innomar SES smart - Get Values from NMEA Data

90 User’s Manual Innomar SES Parametric Sub-bottom Profilers
90 Innomar Technologie GmbH (2020-09)
6.3.2 Get values from NMEA data
In most cases you will get NMEA-like navigation data. That is an ASCII text string starting with a
$-symbol and closing with carriage return and line feed. Values within the string are comma sep-
arated. Examples for typical NMEA data delivered by GNSS receivers are given in appendix A.13
on page 185.
If a GNSS receiver is connected directly to the INNOMAR system usually GGA sentence is used
to get UTC time and position. Additionally, VTG is often used to get speed information.
Let’s assume you get 2 different NMEA sentences (GGA, VTG) like in the following example and
you need position, time, speed and some information about GNSS data quality to be recorded
with your SES data:
$GPGGA,145502.20,5406.62679,N,01204.13714,E,2,05,2.9,22.06,M,38.87,M,4,0000*6E
$GPVTG,000.00,T,358.15,M,000.01,N,000.02,K,D*2F
$GPGGA,145502.40,5406.62680,N,01204.13713,E,2,05,2.9,22.08,M,38.87,M,4,0000*67
$GPVTG,187.08,T,185.22,M,000.07,N,000.12,K,D*28
Position is to be found in the GGA string:
 Latitude on the second value (position 2)
 Longitude on the fourth value (position 4)
$GPGGA,145502.20,5406.62679,N,01204.13714,E,2,05,2.9,22.06,M,38.87,M,4,0000*6E
Time can be taken from position 1 of GGA (time of position fix):
$GPGGA,145502.20,5406.62679,N,01204.13714,E,2,05,2.9,22.06,M,38.87,M,4,0000*6E
Speed can be taken from VTG string (position 5); unit is given in position 6:
$GPVTG,187.08,T,185.22,M,000.07,N,000.12,K,D*28
Information about GNSS data quality can be found in the GGA string:
 GNSS quality indicator (position 6)
 Number of satellites in use (position 7)
 Horizontal dilution of Position (position 8)
$GPGGA,145502.20,5406.62679,N,01204.13714,E,2,05,2.9,22.06,M,38.87,M,4,0000*6E
For recording the values within the SES data there are 8 so-called SIS strings available that can
hold up to 11 characters each. To get the values marked in the incoming NMEA data above into
the SIS strings as follows
SIS 1 Longitude (from GGA position 4)
SIS 2 Latitude (from GGA position 2)
SIS 3 Time (UTC from GGA position 1 or ZDA position 6)
SIS 4 Speed in knots (from VTG position 5)
SIS 5 Information about GNSS quality and position error (GGA position 6-8)
SIS 6 GNSS antenna height from GGA position 9
SIS 7 like SIS 1 (may be later exchanged with UTM coordinates)
SIS 8 like SIS 2 (may be later exchanged with UTM coordinates)
!
At least the three first items are required as minimum information (LON, LAT, UTC).
For the above example you need to set the values according to the screenshot below.