• VL-MPEu-G2 Reference Manual
• Neo-7 Data Sheet
• u-blox 7 Receiver Description: Including Protocol Specification V14

• Install the VL-MPEu-G2 module.
• Start the PC Engines APU.
• Test serial data.

  stty -F /dev/ttyACM0 ispeed 4800 && cat </dev/ttyACM0
  
  $GPTXT,01,01,02,u-blox ag - www.u-blox.com*50
  $GPTXT,01,01,02,HW  UBX-G70xx   00070000 EFFFFFFFo*1B
  $GPTXT,01,01,02,EXT CORE 1.00 (59843) Jun 27 2012 18:25:33*49
  $GPTXT,01,01,02,ROM BASE 1.00 (59842) Jun 27 2012 17:43:52*57
  $GPTXT,01,01,02,MOD NEO-7N-0*26
  $GPTXT,01,01,02,PROTVER 14.00*1E
  $GPTXT,01,01,02,ANTSUPERV=AC SD PDoS SR*20
  $GPTXT,01,01,02,ANTSTATUS=OK*3B
  $GPTXT,01,01,02,FIS 0xBF2601 found*2E
  $GPTXT,01,01,02,LLC FFFFFFFF-FFFFFFED-FFFFFFFF-FFFFFFFF-FFFFFF69*20
  $GPRMC,173337.00,A,5150.86536,N,00420.44234,E,0.203,,190614,,,A*74
  $GPVTG,,T,,M,0.203,N,0.376,K,A*20
  $GPGGA,173337.00,5150.86536,N,00420.44234,E,1,04,7.34,15.3,M,46.0,M,,*63
  $GPGSA,A,3,16,31,27,21,,,,,,,,,11.98,7.34,9.48*35
  $GPGSV,3,1,11,03,16,279,21,05,04,022,,07,07,337,12,16,66,287,44*7F
  $GPGSV,3,2,11,18,28,130,23,19,08,268,,21,69,093,30,22,08,163,16*7A
  $GPGSV,3,3,11,27,39,275,31,29,20,086,,31,08,200,31*49
  $GPGLL,5150.86536,N,00420.44234,E,173337.00,A,A*67

• Install prerequisite packages.

  yum install chrpath scons libxslt-devel ncurses-devel asciidoc python-devel

• Download source code from: https://savannah.nongnu.org/projects/gpsd/
• Extract.

  tar zxvf gpsd-3.10.tar.gz

• Compile.

  cd gpsd-3.10
  scons prefix=/opt/gpsd
  sudo scons udev-install

• Test gpsd.

  gpsd -D 5 -N -n /dev/ttyACM0

# Allow more distance between GPS (USB) and Serial PPS.
# Stratum level 12 when no ref source available
tos mindist 0.010 orphan 12

driftfile /var/lib/ntp/ntp.drift

statsdir /var/log/ntpstats/

statistics loopstats peerstats clockstats
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
filegen clockstats file clockstats type day enable

# Local servers
server ntp1.polaire.nl
server ntp2.polaire.nl
server ntp3.home.polaire.nl

# ATOM PPS (/dev/pps0)
server 127.127.22.0 minpoll 4 maxpoll 4
fudge  127.127.22.0 refid PPS

# GPS (USB /dev/ttyACM0)
server 127.127.28.0 minpoll 4 maxpoll 4 prefer
fudge 127.127.28.0 refid GPSd
fudge 127.127.28.0 time1 0.065

# By default, exchange time with everybody, but don't allow configuration.
restrict -4 default kod notrap nomodify nopeer noquery
restrict -6 default kod notrap nomodify nopeer noquery

# Local users may interrogate the ntp server more closely.
restrict 127.0.0.1
restrict ::1