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Bahasa Melayu Pelan panjang gelombang PON & kewujudan bersama
Pasukan kami sedang menyiapkan terjemahan. Artikel ini buat sementara waktu belum tersedia dalam bahasa Melayu dan dipaparkan dalam bahasa Inggeris.
Every PON generation is defined as much by its wavelengths as by its bit rate: the downstream and upstream colours are chosen so that a new generation can share the same fibre and splitters as the old one. Knowing the plan tells you what a PON module is and whether it belongs on a given network.
Wavelength plans
| System | Downstream | Upstream | Notes |
|---|---|---|---|
| GPON | 1490 nm | 1310 nm | ITU-T G.984 |
| EPON | 1490 nm | 1310 nm | IEEE 802.3ah; same colours as GPON |
| RF video overlay | 1550 nm | — | analogue TV carried alongside GPON |
| XG-PON / XGS-PON | 1577 nm | 1270 nm | ITU-T G.987 / G.9807.1 |
| 10G-EPON | 1577 nm | 1270 nm | IEEE 802.3av; matches XG(S)-PON colours |
| NG-PON2 (TWDM) | 1596–1603 nm | 1524–1544 nm | four tunable channel pairs, ITU-T G.989 |
The upstream band sits in the O-band (1260–1360 nm), where uncooled, inexpensive ONU lasers work well; downstream uses the longer wavelengths where fibre loss is lower.
Coexistence
Because GPON (1490/1310) and XGS-PON (1577/1270) use different colours, both can run on one fibre plant at the same time. A passive coexistence element (a WDM filter, often called WDM1r) at the central office combines the two OLT ports onto the feeder fibre; at the customer, each ONU's filter passes only its own pair. This is how operators upgrade subscribers one at a time without touching the outside plant.
NG-PON2 goes further: ONUs carry tunable optics and are assigned one of several wavelength pairs, so capacity can be added by lighting another pair.
Reading a PON module
The wavelength fields in module memory identify the system:
- Tx 1490 / Rx 1310 → GPON/EPON OLT side; Tx 1310 / Rx 1490 → ONU side.
- Tx 1577 / Rx 1270 → XGS-PON OLT; Tx 1270 / Rx 1577 → XGS-PON ONU.
A module with the wrong pair for the network will simply never see light from the other end. See PON transceivers: OLT & ONU.
In CodingBox
CodingBox shows the transmit wavelength and identity of a PON module on the Check transceiver screen, so an OLT SFP and an ONU stick — or a GPON and an XGS-PON module — can be told apart before they are installed.