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Re: How to avoid 1Hz batching of 10Hz GPS fixes?

From: Chris Dew
Subject: Re: How to avoid 1Hz batching of 10Hz GPS fixes?
Date: Fri, 18 Oct 2024 11:48:31 +0100
User-agent: Mozilla Thunderbird
Hi Gary,

Thanks for your help.

But, before you do any of that, update to gpsd 3.25 or better yet git head.
Now using HEAD:

{"class":"VERSION","release":"3.25.1~dev","rev":"release-3.25-658-gd3a6e3924","proto_major":3,"proto_minor":15}

    serial or USB connection,  

serial

What speed?
9600

{"class":"DEVICES","devices":[{"class":"DEVICE","path":"/dev/ttymxc1","driver":"u-blox","activated":"2024-10-18T10:23:38.545Z","flags":1,"native":1,"bps":9600,"parity":"N","stop...

Send the output of "ubxtool -P CONFIG" and "ubxtool -P STATUS"
root@999AAAAA:~/gpsd# ./gpsd-3.25.1~dev/clients/ubxtool -P CONFIG
usage: ubxtool [OPTIONS] [host[:port[:device]]]
ubxtool: error: argument -P/--protver: invalid float value: 'CONFIG'

root@999AAAAA:~/gpsd# ./gpsd-3.25.1~dev/clients/ubxtool -P STATUS
usage: ubxtool [OPTIONS] [host[:port[:device]]]
ubxtool: error: argument -P/--protver: invalid float value: 'STATUS'

I know this isn't the output you were looking for, but nothing was obvious from --help:

root@999AAAAA:~/gpsd# ./gpsd-3.25.1~dev/clients/ubxtool -V
ubxtool: Version 3.25.1~dev
root@999AAAAA:~/gpsd# ./gpsd-3.25.1~dev/clients/ubxtool --help | grep -i CONFIG
                        Configure receiver speed to SETSPEED
root@999AAAAA:~/gpsd# ./gpsd-3.25.1~dev/clients/ubxtool --help | grep -I STATUS
root@999AAAAA:~/gpsd# ./gpsd-3.25.1~dev/clients/ubxtool --help | grep P
usage: ubxtool [OPTIONS] [host[:port[:device]]]
  -g ITEM,LAYER,POSITION, --getitem ITEM,LAYER,POSITION
                        Get ITEM from LAYER and POSITION. LAYER and POSITION
  -i PORTID, -portid PORTID
                        Specifies receiver PORTID (interface) for port-related
  --port PORT           The gpsd port to connect to. [Default 2947]
  -p PRESET, --preset PRESET
                        Poll the receiver for PRESET. May be used multiple
  -P PROTVER, --protver PROTVER
                        Protocol version for sending commands. [Default 10.0]
  -r, --readonly        Read only. Do not send anything to the GPS.
  -s SPEED, --inspeed SPEED
                        Set local serial port speed to SPEED bps.
  -S SPEED, --setspeed SPEED
                        Configure receiver speed to SETSPEED.
BSD terms apply: see the file COPYING in the distribution root for details.
Options can be placed in the UBXOPTS environment variable.
UBXOPTS is processed before the CLI options.

Or "ubxtool -t".  Try ubstool both with, and without gpsd running.
Using ubxtool -t when gpsd is running shows 8 and 9 batched UBX-NAV_PVT messages per second.

Notice that the (bold/underlined) arrival times are batched, but that the "nano" times are correctly 100ms apart.

root@999AAAAA:~/gpsd# ./gpsd-3.25.1~dev/clients/ubxtool -t
1729247505.8588
UBX-NAV-PVT:
  iTOW 469910700 time 2024/10/18 10:31:32 valid x37
  tAcc 23 nano 699792212 fixType 3 flags x1 flags2 xea
  numSV 14 lon -21990801 lat 522227097 height 91896
  hMSL 43663 hAcc 1075 vAcc 1243
  velN 3 velE 18 velD -23 gSpeed 19 headMot 643516
  sAcc 130 headAcc 4493776 pDOP 199 reserved1 0 16476 12118
  headVeh 3102272 magDec 0 magAcc 0

