LA000504D © 2006 Navman New Zealand. All rights reserved. Proprietary information and specifications subject to change without notice.
3.0 Performance characteristics
3.1 TTFF (Time To First Fix)
TTFF is the actual time required by a GPS receiver to achieve a position solution. This
specification will vary with the operating state of the receiver, the length of time since the last
position fix, the location of the last fix, and the specific receiver design.
3.1.1 Hot start
A hot TTFF results from a software reset after a period of continuous navigation or a return
from a short idle period (i.e. a few minutes) that was preceded by a period of continuous
navigation. In this state, all of the critical data (position, time and satellite ephemeris) is valid
to the specified accuracy and available in SRAM.
3.1.2 Warm start
A warm TTFF typically results from user-supplied position and time initialisation data or
continuous RTC operation with an accurate last known position available. In this state,
position and time data are present and valid but ephemeris data validity has expired.
3.1.3 Cold start
A cold TTFF acquisition state results when position or time data is unknown. Almanac
information stored in Flash memory is used to identify previously healthy satellites.
3.2 Acquisition times
Table 3-1 shows the corresponding TTFF times for each of the acquisition modes.
Mode
J110/J110R
J110S/J110RS
Typ
90%
Typ
90%
TTFF hot (valid almanac, position, time & ephemeris)
8 s
12 s
8 s
12 s
TTFF warm (valid almanac, position & time)
38 s
42 s
38 s
40 s
TTFF cold (valid almanac)
44 s
55 s
45 s
56 s
re-acquisition (<10 s obstruction with valid almanac,
position, time & ephemeris)
100 ms 100 ms 100 ms 100 ms
Table 3-1: Acquisition times
3.3 Battery backup
The battery backup input line powers the RTC section of the baseband receiver. Supplying
power to this pin is required for normal operation and ensures that the RTC continues to operate
even when the main power is interrupted. Refer to Table 4-1 for the Jupiter 110 battery backup
supply voltages.
3.4 Power management
During normal operating mode the Jupiter 110 runs continuously, providing a navigation solution
at a maximum rate of once per second. This continuous mode provides no power saving. For
power saving, TricklePower mode can be set using NMEA or SiRF Binary messages.
3.4.1 TricklePower mode
The TricklePower mode can be enabled to reduce average power consumption. The main
power is supplied to the module continuously. An internal timer wakes the processor from
sleep mode. The module computes a navigation position fix, after which the processor
reverts to sleep mode. The duty cycle is controlled by a user-configurable parameter.
If ephemeris data become outdated, the TricklePower mode will attempt to refresh the data
set within every 30 minute period, or for every new satellite that comes into view.
With TricklePower set to a 20% duty cycle, a power saving of 50% can easily be achieved
with minimal degradation in navigation performance.
In Adaptive TricklePower mode, the processor automatically returns to full power when signal
levels are below the level at which they can be tracked in TricklePower mode.
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