There is a difference between the output of the GPIO and auxiliary ports when set to 1PPS output mode.

1PPS Specifications

The pin is normally low and pulses high for 50 milliseconds to signal the precise second. The 1PPS line starts pulsing approximately 100 milliseconds after power up and always fires irrespective of whether Certus has accurate time or not. It is important to note that when Certus acquires time corrections from it's GNSS receiver, the 1PPS signal may fire at an interval of less than 1 second. This typically only occurs the first time the GNSS receiver obtains a fix after startup. The time initialised status flag can be used to determine whether the time and 1PPS line is accurate or not.

The dedicated 1PPS Signal on the Connector Pin-out or the auxiliary transmit are the recommended 1PPS signals as they have less jitter than the GPIO ports. The validity of the dedicated 1PPS signal can be monitored using the “time initialised” flag in the System State Packet.

In this function, the pin is low when there is no GNSS fix or a 2D fix and high when there is a 3D, SBAS, Differential or RTK GNSS fix.

When using this function, a high state indicates to Certus that it is stationary. The low state indicates that the vehicle is not stationary. Use of this function can prevent drift during periods when a GNSS signal is not available.

This function accepts a digital input with a low state enabling the magnetometers and a high state disabling the magnetometers.

This function accepts a digital input with a low state enabling the GNSS and a high state disabling the GNSS.

This function accepts a digital input with a low state enabling the atmospheric pressure sensor and a high state disabling the atmospheric pressure sensor.

This function accepts a digital input. The input is normally low and a transition from low to high causes Certus to set its alignment so that the current orientation is zero. Due to the risk of exhausting the flash cycles, the change is not permanent and will disappear on reset. To make it permanent the Installation Alignment Packet must be read and then sent back to Certus with the permanent flag set. This function requires de-bouncing if attached to a switch.

This function accepts a digital input. The input is normally low and a transition from low to high causes Certus to send the System State Packet. This function requires de-bouncing if attached to a switch.

This function accepts a digital input. The input is normally low and a transition from low to high causes Certus to send the Raw Sensors Packet. This function requires de-bouncing if attached to a switch.

This function is designed to allow external GNSS receivers to synchronise time with Certus. It triggers on a transition from low to high.

This function is designed to allow external events to be recorded by Certus. The event is recorded in the Filter Status (see Advanced Navigation Packet Protocol), and resets after the next packet is output. The event triggers on a transition from low to high.

This function is designed to allow external events to be recorded by Certus. The event is recorded in the Filter Status (see Advanced Navigation Packet Protocol), and resets after the next packet is output. The event triggers on a transition from low to high.

This function is designed to take a reversing indication input for direction with an odometer or wheel encoder. It should be used in combination with Odometer Input or Wheel Speed Sensor.

This function is designed to take a reversing indication input for direction with an odometer or wheel encoder. It should be used in combination with Odometer Input or Wheel Speed Sensor.

This function is designed to reverse the alignment settings for vehicles that can have two vehicle forward directions, such as locomotives.

This function is designed to reverse the alignment settings for vehicles that can have two vehicle forward directions, such as locomotives.

In this function, a high state indicates to Certus that the vehicle is not rotating. The low state indicates that the vehicle could be rotating. Use of this function can significantly improve heading drift performance when a GNSS signal is not available.

This function is designed for low-resolution vehicle speed sensors and odometers. It expects a normally low input with a high state for the trigger. If the pulse length is more than 0.1 metres then this odometer input function should be used. If it is less than 0.1 metres, the wheel speed sensor function should be used. Contact technical support at support@advancednavigation.com for help integrating with your speed sensor.

Odometer Specifications

This function allows fixed wing aircraft to measure airspeed to improve navigation performance. It requires a differential pressure sensor that has a frequency output such as the Kavlico P992 (frequency output option) or the Paroscientific series 5300. Contact technical support at support@advancednavigation.com for help integrating with a pitot tube.

This function is designed for interfacing with a legacy pressure depth transducer. These are no longer available and the function is now deprecated.

This function is designed for the left wheel of a vehicle with dual wheel speed sensors.

This function is designed for the right wheel of a vehicle with dual wheel speed sensors.

This function is designed for high resolution vehicle speed sensors and wheel speed sensors. It expects a normally low input with a high state for the trigger. If the pulse length is more than 0.1 metres the odometer input function should be used, if it is less than 0.1 metres the wheel speed sensor function should be used. Contact technical support via email at support@advancednavigation.com for with help integrating with your speed sensor.

Wheel Speed Sensor Specifications

This function is designed for rotary incremental quadrature encoders. It should be used in combination with Wheel Encoder Phase B.

This function is designed for rotary incremental quadrature encoders. It should be used in combination with Wheel Encoder Phase A.

This function is designed for interfacing with a rotary incremental quadrature encoder to measure the azimuth angle of a gimbal in which Certus is installed. It should be used in combination with Gimbal Encoder Phase B.

