NMEA read out for altitude
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Posts: 46,084
Can any one tel me if it is possible to read the altimeter data from the
NMEA output of a Garmin 12 XL GPS. I know the data is subject to some in
accuracy error but now that SA has been turned off I think it will do for
what I need.
Also Has any one written code to compare to GPS positions and indicate the
bearing distance time etc to the way point, better than that is there any
way of getting the direction data to a way point from the GPS?
Raj Mallik
NMEA output of a Garmin 12 XL GPS. I know the data is subject to some in
accuracy error but now that SA has been turned off I think it will do for
what I need.
Also Has any one written code to compare to GPS positions and indicate the
bearing distance time etc to the way point, better than that is there any
way of getting the direction data to a way point from the GPS?
Raj Mallik
Comments
It is possible to read altitude from the GPS NMEA strings. However, even
with SA turned off, it can be off by 100 to 150 feet most of the time - not
to be trusted in critical applications.
Regarding waypoints, it's possible - there are great circle navigation
formulas - to calculate distance from a location to a waypoint, but it
involves complex math with arc and angle calculations. If you set a GOTO
from some GPS receivers (like the 12XL) you can read the waypoint navigation
information from a custom NMEA string - but you have to set the GOTO command
manually via keypad on the receiver.
Cheers,
Mike
Mensaje original
De: Raj Mallik [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=dl2OXqaD2JeYG-MjFB9UkDByREe1pGLAf1NqBa77kJI_tGkWyLW785ka3M-C5YmouXBOobOMuwyPeSrSmL6lwQ]ramallik@m...[/url
Enviado el: miercoles, 06 de diciembre de 2000 0:32
Para: basicstamps@egroups.com
Asunto: [noparse][[/noparse]basicstamps] NMEA read out for altitude
Can any one tel me if it is possible to read the altimeter data from the
NMEA output of a Garmin 12 XL GPS. I know the data is subject to some in
accuracy error but now that SA has been turned off I think it will do for
what I need.
Also Has any one written code to compare to GPS positions and indicate the
bearing distance time etc to the way point, better than that is there any
way of getting the direction data to a way point from the GPS?
Raj Mallik
are along a sphere.
a1, b1 and a2, b2 are the lat, lon pair...
R is the radius of the earth in the measurement that you want to use.. For
Statute miles use the folowing.
r=3963.1 ' Statute Miles
distance=Arccos(Cos(a1) * Cos(b1)*Cos(a2)*Cos(b2) +
Cos(a1)*Sin(b1)*Cos(a2)*Sin(b2) + Sin(a1)*Sin(a2))/360 * 2 * Pi * r
I do not know if there is a pack for the stamp that can handle the math but
there is the formula.
MH
Original Message
From: "Raj Mallik" <ramallik@m...>
To: <basicstamps@egroups.com>
Sent: Tuesday, December 05, 2000 6:32 PM
Subject: [noparse][[/noparse]basicstamps] NMEA read out for altitude
> Can any one tel me if it is possible to read the altimeter data from the
> NMEA output of a Garmin 12 XL GPS. I know the data is subject to some in
> accuracy error but now that SA has been turned off I think it will do for
> what I need.
>
> Also Has any one written code to compare to GPS positions and indicate the
> bearing distance time etc to the way point, better than that is there any
> way of getting the direction data to a way point from the GPS?
>
> Raj Mallik
>
>
>
>
>
programed to take 1 - 3 minutes to reaquire it the signal. If someone was
trying to design a autopilot you may have some problems especially if its
for a flying vehicle. A lot can happen in 1 - 3 minutes.
Can anyone confirm this?
Thanks
Cory
>
Original Message
>From: Michael Hendricks [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=RLfaHGPhVCKcBRX_UmE04smes8vbXSE5UEzqtrYOeHqlQy3ZsNxkMSSfMHM6dckoF5S71o4PBKcBd4dw]mjh80@b...[/url
>Sent: Thursday, December 07, 2000 9:09 AM
>To: basicstamps@egroups.com
>Subject: Re: [noparse][[/noparse]basicstamps] NMEA read out for altitude
>
>
>To compute the distance between 2 points you need to compute them
>as if they
>are along a sphere.