1729247505.8604
UBX-NAV-PVT:
  iTOW 469910800 time 2024/10/18 10:31:32 valid x37
  tAcc 23 nano 799792222 fixType 3 flags x1 flags2 xea
  numSV 14 lon -21990799 lat 522227099 height 91930
  hMSL 43698 hAcc 1075 vAcc 1244
  velN -36 velE 29 velD -31 gSpeed 46 headMot 643516
  sAcc 102 headAcc 4493878 pDOP 221 reserved1 0 16476 12118
  headVeh 3102272 magDec 0 magAcc 0

1729247505.8610
UBX-NAV-POSECEF:
  iTOW 469910800 ecefX 391257603 Y -15024309 Z 501809461 pAcc 164

1729247505.8620
UBX-NAV-PVT:
  iTOW 469910900 time 2024/10/18 10:31:32 valid x37
  tAcc 23 nano 899792231 fixType 3 flags x1 flags2 xea
  numSV 14 lon -21990797 lat 522227102 height 91984
  hMSL 43751 hAcc 1075 vAcc 1244
  velN 48 velE 37 velD -47 gSpeed 60 headMot 643516
  sAcc 161 headAcc 4494040 pDOP 221 reserved1 0 16476 12118
  headVeh 3102272 magDec 0 magAcc 0

1729247505.8633
UBX-NAV-PVT:
  iTOW 469911000 time 2024/10/18 10:31:33 valid x37
  tAcc 23 nano -207758 fixType 3 flags x1 flags2 xea
  numSV 14 lon -21990798 lat 522227103 height 91986
  hMSL 43754 hAcc 1076 vAcc 1245
  velN 37 velE -83 velD -29 gSpeed 91 headMot 643516
  sAcc 111 headAcc 4494151 pDOP 221 reserved1 0 16476 12118
  headVeh 3102272 magDec 0 magAcc 0

1729247505.8639
UBX-NAV-DOP:
  iTOW 469911100 gDOP 261 pDOP 221 tDOP 139 vDOP 184
  hDOP 123 nDOP 109 eDOP 58

1729247505.8642
UBX-NAV-TIMEGPS:
  iTOW 469911100 fTOW -207748 week 2336 leapS 18 valid x7 tAcc 3

1729247505.8652
UBX-NAV-PVT:
  iTOW 469911200 time 2024/10/18 10:31:33 valid x37
  tAcc 23 nano 199792261 fixType 3 flags x1 flags2 xea
  numSV 14 lon -21990794 lat 522227104 height 92038
  hMSL 43806 hAcc 1076 vAcc 1246
  velN -43 velE 0 velD -37 gSpeed 43 headMot 643516
  sAcc 95 headAcc 4494359 pDOP 221 reserved1 0 16476 12118
  headVeh 3102272 magDec 0 magAcc 0

1729247505.8657
UBX-NAV-EOE:
 iTOW 469911200

1729247505.8660
UBX-NAV-POSECEF:
  iTOW 469911300 ecefX 391257604 Y -15024305 Z 501809474 pAcc 165

1729247505.8671
UBX-NAV-PVT:
  iTOW 469911400 time 2024/10/18 10:31:33 valid x37
  tAcc 23 nano 399792280 fixType 3 flags x1 flags2 xea
  numSV 13 lon -21990792 lat 522227106 height 92058
  hMSL 43825 hAcc 1076 vAcc 1247
  velN 41 velE 37 velD -12 gSpeed 55 headMot 643516
  sAcc 136 headAcc 4494643 pDOP 221 reserved1 0 16476 12118
  headVeh 3102272 magDec 0 magAcc 0

1729247505.8678
UBX-NAV-POSECEF:
  iTOW 469911400 ecefX 391257604 Y -15024304 Z 501809476 pAcc 165

1729247505.8681
UBX-NAV-VELECEF:
  iTOW 469911400 ecef: VX -2 VY 4 VZ 3 vAcc:14

1729247505.8691
UBX-NAV-PVT:
  iTOW 469911500 time 2024/10/18 10:31:33 valid x37
  tAcc 23 nano 499792290 fixType 3 flags x1 flags2 xea
  numSV 14 lon -21990792 lat 522227105 height 92065
  hMSL 43832 hAcc 1077 vAcc 1248
  velN -43 velE -19 velD -17 gSpeed 47 headMot 643516
  sAcc 109 headAcc 4494752 pDOP 221 reserved1 0 16476 12118
  headVeh 3102272 magDec 0 magAcc 0

