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DCI Minilir-Fennel - 10

Description

Driver for combined RS-232 message from DCI Minilir-Fennel telemetry system.

Driver to decode both horizontal and vertical angle from Minilir system as well as range observation from Fennel EDM system.

Driver Information

Driver DCI Minilir-Fennel  Interface Type Serial  Driver Class Type Terminated <LF> 
UTC Driver (question) No Input / Output Input  Executable DrvMinilirFennel.exe 
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Interfacing Notes

According to DCI specifications, the interface parameters are 9600 baud, 7 data bits, even parity, 1 stop bit.

The latency of the Minilir-Fennel system is the time interval between the angle measurement (FLAG) in the Minilir system and the reception of the string at the COM port, which includes the time interval between the FLAG and sending the string and the time interval of the radio link between sending and receiving the string.

The age of the Fennel range is decoded from the data string. An additional time correction for the length of the Fennel string (actual measurement) is applied as 70.0 ms, according to the latest DCI specifications.

The Minilir-Fennel output is an ordinary RS-232 output. See Chapter 1 for general interfacing remarks.

Database Setup

Add "Object" for the vessel with the reflector unit. Add a "Fixed Node" for the Minilir-Fennel station and for all the calibration targets to be used in the calibration procedure. Add two times a "Variable Node" (located on the same vessel object) for both the Minilir spot and the Fennel prism on the reflector unit to be used for online positioning. Be sure to enter the height difference between prism and spot as difference in Z-offset. Both variable nodes should have the same X-offset and Y-offset (with respect to the unit's reference point), since the Fennel prism node should be defined exactly above (or under) the Minilir spot node. A physical horizontal offset, for example in case of a ring of prisms, should be entered as a correction C4, see below.

Add three "Observations", for the Fennel range and for the Minilir horizontal and vertical angles. Be sure to select the same station node for the fixed "At Node", but different target nodes for the variable "To Nodes".

Add a "Surface Navigation System" with driver "DCI Minilir-Fennel" and enter the appropriate interfacing parameters and the latency value. Connect the three observations (one range and two angles) to the system.

Open the "Station Corrections" tab, select the station node (only one fixed node should have been defined) and enter the corrections H1, C2 and C3; correction H0 is obtained from the instrument height at the node.

Open the "Target Corrections" tab, connect all the target nodes to be used during the calibration procedure (fixed nodes) and/or online (one variable node for the Fennel prism), and by selecting the target nodes, enter the corrections C4 and H5. Correction H5 is only used during calibration, but to obtain a consistent printout, H5 should be the same as the height difference between the two variable nodes for the online positioning.

Be careful with the signs of the corrections. A height difference dH in upward direction is positive, for example if the Fennel prism is located above the Minilir spot. A range correction dL which should be added to the observed range to get the corrected value to be used in the calibration procedure and/or the online positioning is positive, hence a ring of prisms on a reflector unit will result in a positive correction C4.

Carry out a calibration procedure to determine the (additional) instrumental constant for the range and the zero directions for the angle observations. Before starting QINSy for online positioning, edit the database to enter the calibration (C-O) results in the "Fixed (C-O)" or "Variable (C-O)" properties of the three Minilir-Fennel observations. Do not enter any additional "Node Corrections" in the Minilir-Fennel system definition.

Additional Information

Refer for the calibration procedure to the separate MINILIR-FENNEL CALIBRATION MANUAL RWS-MD.