>
>a1, b1 and a2, b2 are the lat, lon pair...
>
>R is the radius of the earth in the measurement that you want to use.. For
>Statute miles use the folowing.
>
>r=3963.1 ' Statute Miles
>
>distance=Arccos(Cos(a1) * Cos(b1)*Cos(a2)*Cos(b2) +
>Cos(a1)*Sin(b1)*Cos(a2)*Sin(b2) + Sin(a1)*Sin(a2))/360 * 2 * Pi * r
>
>I do not know if there is a pack for the stamp that can handle the math but
>there is the formula.
>
>MH
>
>
>
Original Message
>From: "Raj Mallik" <ramallik@m...>
>To: <basicstamps@egroups.com>
>Sent: Tuesday, December 05, 2000 6:32 PM
>Subject: [noparse][[/noparse]basicstamps] NMEA read out for altitude
>
>
>> Can any one tel me if it is possible to read the altimeter data from the
>> NMEA output of a Garmin 12 XL GPS. I know the data is subject to some in
>> accuracy error but now that SA has been turned off I think it will do for
>> what I need.
>>
>> Also Has any one written code to compare to GPS positions and
>indicate the
>> bearing distance time etc to the way point, better than that is there any
>> way of getting the direction data to a way point from the GPS?
>>
>> Raj Mallik
>>
>>
>>
>>
>>
>
>
>
>
>
This only happens with certain type of receivers, all the ones I have seen,
both consumer type and OEM have re-aquisition times of between 10
milliseconds to 15-20 seconds for old units.
One thing to take into account in the design of the vehicle is that the GPS
will draw some 150mA, which is quite a bit.
Cheers,
Mike
Mensaje original
De: Stratton Design Studios [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=f7ghyVjAjCf2JSAtGFfZap41edCybqmuObrZv7y5CDuR-tsBP8cXO7hhKsE1IiBuaiqCKYZ_Z2e1wkYPXuu-GfZbipH30Q]cory@s...[/url
Enviado el: jueves, 07 de diciembre de 2000 17:52
Para: basicstamps@egroups.com
Asunto: RE: [noparse][[/noparse]basicstamps] NMEA read out for altitude
I was reading in a book that stated that if your GPS looses its signal it is
programed to take 1 - 3 minutes to reaquire it the signal. If someone was
trying to design a autopilot you may have some problems especially if its
for a flying vehicle. A lot can happen in 1 - 3 minutes.
Can anyone confirm this?
Thanks
Cory
>
Original Message
>From: Michael Hendricks [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=ccvxYulE0-vbsG-odJLg-ghUllV8Hcs1Z5aOf9wQXOgnROWNFtQPOuwHzkZ0yFuRgcD21YDua52I6f0]mjh80@b...[/url
>Sent: Thursday, December 07, 2000 9:09 AM
>To: basicstamps@egroups.com
>Subject: Re: [noparse][[/noparse]basicstamps] NMEA read out for altitude
>
>
>To compute the distance between 2 points you need to compute them
>as if they
>are along a sphere.
>
>a1, b1 and a2, b2 are the lat, lon pair...
>
>R is the radius of the earth in the measurement that you want to use.. For
>Statute miles use the folowing.
>
>r=3963.1 ' Statute Miles
>
>distance=Arccos(Cos(a1) * Cos(b1)*Cos(a2)*Cos(b2) +
>Cos(a1)*Sin(b1)*Cos(a2)*Sin(b2) + Sin(a1)*Sin(a2))/360 * 2 * Pi * r
>
>I do not know if there is a pack for the stamp that can handle the math but
>there is the formula.
