|
Why are the transceivers in a BiDi link priced so differently? |
Bi-direction transmission on a single fiber is accomplished by using two separate 'channels' or wave lengths on the same fiber. In ours and most BiDi from other vendors those wave lengths are 1310nm and 1550nm.
The following is a text diagram of the transmission mechanism using the BiDi or WDM type transceivers.
"A" type "B" type
>data stream>---Tx 1310-->\ />--Rx 1310--->data stream>
(laser) \ / (receiver)
--o--
(receiver) / \ (laser)
<data stream<---Rx 1550--</ \<--Tx 1550---<data stream<
From the above diagram we can see that there are 2 basic components in each transceiver, a laser and a receiver. In the set, there are 4 different components. What makes the "B" type transceiver much more expensive is the laser component for 1550nm transmit. The 1310nm laser is an FP (Fabry Perot) type and is relatively inexpensive. However the 1550 laser is an expensive DFB (Distributed FeedBack) type.
Therefore, the price difference between the A and B type transceivers is a direct reflection of the different cost for each.
Also note that very long haul 2 fiber transceivers (over 50KM) also use expensive DFB type lasers, making them much more expensive than normal long haul (10-50km) transceivers. (last edit May 6, 2008)
|
