Jackson Labs Mini-JLT GNSS - 2.1.3 Notes on Signal Interfacing

Mini-JLT™ User Manual
6 © 2017 Jackson Labs Technologies, Inc.
2.1.3 Notes on Signal Interfacing
The optional LOCK_OK_OUT is a 3.3V LVCMOS signal, and thus require a series resistor of
typically 390 to 470 Ohms when used to drive an external LED.
The serial port RX and TX lines cannot be directly connected to a DB9 connector as these are driven
with TTL signal levels. Connecting these pins to an RS-232 serial interface may damage the board.
J5 Pin 3 LOCK OK Lock and Event#
indicator
3.3V LVCMOS 3.3V: Unit Locked to GPS, and no
events pending
0V: Event is pending (events can
be queried via the sync:health?
command).
Not stuffed by default
for legacy compatibility
J5 Pin 2 ISP# and GPS
Detect
Enable ISP mode,
indicate GPS signal
detection
3.3V LVCMOS open collector,
pulled to +3.3V via 4.7K resistor.
Do not load this pin to
ground, as this would enable
ISP mode during power on.
Use an LVCMOS input to
query the state of this pin.
Enables In System Programming
mode (ISP) when pulled-low during
power-on (typically enabled by using
a jumper to pin 1)
3.3V: GPS is receiving a sat fix
0V: GPS is not receiving a sat fix
Not stuffed by default for legacy
compatibility.
J5 Pin 1 Ground Ground Ground Ground
Not stuffed by default for legacy
compatibility.
J4 GNSS Antenna Antenna Input L1, +3.3V (default) to +5.5V Supplies 3.3V by default, and up to
+5.5V when using external antenna
power feed on J1. Fused with 100mA
self-resetting fuse
J6 10MHz output 10MHz Sine Wave
Output
+13dBm, +/-3dBm 10MHz output from isolated
distribution amplifier, driven by
on-board OCXO. Not stuffed by
default for legacy compatibility
J2 10MHz output 10MHz Sine Wave
Output
+5dBm, +/-3dBm 10MHz output output from isolated
distribution amplifier, driven by
on-board OCXO
U17 USB USB command and
control
USB 2.0 USB interface for SCPI and NMEA
sentences. Runs in paralell to TTL
serial port. Auto-switchover between
TTL and USB ports.
J3 1PPS output 1PPS output signal,
aligned to UTC
3.3V LVCMOS, <5ns rise-time.
10 Ohms output impedance,
can drive 50 Ohms
end-terminated cables
1PPS output signal, rising-edge
aligned to UTC when locked to GPS