User's Manual

8 - 2 ES400 User Guide
To access the GPS receiver from multiple programs simultaneously, the user can either use the Microsoft GPS API
or change the GPS program port setting and access the GPS program port in the multiplexed way.
Operation
Acquiring satellite signals may take several seconds to a few minutes. It is best to be outside and have a clear,
unobstructed view of the sky. Without a clear view, acquisition takes much longer and could result in the ES400
being unable to compute the initial position quickly. When operating the device indoors access to the GPS signals
may be limited or unavailable.
GPS Maps on microSD Cards
GPS navigation software vendors may sell maps on microSD cards. If using a microSD card with the GPS
navigation software install the microSD memory card using procedure in Installing a microSD Card on page 1-2.
Answering a Phone Call While Using GPS
If you receive a phone call while using your GPS navigation software:
1. Answer the phone call by pressing the Answer button.
2. Once you end the phone call, press the End Call button to resume the audio on the GPS software.
Losing the GPS Signal While in a Vehicle
GPS performance on the ES400 may be affected if the vehicle has thermal glass windows and windshields, which
can block the ES400 from receiving a GPS signal from satellites. To improve GPS signal strength, place the ES400
where there is a clear view of the sky. A direct line of sight is required between the ES400 and the GPS satellites to
access information from the satellites.
The Global Positioning System (GPS) is a system that allows the user to track their position anywhere on the earth.
Assisted GPS
GPS can be used in stand-alone or Assisted GPS (A-GPS) modes. A Stand-alone GPS receiver downloads data
from GPS satellites. In certain environments, it can take several minutes to get a fix. By using GPS Location
servers, A-GPS dramatically reduces the TTFF (Time To First Fix) and improves the sensitivity of GPS receivers by
providing them with data that they would ordinarily have to download from the GPS satellites. With the A-GPS data,
GPS receivers can operate faster and more reliably.
A-GPS follows the Secure User Plane Location (SUPL) protocol which allows a mobile device to communicate with
a SUPL server. Refer to the EMDK Help file for information on setting up SUPL on the ES400.
NOTE When using a GPS navigation application, ensure that the ES400 does not go into suspend mode. If the ES400
suspends then the power to the GPS radio is removed. Upon resume the GPS receiver must reacquire a valid GPS
signal, resulting in a a delay of positional information.
NOTE Anytime you are using GPS on the ES400 and you receive a phone call, the audio on the GPS navigation software
is muted until you finish the call.