>
>MH
>
>
>
Original Message
>From: "Raj Mallik" <ramallik@m...>
>To: <basicstamps@egroups.com>
>Sent: Tuesday, December 05, 2000 6:32 PM
>Subject: [noparse][[/noparse]basicstamps] NMEA read out for altitude
>
>
>> Can any one tel me if it is possible to read the altimeter data from the
>> NMEA output of a Garmin 12 XL GPS. I know the data is subject to some in
>> accuracy error but now that SA has been turned off I think it will do for
>> what I need.
>>
>> Also Has any one written code to compare to GPS positions and
>indicate the
>> bearing distance time etc to the way point, better than that is there any
>> way of getting the direction data to a way point from the GPS?
>>
>> Raj Mallik
>>
>>
>>
>>
>>
>
>
>
>
>
purchase?
Thanks
Cory
>
Original Message
>From: Miguel Puchol [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=aqPfNSGs81PyTcYDPROd-O9M42xyPFh5XI78lqYkGk1hs297-sz-UTLj3D6zRueom_vomTtVGpk]mpuchol@w...[/url
>Sent: Thursday, December 07, 2000 10:02 AM
>To: basicstamps@egroups.com
>Subject: RE: [noparse][[/noparse]basicstamps] NMEA read out for altitude
>
>
>Cory,
>
>This only happens with certain type of receivers, all the ones I have seen,
>both consumer type and OEM have re-aquisition times of between 10
>milliseconds to 15-20 seconds for old units.
>One thing to take into account in the design of the vehicle is that the GPS
>will draw some 150mA, which is quite a bit.
>
>Cheers,
>
>Mike
>
>
Mensaje original
>De: Stratton Design Studios [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=DO5nrmosQOuLfJR149rEs-Gx6BM5V4IV05tAIi9Yp5jKCC4yJxlWdoYgnoI-x-jI31d2QgZfpzMPHWDiApmOoRupg-avS20]cory@s...[/url
>Enviado el: jueves, 07 de diciembre de 2000 17:52
>Para: basicstamps@egroups.com
>Asunto: RE: [noparse][[/noparse]basicstamps] NMEA read out for altitude
>
>
>I was reading in a book that stated that if your GPS looses its
>signal it is
>programed to take 1 - 3 minutes to reaquire it the signal. If someone was
>trying to design a autopilot you may have some problems especially if its
>for a flying vehicle. A lot can happen in 1 - 3 minutes.
>
>Can anyone confirm this?
>
>Thanks
>Cory
>
>>
Original Message
>>From: Michael Hendricks [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=dXAMZsNezBbN1MDH6W_d7nkClnecIA4KXxFpnoMrXoRfgnAlXUDXtGEdnHHDMpVuaqxbFydjpQc]mjh80@b...[/url
>>Sent: Thursday, December 07, 2000 9:09 AM
>>To: basicstamps@egroups.com
>>Subject: Re: [noparse][[/noparse]basicstamps] NMEA read out for altitude
>>
>>
>>To compute the distance between 2 points you need to compute them
>>as if they
>>are along a sphere.
>>
>>a1, b1 and a2, b2 are the lat, lon pair...
>>
>>R is the radius of the earth in the measurement that you want to use.. For
>>Statute miles use the folowing.
>>
>>r=3963.1 ' Statute Miles
>>
>>distance=Arccos(Cos(a1) * Cos(b1)*Cos(a2)*Cos(b2) +
>>Cos(a1)*Sin(b1)*Cos(a2)*Sin(b2) + Sin(a1)*Sin(a2))/360 * 2 * Pi * r
>>
>>I do not know if there is a pack for the stamp that can handle
>the math but
>>there is the formula.
>>
>>MH
>>
>>
>>
Original Message
>>From: "Raj Mallik" <ramallik@m...>
>>To: <basicstamps@egroups.com>
>>Sent: Tuesday, December 05, 2000 6:32 PM
>>Subject: [noparse][[/noparse]basicstamps] NMEA read out for altitude
>>
>>
>>> Can any one tel me if it is possible to read the altimeter data from the
>>> NMEA output of a Garmin 12 XL GPS. I know the data is subject to some in
>>> accuracy error but now that SA has been turned off I think it
>will do for
>>> what I need.
