Using Gps By Nmea Port; Pcm Interface - SimCom SIM5218E Hardware Design

SIM5218E Hardware Design
In standalone (autonomous) mode, the handset demodulates the data directly from the GPS
satellites. This mode has some reduced cold-start sensitivity, and a longer time to first fix as
compared to the assisted modes. However, it requires no server interaction and works out of
network coverage.
This combination of GPS measurements and available network information provides:
■High-sensitivity solution that works in all terrains: indoor, outdoor, urban, and rural
■High availability that is enabled by using both satellite and network information
Therefore, while network solutions typically perform poorly in rural areas and areas of poor cell
geometry/density, and while unassisted, GPS-only solutions typically perform poorly indoors, the
SIM5218E GPS solution provides optimal time to fix, accuracy, sensitivity, availability, and
reduced network utilization in both of these environments, depending on the given condition.
The SIM5218E GPS solution in assisted modes provides cold-start GPS sensitivity that is an
approximately 20 to 30 dB improvement over unassisted, conventional GPS receivers.
Compared to network solutions that require equipment at each cell site, the SIM5218E GPS
solution integrates a complete GPS receiver in every module. This means that each handset is
capable of position location without requiring expensive cell site equipment. This solution not
only can be used to help operators address the FCC E911 mandate in the United States (and
mandates planned for other countries), but also provides a ubiquitous platform for location-based
applications, since SIM5218E GPS technologies will also enable consumer-priced,
position-capable handsets for location-based services worldwide.

3.18.2 Using GPS by NMEA port

SIM5218E uses GPS by NMEA port. You can select NMEA output over the UART or USB by
configuration. Output of NMEA sentences is automatic; no control vian at commands is provided.
Supported NMEA sentences include GSV, GGA, RMC, GSA, and VTG.
Before using GPS, we should configure SIM5218E to be in properly operating type by AT
command. Please refer related document for detailed information.
SIM5218E can get position location information through AT command directly, it's unnecessary
decode the NMEA code.

3.19 PCM Interface

SIM5218E provides PCM interface. The SIM5218E PCM interface can be used in two modes:
1) the default mode is its auxiliary PCM that runs at 128 kHz， and uses a 62.5 μs sync pulse (half
a time frame); 2) the other mode is its primary PCM that runs at 2.048 MHz， and uses 488 ns sync
pulse (one 2.048 MHz clock tick) .
Both the PCM interface modes, auxiliary and primary, use the same SIM5218E pins. The
PCM pin assignment is shown in the table below.
SIM5218E_HD_V1.03
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11.06.2009