usb GPS

[Velio Cov]

Hi, I am testing a usb GPS (Vk-162 U-blox 7 chipset) on my shake but it is not working, the GPS device is recognized by the shake via usb but the time still comes from the internet

I noticed that with my GPS the shakes is mounting ttyACM0 instad of ttyUSB0, any ideas?!

Thanks,

Velio

[Branden Christensen]

Hi Velio:

Buenas tardes and thank you for your message.

Supporting any GPS is not in the cards for us. That would not be possible. We only offer support and plug-and-play automation for the GPS antenna available on the shop at shop.raspberryshake.org. Any other modules require custom solutions developed by their end users. 

Yours,

Branden Christensen

Director, Raspberry Shake project, Social Media: @raspishake

USA: +1-845-418-5735; Panamá (Whatsapp): +507-6747-1427

--
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[Marco Walther]

On 06/06/2018 11:01 AM, Branden Christensen wrote:
> Hi Velio:
>
>
> Buenas tardes and thank you for your message.
>
> Supporting any GPS is not in the cards for us. That would not be
> possible. We only offer support and plug-and-play automation for the GPS
> antenna available on the shop at shop.raspberryshake.org

> <http://shop.raspberryshake.org>. Any other modules require custom

> solutions developed by their end users.
>

Hello Velio,

I did a write-up on my GPS/time setup for this list some time ago. It's
probably still in the archives somewhere when you're interested.

For this usage, there should not be any difference between the
/dev/ttyUSB* or /dev/ttyACM* device files. You could try to do a

$ cat /dev/ttyACM0

and should see some [somewhat] readable lines fly by.

Example from my receiver [somewhat sanitized]:

$GNRMC,215659.00,A,3700.00000,N,12100.00000,W,2.656,,060618,,,A*78
$GNVTG,,T,,M,2.656,N,4.918,K,A*3E
$GNGGA,215659.00,3700.00000,N,12100.00000,W,1,06,2.00,3.3,M,-28.8,M,,*71
$GNGSA,A,3,02,12,24,06,19,,,,,,,,3.49,2.00,2.86*15
$GNGSA,A,3,81,,,,,,,,,,,,3.49,2.00,2.86*15
$GPGSV,3,1,12,02,77,164,18,05,10,158,,0650,052,11,12,65,331,32*7C
$GPGSV,3,2,12,17,14,067,08,19,32,057,19,24,43,225,24,25,23,312,21*75
$GPGSV,3,3,12,29,08,263,18,46,46,193,,48,45,199,,51,44,158,*78
$GLGSV,3,1,10,65,03,101,,71,00,013,,72,07,058,,77,29,162,*63
$GLGSV,3,2,10,78,77,212,,79,49,322,,81,47,261,15,82,03,238,*60
$GLGSV,3,3,10,87,20,040,,88,61,002,*68
$GNGLL,3700.00000,N,12100.00000,W,215659.00,A,A*6F
$GNTXT,01,01,01,NMEA unknown msg*46
$GNTXT,01,01,01,NMEA unknown msg*46


So, yes different receivers require somewhat different setups, but the
general idea is always the same and most software tools support all the
common (UBlox and others) receivers;-)

Have fun,
-- Marco


>
> Yours,
>
>
> *Branden Christensen*
> Director, Raspberry Shake project <http://raspberryshake.org>, Social

> Media: @raspishake
> USA: +1-845-418-5735; Panamá (Whatsapp): +507-6747-1427

> <tel:%2B507-6747-1427>

> send an email to raspberryshak...@googlegroups.com
> <mailto:raspberryshak...@googlegroups.com>.

> To post to this group, send email to raspber...@googlegroups.com

> <mailto:raspber...@googlegroups.com>.

> Visit this group at https://groups.google.com/group/raspberryshake

> <https://groups.google.com/group/raspberryshake>.

> To view this discussion on the web visit
> https://groups.google.com/d/msgid/raspberryshake/b1156841-05b6-40ce-98bb-daf7400a252d%40googlegroups.com

> <https://groups.google.com/d/msgid/raspberryshake/b1156841-05b6-40ce-98bb-daf7400a252d%40googlegroups.com?utm_medium=email&utm_source=footer>.

