3-72 Theory of Operation: Global Positioning System (GPS)
• The GPS TX output (U2206 pin J6 for MHLN6977 and pin F5 for MHLN7035), connects to
OMAP UART2_RX (U6302 pin R9) – TP2205
• The GPS RX input (U2206 pin K6 for MHLN6977 and pin E3 for MHLN7035) connects to
OMAP UART2_TX (U6302 pin M18) – TP2206
NOTE:
• SAW filter FL1301 is used by all APX7000/ APX 7000XE radios with expander board
HLN7035A.
.
Figure 3-55. GPS Block Diagram (VHF/700–800 MHz) – Expander Board MHLN6977A
RF-Vocon-Exp
Interconnect
RF Board
Ant
LNA
3.0V
Unbalanced
SAW
LNA
GPS_2.8V
LNA Enable
3.6V
(VSW_3.6)
2.8V 1.8V 1.2V
GPS_2.8V
[OMAP 1710]
UART2_Rx (R9)
RF Vcc I/O Vcc Core Vdd
UART2_Tx (M18)
IO74 (E2)
IO91 (D12)
FDOUT (H1)
RFA_INP (A5)
RFA_INM (B5)
REF_CLK_IN (D4)
MISO_TXD0 (J6)
MOSI_RXD0 (K6)
LOW_REF_CLKI (D1)
NRESET (C1)
SiRF GSCi-5001
GPS IC
Reset
32kHz RTC
GPS Rx
GPS Tx
TCXO
26MHz
<0.5ppm
External Regulators
Expansion Board
Balanced
SAW