Gnss Operate Mode; Gnss Application Guide - SIM Tech SimCom SIM7100 Hardware Design

GNSS antenna
There is no power supply on GPS antenna pad, if the antenna is active type, the power should be given by
main board. It is suggested either the external LNA or active antenna used. It is not needed for both of
them at the same time.
Note: Performance will vary depending on the environment, antenna type and signal conditions and so
on.
4.3.2

GNSS Operate Mode

SIM7100 supports both A-GPS and S-GPS, and then provides three operating modes: mobile-assisted
mode, mobile-based mode and standalone mode. A-GPS includes mobile-assisted and mobile-based mode.
In mobile-assisted mode, when a request for position location is issued, available network information is
provided to the location server (e.g. Cell-ID) and assistance is requested from the location server. The
location server sends the assistance information to the handset. The handset/mobile unit measures the
GNSS observables and provides the GNSS measurements along with available network data (that is
appropriate for the given air interface technology) to the location server. The location server then
calculates the position location and returns results to the requesting entity.
In mobile-based mode, the assistant data provided by the location server encompasses not only the
information required to assist the handset in measuring the satellite signals, but also the information
required to calculate the handset's position. Therefore, rather than provide the GNSS measurements and
available network data back to the location server, the mobile calculates the location on the handset and
passes the result to the requesting entity.
In standalone (autonomous) mode, the handset demodulates the data directly from the GNSS 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 GNSS 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, GNSS-only solutions typically perform poorly indoors. The
SIM7100 GNSS solution provides optimal time to fix, accuracy, sensitivity, availability, and reduced
network utilization in both of these environments, depending on the given condition.
4.3.3

GNSS Application Guide

Users can adopt an active antenna or a passive antenna as GNSS signal transceiver. In this document, all
GNSS specification mentioned is from passive antenna. The following is the reference circuit.
SIM7100_Hardware Design_V1.01
Passive/Active antenna
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Smart Machine Smart Decision
2015-01-20