> For more options, visit https://groups.google.com/d/optout

> <https://groups.google.com/d/optout>.

>
>
> --
> Some useful links:
>
> Manual: http://manual.raspberryshake.org/
> Do It YourSelf Page: http://raspberryshake.org/do-it-yourself
> Shop: https://shop.raspberryshake.org/
> Website: http://raspberryshake.org/
>
> Instagram: https://www.instagram.com/raspishake/
> Facebook: https://www.facebook.com/raspishake/
> Twitter: https://twitter.com/raspishake/
> Hashtag: #rasperryshake, @raspishake
> DOI: https://doi.org/10.7914/SN/AM
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[Larry Cochrane]

Hi Velio,

For accurate time keeping you need a 1 pulse per second signal from the GPS receivers as well as the NMEA messages. It looks like your Vk-162 U-blox receiver does not supply the 1PPS to the PI. I have two web pages documenting my GPS testing with the RShake. This one http://www.seismicnet.com/shake/ uses a Garmin GPS18x LVC and a FTDI RS-232 to USB Adapter. And I recently wrote up this page http://www.seismicnet.com/shake/usbgps.html on how to make your own USB timing module with 1PPS signal using  a U-BLOX UBX-G7020-KT receiver and a FTDI FT232RL breakout board made by Sparkfun.com. Some soldering is required to make this module.

Regards,

Larry Cochrane

Redwood City, PSN

[Marco Walther]

On 06/07/2018 02:13 PM, Larry Cochrane wrote:
>
> Hi Velio,
>
> For accurate time keeping you need a 1 pulse per second signal from the
> GPS receivers as well as the NMEA messages. It looks like your Vk-162
> U-blox receiver does not supply the 1PPS to the PI. I have two web pages
> documenting my GPS testing with the RShake. This one
> http://www.seismicnet.com/shake/ uses a Garmin GPS18x LVC and a FTDI
> RS-232 to USB Adapter. And I recently wrote up this page
> http://www.seismicnet.com/shake/usbgps.html on how to make your own USB
> timing module with 1PPS signal using  a U-BLOX UBX-G7020-KT receiver and
> a FTDI FT232RL breakout board made by Sparkfun.com. Some soldering is
> required to make this module.

The only problem with that is that USB is buffered all over the place.
That would create some jitter.

My write-up on a USB + GPIO PPS setup is in the archives here:

https://groups.google.com/forum/#!msg/raspberryshake/0NX8vaAas1U/oXTsvNWDBQAJ;context-place=forum/raspberryshake

As always, any GPS-based clock is better than just the clock on the Pi;-)

Have fun,
-- Marco

>

> Regards,
> Larry Cochrane
> Redwood City, PSN
>
> On Wednesday, June 6, 2018 at 10:53:37 AM UTC-7, Velio Cov wrote:
>
> Hi, I am testing a usb GPS (Vk-162 U-blox 7 chipset) on my shake but
> it is not working, the GPS device is recognized by the shake via usb
> but the time still comes from the internet
>
> I noticed that with my GPS the shakes is mounting ttyACM0 instad of
> ttyUSB0, any ideas?!
>
> Thanks,
>
> Velio
>

> --
> Some useful links:
>
> Manual: http://manual.raspberryshake.org/
> Do It YourSelf Page: http://raspberryshake.org/do-it-yourself
> Shop: https://shop.raspberryshake.org/
> Website: http://raspberryshake.org/
>
> Instagram: https://www.instagram.com/raspishake/
> Facebook: https://www.facebook.com/raspishake/
> Twitter: https://twitter.com/raspishake/
> Hashtag: #rasperryshake, @raspishake
> DOI: https://doi.org/10.7914/SN/AM
> ---
> You received this message because you are subscribed to the Google
> Groups "RaspberryShake" group.
> To unsubscribe from this group and stop receiving emails from it, send
> an email to raspberryshak...@googlegroups.com
> <mailto:raspberryshak...@googlegroups.com>.
> To post to this group, send email to raspber...@googlegroups.com
> <mailto:raspber...@googlegroups.com>.
> Visit this group at https://groups.google.com/group/raspberryshake.
> To view this discussion on the web visit

> https://groups.google.com/d/msgid/raspberryshake/9e51361d-4ff4-4b4e-9a62-ed61c1d36907%40googlegroups.com
> <https://groups.google.com/d/msgid/raspberryshake/9e51361d-4ff4-4b4e-9a62-ed61c1d36907%40googlegroups.com?utm_medium=email&utm_source=footer>.

