RXM-GPS-F4-T Linx Technologies, RXM-GPS-F4-T Datasheet - Page 17

no-image

RXM-GPS-F4-T

Manufacturer Part Number
RXM-GPS-F4-T
Description
GPS Modules F4 Series GPS Recvr Module Tape and Reel
Manufacturer
Linx Technologies
Datasheet

Specifications of RXM-GPS-F4-T

Rohs
yes
Frequency Band
1575.42 MHz
Number Of Channels
48
Time To First Fix (cold Start)
32 s
Acquisition Sensitivity
- 159.5 dBm
Horizontal Position Accuracy
3 m
Operating Supply Voltage
1.8 V
Operating Supply Current
56 mA
Interface Type
Serial
Maximum Operating Temperature
+ 85 C
Mounting Style
SMD/SMT
Dimensions
15 mm x 13 mm x 2.2 mm
Minimum Operating Temperature
- 30 C
Slow Start Time
The most critical factors in start time are current ephemeris data, signal
strength and sky view. The ephemeris data describes the path of each
satellite as they orbit the earth. This is used to calculate the position of
a satellite at a particular time. This data is only usable for a short period
of time, so if it has been more than a few hours since the last fi x or if the
location has signifi cantly changed (a few hundred miles), then the receiver
may need to wait for a new ephemeris transmission before a position can
be calculated. The GPS satellites transmit the ephemeris data every 30
seconds. Transmissions with a low signal strength may not be received
correctly or be corrupted by ambient noise. The view of the sky is important
because the more satellites the receiver can see, the faster the fi x and the
more accurate the position will be when the fi x is obtained.
If the receiver is in a very poor location, such as inside a building, urban
canyon, or dense foliage, then the time to fi rst fi x can be slowed. In very
poor locations with poor signal strength and a limited view of the sky with
outdated ephemeris data, this could be on the order of several minutes.
In the worst cases, the receiver may need to receive almanac data, which
describes the health and course data for every satellite in the constellation.
This data is transmitted every 15 minutes. If a lock is taking a long time, try
to fi nd a location with a better view of the sky and fewer obstructions. Once
locked, it is easier for the receiver to maintain the position fi x.
Protocols
Linx GPS modules use the SiRFstar IV chipset. This chipset allows two
protocols to be used, NMEA-0183 and SiRF Binary. Switching between the
two is handled using a single serial command. The NMEA protocol uses
ASCII characters for the input and output messages and provides the most
common features of GPS development in a small command set. The SiRF
Binary protocol uses BYTE data types and allows more detailed control
over the GPS receiver and its functionality using a much larger command
set. Although both protocols have selectable baud rates, it’s recommended
that SiRF Binary use 115,200bps. For a detailed description of the SiRF
Binary protocol, see the SiRF Binary Protocol Reference Manual, available
from SiRF Technology, Inc.
Note:
Linx only offers tech support for the NMEA protocol.
Although SiRF Binary protocol may be used with the module,
13

Related parts for RXM-GPS-F4-T