Maestro A2100-A Bedienungsanleitung PDF herunterladen (Seite 15)

V1.2 – May-11 User’s Manual Page 15 of 37

NOTE: Care must be taken to implement an orderly shut-down sequence along

with supplying power for a certain period of time after initiating the shut-down

sequence. Abrupt removal or drop of power while the module is running has

risks ranging from minor impact on TTFF to fatal corruption of flash memory

code area!

GND

0.1µF

RS232 Level Shifter

RS232 Out

DB9 female

3.3V

Vcc

GND

T1O

R1I

R1O

T1I

T2I

R2O

C1+

V+

C1-

C2+

C2-

V-

T2O

R2I

MAX3232

GND

0.1µF

RS232 Level Shifter

RS232 Out

DB9 female

3.3V

Vcc

GND

T1O

R1I

R1O

T1I

T2I

R2O

C1+

V+

C1-

C2+

C2-

V-

T2O

R2I

MAX3232

Figure 6: RS232 level shifter

Remarks:

• Place C1 to C5 (here: 0.1µF) close to MAX3232. For capacity values see

datasheet of actual component used.

• Use 3.3V level shifter (MAX3232 or equivalent).

• External antenna input impedance is 50 Ω. Match as close as possible.

3.2 Antennas

Generally, the quality of the GPS antenna chosen (passive or active) is of paramount

importance for the overall sensitivity of the GPS system. Losses through a bad

antenna, long cables or tracks or a bad antenna position can’t be compensated

afterwards!

3.2.1 Passive Antennas

The A2100-A supports passive antennas via an integrated LNA directly.

3.2.2 Active Antennas

The A2100-A also supports active antennas directly, i.e. by offering an antenna

voltage feed pin (VANT – pin 15). It is recommended to use an active antenna with a

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

should have a gain ≥ 15dB but the total gain (antenna gain minus cable loss at the

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