[SI-LIST] Re: NRZ signaling
- From: "Clewell, Craig" <cclewell@xxxxxxxxxxxxxx>
- To: "'herbert_lage@xxxxxxxxxxx'" <herbert_lage@xxxxxxxxxxx>
- Date: Tue, 4 Mar 2003 10:57:39 -0500
Herbert,
Interesting point you brought up. Why is it that in optical transmission a
LPF is used to cut-off the frequency to 0.8 * BitRate? Just curious....
Craig
-----Original Message-----
From: herbert_lage@xxxxxxxxxxx [mailto:herbert_lage@xxxxxxxxxxx]
Sent: Tuesday, March 04, 2003 10:49 AM
To: sunil-chandra.kasanyal@xxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: NRZ signaling
Hi Sunil,
The main feature of a Non-Return-to-Zero (NRZ) pattern is shown in the
little graph below. For consecutive "Ones" the signal stays at the logic
"high" level.
Bit-Sequence: 0 | 1 | 1 | 0
-- --
Return-toZero: / \ / \
----- - ------
--------
NRZ: / \
----- ------
The advantage is that the fundamental frequency of NRZ signals is only half
the bit rate, so it requires less bandwidth for transmission. You can see
that easily when you compare a 1010 sequence in both formats. In optical
transmission people typically use a low-pass filter that cuts off at about
0.8*bitrate. So for 10Gb/s data transmission you only need 8Ghz analog
bandwidth.
It also has a consequence when simulating NRZ patterns - if a clock-like
source is used, it needs to be run at half the bitrate to create a 1010 NRZ
signal.
Best Regards,
Herbert.
-----Original Message-----
From: sunil-chandra.kasanyal@xxxxxx
[mailto:sunil-chandra.kasanyal@xxxxxx]
Sent: 04 March 2003 13:10
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] NRZ signaling
Dear All,
What is the NRZ (Non Return to Zero) Signaling. How it makes high
speed interfacing possible.
Thanks and Regards,
Sunil C Kasanyal
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