16 Sept 04IEEE802.3aq Channel model ad hoc Task 2: Time variation and modal noise 1 Task 2 update: Time variation and modal noise study

16 Sept 04IEEE802.3aq Channel model ad hoc Task 2: Time variation and modal noise 2 Task 2 Progress To date: 'Standard link' for modeling and experiments agreed –4 connectors with 2 connectors at 7micron offset (worst case consistent with preceding standards and existing link specs) Adopted GR-63-CORE describing in-building environments office environment vibration tests at 'constant acceleration' (0.1G & 1G) from Hz (vibration amplitude ~ 1/f 2 ) Active: Experiments to determine relationship of perturbation spectrum to modal noise spectrum just started. Initial experiments at Hz, 3-5mm p-p movement up to 3x frequency multiplication observed Study of temperature effects in progress –Comprehensive list of mechanisms compiled and size of each effect being determined. Most significant effects will be for further study Modal Noise calculations in progress –not likely to be ready for September interim

16 Sept 04IEEE802.3aq Channel model ad hoc Task 2: Time variation and modal noise 3 Standard link: Agreed worst-case test configuration for channel variance measurements from '62 MMF con loss and draft worst case configuration' - David Cunningham

16 Sept 04IEEE802.3aq Channel model ad hoc Task 2: Time variation and modal noise 4 Vibration tests representative of office environment GR 63 CORE describes office environment vibration tests at 'constant acceleration' (0.1G & 1G) from Hz –(vibration amplitude ~ 1/f 2 ) Perturbation to be applied to 10m fibre loop prior to main MM fibre –0.1G acceleration at 1Hz corresponds to a 2.5cm perturbation amplitude - similar to TIA/EIA fibre shaker –1G acceleration at 1Hz corresponds to 25cm amplitude - similar to 'shaking the fibre' from summary of GR-63-CORE in 'LRM080404' - John Dellasasse

16 Sept 04IEEE802.3aq Channel model ad hoc Task 2: Time variation and modal noise 5 Summary table of temperature variation impact from Sept 15th rev of 'Temperature variation' - Petre Popescu

16 Sept 04IEEE802.3aq Channel model ad hoc Task 2: Time variation and modal noise 6 Experimental study of channel variation vs perturbation frequency Experimental test set up and intitial results are described in document: 'TimevarianceinMMFlinks-initialtestresults' - Robert Coenen