1729247505.8703
UBX-NAV-PVT:
  iTOW 469911700 time 2024/10/18 10:31:33 valid x37
  tAcc 23 nano 699792310 fixType 3 flags x1 flags2 xea
  numSV 14 lon -21990789 lat 522227109 height 92140
  hMSL 43908 hAcc 1077 vAcc 1249
  velN -43 velE -60 velD -24 gSpeed 74 headMot 643516
  sAcc 86 headAcc 4494951 pDOP 221 reserved1 0 16476 12118
  headVeh 3102272 magDec 0 magAcc 0

1729247506.9207
UBX-NAV-PVT:
  iTOW 469911800 time 2024/10/18 10:31:33 valid x37
  tAcc 23 nano 799792319 fixType 3 flags x1 flags2 xea
  numSV 14 lon -21990787 lat 522227111 height 92146
  hMSL 43913 hAcc 1077 vAcc 1249
  velN 136 velE 86 velD -2 gSpeed 161 headMot 2099617
  sAcc 135 headAcc 3956064 pDOP 221 reserved1 0 16476 12118
  headVeh 3102272 magDec 0 magAcc 0

1729247506.9222
UBX-NAV-PVT:
  iTOW 469911900 time 2024/10/18 10:31:33 valid x37
  tAcc 23 nano 899792329 fixType 3 flags x1 flags2 xea
  numSV 14 lon -21990787 lat 522227110 height 92151
  hMSL 43918 hAcc 1077 vAcc 1250
  velN -47 velE -35 velD 2 gSpeed 59 headMot 2099617
  sAcc 133 headAcc 3956215 pDOP 221 reserved1 0 16476 12118
  headVeh 3102272 magDec 0 magAcc 0

1729247506.9228
UBX-NAV-POSECEF:
  iTOW 469911900 ecefX 391257607 Y -15024300 Z 501809486 pAcc 165

1729247506.9239
UBX-NAV-PVT:
  iTOW 469912000 time 2024/10/18 10:31:34 valid x37
  tAcc 23 nano -207660 fixType 3 flags x1 flags2 xea
  numSV 14 lon -21990785 lat 522227114 height 92212
  hMSL 43979 hAcc 1077 vAcc 1250
  velN 59 velE -25 velD -26 gSpeed 65 headMot 2099617
  sAcc 168 headAcc 3956406 pDOP 199 reserved1 0 16476 12118
  headVeh 3102272 magDec 0 magAcc 0

1729247506.9245
UBX-NAV-POSECEF:
  iTOW 469912000 ecefX 391257607 Y -15024299 Z 501809493 pAcc 165

1729247506.9254
UBX-NAV-PVT:
  iTOW 469912100 time 2024/10/18 10:31:34 valid x37
  tAcc 23 nano 99792349 fixType 3 flags x1 flags2 xea
  numSV 14 lon -21990785 lat 522227112 height 92206
  hMSL 43973 hAcc 1077 vAcc 1250
  velN -65 velE -28 velD -2 gSpeed 70 headMot 2099617
  sAcc 141 headAcc 3956567 pDOP 204 reserved1 0 16476 12118
  headVeh 3102272 magDec 0 magAcc 0

1729247506.9267
UBX-NAV-PVT:
  iTOW 469912200 time 2024/10/18 10:31:34 valid x37
  tAcc 23 nano 199792359 fixType 3 flags x1 flags2 xea
  numSV 14 lon -21990783 lat 522227114 height 92225
  hMSL 43993 hAcc 1078 vAcc 1251
  velN 29 velE 49 velD 8 gSpeed 57 headMot 2099617
  sAcc 93 headAcc 3956672 pDOP 204 reserved1 0 16476 12118
  headVeh 3102272 magDec 0 magAcc 0

1729247506.9279
UBX-NAV-PVT:
  iTOW 469912300 time 2024/10/18 10:31:34 valid x37
  tAcc 23 nano 299792368 fixType 3 flags x1 flags2 xea
  numSV 14 lon -21990782 lat 522227119 height 92302
  hMSL 44070 hAcc 1078 vAcc 1251
  velN 54 velE -41 velD -19 gSpeed 67 headMot 2099617
  sAcc 148 headAcc 3956841 pDOP 204 reserved1 0 16476 12118
  headVeh 3102272 magDec 0 magAcc 0

