RXM-GPS-SG-T Linx Technologies Inc, RXM-GPS-SG-T Datasheet - Page 3

• Manufacturer Part Number: RXM-GPS-SG-T
• Description: GPS MODULE SMD SIRF
• Manufacturer: Linx Technologies Inc
• Series: SGr
• Type: GPS Moduler

Specifications of RXM-GPS-SG-T

• Package / Case: Module
• Operating Voltage: 4.2 V
• Operating Current: 46 mA
• Frequency Range: 1575.42 MHz
• Interface Type: UART, USB
• Operating Temperature Range: - 30 C to + 85 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Voltage - Supply: -
• Frequency: -
• Operating Temperature: -
• Applications: -
• Sensitivity: -
• Memory Size: -
• Data Interface: -
• Data Rate - Maximum: -
• Modulation Or Protocol: -
• Antenna Connector: -
• Current - Receiving: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

PIN ASSIGNMENTS
Figure 2: SG Series Receiver Pinout (Top View)
PIN DESCRIPTIONS
Page 4
18,20-22
1, 2, 16
Pin #
10
11
12
13
14
15
17
19
3
4
5
6
7
8
9
RFPWRUP
VBACKUP
ON_OFF
Name I/O
GPIO10
LCKIND
GPIO14
GPIO15
GPIO13
GPIO1
VOUT
1PPS
RFIN
VCC
GND
TXA
RXA
NC
I/O
I/O
I/O
I/O
I/O
O
O
O
O
P
P
P
P
–
I
I
I
1
2
3
4
5
21
6
7
8
9
10
used to wake up the module when the RFPWRUP line
NC
NC
1PPS
TXA
RXA
GND
GPIO10
LCKIND
GPIO1
RFPWRUP
ON_OFF
Edge triggered soft on/off request. Should only be
Backup battery supply voltage. This line must be
Serial output for channel A (default NMEA)
Serial input for channel A (default NMEA)
General Purpose I/O, 100kΩ pull down
No Connect. No electrical connection.
General Purpose I/O, 100kΩ pull up
General Purpose I/O, 100kΩ pull up
2.85V Linear regulator power output
powered to enable the module.
Pulse per second (1uS pulse)
VBACKUP
General Purpose I/O
General Purpose I/O
GPS RF signal input
Indicate power state
GPIO13
GPIO15
GPIO14
Description
VOUT
Supply Voltage
RFIN
GND
GND
GND
VCC
Lock Indicator
NC
Ground
is low.
20
19
18
17
16
22
15
14
13
12
11
A BRIEF OVERVIEW OF GPS
The Global Positioning System (GPS) is a U.S.-owned utility that freely and
continuously provides positioning, navigation, and timing (PNT) information.
Originally created by the U.S. Department of Defense for military applications,
the system was made available without charge to civilians in the early 1980s.
The global positioning system consists of a nominal constellation of 24 satellites
orbiting the earth at about 12,000 nautical miles in height. The pattern and
spacing of the satellites allow at least four to be visible above the horizon from
any point on the Earth. Each satellite transmits low power radio signals which
contain three different bits of information; a pseudorandom code identifying the
satellite, ephemeris data which contains the current date and time as well as the
satellite’s health, and the almanac data which tells where each satellite should
be at any time throughout the day.
A GPS receiver such as the Linx SG Series GPS module receives and times the
signals sent by multiple satellites and calculates the distance to each satellite. If
the position of each satellite is known, the receiver can use triangulation to
determine its position anywhere on the earth. The receiver uses four satellites to
solve for four unknowns; latitude, longitude, altitude, and time. If any of these
factors is already known to the system, an accurate position (Fix) can be
obtained with fewer satellites in view. Tracking more satellites improves
calculation accuracy. In essence, the GPS system provides a unique address for
every square meter on the planet.
A faster Time To First Fix (TTFF) is also possible if the satellite information is
already stored in the receiver. If the receiver knows some of this information,
then it can accurately predict its position before acquiring an updated position fix.
For example, aircraft or marine navigation equipment may have other means of
determining altitude, so the GPS receiver would only have to lock on to three
satellites and calculate three equations to provide the first position fix after
power-up.
TTFF is often broken down into three parts:
Cold: A cold start is when the receiver has no accurate knowledge of its position
or time. This happens when the receiver’s internal Real Time Clock (RTC) has
not been running or it has no valid ephemeris or almanac data. In a cold start,
the receiver takes 35 to 40 seconds to acquire its position. If new almanac data
is required, this may take up to 15 minutes (see page 9 for more details).
Warm or Normal: A typical warm start is when the receiver has valid almanac
and time data and has not significantly moved since its last valid position
calculation. This happens when the receiver has been shut down for more than
2 hours, but still has its last position, time, and almanac saved in memory, and
its RTC has been running. The receiver can predict the location of the current
visible satellites and its location; however, it needs to wait for an ephemeris
broadcast (every 30 seconds) before it can accurately calculate its position.
Hot or Standby: A hot start is when the receiver has valid ephemeris, time, and
almanac data. This happens when the receiver has been shut down for less than
2 hours and has the necessary data stored in memory with the RTC running. In
a hot start, the receiver takes 1 to 2 seconds to acquire its position. The time to
calculate a fix in this state is sometimes referred to as Time to Subsequent Fix
or TTSF.
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