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.
Table 6.2. Byte sructure for all commands and messages to/from INS
| Byte number | 0 | 1 | 2 | 3 | 4 and 5 | 6... (n+5) | n+6, n+7 |
|---|---|---|---|---|---|---|---|
|
Parameter |
Header 0 |
Header 1 |
Message type |
INS data identifier |
Message length |
Payload |
Check sum |
|
Lenght |
1 byte |
1 byte |
1 byte |
1 byte |
1 word |
n bytes (variable) |
1 word |
|
Note |
0xAA |
0x55 |
|
in INS messages |
n+6 |
|
|
Table 6.81. Aiding data measurements structure (to be further expanded)
| Type | Semantic | Size, bytes | Structure | |
|---|---|---|---|---|
|
0x00 |
Reserved |
TBD |
TBD |
|
|
0x01 |
Odometr |
4 |
Signed long |
Accumulated distance in mm |
|
0x02 |
Air speed |
2 |
Signed short |
Air speed in 0.01 kt |
|
0x03 |
Win data |
8 |
Signed short |
North wind component in 0.01 kt |
|
Signed short |
East wind component in 0.01 kt |
|||
|
Unsigned short |
North wind STD in 0.01 kt |
|||
|
Unsigned short |
East wind STD in 0.01 kt |
|||
|
0x04 |
External position |
20 |
Signed long |
Latitude external in signed deg*1.0e7 |
|
Signed long |
Longitude external in signed deg*1.0e7 |
|||
|
Signed long |
Altitude external above MSL in mm |
|||
|
Unsigned short |
Latitude external STD in 0.01 m |
|||
|
Unsigned short |
Longitude external STD in 0.01 m |
|||
|
Unsigned short |
Altitude external STD in 0.01 m |
|||
|
Unsigned short |
External position latency in msec |
|||
|
0x05 |
Doppler shift from locator |
16 |
||
|
Signed long |
Locator latitude in signed deg*1.0e7 |
|||
|
Signed long |
Locator longitude in signed deg*1.0e7 |
|||
|
Signed long |
Locator altitude above MSL in mm |
|||
|
Signed short |
Doppler shift in cm/sec |
|||
|
Unsigned short |
Doppler shift STD in cm/sec |
|||
|
0x06 |
Heading external |
6 |
Unsigned short |
Heading external in 0.01 deg |
|
Unsigned short |
Heading external STD in 0.01 deg |
|||
|
Unsigned short |
Heading external latency in msec |
|||
|
0x07 |
DVL data (depends on reference frame, see note №3) |
24 |
Signed long |
Lateral velocity, 1000*m/sec |
|
Signed long |
Forward velocity, 1000*m/sec |
|||
|
Signed long |
Vertical velocity, 1000*m/sec |
|||
|
Unsigned short |
Lateral velocity STD, 1000*m/sec |
|||
|
Unsigned short |
Forward velocity STD, 1000*m/sec |
|||
|
Unsigned short |
Vertical velocity STD, 1000*m/sec |
|||
|
Unsigned short |
Velocity latency, msec |
|||
|
Unsigned long |
Reserved |
|||
|
0x08 |
Sensor bias external |
7 |
Signed byte |
Gyro bias X, 0.5*10^4*deg/s |
|
Signed byte |
Gyro bias Y, 0.5*10^4*deg/s |
|||
|
Signed byte |
Gyro bias Z, 0.5*10^4*deg/s |
|||
|
Signed byte |
Accel bias X, 0.5*10^5*g |
|||
|
Signed byte |
Accel bias Y, 0.5*10^5*g |
|||
|
Signed byte |
Accel bias Z, 0.5*10^5*g |
|||
|
Byte |
Reserved |
|||
|
0x09 |
Pitch and Roll external |
4 |
Signed short |
Pitch external in 0.01 deg |
|
Signed short |
Roll external in 0.01 deg |
|||
Question: 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 4.2.4.4 “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.