1729247506.9291
UBX-NAV-PVT:
  iTOW 469912400 time 2024/10/18 10:31:34 valid x37
  tAcc 23 nano 399792378 fixType 3 flags x1 flags2 xea
  numSV 14 lon -21990782 lat 522227116 height 92281
  hMSL 44048 hAcc 1078 vAcc 1251
  velN -75 velE -26 velD 16 gSpeed 80 headMot 2099617
  sAcc 161 headAcc 3957024 pDOP 204 reserved1 0 16476 12118
  headVeh 3102272 magDec 0 magAcc 0

1729247506.9304
UBX-NAV-PVT:
  iTOW 469912500 time 2024/10/18 10:31:34 valid x37
  tAcc 23 nano 499792388 fixType 3 flags x1 flags2 xea
  numSV 13 lon -21990779 lat 522227122 height 92364
  hMSL 44131 hAcc 1078 vAcc 1251
  velN 81 velE 13 velD -25 gSpeed 82 headMot 2099617
  sAcc 174 headAcc 3957222 pDOP 204 reserved1 0 16476 12118
  headVeh 3102272 magDec 0 magAcc 0

1729247506.9316
UBX-NAV-PVT:
  iTOW 469912600 time 2024/10/18 10:31:34 valid x37
  tAcc 23 nano 599792398 fixType 3 flags x1 flags2 xea
  numSV 13 lon -21990779 lat 522227121 height 92364
  hMSL 44132 hAcc 1078 vAcc 1252
  velN -26 velE -19 velD -7 gSpeed 32 headMot 2099617
  sAcc 111 headAcc 3957349 pDOP 204 reserved1 0 16476 12118
  headVeh 3102272 magDec 0 magAcc 0

 
without gpsd running.
Using ubxtool -t when gpsd is stopped:

root@999AAAAA:~/gpsd# ./gpsd-3.25.1~dev/clients/ubxtool -t
ubxtool: failed to connect to gpsd [Errno 111] Connection refused

Can I make ubxtool connect directly to /dev/ttymxc1, without gpsd?  I tried:

root@999AAAAA:~/gpsd# ./gpsd-3.25.1~dev/clients/ubxtool --device=/dev/ttymxc1
ubxtool: failed to connect to gpsd [Errno 111] Connection refused


All the best, Chris.



On 16/10/2024 21:08, Gary E. Miller wrote:
Yo Chris!

On Wed, 16 Oct 2024 10:46:11 +0100
Chris Dew <chris.dew@thorcom.co.uk> wrote:


    what version gpsd,  

root@C934E761:~# gpsd --version
gpsd: *3.22* (revision 3.22)

That is almost 4 year old.  A lot of fix and improvements since then


    gpsd binary from where,  

root@C934E761:~# dpkg --list | grep gpsd | head -1
ii  gpsd 3.22-4+devuan2                     arm64        Global 
Positioning System - daemon

You need to file a bug with them.  Shame on them for shipping old stuff.


    what hardware are you running on  

iMX8M

That is a family name, not a model number.  What model number?
Quad core?  A a lot of unused CPU?


    what command line to start gpsd,  

root@C934E761:~# ps -ef | grep gpsd | head -1
gpsd      3332     1  0 08:10 ?        00:00:07 /usr/sbin/gpsd -n -P 
/run/gpsd.pid */dev/ttymxc1

Should be fine, what is that asterisk doing there?


    serial or USB connection,  

serial

What speed?


    how are you measuring "arrival"  

By eyeball.  Do you know of a time-stamping gpsd client?

Many good ways.  "gpspipe -w -t", or send the gpsd log to a timestamping
syslog.  Or "ubxtool -t".  Try ubstool both with, and without gpsd running.

Or, run gpsd under strace.


Could you suggest a way that I could see whether the traffic from 
/dev/ttymxc1 into gpsd is also batched?  This might be a ublox issue, 
rather than gpsd.

Send the output of "ubxtool -P CONFIG" and "ubxtool -P STATUS"

But, before you do any of that, update to gpsd 3.25 or better yet git head.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem@rellim.com  Tel:+1 541 382 8588

	    Veritas liberabit vos. -- Quid est veritas?
    "If you can't measure it, you can't improve it." - Lord Kelvin

--

Chris Dew / Senior Developer
Email: chris.dew@thorcom.co.uk

Thorcom Systems Limited
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