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MN002000A © 2004 Navman NZ Ltd. All rights reserved. Proprietary information and specifications subject to change without notice.
Message ID: GSA
Rate: variable
Fields: 17
Field No. Symbol Field description Field type Example
$_GSA Start of sentence and address field $GPGSA
1 OP _MODE Mode (Note 1) a A
2 FIX_MODE Mode (Note 2) x 3
3-14 SATN PRNs of satellites used in solution (null for unused fields) xx,xx,.... 04, 16, 09, 24...
15 PDOP Position dilution of precision (Note 3) x.x 3.33
16 HDOP Horizontal dilution of precision (Note 3) x.x 1.96
17 VDOP Vertical dilution of precision (Note 3) x.x 2.70
CKSUM Checksum *hh *06
<CR><LF> Sentence terminator <CR><LF>
Note 1: Mode (operating), M = manual (forced to operate in 3D mode), A = automatic (can automatically switch between 2D and
3D).
Note 2: Mode (fix), 1 = fix not available, 2 = 2D, 3 = 3-D
Note 3: DOPs are based on the set of satellites above the elevation mask angle, this may differ from the set used for navigation.
Table 3-48 GSA message (GPS DOP and active satellites)
Message ID: GSV
Rate: variable; defaults to 0.5 Hz
Fields: 19
Field No. Symbol Field description Field type Example
$_GSV Start of sentence and address field $GPGSV
1 MAX_MSG Total number of messages (1 to 3) X 2
2 NUM_MSG message number (1 to 3) X 1
3 NUM_SATS Total number of satellites in view Xx 07
4 SAT_PRN Satellite PRN number (Note 1) Xx 24
5 ELEV Elevation in degrees (90 degrees maximum) (Note 2) Xx 60
6 AZ Azimuth in true degrees (000 to 359) (Note 2) Xxx 216
7 SNR SNR (C/No) 00 to 99 dB, null when not tracking Xx 50
8-11 ... 2nd satellite PRN number, elevation, azimuth, SNR (Note 1) xx, xx, xxx, xx ...
12-15 ... 3rd satellite PRN number, elevation, azimuth, SNR (Note 1) xx, xx, xxx, xx ...
16-19 ... 4th satellite PRN number, elevation, azimuth, SNR (Note 1) xx, xx, xxx, xx ...
CKSUM Checksum *hh *75
<CR><LF> Sentence terminator <CR><LF>
Note 1: The visible satellites may include one or more that are below the horizon. Since NMEA does not account for negative
elevation angles, the elevation field will be null for these satellites.
Note 2: Azimuth and elevation are null when the satellite is in track, but a visible list is not available.
Table 3-49 GSV message (GPS satellites in view)
5.6.1.4 GPS satellites active and DOP (GSA) .
This message contains the Jupiter receiver’s
operating mode, satellites used for navigation, and
DOP values. The contents of the ‘GSA’ message
are described in Table 3-48.
Sample message:
$GPGSA,A,3,04,16,09,24,,,,,3.33,1.96,2.70*
06
3.6.1.5 GPS satellites in view (GSV)
This message contains the number of satellites
in view, PRN numbers, elevation, azimuth,
and Signal-to-Noise Ratio (SNR) values. Each
transmission identifies up to four satellites (max);
additional satellite data is sent in a second or third
message. The total number of messages being
transmitted and the number of the message being
transmitted is indicated in the first two fields. The
contents of the ‘GSV’ message are described in
Table 3-49.
Sample message:
$GPGSV,2,1,07,24,60,216,50,20,47,135,47,12,
40,020,47,16,36,319,46*75