Miniature GPS module with 10Hz update rate

[Mook Johnson]

I need a small ~(1"x1") OEM GPS modue that runs off 3.3V and can supply a
new speed output at a rate of at least 5Hz, 10Hz would be more desirable.
I'm not interested in position inforation at this time.

This will be used in a embedded system and feed a small microprocessor for
further processing.

There are many that can output at 1Hz but I need 5 - 10Hz for best
performace in this application.

 

[Rene Tschaggelar]

I need a small ~(1"x1") OEM GPS modue that runs off 3.3V and can supply a
new speed output at a rate of at least 5Hz, 10Hz would be more desirable.
I'm not interested in position inforation at this time.

This will be used in a embedded system and feed a small microprocessor for
further processing.

There are many that can output at 1Hz but I need 5 - 10Hz for best
performace in this application.

It is not the module that provides the 1 Hz but the GPS system.
There is just not more data. Except for those using the military
version. I have no idea how precious these parts are nowadays,
but at least for now you should forget them.

The reason why the current commercial GPS is not delivering
more updates ? Even kids could build a cruise missile or similar.

Rene

 

[dalai lamah]

Un bel giorno Rene Tschaggelar digitò:

It is not the module that provides the 1 Hz but the GPS system.
There is just not more data. Except for those using the military
version. I have no idea how precious these parts are nowadays,
but at least for now you should forget them.

Are you sure? I knew that the military band just allowed to get better
resolution by using the P-codes, but the fix frequency was just a matter of
processing power. There are lots of 4 Hz consumer GPS (look at U-Blox), and
I've seen non-military GPS up to 100 Hz.

 

[Mac]

It is not the module that provides the 1 Hz but the GPS system.
There is just not more data. Except for those using the military
version. I have no idea how precious these parts are nowadays,
but at least for now you should forget them.

The reason why the current commercial GPS is not delivering
more updates ? Even kids could build a cruise missile or similar.

Rene

It is completely untrue that the GPS system doesn't provide enough
information to update (especially speed) more than once per second. The
GPS unit can get the speed directly from Doppler on the various
satellites, and it can (in principle) compute Doppler shift before
it even decodes the messages.

I searched using Google with the terms "gps," "update," and "rate," and
found several links in the first result page to non-military GPS's with a
5 Hz update rate. They are not OEM units like the OP is looking for, but
this result disproves your assertion that 1 Hz is a system limitation.

There ARE export restrictions on some GPS units, but as far as I know,
the export restrictions only apply when the unit has high altitude, speed,
and acceleration envelopes.

Selective availability, AFAIK, has been turned off for several years, and
anyway I don't think it had anything to do with update rate.

--Mac

 

[Ian Stirling]

Un bel giorno Rene Tschaggelar digit?:


Are you sure? I knew that the military band just allowed to get better
resolution by using the P-codes, but the fix frequency was just a matter of
processing power. There are lots of 4 Hz consumer GPS (look at U-Blox), and
I've seen non-military GPS up to 100 Hz.

From memory...
GPS basic 'data rate' is 1000Hz.
This is a 'bit' of data.
Every bit is transmitted 20 times, so that's 50 bits per second of data.
A navigation message (day/time/basic orbit of satellite) is 300 bits.
So, ever 6 seconds or so you get a complete message for one satellite.

You can generate position information at the 1000Hz rate.
It'll be very inaccurate.

The longer the period you integrate over, the less noisy it becomes.

 

[Mook Johnson]

Do you guys thin that a 5 or 10Hz GPS module exists?

I've seen some that sat .1S reacquisition time. Don't know if that means
that a new speed is measured and ready to be polled in .1S or not.


Lets say this one for instance..

http://www.leadtek.com/gps/gps9543/9543.htm

 

[Mook Johnson]

Do you guys thin that a 5 or 10Hz GPS module exists?

I've seen some that sat .1S reacquisition time. Don't know if that means
that a new speed is measured and ready to be polled in .1S or not.


Lets say this one for instance..

http://www.leadtek.com/gps/gps9543/9543.htm

 

[Mac]

Do you guys thin that a 5 or 10Hz GPS module exists?

[snip]

I have seen, touched and witnessed the functioning of two different GPS's
with update rates of 10 Hz or better. Unfortunately, I don't remember the
exact make or model. I will try to find some old notes when I go back to
work on Monday (if I remember). They are NOT cheap.

There may not be a 10 Hz GPS which meets your size, power, and price
points.

There are also integrated GPS and IMU units out there which can give you
accurate position (and orientation, as long as you are moving) information
at 100 Hz, but they definitely don't meet your size spec, and probably
cost too much for your application by several orders of magnitude. To tell
the truth the only one I actually know about is export restricted, meaning
that you have to jump through some kind of hoops to get it if you are in
the US, and probably can't get it outside the US.

--Mac

 

[Tim Shoppa]

I'm not interested in position inforation at this time.

[...]
but I need 5 - 10Hz for best performace in this application.

If you're only interested in velocity there are other methods that may
work better. You can buy chintzy but operational microwave speed guns
for $60 or so from Ramsey. The Doppler shift is an audio output and
could be hooked straight up to a microprocessor for sampling as fast as
you want. Whether this'll work or not depends on how many axes you
need and how far away it is to a known stationary object...

Tim.

 

[dalai lamah]

Un bel giorno Mook Johnson digitò:

Do you guys thin that a 5 or 10Hz GPS module exists?

As I've written, u-blox (www.u-blox.com) sells low-cost 4-Hz GPS modules,
they cost around 100$. If you need more speed, be prepared to spend a lot
more (ten times minimum). Look for example Thales Navigation
(www.thalesnavigation.com), they have GPS modules up to 20 Hz.

Other links (but I haven't used their modules - by the way, someone has?):

www.navtechgps.com: modules up to 25 Hz (or 50-Hz raw data);
www.novatel.com: modules up to 20 Hz.

I've seen some that sat .1S reacquisition time. Don't know if that means
that a new speed is measured and ready to be polled in .1S or not.

No, reacquisition time is the time needed to restart the acquisition after
a "short blackout" (10-30 s), e.g. when you enter a tunnel.

http://www.leadtek.com/gps/gps9543/9543.htm

It looks like a 1 Hz model.

 

[Ian Stirling]

I need a small ~(1"x1") OEM GPS modue that runs off 3.3V and can supply a
new speed output at a rate of at least 5Hz, 10Hz would be more desirable.
I'm not interested in position inforation at this time.

This will be used in a embedded system and feed a small microprocessor for
further processing.

There are many that can output at 1Hz but I need 5 - 10Hz for best
performace in this application.

Small MEMS accellerometers and gyros can offer good performance in this
range (giving info from second down to millisecond)
That's probably the cheapest way.