Locosys MC-1612 Hardware Design Manual page 3

2.3 UART (RX/TX) –Serial Interface
(1). UART is the default interface (TTL level) that has the baud rate ranging from 4800 bps to
115200bps.
(2). Placing damping resistor on the RX and TX of the GPS module could limit the interference
from host MCU or high speed digital logics. Fine tuning the damping resistor is required to
suppress interference efficient. The damping resistor would be a chock coil as well.
(3). Please leave RX open if it is not used as there is an internal pull-up to VCC.
(4). Please don't connect diode(s) to RX/TX as it will decrease signal driving capability which
might adversely affect RX/TX signal level (ex. no data output).
(5). If RS232 logic-level is needed for any particular application, and then the level shifter is
necessary.
(6). If USB logic-level is needed for any particular application and then the USB bridge is
necessary.
2.4 GND-Ground
Make sure all GND pins of module are connected to a good ground plane.
2.5 Antenna Compliance Design
GPS antenna is a receiving device to acquire weak GPS signal from sky. Popular solution would
be ceramic patch antenna because of its small form factor with low cost. There are two types of
antennas, passive and active.
Passive antenna is with solely antenna itself such as patch antenna and chip antenna.
An external antenna is a stand long device integrates with LNA, patch antenna and cable to have
high gain and good performance.
Antenna can be chosen according to radiation efficiency, radiation pattern, gain, bandwidth, form
factor and cost. Make sure the ground plane is sufficient for the antenna to operate with good
enough performance
The recommended antenna specification is given in following table.
Antenna Type
Passive antenna
Active antenna
GPS frequency:
VSWR:
Polarization:
Gain:
GPS frequency:
VSWR:
2
LOCOSYS Technology Inc.
20F.-13, No.79, Sec. 1, Xintai 5th Rd.,
Xizhi Dist., New Taipei City 221, Taiwan
Specification
1575.42±2 MHz
<2 (Typ.)
RHCP or Linear
>0 dBi
1575.42±2 MHz
<2 (Typ.)
886-2-8698-3698
886-2-8698-3699
www.locosystech.com