Showing posts with label 1986 - GEC Marconi. Show all posts
Showing posts with label 1986 - GEC Marconi. Show all posts

MBB105 Helmet Display

This project was a helmet mounted display for the MBB105 helicopter.  The display had some HUD function but was also slaved to the under mounted gun.  As the pilot's head moves, so the gun under the helicopter moves with it, and the optical system identifies hard edges of vehicles and buildings for targeting. 

MBB Bo 105

We take this stuff for granted today but back then (the late 80s) this was cutting edge military technology.  Now, your cell phone camera identifies faces, even as your subjects move around. It's basically the same technology, in a phone!

My part in all of this was again, the analog interfaces for the display itself. In this case the analogue card was shrunk down into a module, that would be mounted to the board. This meant we used all new devices, a lot of surface mount which was very new technology at the time. It presented a whole set of new challenges and that's what made this project fun.

V22 Helmet Mount Display

Given that I worked in the airborne display division and my specialty was analog electronics, I was added to the project team for the V22 Osprey helmet mount display.  My responsibility was the implementation of the analog output card.
V22 Osprey

The analog output card took digital data from the display system and turned that into analog signals for driving a CRT.  Yup back then these things still used CRTs. 

I had just completed the C17 design so it will come as no surprise that the V22 card was a very similar design to the C17 card.  The interface to the digital system was via programmable logic devices (CPLDS) and these interfaces to some DACs.  The output of the DACs was a current and this was turned into a voltage and then buffered off the card using amplifiers.

It's a pretty simple set up but if course the design had to be resilient and military spec to survive the extremes in temperature, vibration and other environmental concerns.

Tornado E-Scope

 The Panavia Tornado was the primary strike aircraft for the royal air force in the 80s.  GEC Marconi was tasked with providing an avionics upgrade package that included a partial redesign of the e-scope


The e-scope is the display for the terrain following radar.  This radar enables the tornado to follow the contour of the land at low level. 

My role in this as a design engineer was to put together part of the display interface. This was a much smaller project than the C17 project for instance. 

F5 Interface Card

A number of the Northrop F5's were used for training in the USA and were due an avionics refit. As a part of that refit, an interface between a radar system and HUD needed to be created.

This was a simple interface card to connect the radar system to the HUD.  Essentially the radar system had an XY analog output, but the signals were of the wrong polarity.  So the interface card buffered the signals and then inverted them, and buffered them out to the HUD.

F5E Tiger II

The design was a quick and easy one, compared to some of the others.  

C17 Globemaster HUD

Much of my time at GEC Marconi Avionics was spent on the C17 Globemaster project.  GEC were putting together an avionics package including the Head Up Display (HUD).  HUD systems back then were usually comprised of two parts; the optics assembly, mounted in the pilot's field of view, and the computer system that drives the optics.

C17 Globemaster

I don't know what HUD technology looks like now but back then, HUDs were based on CRTs with vector scanning. This required analog connections to CRT/Optical module, usually X, Y & Z where X and Y are the left/Right and up/down signal controls and Z is on/off.  

My role in this project was to take the digital data from the frame buffers, and turn them into analog signals. The challenge here was this had to be 14 bit accurate over the MIL-STD temperate range of -55C to +125C.  That is a tremendous amount of thermal problems.

Everyone gets a HUD
Back in those days, surface mount technology was just beginning to be a main stream thing, and the issue when dealing with extended temperature ranges was the surface mount components popping off the boards when subject to temperature extremes.

The temperature and accuracy challenges were eventually overcome and as we can see, the Globemaster is  extensively used, 25 years after I worked on it.

Abrams M1A1 Laser Rangefinder

Way back in the 80s I worked for GEC Marconi Avionics.  I have no idea why we were asked to do this but we had to design the laser rangefinder receiver for the Abrams tank. Of course in a company that does military work you never get to see the big picture.

Abrams A1M1 (pic from Popular Mechanics)

The design challenge was that the return signal from the laser was so faint that thermal noise in the circuit would swamp the signal.  The design solution was a discrete low noise transistor amplifier, mounted on a peltier cooler to reduce the thermal noise. The output signal was then pushed through a logarithmic amplifier to provide a meaningful signal for the targeting systems.

It was an interesting project and as a new engineer, I found it fascinating and exciting.