the sacrifice time and get better position. I have not
seen any discussions about that in manuals, books or papers. Do you have
reference?
What would be the difference between timing and navigation versions of
cheap commercial receivers?
1) Timing receivers are often s
Hi Björn,
On 29/12/12 23:42, b...@lysator.liu.se wrote:
Hi Bob,
I am curious about the sacrifice time and get better position. I have not
seen any discussions about that in manuals, books or papers. Do you have
reference?
What would be the difference between timing and navigation versions of
c
Hi
The gotcha is that often the "navigation" and "timing" receivers are identical
in terms of hardware. There is no upgraded hardware in the timing device.
When you put a receiver into position hold, you are telling it "I don't care
about the location solution". It reduces the weight of that pa
On 12/29/12 6:34 PM, Bob Camp wrote:
Hi
The gotcha is that often the "navigation" and "timing" receivers are identical
in terms of hardware. There is no upgraded hardware in the timing device.
When you put a receiver into position hold, you are telling it "I don't care about
the location solu
Hi
The interesting thing is that you sometimes can get a position hold receiver to
report it's estimated location…. Not so much on current product, but on some of
the old stuff.
Bob
On Dec 29, 2012, at 9:51 PM, Jim Lux wrote:
> On 12/29/12 6:34 PM, Bob Camp wrote:
>> Hi
>>
>> The gotcha is
li...@rtty.us said:
> When you put a receiver into position hold, you are telling it "I don't care
> about the location solution". It reduces the weight of that part of the
> filter. Yes, that's only one way to look at it and there are other ways to
> look at it.
I thought it was better than tha
Bob,
Our Position-Hold enabled units (Fury, Mini-JLT, various CSAC units, and
GPS-405 support accurate position reporting in ECEF, NMEA, and various other
standards.
Users can select how many fixes are averaged for the position report.
They can also be instantly switched back and forth between
Hi
The more interesting event is when you re-flash a +/- 1 us navigation receiver
and it instantly becomes a < +/- 100 ns timing receiver *without* position hold
engaged.
Bob
On Dec 29, 2012, at 10:20 PM, Said Jackson wrote:
> Bob,
>
> Our Position-Hold enabled units (Fury, Mini-JLT, vario
Hi Magnus,
>> 2) Timing versions might get an upgraded oscillator. Maybe a TCXO
>> instead
>> of a standard XO.
>
> Don't think so. The noise and systematic stability is as important for
> positional as for timing versions, the timing version can benefit of the
> fixed position.
Look at the uBlox
Moin,.
On Sat, 29 Dec 2012 19:20:16 -0800
Said Jackson wrote:
> We recently did a test by putting an antenna in a side window in
> the office that had maybe 10% view of the sky, then let the unit
> run in mobile mode while doing the auto survey. After two days,
> we switched it into position ho
On 30/12/12 10:06, b...@lysator.liu.se wrote:
Hi Magnus,
2) Timing versions might get an upgraded oscillator. Maybe a TCXO
instead
of a standard XO.
Don't think so. The noise and systematic stability is as important for
positional as for timing versions, the timing version can benefit of the
and maybe that reflashing a 1uS nav receiver to have a 100nS timing
receiver is related only to firmware improvements. Accurate timing is
mandatory for accurate position/navigation. The CW12 timing receiver has a
position hold mode that can't be turned off but always gives the computed
position.
O
On 30/12/12 13:56, Azelio Boriani wrote:
and maybe that reflashing a 1uS nav receiver to have a 100nS timing
receiver is related only to firmware improvements.
Most probably. A possibility would be to have a bad running state, but
this should not be the case and then a firmware upgrade should
Hi
When asked about the difference, that's not what the people who wrote the code
had to say about it….
Bob
On Dec 30, 2012, at 7:56 AM, Azelio Boriani wrote:
> and maybe that reflashing a 1uS nav receiver to have a 100nS timing
> receiver is related only to firmware improvements. Accurate ti
An update regarding the GPS module,
simply shielding it from air currents
improved the things:
http://www.flickr.com/photos/14336723@N08/8327229820/
At 48000s I swapped references, hence
the change in slope.
I think the poor receiver module
(Azelio, 20€, I think it can be
considered cheap :) is n
Hi
If you go back far enough in the NIST papers done for the Frequency Control
Symposium, you can find a number of them on GPS receivers. One that got a
pretty full go through was the (now golden) Motorola timing receiver. They
found a number of issues with it. The receiver did get better as th
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