Product specifications

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If used, Port D will free up the task of Port A, B or C from being used for
external correction input. If you wish to support external correction input
when the product is in the field, we recommend that you offer the facility to
the user to input corrections on Port A, B or C, and that Port D remain within
the integration only.
Note: DGPS corrections are not required for heading accuracies as specified.
External corrections will only affect positioning performance.
LED I NDICATORS
There are seven SMT LEDs onboard the Crescent Vector module for indication
of power, Master GPS lock, differential lock, DGPS position, Secondary GPS
lock, Auxiliary GPS lock (not in use) and heading lock. These LEDs have
respective silk-screening of ‘PWR’, ‘M-GPS’, ‘DIFF’, ‘DGPS’, ‘S-GPS’, ‘A-GPS’
(not in use) and ‘HDG’.
The signals that drive these LEDs are also available via the 34-pin header
connector (excluding a power indication which could drive an LED from
somewhere else in the power supply chain). Please refer to the Pin-out table
of the Crescent Vector for their pin number. Please note, however, that each
of these signal pins can offer only 1 mA of current and are active low. Since 1
mA of current may be inadequate for your application, you may want to
transistor-buffer these signals in order to provide more current capacity for
acceptable LED luminance.
1 PPS T IMING S IGNAL
The one pulse per second (1 PPS) timing signal is used in applications where
devices require time synchronization. This signal output is typical of most
GPS modules and is not an obligatory feature.
If you have no need for this function, simply do not connect the pin.
The 1 PPS signal is 3.3 V HCMOS active low with rising edge synchronization.
The 1 PPS signal is capable of driving a load impedance which is greater than
10 kΩ in parallel with 10 pF.
E VENT M ARKER I NPUT
Depending on your application, you may have the need to force a GPS
solution at a particular instance, not synchronized with GPS time. Such an
application could be to compute the location of a perspective center of a
camera being used for a photogrammetric application, where the aircraft
moves with considerable speed and an interpolation between two GPS epochs
could be unreliable.
If you have no need for this feature, do not connect this pin in your
integration.