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- Question-About-Garmin-Hot-Fix-Data
- 08-02-2010
   Re: Question About Garmin "Hot Fix Data"
| Harvey Gratt | 08-04-2010 |
  Re: Question About Garmin "Hot Fix Data"
| Greg Russell | 08-04-2010 |
  Re: Question About Garmin "Hot Fix Data"
| Gene E. Bloch | 08-05-2010 |
 Re: Question About Garmin "Hot Fix Data"
| Harvey Gratt | 08-05-2010 |
| Re: Question About Garmin "Hot Fix Data"
| Darren Dunham | 08-16-2010 |
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Gene E. Bloch wrote:
> On Wed, 04 Aug 2010 17:53:45 -0500, Sunshine wrote:
>> The only reference to Doppler that I've run across so far was in
>> regards to an obsolete system used in the mid-1950's to track the
>> Russian Sputnik satellite from Earth.
>> regards to an obsolete system used in the mid-1950's to track the
>> Russian Sputnik satellite from Earth.
> Here's a newer one.
> http://gauss.gge.unb.ca/papers.pdf/ionntm2004.serrano.pdf
> I don't have any idea whether it is used in my GPS device, of course.
> Also, it claims accuracy of speed measurements in the range of 1 cm/sec at
> 2 sigma.
> FYI, 1 m/sec is approximately 2.2 mph (the similarity to 2.2 kg/lb is pure
> coincidence).
I think that there is a distinction between commercial automotive GPS
> http://gauss.gge.unb.ca/papers.pdf/ionntm2004.serrano.pdf
> I don't have any idea whether it is used in my GPS device, of course.
> Also, it claims accuracy of speed measurements in the range of 1 cm/sec at
> 2 sigma.
> FYI, 1 m/sec is approximately 2.2 mph (the similarity to 2.2 kg/lb is pure
> coincidence).
products and military, commercial airline, etc useage. The latter
generally employ full-up GPS aided navigation solution utilizing a
reasonable quality IMU (3 gyros, 3 accelerometers). I believe that these
more sophisticated applications can make use of Doppler for the velocity
calculations in addition to the "normal" tracking functions
(code/Carrier signal(includes Doppler) ) - i.e., searching and
maintaining of satellite lock. However, these functions are best served
with the full-up nav. solution which utilizes more sophisticated
estimation algorithms (extended kalman filters).
My guess is that the less stressful (vehicle dynamics)automotive case
simply utilize a least squares and simple filtering algorithm to
determine vehicle position and speed from position only measurements.
On Thu, 05 Aug 2010 14:02:01 -0500, Harvey Gratt wrote:
> Gene E. Bloch wrote:
>> On Wed, 04 Aug 2010 17:53:45 -0500, Sunshine wrote:
>>> The only reference to Doppler that I've run across so far was in
>>> regards to an obsolete system used in the mid-1950's to track the
>>> Russian Sputnik satellite from Earth.
>>> regards to an obsolete system used in the mid-1950's to track the
>>> Russian Sputnik satellite from Earth.
>> Here's a newer one.
>> http://gauss.gge.unb.ca/papers.pdf/ionntm2004.serrano.pdf
>> I don't have any idea whether it is used in my GPS device, of course.
>> Also, it claims accuracy of speed measurements in the range of 1 cm/sec at
>> 2 sigma.
>> FYI, 1 m/sec is approximately 2.2 mph (the similarity to 2.2 kg/lb is pure
>> coincidence).
>> http://gauss.gge.unb.ca/papers.pdf/ionntm2004.serrano.pdf
>> I don't have any idea whether it is used in my GPS device, of course.
>> Also, it claims accuracy of speed measurements in the range of 1 cm/sec at
>> 2 sigma.
>> FYI, 1 m/sec is approximately 2.2 mph (the similarity to 2.2 kg/lb is pure
>> coincidence).
> I think that there is a distinction between commercial automotive GPS
> products and military, commercial airline, etc useage. The latter
> generally employ full-up GPS aided navigation solution utilizing a
> reasonable quality IMU (3 gyros, 3 accelerometers). I believe that these
> more sophisticated applications can make use of Doppler for the velocity
> calculations in addition to the "normal" tracking functions
> (code/Carrier signal(includes Doppler) ) - i.e., searching and
> maintaining of satellite lock. However, these functions are best served
> with the full-up nav. solution which utilizes more sophisticated
> estimation algorithms (extended kalman filters).
>
> My guess is that the less stressful (vehicle dynamics)automotive case
> simply utilize a least squares and simple filtering algorithm to
> determine vehicle position and speed from position only measurements.
> products and military, commercial airline, etc useage. The latter
> generally employ full-up GPS aided navigation solution utilizing a
> reasonable quality IMU (3 gyros, 3 accelerometers). I believe that these
> more sophisticated applications can make use of Doppler for the velocity
> calculations in addition to the "normal" tracking functions
> (code/Carrier signal(includes Doppler) ) - i.e., searching and
> maintaining of satellite lock. However, these functions are best served
> with the full-up nav. solution which utilizes more sophisticated
> estimation algorithms (extended kalman filters).
>
> My guess is that the less stressful (vehicle dynamics)automotive case
> simply utilize a least squares and simple filtering algorithm to
> determine vehicle position and speed from position only measurements.
I was actually addressing Sunshine's remark that "The only reference to
Doppler that I've run across so far...". That is in fact exactly why I
quoted only that part of his post.
