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NCS1 Gyro Constants Circuit Board

Technical Information

Catalogue No: C1609
Category: Navigation/Inertial
Object Type: Module/Sub-Assembly/Component
Object Name: NCS1 Gyro Constants Circuit Board
Part No: CD12118
Serial No: 094 & 245
Manufacturer: Marconi-Elliott Avionic Systems Ltd
Division: Inertial Navigation [IND]
Platform(s): Naval 
Year of Manufacture: 1987
Dimensions:
Width (mm):
100 
Height (mm):
165 
Depth (mm):
15 
Weight (g):
135 
Location: Main Object Store
Inscription(s):

[front]
CD12118AA/B DL Issue 6
[PCB1] 87FJB373/245/R
[PCB2] 87FJB196/094R
Mod Record -
────────────────
[rear]
CD 12118 AA/A Issue 7
CMC
[PCB1] A8106570
[PCB2] 7742258
NSN 6605-99-529-2336

Notes:

Qty: 2
One of two PCB's containing Individual Gyro Data for the Naval Compass Stabilizer - one for vertical constants, the other for horizontal constants.

The two sides of this PCB seem identical, the through-hole solder joints from the other side being clearly visible in each view. The reason for this form of construction is unclear but may have been a way of fitting duplicate circuits on a single board whilst maximising the isolation between them.

The Naval Compass Stabiliser NCS1 is a stabilised gyrocompass system designed to provide heading and vertical reference data for systems that use such data, on board a ship. Development of NCS1 started in 1971 and quantity production was underway by 1976 with 80 systems delivered to British and other Navies by 1984. NCS1 provides as standard outputs of Heading, Pitch, and Roll but with an additional card can give own ship acceleration and velocity. The ships Latitude and Longitude are continuously computed.

There are three major units; Space Reference Unit (SRU), Electronic Pack (EP) and a Mount Assembly. The SRU comprises a stabilised platform containing 2 two axis gyroscopes and 2 single axis accelerometers mounted in a gimbal system which is contained in a closed binnacle with associated control electronics. The SRU is protected against shock by the Mount Assembly which provides the interface to the deck.
The EP contains power inverters, a digital computer, control /indicator Panel and a standby battery. The Transformer Rectifier units convert ship’s power to 28v dc and in the event of a supply failure the standby battery will support the system. Two identical controlled inverters produce all the regulated dc supplies required by NCS1. The computer is the 12/12P, a variant of the standard Company unit. The Interface Unit carries out such functions as synchro-to-digital conversion, analogue-to-digital conversion and the reverse, signal buffering and built-in test. A Control and Indicator panel hosts switches and displays to select the mode of operation, set in information, display selected outputs and enable computer controlled or manual testing.

Initial sea trials were carried out in HMS Antrim. NCS1 was designed and manufactured within the Guidance Systems Division at Rochester between 1976 and possibly beyond 1984.

The NCS1 is a tall unit and there is a story that, in order to calibrate the system using the Pole Star, a hole had to be cut in the roof of the clean room test area!

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