OmniSTAR 5220HP, Руководство пользователя

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OmniSTAR 5220HP User Manual
Issue 1.32 12/2010
42
$JMASK
The system masks control whether or not the receiver will use a
certain GPS satellite for its position calculations. Since the signals of
low-elevation satellites have a larger distance to travel, the signals of
those satellites will be weaker and may cause a larger position error
than the signals of satellites at higher elevations.
By default, all satellites with a signal to noise ratio of 37dB or less
and all satellites with an elevation below 5 degrees will not be used
in the position calculations. Valid SNR values lie between 10 and 60,
valid elevation values lie between 0 (satellite at horizon) and 90
(degrees).
The default angle is 5 degrees, as satellites available below this
angle will have significant tropospheric refraction errors.
This command has the following layout:
$JMASK,E<CR><LF>
The variable ‘E’ is the elevation mask cut-off angle. The value of ‘E’
may vary from 0 to 60 degrees.
The receiver will reply with the following response:
$>
$JNP
This command allows the user to specify the number of decimal
places in the output for latitude and longitude of the NMEA
messages such as GGA, GLL and RMC.
This command has the following layout:
$JNP,X<CR><LF>
'X' specifies the number of decimal places from 1 to 8. (default = 5)
This command will affect the GGA, GLL as well as the RMC
messages.
The receiver will reply with the following response:
$>