IMO, his citation was way more OT than mine :-)
--
Gene E. Bloch (Stumbling Bloch)
On Thu, 5 Aug 2010 15:34:16 -0700, "Gene E. Bloch"
>On Thu, 05 Aug 2010 14:02:01 -0500, Harvey Gratt wrote:
>> Gene E. Bloch wrote:
>>> On Wed, 04 Aug 2010 17:53:45 -0500, Sunshine wrote:
>>>> The only reference to Doppler that I've run across so far was in
>>>> regards to an obsolete system used in the mid-1950's to track the
>>>> Russian Sputnik satellite from Earth.
>>> Here's a newer one.
>>> http://gauss.gge.unb.ca/papers.pdf/ionntm2004.serrano.pdf
>>> I don't have any idea whether it is used in my GPS device, of course.
>>> Also, it claims accuracy of speed measurements in the range of 1 cm/sec at
>>> 2 sigma.
>>> FYI, 1 m/sec is approximately 2.2 mph (the similarity to 2.2 kg/lb is pure
>>> coincidence).
>>>> The only reference to Doppler that I've run across so far was in
>>>> regards to an obsolete system used in the mid-1950's to track the
>>>> Russian Sputnik satellite from Earth.
>>> Here's a newer one.
>>> http://gauss.gge.unb.ca/papers.pdf/ionntm2004.serrano.pdf
>>> I don't have any idea whether it is used in my GPS device, of course.
>>> Also, it claims accuracy of speed measurements in the range of 1 cm/sec at
>>> 2 sigma.
>>> FYI, 1 m/sec is approximately 2.2 mph (the similarity to 2.2 kg/lb is pure
>>> coincidence).
>> I think that there is a distinction between commercial automotive GPS
>> products and military, commercial airline, etc useage. The latter
>> generally employ full-up GPS aided navigation solution utilizing a
>> reasonable quality IMU (3 gyros, 3 accelerometers). I believe that these
>> more sophisticated applications can make use of Doppler for the velocity
>> calculations in addition to the "normal" tracking functions
>> (code/Carrier signal(includes Doppler) ) - i.e., searching and
>> maintaining of satellite lock. However, these functions are best served
>> with the full-up nav. solution which utilizes more sophisticated
>> estimation algorithms (extended kalman filters).
>>
>> My guess is that the less stressful (vehicle dynamics)automotive case
>> simply utilize a least squares and simple filtering algorithm to
>> determine vehicle position and speed from position only measurements.
>> products and military, commercial airline, etc useage. The latter
>> generally employ full-up GPS aided navigation solution utilizing a
>> reasonable quality IMU (3 gyros, 3 accelerometers). I believe that these
>> more sophisticated applications can make use of Doppler for the velocity
>> calculations in addition to the "normal" tracking functions
>> (code/Carrier signal(includes Doppler) ) - i.e., searching and
>> maintaining of satellite lock. However, these functions are best served
>> with the full-up nav. solution which utilizes more sophisticated
>> estimation algorithms (extended kalman filters).
>>
>> My guess is that the less stressful (vehicle dynamics)automotive case
>> simply utilize a least squares and simple filtering algorithm to
>> determine vehicle position and speed from position only measurements.
>I was actually addressing Sunshine's remark that "The only reference to
>Doppler that I've run across so far...". That is in fact exactly why I
>quoted only that part of his post.
>IMO, his citation was way more OT than mine :-)
>Doppler that I've run across so far...". That is in fact exactly why I
>quoted only that part of his post.
>IMO, his citation was way more OT than mine :-)
Thanks to both of you for your inputs, but huh? :-)
Harvey Gratt wrote:
> My guess is that the less stressful (vehicle dynamics)automotive case
> simply utilize a least squares and simple filtering algorithm to
> determine vehicle position and speed from position only measurements.
> simply utilize a least squares and simple filtering algorithm to
> determine vehicle position and speed from position only measurements.
Garmin has had doppler calculations in its algorythms for more than a
decade. It wouldn't make sense to produce a separate version of its core
GPS engine for different models.
A car system may have an accelerometer in it, so perhaps they had to
tweak the engine to factor this because in urban canyons, you may lose
sufficient GPS fix at which point the accelerometre provides information
that allows the GPS to guess your speed/direction and hence position.
But once it has a GPS fix, it would use the standard engine which
includes doppler.
JF Mezei wrote:
> Harvey Gratt wrote:
>> My guess is that the less stressful (vehicle dynamics)automotive case
>> simply utilize a least squares and simple filtering algorithm to
>> determine vehicle position and speed from position only measurements.
>> simply utilize a least squares and simple filtering algorithm to
>> determine vehicle position and speed from position only measurements.
> Garmin has had doppler calculations in its algorythms for more than a
> decade. It wouldn't make sense to produce a separate version of its core
> GPS engine for different models.
> A car system may have an accelerometer in it, so perhaps they had to
> tweak the engine to factor this because in urban canyons, you may lose
> sufficient GPS fix at which point the accelerometre provides information
> that allows the GPS to guess your speed/direction and hence position.
> But once it has a GPS fix, it would use the standard engine which
> includes doppler.
> decade. It wouldn't make sense to produce a separate version of its core
> GPS engine for different models.
> A car system may have an accelerometer in it, so perhaps they had to
> tweak the engine to factor this because in urban canyons, you may lose
> sufficient GPS fix at which point the accelerometre provides information
> that allows the GPS to guess your speed/direction and hence position.
> But once it has a GPS fix, it would use the standard engine which
> includes doppler.
The question is whether the "Doppler calculations" are used in aiding
the position measurements or is it used only for the satellite search
and tracking functions. Maybe someone can ask Garmin (or Tom-Tom, etc).
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