Some notes on using ubxtool to configure a u-blox GNSS receiver for timing applications.

References:

• https://gpsd.io/ubxtool-examples.html
• https://gpsd.gitlab.io/gpsd/ubxtool.html
• https://www.u-blox.com/sites/default/files/NEO-M9N_Interfacedescription_%28UBX-19035940%29.pdf
• https://www.u-blox.com/sites/default/files/products/documents/u-blox8-M8_ReceiverDescrProtSpec_UBX-13003221.pdf

Crank up the baud rate

ubxtool -S 115200

(Will probably have to restart GPSD aftwards)

Set the power management setting to full power

ubxtool -p CFG-PMS,0

Export protocol version and verbrosity

export UBXOPTS="-P 22.00 -v2"

v3 verbosity includes the raw hex values!

Class x06 (CFG) ID x24 (NAV5), len: 0x24
header: b5,62,06,24,24,00
payload: 01,00,02,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00
chksum: 51,2c
UBX-CFG-NAV5:
 mask 0x1 dynModel 2 fixmode 0 fixedAlt 0 FixedAltVar 0
 minElev 0 drLimit 0 pDop 0 tDop 0 pAcc 0 tAcc 0
 staticHoldThresh 0 dgpsTimeOut 0 cnoThreshNumSVs 0
 cnoThresh 0 res 0 staticHoldMaxDist 0 utcStandard 0
 reserved x0 0
   dynModel (Stationary) fixMode (Unk) utcStandard (Default)
   mask ()

Set model to stationary

ubxtool -p MODEL,2

ubxtool -S 38400
ubxtool -e BINARY
ubxtool -d NMEA
ubxtool -d GLONASS
ubxtool -p MODEL,2
ubxtool -p CFG-PMS,0

#!/bin/bash
# Init MAX-M8Q

# set protver
export UBXOPTS="-P 18.00"

# Enable UBX format, disable NMEA
ubxtool -e BINARY
ubxtool -d NMEA

# Disable GLONASS
ubxtool -d GLONASS

# Switch to stationary & full power mode
ubxtool -p MODEL,2
ubxtool -p CFG-PMS,0

# set baud rate & serial port speed
gpsctl -s 38400

Export options

export UBXOPTS="-P 22 -v2"

Survey

ubxtool -e SURVEYIN,3600,500000

Time in seconds, accuracy in 0.1mm increments.

Check survey status:

ubxtool -p TIM-SVIN | grep SVIN -A 2

UBX-TIM-SVIN:
  dur 31 meanX 163983910 meanY -422921845 meanZ 446887812 meanV 1415408128
  obs 32 valid 0 active 1

Save

ubxtool -p SAVE

#!/bin/bash
# Init MAX-M8Q

# set protver
export UBXOPTS="-P 22.00"

# Enable UBX format, disable NMEA
ubxtool -e BINARY
ubxtool -d NMEA

# Disable GLONASS
ubxtool -d GLONASS

# Switch to stationary & full power mode
ubxtool -p MODEL,2
ubxtool -p CFG-PMS,0

# set baud rate & serial port speed
gpsctl -s 115200

Use configuration items!

ubxtool -g CFG-NAVSPG,0

Enable 2D only fix mode:

ubxtool -z CFG-NAVSPG-FIXMODE,1

Manually specify MSL altitude (in meters)

ubxtool> -z CFG-NAVSPG-CONSTR_ALT,35

Manually specify the allowed altitude variance

ubxtool> -z CFG-NAVSPG-CONSTR_ALTVAR,10000

(this is already set and doesn't need to be changed)