Wave-radio iGPS-M, User Manual

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iGPS-M USER’S MANUAL
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GSV – Satellites in view
Number of satellites in view, satellite ID (PRN) numbers, elevation, azimuth, and
SNR value. The information for four satellites maximum per one m essage, additional
messages up to maximum of eight sent as needed. The satellites are in PRN number order.
Before a position fix is acquired the information contains only the SNR (signal to
noise ratio) value. After a fix is acquired, also the elevation and azimuth angles
are added. Note that there can be also “theoretical” satellites in the GSV message.
These are satellites of which the angles (elevation, azimuth) are known but for some
reason, e.g. due to an obstruction, have not been found by iTrax02. The
SNR value for these satellites is therefore zero.
Format: $GPGSV,n,m,ss,xx,ee,aaa,cn,…………. ,xx,ee,aaa,cn*hh<CR><LF>
Example:
$GPGSV,4,1,14,03,66,207,50,08,09,322,44,11,01,266,42,14,00,155,00*79
$GPGSV,4,2,14,15,41,088,48,17,21,083,44,18,57,087,51,21,57,173,50*78
$GPGSV,4,3,14,22,05,203,00,23,52,074,49,26,17,028,44,27,00,300,00*79
$GPGSV,4,4,14,28,32,243,00,31,48,286,00*70
Note: There are 14 satellites in view. The examples in following table only explain
the information of satellite No.03 on the first message.
Parameter Description Example
n Total number of messages, 1 to 9 4 messages
m Message number, 1 to 9 Message No.1
ss Total number of satellites in view 14 satellites
xx Satellite ID (PRN) number No.03
ee Satellite elevation, degrees 90 max 66 deg.
aa Satellite azimuth, degrees True, 000 to 359 207 deg.
cn SNR ( C/No) 00-99 dB-Hz. zero when not tracking 50 dB-Hz
hh Check sum 79
PFST,FOM – Position figure of merit
Figure of merit (FOM) value for the position fix. Indicates the accuracy of the position
in meters. The FOM value cannot be calculated before at least one fix has been made
with more than four observations (five satellites, or four satellites and an altitude
aid); before that a value “ –1” is reported, indicating that FOM is not available yet.
After this the FOM value is always available the only exception being the altitude
aiding modes when a fix has been calculated using three satellites.
Format: $PFST,FOM,n*hh<CR><LF>
Example: $PFST,FOM,3*66
Parameter Description Example
n Position FOM value,
i.e. the position accuracy in meters.
3 meters
hh Check sum 66