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LA000577C © 2006 Navman New Zealand. All rights reserved. Proprietary information and specications subject to change without notice.
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3.7 Antenna power monitor messages
The Jupiter software includes antenna monitor messages driven by the state of the antenna
monitor inputs. The inputs NANT_SC (short circuit detect – active low) and ANT_OC (open
circuit detect – active high) are congured as inputs, and ANT_CTRL (active antenna control) is
congured as an output.
If the function of any of these pins is overridden using the procedure described in Section 3.6,
then this feature is disabled. However if an antenna short circuit has occurred before any pins
are overridden in this manner, the status will continue to be reported as ‘short circuit’ until such
time as the active antenna control output is overridden.
In normal operation, the active antenna control output is high. If the short circuit detect pin goes
low, the active antenna control signal will go low. This condition is latched until the user resets
the module.
The active antenna control pin output is low when the receiver enters a low power mode due to
TricklePower, Push-to-Fix or APM, and returns to its previous state when the receiver starts up
again. No checking of the antenna current is performed while the output is low for this reason.
The antenna status output message is an NMEA message in the form:
$PTTK,ANT,d*CS
Where
d represents any of the following numbers:
d Description
0 normal antenna operation
1 antenna open circuit
2 antenna short circuit - antenna disabled
-1
antenna sensing disabled (due to GPIO
override)
Table 3-4: Antenna status output message values
The antenna status message is output automatically in the event of a short circuit or open circuit
being detected, or an open circuit condition coming to an end.
In addition, this message is output on the receipt of the NMEA input message:
$PSRF199[*CS]
The antenna status is also output as the SiRF binary message with message ID 99. It contains
one byte of data, being the appropriate value from Table 3-4. This gives a payload length of
2 bytes, since the message ID is considered part of the payload.
The antenna status message is output automatically in the event of a short circuit, or open circuit
being detected, or an open circuit condition coming to an end.
In addition, this message is output on the receipt of the SiRF binary message with message ID
199. The output rate of this message is also under the normal control of the SiRF Binary Query/
Rate Control input message, however this message is not output at a regular rate by default.
3.8 Custom application software
The module provides custom modication of the rmware to use available CPU processing
capacities and I/O capabilities. The custom application software can be invoked internally or
externally, providing the ability to dedicate the module as the host application or an external
processor as the host. The module also provides the ability to communicate externally with
standard or customer specic communication protocols.
The custom application software has access to the ash memory, navigation data from the GPS
Navigation software, and access to various I/O lines used on the module.
This can be developed using the SiRF SDK. The SDK provides all the tools and resources
necessary for custom software development. Refer to http://www.sirf.com for more information
about the SDK.