Wednesday, November 21, 2012

Some more training notes

Video Measurement - Principals (4 days)

Course Aim The aim of the course is to provide grounding in video fundamentals, compression and picture quality analysis for staff who work with video processing, detection and vision systems.

Course Structure 
  • Day 1 - TV Fundamentals; Scanning and Sampling, Colour Systems, Analogue Composite Coding - notes
  • Day 2 - TV Fundamentals; Digital Component Coding, Conversion of Film to Television, High Definition - notes
  • Day 3 - Compression; DCT principles, Intra-Frame vs Inter-Frame Encoding, blocks and macroblocks etc. Video Tape Recording; Magnetic recording principles, rotary recording, Simple VT maintenance - morning notes, afternoon notes
  • Day 4 - Television Measurements; Analogue, Digital, Picture Quality Analysis; Analogue picture impairments, digital picture impairments, compression, TV Displays; CRT, LCD and Plasma displays. Problems with LCD and Plasma, Projection systems - morning notes, afternoon notes

Sunday, November 04, 2012

Cladding vs Core Alignment fusion splicers

For seven years we've been using Tritec Fase II fusion splicers; we have two kits composing the splicers themselves (camera or microscope inspection), clevers and finishing ovens for the splice-protectors. If you're in the business of bespoke fibre then fusion splicing really is the only way to go as you get superior performance in termination and you can base infrastructure entirely on loose-tube multi-core cable (tight-buffered cable is really only suitable for use within cabinets or at most between cabinets - it isn't man enough for running in voids and risers).

Anyway, the Tritecs have been solid workhorses clocking up many thousands of terminations between them and we've been entirely happy. In 2004 and then again in 2007 when we upgraded them they were the best sub £10k machines.
The only thing you could criticise them for is that they are "cladding alignment splicers" - they rely on the diameter of the cladding being correct (125 microns, fact fans!) and the core being correctly positioned within the fibre. The guys at Tritec tell me this is a non-problem as contemporary fibre optic stock is always spot on - ten years ago, not so much, but for now it's a problem that's solved and it is fair to say we have seen very little badly made fibre since we started; and that's many hundreds of kilometers of fibre cable!

The other side of the coin is the newer style of fibre machines called "core alignment splicers" where two cameras set at 90 degrees examine the cleaved ends of the fibres  and the software dynamically aligned the ends and dried the splicing arc. The machine is then able to illuminate the join and make an estimation of the loss across the join. Fujikoura were the pioneers in this field in the mid-noughties with machines like the FSM-series costing more than £30k - clearly you'd have to do a lot of fibre work to pay off one of those! Guys who use both types a lot reckon that core-alignment machines allow you to work about twice as fast as the machine produces a much greater consistency of good splices and doesn't rely on the operator to maintain precise splice measurements. Ask any wireman about the 'fibre-blindness' that sets in around 15:00 each day; you just need to walk away and forget about squinting down a microscope for an hour or so; these are very small measurements after all!

So, we've just splashed out on an INNO IFS-10 which gets really good crits when compared to the current FSM-60 machine from Fujikura. We're going to take it on a big job we're just starting and so I'll get a good feel for it.

Here is an excellent "torture test" video of the machine in action.