[David J Taylor]

From: Marco Walther

The only problem with that is that USB is buffered all over the place.
That would create some jitter.

My write-up on a USB + GPIO PPS setup is in the archives here:

https://groups.google.com/forum/#!msg/raspberryshake/0NX8vaAas1U/oXTsvNWDBQAJ;context-place=forum/raspberryshake

As always, any GPS-based clock is better than just the clock on the Pi;-)

Have fun,
-- Marco

============================================

Not so in my experience. A GPS serial output can easily have jitter in
excess of 100 milliseconds. Unless you are unfortunate, using an Internet
source will be better (e.g. tens of milliseconds or less), and if you have a
local stratum-1 server you can get down to the fractions of milliseconds
even over a powerline Ethernet connection (yuk!).

http://www.satsignal.eu/mrtg/raspi14_ntp_3.html

With a direct PPS connection to the RPi, a few microseconds can be achieved:

http://www.satsignal.eu/mrtg/raspi1_ntp.html

but is likely far in excess of the requirements for seismology. Agreed with
your comments about USB!

Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-...@blueyonder.co.uk
Twitter: @gm8arv

[Marco Walther]

Hello David,

On 06/08/2018 09:18 AM, David J Taylor wrote:
> From: Marco Walther
>
> The only problem with that is that USB is buffered all over the place.
> That would create some jitter.
>
> My write-up on a USB + GPIO PPS setup is in the archives here:
>
> https://groups.google.com/forum/#!msg/raspberryshake/0NX8vaAas1U/oXTsvNWDBQAJ;context-place=forum/raspberryshake
>
>
> As always, any GPS-based clock is better than just the clock on the Pi;-)
>
> Have fun,
> -- Marco
> ============================================
>
> Not so in my experience.  A GPS serial output can easily have jitter in
> excess of 100 milliseconds.

My comment above was more in regards of pulling the PPS signal through USB.

Yes, the NMEA/UBlox/... sentences will have some jitter which is much
higher regardless if you use USB or serial.

> Unless you are unfortunate, using an
> Internet source will be better (e.g. tens of milliseconds or less), and
> if you have a local stratum-1 server you can get down to the fractions
> of milliseconds even over a powerline Ethernet connection (yuk!).
>
>  http://www.satsignal.eu/mrtg/raspi14_ntp_3.html
>
> With a direct PPS connection to the RPi, a few microseconds can be
> achieved:
>
>  http://www.satsignal.eu/mrtg/raspi1_ntp.html
>
> but is likely far in excess of the requirements for seismology.  Agreed
> with your comments about USB!

After I read Larry's reply and his pages yesterday, I decided to enable
the stats collection on my Shake/GPS setup.

The first couple of hours are in and it looks very good;-) No long-term
adjustments or anything from ntpd, the plots start about 10 minutes
after the restart.

Have fun;-)
-- Marco


>
> Cheers,
> David

[David J Taylor]

From: Marco Walther

My comment above was more in regards of pulling the PPS signal through USB.

Yes, the NMEA/UBlox/... sentences will have some jitter which is much
higher regardless if you use USB or serial.

[]

After I read Larry's reply and his pages yesterday, I decided to enable
the stats collection on my Shake/GPS setup.

The first couple of hours are in and it looks very good;-) No long-term
adjustments or anything from ntpd, the plots start about 10 minutes
after the restart.

Have fun;-)
-- Marco

============================================

Marco,

Yes, USB is not the best way to get a precision PPS signal! It might be
better than the Internet, though. I've not compared those options, but did
try both a user-mode and kernel-mode PPS into the RPi, and if the RPi was
busy (higher CPU) the kernel-mode was better, as you would expect.

I've already had a lot of fun with NTP on different devices, including the
RPi:

http://www.satsignal.eu/ntp/Raspberry-Pi-quickstart.html