DS34S132GNA2+ Maxim Integrated, DS34S132GNA2+ Datasheet - Page 48

• Manufacturer Part Number: DS34S132GNA2+
• Description: Communication ICs - Various 32Port TDM-Over-Pack Transport Device
• Manufacturer: Maxim Integrated

Specifications of DS34S132GNA2+

• Rohs: yes
• Part # Aliases: 90-34S13+2N2

The
After “play-out” begins the Jitter Buffer will continue to supply data until the Jitter Buffer is empty. If the Jitter Buffer
empties, then the Jitter Buffer must again fill to the
The
(overrun) level. This can be used to monitor for “unexpected” fill levels (e.g. too much data accumulated because of
improperly configured input or output clocks or if the
can be monitored to implement a discard process that prevents each Bundle’s Jitter Buffer from over-filling and
adding to the latency of the data (some Clock Recovery Engine firmware revisions may include a function to
discard Jitter Buffer data when
programmed to a level that is lower than the
JBMD
blue area depicts data that is stored in the Jitter Buffer FIFO).
Figure 9-16. Bundle Jitter Buffer FIFO
The purpose of the Jitter Buffer is to store data that can be transmitted during time periods when the S132 must
wait for a packet that has been “delayed”. At the receiving end of a PW, when a packet is received the PW end
point cannot know whether the PDV for that packet was “zero”, the maximum PDV value or any value in between.
If the receiving PW end point knew that the PDV for a received packet was zero, then the best situation would be to
begin storing data and not forward that data until a time period equal to the maximum PDV. Or, if the PW end point
instead knew that a packet was received with the maximum PDV, then the best situation would be to immediately
forward the data (data will never come later than the maximum PDV; storing would add unnecessary delay).
However the PW end point does not know the PDV level for each packet and thereby must make an assumption.
There are three approaches for setting the
which approach is preferred. In each of these approaches the minimum Jitter Buffer delay is equal to the
setting, while the maximum Jitter Buffer delay (maximum fill level) is either equal to the
(MJBS
The first approach assumes that it is important to never discard data. This approach results in “2 * Total PDV” ≤
“Jitter Buffer Delay” ≤
over PW services. The settings for this approach are specified by the following equations:
The PCT value is included as part of the
the PDVT (playout) watermark and because the originating and terminating ends of the PW cannot be perfectly
phase synchronized together. When the PCT is included as part of the MJBS value, in most cases, the S132 fixed
circuit processing delays can be disregarded (included as part of the PCT value, e.g.
The second approach assumes that delay must be minimized and only a small amount of discarding should be
allowed. This approach results in a temporary, maximum latency = “2 PDV + PCT”. But as the PDV varies from its
19-4750; Rev 1; 07/11
SAT/CES data is read out from here and sent to TDM Port
JBMD level data, new data is discarded.
SAT/CES TDM Data is not forwarded to
the TDM Line until the fill level exceeds
If the SAT/CES TDM Data exceeds the
If the SAT/CES TDM Data exceeds the
PDVT
MJBS
discarding begins.
is the maximum if
PDVT
MJBS
MJBS Watermark, a Jitter Buffer
setting specifies how much data must be stored by the Jitter Buffer before “play-out” (FIFO read) begins.
watermark can be used to indicate when the level of stored data exceeds an “expected” maximum
1
1
(in ms) = 2 * Total PDV (in ms)
(in ms) = PCT (in ms) + 2 * Total PDV (in ms)
Overrun event is counted
the PDVT Watermark.
(B.BDSR2.JEBEC).
“MJBS
MJBS
Figure 9-16
or JBMD”. This may be the most commonly used setting for existing/installed TDM
MJBS
is monitored as a watermark for discarding; otherwise the maximum is JBMD).
indicates the Jitter Buffer has too much data). The
depicts the relationship between the JBMD,
Bundle Jitter Buffer FIFO
MJBS
PDVT
JBMD
setting to provide a watermark condition that is slightly higher than
JBMD
MJBS
PDVT
and
PDVT
level so that an
MJBS
MJBS
level before data will again be forwarded.
values. Each system should be analyzed to determine
setting does not allow for the maximum PDV).
MJBS
This area is empty and
can store SAT/CES TDM
Data from RXP packets.
This area is filled with
SAT/CES TDM Data that
is waiting to be transmited
on the TDM line.
Overrun condition can be detected before
New SAT/CES packet data is stored here
MJBS
BFD
DS34S132 DATA SHEET
PDV).
MJBS
and
MJBS
PDVT
register should be
or
JBMD
settings (the
48 of 194
setting
MJBS
PDVT