The event pulse output by many cameras and other aerial survey sensors does not have sufficient power to trigger the GPS event latch circuitry. The even latch interface conditions and amplifies the pulse so that it can be successfully integrated with the GPS receiver. It eliminates the requirement of 3-6V DC with 50 Ohm load input impedance.
Connect the LEMO connector to the EVT MKR/CAN connector located at the back panel of your SF-2050M GPS Receiver. Input is through a female BNC connector, where the center pin is the signal and outer shell is ground.
Logging the 0xB4 binary message at a rate of “On Trigger” will output a message containing the time mark of when the trigger occurred. The position in the B1 records on both sides of the event must be interpolated by post mission software to obtain the exact position of the event NavCom’s StarPac is available for such a purpose.
The event latch triggers on the falling edge of the pulse. However, use of the Event Latch Interface will condition the pulse appropriately, so is able to accept either rising or falling edge configurations (a.k.a. active high or active low).
The precision time of an event is 1µsec, but hardware delays (12µsec) are also associated with this precision, accumulating to a total system delay of ~13µsec. The precision will be incumbent upon the velocities experienced, but typically cancel out due to the consistency of the total delay.