This function is designed for interfacing with a rotary incremental quadrature encoder to measure the azimuth angle of a gimbal in which Certus is installed. It should be used in combination with Gimbal Encoder Phase A.

This function accepts external data in the NMEA 0183 format. Advanced Navigation recommends against using NMEA 0183 input wherever possible due to the inefficiency, low accuracy and precision and weak error checking of the format. All NMEA messages received must have a valid checksum. Supported messages are listed below. The recommended combination of messages are RMC with optional messages GPGSV and GPGSA. If RMC is not available, GGA and VTG can be used.

Supported NMEA messages

This function is designed for interfacing Certus with a Novatel GNSS receiver. It accepts data in the Novatel binary format and requires messages BESTPOSB and BESTVELB at rates higher than 1 Hz (20 Hz recommended). The message BESTSATSB is optional to display detailed satellite information. The message HEADING is also supported for ALIGN capable receivers.

This function is designed for interfacing Certus with a Topcon GNSS receiver. It accepts data in the GRIL TPS binary format and expects messages PG and VG at rates higher than 1 Hz.

This function accepts data in the ANPP format as specified in Advanced Navigation Packet Protocol.

When this function is enabled, the GPIO and auxiliary ports function the same as the primary port, with one exception:

• When setting the ANPP packet and message output rates, the changes only apply to the port you are connected to. For example, you cannot change the primary port or GPIO port packet and message rates when connected to the auxiliary port.

This function accepts RTCM v3 GNSS corrections messages. This allows for Differential GNSS or RTK with the Certus internal GNSS receiver.

This function is designed for interfacing Certus with an external Trimble GNSS receiver. It accepts data in the Trimble binary format GSOF and expects packet 0x40 with records 1, 2, 8, and 12 at rates higher than 1Hz (20 Hz recommended) and optional records 9 and 34 at 1 to 2 Hz.

This function is designed for interfacing Certus with an external u-blox GNSS receiver. It accepts data in the u-blox binary format and expects message NAV-PVT at rates higher than 1 Hz.

This function is designed for interfacing Certus with an external Hemisphere GNSS receiver. It accepts data in the Hemisphere binary format and expects message Bin1 at rates higher than 1 Hz. For Hemisphere receivers that provide heading using two antennas, NMEA should be used instead as the binary format does not allow for transmission of heading information.

This function accepts DVL data from a Teledyne DVL. For assistance with configuration, contact support@advancednavigation.com.

This function accepts USBL data from a Tritech USBL. For assistance with configuration, contact support@advancednavigation.com.

This function accepts DVL data from a Linkquest DVL. For assistance with configuration, contact support@advancednavigation.com.

This function accepts DVL data in the Nortek DVL binary format. It accepts the packets 0x1B (DVL Bottom Track) and 0x1D (DVL Water Track). The recommended update rate is 8 Hz.

This function outputs a configurable combination of the NMEA messages GPZDA, GPGGA, GPVTG, GPRMC, GPHDT, PASHR, GPROT, GPHEV, GPGSV, PFECGPAtt, and PFECGPHve at up to 50 Hz. The messages output and the output rate can be configured using the web UI or Certus Manager. An example output is shown below.

$GPZDA,031644.460,07,05,2013,00,00*52

$GPGGA,031644.460,3352.3501851,S,15112.2355488,E,6,00,1.4,150.0,M,0.0,M,,*7E

$GPVTG,089.19,T,089.19,M,000.00,N,000.00,K,E*27

$GPRMC,031644.460,A,3352.3501851,S,15112.2355488,E,0.0,89.2,070513,12.5,W,E*02

$GPHDT,89.2,T*06

$PASHR,031644.460,089.19,T,-00.01,-00.47,-00.00,,,,0,0*2E

This function outputs data in the ANPP format as specified in Advanced Navigation Packet Protocol. This function is for ANPP peripheral devices only.

When this function is enabled, the GPIO and auxiliary ports function the same as the primary port, with one exception:

• When setting the ANPP packet and message output rates, the changes only apply to the port you are connected to. For example, you cannot change the primary port or GPIO port packet and message rates when connected to the auxiliary port.

This function outputs the TSS1 format at a user configurable rate of up to 50 Hz. The output rate can be configured using the page in the web UI.

This function outputs the Simrad 1000 format at a user configurable rate of up to 50 Hz. The output rate can be configured using the GPIO page in the web UI or the GPIO Output dialogue in the Certus Manager.

This function outputs the Simrad 3000 format at a user configurable rate up to 50 Hz.The output rate can be configured using the GPIO page in the web UI or the GPIO Output dialogue in the Certus Manager.

This function allows passthrough communication through either GPIO 1 and 2 or the Auxiliary port. To transmit data use the Serial Port Passthrough Packet. When data is received it will be sent back using the same Serial Port Passthrough Packet.

This function allows for pass through connection to the internal GNSS receiver. This is useful for firmware updates of the internal GNSS receiver.