>>>
>>> Also Has any one written code to compare to GPS positions and
>>indicate the
>>> bearing distance time etc to the way point, better than that is
>there any
>>> way of getting the direction data to a way point from the GPS?
>>>
>>> Raj Mallik
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>>
>
>
>
>
>
>
>
>
richard
Original Message
From: "Stratton Design Studios" <cory@s...>
To: <basicstamps@egroups.com>
Sent: Thursday, December 07, 2000 10:51 AM
Subject: RE: [noparse][[/noparse]basicstamps] NMEA read out for altitude
> I was reading in a book that stated that if your GPS looses its signal it
is
> programed to take 1 - 3 minutes to reaquire it the signal. If someone was
> trying to design a autopilot you may have some problems especially if its
> for a flying vehicle. A lot can happen in 1 - 3 minutes.
>
> Can anyone confirm this?
>
> Thanks
> Cory
>
> >
Original Message
> >From: Michael Hendricks [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=g6zgG-6Ne3JrkpxAIHugimgO6bONHc8FxWsm061GAT5eHuiUBM9oJq5asQVYzcdz73U-923MFTW8cHE]mjh80@b...[/url
> >Sent: Thursday, December 07, 2000 9:09 AM
> >To: basicstamps@egroups.com
> >Subject: Re: [noparse][[/noparse]basicstamps] NMEA read out for altitude
> >
> >
> >To compute the distance between 2 points you need to compute them
> >as if they
> >are along a sphere.
> >
> >a1, b1 and a2, b2 are the lat, lon pair...
> >
> >R is the radius of the earth in the measurement that you want to use..
For
> >Statute miles use the folowing.
> >
> >r=3963.1 ' Statute Miles
> >
> >distance=Arccos(Cos(a1) * Cos(b1)*Cos(a2)*Cos(b2) +
> >Cos(a1)*Sin(b1)*Cos(a2)*Sin(b2) + Sin(a1)*Sin(a2))/360 * 2 * Pi * r
> >
> >I do not know if there is a pack for the stamp that can handle the math
but
> >there is the formula.
> >
> >MH
> >
> >
> >
Original Message
> >From: "Raj Mallik" <ramallik@m...>
> >To: <basicstamps@egroups.com>
> >Sent: Tuesday, December 05, 2000 6:32 PM
> >Subject: [noparse][[/noparse]basicstamps] NMEA read out for altitude
> >
> >
> >> Can any one tel me if it is possible to read the altimeter data from
the
> >> NMEA output of a Garmin 12 XL GPS. I know the data is subject to some
in
> >> accuracy error but now that SA has been turned off I think it will do
for
> >> what I need.
> >>
> >> Also Has any one written code to compare to GPS positions and
> >indicate the
> >> bearing distance time etc to the way point, better than that is there
any
> >> way of getting the direction data to a way point from the GPS?
> >>
> >> Raj Mallik
> >>
> >>
> >>
> >>
> >>
> >
> >
> >
> >
> >
>
>
>
>
>
A good, light-weight integrated receiver is the Pharos iGPS (weighs 2.4oz),
takes about 150mA at 5V and has a re-aquisition time of 100ms. Take a look
at www.pharosgps.com.
Time to first fix is around 45 seconds with a good view of the sky, and
hot-start is stated as being 8 seconds.
All the best,
Mike
Mensaje original
De: Stratton Design Studios [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=c9Gpg-hhyYWUvrQXGFKOxdYacMQXRa51JeThEcDyqKJLhEibTske7S1mXQaQ7kvFL4Due2RYprR_5CuKF7NV59cpEMNA6Uo]cory@s...[/url
Enviado el: jueves, 07 de diciembre de 2000 18:09
Para: basicstamps@egroups.com
Asunto: RE: [noparse][[/noparse]basicstamps] NMEA read out for altitude
Can you recommend a receiver to stay away from? Or one I should look at to
purchase?
