FLEX-6400/FLEX-6600 Hardware Reference Manual
Page
42 of 45
Copyright 2018 FlexRadio Systems. All Rights Reserved.
14
OPTIONAL GPS DISCIPLINED OSCILLATOR (GPSDO) SETUP
14.1
GPSDO INTRODUCTION
The FLEX-6400 and FLEX-6600 have the ability to attain extremely precise frequency
control through the use of an optional Global Positioning System Disciplined Oscillator
(GPSDO) module. After satellite acquisition and synchronization, the GPSDO is capable of
maintaining frequency accuracy to <5.0 x 10
-12
in a stable temperature environment.
14.2
GPS ANTENNA PLACEMENT
In order for the GPSDO to function properly, the indoor GPS receiver antenna must be
positioned so it has an unobstructed view of the sky in order to receive timing
information from the GPS satellite constellation. While the best location for a GSP
antenna is outside in the clear, most of the time simply placing the indoor antenna in a
window will suffice. In general, the better the view of the sky (south in the northern
hemisphere and north in the southern hemisphere), the quicker the GPS will lock to a
high accuracy level. Some experimenting may be required to find the optimal location.
I - The included low-profile GPS antenna is not waterproof; it is not suitable for outdoor
use.
I - The included low-profile GPS antenna may be
marked with the word “PULSE”. This is actually the
BOTTOM of the antenna and should be placed down
and away from the sky. An included adhesive tape
strip is available for permanently affixing the GPS
antenna to a window sill or outside location.
Δ –
CAUTION: USE CARE IN ATTACHING OR
REMOVING SMA CONNECTORS. BEST PRACTICE IS
TO HOLD THE COAX WITH ONE HAND WHILE
TWISTING THE SMA CONNECTOR SHELL WITH THE OTHER. ONCE THE MALE AND
FEMALE CONNECTORS MATE, TURN UNTIL SNUG BUT DO NOT OVER TIGHTEN!
14.3
GPSDO LOCK SEQUENCE AND STATUS INDICATORS
Please consult the
SmartSDR Software User’s Guide
for a complete description of the on-
screen displays and software setup of the GPSDO.
Upon FLEX-6400/FLEX-6600 initialization, the radio will sense a GPSDO module is installed
and switch from the default oscillator to the GPSDO reference output signal. The
MULTIFUNCTION STATUS INDICATOR (MSI) will illuminate FLASHING YELLOW to indicate
the GPSDO is in “
warm up
” mode.
