Presentation is loading. Please wait.

Presentation is loading. Please wait.

12 Aug 04 jonathan kingIEEE802.3aq Channel model ad hoc Task 2: Time variation and modal noise 1 Task 2 update: Time variation and modal noise study.

Similar presentations


Presentation on theme: "12 Aug 04 jonathan kingIEEE802.3aq Channel model ad hoc Task 2: Time variation and modal noise 1 Task 2 update: Time variation and modal noise study."— Presentation transcript:

1 12 Aug 04 jonathan kingIEEE802.3aq Channel model ad hoc Task 2: Time variation and modal noise 1 Task 2 update: Time variation and modal noise study

2 12 Aug 04 jonathan kingIEEE802.3aq Channel model ad hoc Task 2: Time variation and modal noise 2 Contents Task 2 has agreed some –goals –time variation mechanisms –tasks Summary of progress to date

3 12 Aug 04 jonathan kingIEEE802.3aq Channel model ad hoc Task 2: Time variation and modal noise 3 Goals Study the impact of time varying effects on the LRM draft spec –Provide input to the time varying component of the receiver compliance test Set a frequency below which EDC should track (TP3 test rate) Define tracking 'mask' - magnitude of perturbation vs frequency of perturbation –Measure spectrum of time variation effects what is the product expected to cope with in real life ? what's already out there ? consensus that measuring this for statistically significant numbers installed links would be an extremely difficult task; –Modeling of extent of time variance of links e.g. delay vs mode sets for quasi-continuous perturbed link for listed mechanisms generate impulse responses for quasi-continuously perturbed link for selected launches, over Cambridge fibre set (tbc) and a 'standard link' Study modal noise of the MMF channel and ensure modal noise is properly accounted for in the LRM draft spec –Assess modal noise penalty for different laser types Timeline - input to September interim meeting

4 12 Aug 04 jonathan kingIEEE802.3aq Channel model ad hoc Task 2: Time variation and modal noise 4 Mechanisms leading to channel variability Connector offset: –connector offset may be a gearing factor for temporal effects through mode selective loss and mode coupling static offset 3.5um average, 1.8um standard deviation for 50 micron fibre (i.e. 95% less than 7um); scaling for 62.5 micron fibre ? Fibre perturbation: –Fibre shaker (TIA/E!A-455-203) may be necessary part of task 2 measurements, may not be sufficient –May require a range of frequency and amplitude - 'perturbation mask' large amplitude at low frequency, small amplitude at high frequency Laser wavelength –Rapid changes in laser wavelength result in modal noise; variance can be estimated using previous modal noise work Temperature –Evolution of channel characteristics as link and laser source temperature vary can be modeled How fast and by how much does each vary in a realistic link ?

5 12 Aug 04 jonathan kingIEEE802.3aq Channel model ad hoc Task 2: Time variation and modal noise 5 Tasks 1)Real environments a)What's already out there describing in-building environments ? existing standards ? b)Measurements of spectrum of time variation effects - volunteers tbd 2)Mechanisms: determine mechanical vibration rates and amplitudes for each mechanism 3)Experiment: relationship of perturbation spectrum to modal noise spectrum for each mechanism 4)Modeling: a)Generate delay vs mode sets, and impulse responses for quasi-continuous perturbation mechanisms, for selected launches, over 'standard link' b)Effect of temperature (link and source) over 'standard link' 5)Modal noise: penalty for different laser types over 'standard link' 6)'Standard link' for modeling and experiment

6 12 Aug 04 jonathan kingIEEE802.3aq Channel model ad hoc Task 2: Time variation and modal noise 6 Progress Volunteers actively working each task ! To date: Identified existing standards describing in-building environments –GR-63-CORE - describes office environment vibration tests at 'constant acceleration' (0.1G & 1G) from 5-100 Hz (vibration amplitude ~ 1/f 2 ) –IEC 61300-2-1 max frequency 55Hz 'Standard link' for modeling and experiments is in progress –Includes polarization controller and fibre shaker –up to 3 connectors with worst case offset consistent with preceding standards and existing link specs Proposed measurement technique to determine relationship of perturbation spectrum to modal noise spectrum


Download ppt "12 Aug 04 jonathan kingIEEE802.3aq Channel model ad hoc Task 2: Time variation and modal noise 1 Task 2 update: Time variation and modal noise study."

Similar presentations


Ads by Google