3
rd
Generation Rack-
Mount RDMS™
135
Quasonix, Inc.
When enabled, the Time Aligner continuously measures skew between channels but remains in a “monitor” state
(with no timing correction) as long as the skew remains below a predefined threshold. When the skew exceeds the
threshold, the Time Aligner switches to a “run” state (with full timing correction) as long as the signal quality is
sufficient for it to continue to track timing skew.
If the propagation delay between channels is well-controlled and small, the Time Aligner may be disabled to
guarantee minimal timing jitter.
4.5.3.3.8 PCM Encoding
The PCM Encoding setting controls the RDMS receiver output PCM data format. Two primary options are
available: the receiver can convert encoded data to NRZ-L, or it can preserve transmit encoding.
The first option allows conversion of any of the following encoding formats to NRZ-L:
•
NRZ-L: Non-return-to-zero, level
•
NRZ-M: Non-return-to-zero, mark
•
NRZ-S: Non-return-to-zero, space
•
RZ: Return-to-zero
•
Biphase-L: Bi
ϕ
, level
•
Biphase-M: Bi
ϕ
, mark
•
Biphase-S: Bi
ϕ
, space
•
DM-M: Delay modulation (Miller code), mark
•
DM-S: Delay modulation (Miller code), space
•
M2-M: Modified delay modulation (Miller squared code), mark
•
M2-S: Delay modified modulation (Miller squared code), space
The second option allows the transmit encoding to be preserved and output from the RDMS unaltered. To
accomplish this, PCM Encoding must be set to NRZ-L
–
regardless of the actual transmit encoding. Also, for
encoding formats that use di-bits to represent each user bit (i.e., RZ, Bi
ϕ
, DM, or M2), the RDMS bit rate must be
set to twice the user bit rate. Note that the RDMS output clock will clock at twice the user bit rate in this
configuration.
Select the desired encoding format from the drop down menu, as shown in Figure 226.
Figure 226: Advanced Settings Window, PCM Encoding Drop Down Menu
