Meeting minutes 5 - 30/11/11

Leanne has taken over responsibility for the presentation which is due to be completed for Friday (2nd December) ready for the presentation on Monday. This leaves the weekend for practice and tweaking.

David is using a LaTeX editor to compile the technical document, finish sections are to be forwarded to David by Friday at the latest, with an aim to have a finished document on Monday ready for proof reading. The nature of LaTeX makes late edits easy without causing any presentation errors.

Alan and Will are to be free to assist in anyway.

Friday will be left free so we can have a run through of both the presentation and the technical document.

The Cable
On Deciding on a fibre optic cable a few important question arise.

What type of Cable?
We need to detect a signal over a distance of 45km using a multimode fibre optic cable. The two types possible to use are Stepped index or Graded index? We have decided on using a graded index cable as it has a low modal dispersion and high bandwidth.

What wavelength of light are we using?
The two main wavelengths used to transmit are 850nm or 1300nm. A low lost window sits at 1300nm so this will yield the lowest attenuation.
Important criteria

We need the longest cable possible so has the least splices - 45km needed
The lowest possible attenuation - 0.5dB per km found
A bandwidth of at least 12MHz
A cable that matches this description has been found.

Power Budget
A power budget has been calculated showing a loss of about 28 dBm

LEDs Leanne has found

LEDs Leanne has found…

1.     Power = 0.01mW, Spectral bandwidth = 150nm

2.    Power = 2mW, Spectral bandwidth = 100nm (1300nm & ? emitting)

3.     Power = 0.02mW, Spectral bandwidth = 140nm

4.     Power = 0.04mW, Spectral bandwidth = 80nm

5.    Power = 1mW, Spectral bandwidth =40nm (1310nm & edge emitting)

6.     Power = 0.13mW, Spectral bandwidth = 60nm

7.     Power = 0.02mW, Spectral bandwidth = 50nm

·      Is it more important to have a higher power or a smaller spectral bandwidth?

·      LED 2 and 5 look like the best options, we need to decide on which one is best

Meeting minutes 4 - 25/11/11

Meeting minutes 4 – 25/11/11 – Team 1

Leanne – has found two good LEDs: 1) Power = 2mW, Spectral bandwidth = 100nm or 2) Power = 1mW, Spectral bandwidth = 40nm

Dave – will look at calculations and decide on whether the power or bandwidth is more important for LED, has decided on a cable

Will – has decided on a detector

Alan – turned up late but has found a method of splicing for 0.02dBm per slice

Everyone is happy and will now start writing up the report for next week

Report

1.     Brief intro on problem

2.     Technical specification section

a.     Component, why we chose it and some physics if we want

3.     Calculations

4.     Cost of system, total cost (including wages)

Write in 3^rd person (This LED was picked because….)

Wednesday 30^th Nov – have a rough report ready for Ross to read over

Finding a Good Detector:

First of all: PIN or APD?

While APDs do have internal gain and consequently a greater power output, they need a higher voltage supplied to them. Unfortunately, this supply voltage increases the Dark Noise in the system and the gain increases noise in general. PIN Photodiodes, on the other hand, do not have internal gain and subsequently lower noise.

=> PIN Photodiodes are preferable.

Detector Characteristics:

- Low rise time,
- Low dark noise,
- Low NEP,
- Low Cost,
- High Frequency.
- High S/N Ratio

MenloSystems' FPD510 fits these requirements quite well, having a Dark noise level of -120dBm, NEP of 3pw/(Hz^1/2) and a maximum frequency of 250MHz. The rise time is 2ns and, while this is higher than the rise time of the FPD310, the FPD310 has a Dark noise level of -90dBm and NEP of 15.7pw/(Hz^1/2).

Although this detector fits most criteria, we're still on the lookout incase another, better detector is out there.

Meeting minutes 22/11/11

Collaboarative work session:

Dave - Decided upon a cable to be used, has set in motion the finalized search shift from general products to specifics in the rest of the group.

• Calculated bandwidth requirement
• Determined the dispersion
• Sketched a rough power budget to work out the necessary power/attenuation/coefficents for the remaining components.
• Detector has max input power of 10mW, we used this for the basis for the power budget. A 1W LED would fit our need.
• Shifted search focus from Cable to LED, began to consider SLED.
• Connectors - adapters available for connection to equipment.
• Fusion splicing for connecting cable to cable ends.

Leanne - Find a 1W SLED suitable for use with the Fiber Optic cable.
Alan - With knowledge of the cable reduce power loss associated with splicing.
Will - Widen the knowledge of available detectors in case no suitable LED is found.

Further discussion in the preparation of the report went ahead. Idea to create different sections than our research goals with the aim of fluidity.
Leanne - Started the Presentation, decided upon a theme and order.



NOTE the usual meeting on Wednesday  23/11/11 has been turned into a Q and A with the Client due to the success of todays meeting and Leanne's absence.

Meeting minutes 18/11/11

Dave - Found several unreasonable and a few reasonable choices for the fiber optic cable, moving towards a usable products
Leanne - started looking through websites for LEDs
Will - looking and comparing detectors
Alan - evaluating data sheets and products on couplers/splicers

• Dave will work out what power is required for LED - he needs to know how many couplers we need and the lowest power the detectors can detect
• Will will look up what the lowest power that can be detected.
• Alan will decide how many splices we need and associated attunation- depending on length of cables.
• Leanne will wait until specifics are given before looking for exact models. She needs power and frequency requirement. Power in watts - not decibels.Wavelength from LED needed for rise time.

Questions

1. Do we have to worry about how it is all installed?

“No, just trail the cable”, said Ross.

2. What’s the coupling ratio?

“Depends on type of LED, ie edge or surface emitting”, said Dr Macpherson.

Meeting minutes 16/11/11

Team 1 - Meeting minutes 2 - 16/11/11

Leanne - has researched sources but due to the highly dependent nature is waiting upon David's work before finalizing any choices
Dave - has been researching cables and has reported back several decisions that need to be made, we have designated attenuation and length as critical factors
Alan - has been researching function of couplers, there are multiple possilities.
Will - has been looking at different detectors and has found several suitable models depending on the nature of the rest of the design.



Deadlines:
Tuesday 22/11/11 Meeting at 11am in the hub to combine research and link in the sections, partly due to Leanne's absence on Wednesday.
Monday (28th) Individual sections in the first draft report ready and have the powerpoint started (Leanne will take responsibility for the connecting sections and weaving together individual sections).
Friday 2ndA finished power point to be assembled ready for a trail run through
Monday 5thFinal adjustments made as needed before today

Meeting minutes - 11/11/11

Blog at: www.spying-r-us.blogspot.com
Google document at: http://tinyurl.com/spyingrus
Facebook group called Team Awesome MK2

Allocate each person a task from the list:

I.     Light sources - Leanne
II.    Optical fibres - Alan & Dave
III.   Detectors - Will
IV.   Couplers and connectors - Alan

• Everyone will write their own section in the report and then one person will check over

the whole report.
Research individual topics for the next two weeks and write up sections in the report as
we go. Remember to reference!!!
Finish up report by Friday 25th November and Dave will convert to LaTex
Start presentation on Friday 25th November and look over report
Run through presentation on Friday 2nd December
Presentation on Monday 5th December

Questions for Ross

Technical doc or sales doc? Tech
Add meeting minutes to blog? yes
Light one way or two? One way

For next time: Research own sections and see pros and cons of different components
then discuss what components will work best with other ones