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TRANSMIT CHARACTERISTIC OF 1000BASE-SX SFP

These items is described on ITU-T standard : 802.3-2005

UNDERSTANDING LAUNCHED OPTICAL POWER WITHOUT INPUT TO TRANSMITTER

This is term that is used in Passive Optical Network Technology (PON). PON devices consist of : OLT and ONU/ONU. Downstream is direction from OLT to ONU/ONT, while upstream is direction from ONU/ONT to OLT.

Launched optical power without input to transmitter is different from mean launched optical power.

The mean launched power at OLT and ONU/ONT is the average power of a pseudo-random data sequence coupled into the fibre by the transmitter. It is given as a range to allow for some cost optimization and to cover all allowances for operation under standard operating conditions, transmitter connector degradation, measurement tolerances, and ageing effects.

In operating state, the lower figure is the minimum power which shall be provided and the higher one is the power which shall never be exceeded.

NOTE - The measurement of the launched power at the ONU/ONT optical interface shall take into account the bursty nature of the upstream traffic transmitted by the ONU/ONT.

In the upstream direction, the ONU transmitter shall launch no power into the fibre in all slots which are not assigned to that ONU. The ONU shall also launch no power during the Guard time of slots that are assigned to it, with the exception of the last Tx Enable bits which may be used for laser pre bias, and the Tx Disable bits immediately following the assigned cell, during which the output falls to zero. The launched power level during laser pre-bias must be less than 0.1 of the one level.

www.mblast.com/files/companies/89960/Document/gpon_pmd_white_v01.doc

Optical Power Bidget Calculation

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Solution

Optical power budget is term used to describe total amount of light energy amplitude available over a certain link path. The budget can be determined by subtracting the Receiver Sensitivity from the Optical Output Power. The optical budget serves as a useful estimation to determine if sufficient optical output power remains on the receiver side of an optical link. The optical power budget also refers to the allocation of available optical power (transmitted into a given fiber by a given source) among various loss-producing mechanisms.

The loss is caused by various factors. Typical losses are caused by fiber attenuation (per km), slice attenuation (per slice), and connector attenuation (per connector pair).

[Suggestions]

1. Power Budget = (Output / Launch Power) - (Receiver Sensitivity)
2. Worse case Optical Power Budget = (Min TX power) - (Max RX sensitivity) - (LED aging factor) - (insertion loss)

We'll use the following values to illustrate:
Min Tx Power = -9.5 dBm
Max Rx Sensitivity = -20 dBm
Estimated LED aging = 1 dB
Estimated Insertion loss = 1 dB

3. Therefore:
Optical Power Budget = (-9.5 dBm) - (-20 dBm)
Maximum Allowable Loss = 10.5 dB

4. Worst case OPB = Power Budget - Total Optical Power Loss =>
10.5 dB - 1dB (for LED aging) - 1dB (for insertion loss) - 1 dB (for per connector pair) - 2dB (safety factor) = 5 dB

5. Worst case distance = {Worst case OPB, in dB} / [Cable Loss, in dB/Km]

The Optical Power Budget is based on a theoretical calculation, and is for reference only. We still strongly recommend that you perform on-site testing to verify the result. On the data sheet, the supported fiber transmission distances are stated on each switch, with fiber port orSFP fiber modules. The customer can select the desired model without performing the power budget calculation.

http://www.moxa.com/support/faq/faq_detail.aspx?f_id=1239

Optical Power Bidget Calculation

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Technical FAQs

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Question	How do I calculate the Optical Power Budget?
Question Type	Application
Updated	Feb 27,2008
Hits	797
Products	SFP-1G Series, EDS-510A Series, EDS-726 Series, EDS-518A Series, EDS-516A Series, EDS-505A/508A Series, EDS-405A/408A Series, EDS-316 Series, EDS-309 Series, EDS-P308 Series, EDS-305-M12 Series, EDS-305/308 Series, EDS-205/208 Series, ED6008, EDS-405, EDS-50/505, OS5008, EDS-728 Series, PT-7

Solution

Optical power budget is term used to describe total amount of light energy amplitude available over a certain link path. The budget can be determined by subtracting the Receiver Sensitivity from the Optical Output Power. The optical budget serves as a useful estimation to determine if sufficient optical output power remains on the receiver side of an optical link. The optical power budget also refers to the allocation of available optical power (transmitted into a given fiber by a given source) among various loss-producing mechanisms.

The loss is caused by various factors. Typical losses are caused by fiber attenuation (per km), slice attenuation (per slice), and connector attenuation (per connector pair).

[Suggestions]

1. Power Budget = (Output / Launch Power) - (Receiver Sensitivity)
2. Worse case Optical Power Budget = (Min TX power) - (Max RX sensitivity) - (LED aging factor) - (insertion loss)

We'll use the following values to illustrate:
Min Tx Power = -9.5 dBm
Max Rx Sensitivity = -20 dBm
Estimated LED aging = 1 dB
Estimated Insertion loss = 1 dB

3. Therefore:
Optical Power Budget = (-9.5 dBm) - (-20 dBm)
Maximum Allowable Loss = 10.5 dB

4. Worst case OPB = Power Budget - Total Optical Power Loss =>
10.5 dB - 1dB (for LED aging) - 1dB (for insertion loss) - 1 dB (for per connector pair) - 2dB (safety factor) = 5 dB

5. Worst case distance = {Worst case OPB, in dB} / [Cable Loss, in dB/Km]

The Optical Power Budget is based on a theoretical calculation, and is for reference only. We still strongly recommend that you perform on-site testing to verify the result. On the data sheet, the supported fiber transmission distances are stated on each switch, with fiber port orSFP fiber modules. The customer can select the desired model without performing the power budget calculation.

Mengenal G.SHDSL

Type of standard for DSL* capable of speeds of 2.3mbps, or up to 4.6mbps in some cases, for both upload and download speeds. (1)

G.SHDL is the acronym of Giga Single-pair High bit rate Digital Subscriber Line (2)

G.SHDSL is a new international standard for single-pair, high-speed DSL, as defined in the ITU-T Standard G.991.2. Unlike asymmetric DSL, which was designed for residential applications in which more bandwidth is delivered downstream (to the house) than is available upstream (to the Internet), G.SHDSL is symmetrical - offering 2.3M bit/sec in both directions.

This makes G.SHDSL better-suited for business applications, which require higher-speed bandwidth in both directions.

G.SHDSL combines the positive aspects of existing copper-based, high-speed communications with the benefits of increased data rates, longer reach and less noise.

*DSL = Digital line subscriber


(1) http://www.computerhope.com/jargon/g/gshdsl.htm
(2) http://www.acronymdb.com/acronym/G.SHDSL

MLM dan SLM

Kalau multimode dan singlemode adalah pembagian jenis kabel fiber optik, MLM dan SLM adalah jenis spektrum sinyal optik yang dipancarkan.

MLM = Multi longitudinal mode
SLM = Singe longitudinal mode

Figure 1 - MLM Laser Spectral Output

Figure 2 - SLM Laser Spectral Output