Thanks
Cory
>
Original Message
>From: Miguel Puchol [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=jGsU_PQqptwF_sgZajMYwxnIsjS8x4loxLcQ4sp7zE2GzmxC8x0AkJRoIUOdHhJN3XGfLoQHqk6F]mpuchol@w...[/url
>Sent: Thursday, December 07, 2000 10:02 AM
>To: basicstamps@egroups.com
>Subject: RE: [noparse][[/noparse]basicstamps] NMEA read out for altitude
>
>
>Cory,
>
>This only happens with certain type of receivers, all the ones I have seen,
>both consumer type and OEM have re-aquisition times of between 10
>milliseconds to 15-20 seconds for old units.
>One thing to take into account in the design of the vehicle is that the GPS
>will draw some 150mA, which is quite a bit.
>
>Cheers,
>
>Mike
>
>
Mensaje original
>De: Stratton Design Studios [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=c9Gpg-hhyYWUvrQXGFKOxdYacMQXRa51JeThEcDyqKJLhEibTske7S1mXQaQ7kvFL4Due2RYprR_5CuKF7NV59cpEMNA6Uo]cory@s...[/url
>Enviado el: jueves, 07 de diciembre de 2000 17:52
>Para: basicstamps@egroups.com
>Asunto: RE: [noparse][[/noparse]basicstamps] NMEA read out for altitude
>
>
>I was reading in a book that stated that if your GPS looses its
>signal it is
>programed to take 1 - 3 minutes to reaquire it the signal. If someone was
>trying to design a autopilot you may have some problems especially if its
>for a flying vehicle. A lot can happen in 1 - 3 minutes.
>
>Can anyone confirm this?
>
>Thanks
>Cory
>
>>
Original Message
>>From: Michael Hendricks [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=xzdAIKma7J6gA8w1Ye_XZAZCVaLJvcvn9R7rXRUl2eIb3al1cItAoLBZmP9Pp1ZO1jqwZ8jaW28O]mjh80@b...[/url
>>Sent: Thursday, December 07, 2000 9:09 AM
>>To: basicstamps@egroups.com
>>Subject: Re: [noparse][[/noparse]basicstamps] NMEA read out for altitude
>>
>>
>>To compute the distance between 2 points you need to compute them
>>as if they
>>are along a sphere.
>>
>>a1, b1 and a2, b2 are the lat, lon pair...
>>
>>R is the radius of the earth in the measurement that you want to use.. For
>>Statute miles use the folowing.
>>
>>r=3963.1 ' Statute Miles
>>
>>distance=Arccos(Cos(a1) * Cos(b1)*Cos(a2)*Cos(b2) +
>>Cos(a1)*Sin(b1)*Cos(a2)*Sin(b2) + Sin(a1)*Sin(a2))/360 * 2 * Pi * r
>>
>>I do not know if there is a pack for the stamp that can handle
>the math but
>>there is the formula.
>>
>>MH
>>
>>
>>
Original Message
>>From: "Raj Mallik" <ramallik@m...>
>>To: <basicstamps@egroups.com>
>>Sent: Tuesday, December 05, 2000 6:32 PM
>>Subject: [noparse][[/noparse]basicstamps] NMEA read out for altitude
>>
>>
>>> Can any one tel me if it is possible to read the altimeter data from the
>>> NMEA output of a Garmin 12 XL GPS. I know the data is subject to some in
>>> accuracy error but now that SA has been turned off I think it
>will do for
>>> what I need.
>>>
>>> Also Has any one written code to compare to GPS positions and
>>indicate the
>>> bearing distance time etc to the way point, better than that is
>there any
>>> way of getting the direction data to a way point from the GPS?
>>>
>>> Raj Mallik
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>>
>
>
>
>
>
>
>
>