External Heading Input/Using Internal + External GNSS Simultaneously/Sending RCTM Corrections for INS

Posted by Will Dillingham on Aug 18, 2020 1:31:48 PM

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Purpose: Answering common questions about applying external heading input; internal + external GNSS simultaneously; and sending RTCM corrections.

Last Updated: July 2019

Question: Does the INS support external heading input?

Answer: Yes! The INS supports the input of external heading via the main COM1 port (the same port that is used for INS configuration and main data output). For details on all supported aiding data, Section 6.6.3 "Aiding data input through the main COM port" of the INS ICD gives thorough information to help you with your application. The structure of the input message should correspond to standard INS message shown in Table 6.2 below with payload described in Table 6.81 also below, both of which are located in the ICD.

Byte Structure for INS CommandsAiding Data Measurements StructureQuestion: Can the INS use the internal and an external GNSS simultaneously?

Answer: Unfortunately no, the INS can use only the internal or external receiver. This should be specified in the INS GUI. In the case of an external receiver being used, the receiver should be configured to output specific logs (position, velocity, and heading) and should be connected to COM2 of the INS. The type of receiver's data, data rate, and baud rate should be specified in the INS GUI (please see section "Using external GNSS receiver" of the INS GUI Manual). Please note, that in the case of the external receiver being used, the INS cannot configure the receiver's data on COM2 and COM3 (for example, the output of raw GNSS data, NMEA data, and input of RTCM corrections) will not be available.

Question: How do you send RTCM corrections to the INS?

Answer: If the model of the GNSS receiver allows it, the internal receiver can receive both RTCM v2 and RTCM v3 corrections via COM3. If you would like specific details, please see subsection "GNSS corrections" which is in Section 4.2.2 "GNSS receiver tab of Device options window" of the INS GUI Manual. In the case that you are interested in an INS that provides RTCM corrections, Inertial Labs produces the base stations for these as well.

Topics: GNSS, Heading, external, Input, RTCM

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