Maestro A2200-A Bedienungsanleitung PDF herunterladen (Seite 16)

V1.0 – Aug-13

User’s Manual

Page 16 of 37

3.2 Antenna

Although the A2235-H offers an on-module antenna, an additional external active

antenna can be used. Switching between both antennas is done via pin 12 (see also

“5.2Description A2235-H Signals”). It is recommended to use an active GPS antenna

with supply voltage of 3 to 5 VDC and a current draw of 50 mA maximum. The quality

of the GPS antenna chosen is off great importance to the overall sensitivity of the

GPS system. An active antenna should have a gain ≥ 20 dB and a noise figure ≤

1.5 dB, which applies to more than 95% of the active antennas available in the

market.

3.3 Serial Port Settings

The default configuration within the custom-specific GPS firmware is:

 Serial 0 (NMEA) 4800 baud, 8 data bits, no parity, 1 stop bit, no flow control

3.4 Improved TTFF

In order to improve the TTFF (Time To First Fix), it is recommended to keep Vcc

supplied at all times. This will allow taking advantage of sophisticated low power

mode features of the SiRFstarIV ROM chip set.

3.5 Self-start configuration

In order to minimize the GPIO required for operating A2235-H, WAKEUP (pin 4) and

ON_OFF (pin 19) can be tied together for entering the self-start mode such that no

ON_OFF pulse requires. Figure 7 shows the recommended connection for self-start

configuration with UART host port enabled.

Figure 7: Self-start configuration A2235-H

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Maestro A2200-A Bedienungsanleitung Seite 16