Message Type 136, $PACCEL

Proprietary NMEA message containing hard acceleration/deceleration information obtained from GPS velocity or accelerometer data. This NMEA message is designed to be sent whenever the GPS hard acceleration/deceleration thresholds are exceeded (see cmd accelsensor? cmd gpsaccel?).

PACCEL contains data obtained from the sensor configured in cmd accelsensor?.

Message format is:

$PACCEL,hhmmss.ss, llll.llll,a,yyyyy.yyyy,b,vvv.v,uuu.u,ddmmyy,ggggggggggg*hh<CR><LF>

Where:

hhmmss.ss is the UTC time in hours, minutes, seconds, and decimal seconds

llll.llll is the position latitude in degrees, minutes and decimal minutes

a is N(orth) or S(outh)

yyyyy.yyyy is the position longitude in degrees, minutes and decimal minutes

b is E(ast) or W(est)

vvv.v is the velocity in km/h

uuu.u is the acceleration/deceleration in km/h/s

ddmmyy is the day, month and year

ggggggggggg is the modems ID

hh is the message checksum

Example:

$PACCEL,161059.00,4915.4209,N,12259.8663,W,018.8,-04.0,260411,09604204933*15[0x0D][0x0A]

In the above example the recorded acceleration/deceleration value is -4.0 km/hr/sec, or -1.11 m/s^2.

A reasonable value to set for a "hard" acceleration event should be around 10 km/hr/sec or 2.77 m/s² (10/3.6=2.77)

1g = 9.8 m/s² would be 35.3 km/hr/sec. For comparison, an extremely fast sports car is capable of 0-100 Kph acceleration of 7.6 m/s² or 27.4 km/hr/sec.

from 60 mph or 96kph on dry roads the typically emergency brake time to stop on dry roads is about 5 seconds this correlates to 19.2 km/hr/sec, a typical hard brake value should be around 15 km/hr/sec

for controlled hard braking the maximum deceleration on dry roads is about 15 fps or 16.5 km/hr so 15 km/hr/sec is a good value for a hard brake value