DXD8/PTP User Manual (rev 2.15)
Page 7
4.4 PORT TIMING (MENU 5.4)
•
Announce Interval
: -3 to 4 (1/8sec - 16sec)
Sets the rate at which the master will send Announce messages. These messages
are used to determine which device will be the Grandmaster using the BMCA
(Best Master Clock Algorithm)
Per IEEE 1588 this value should be uniform throughout a domain.
•
Announce Receipt Timeout
: 2 to 10 announce intervals
Sets the number of Announce messages that can be missed before it is assumed the master is no longer present and the
process of selecting a new one begins.
Per IEEE 1588 this value should be uniform throughout a domain.
•
Sync Interval
: -7 to 1 (1/128sec - 2sec)
Sets the rate at which the master will send Sync messages.
•
Min Delay Req Interval:
1 to 32 the number of Sync Interval
Sets the minimum time interval between 2 adjacent Delay Requests.
This field shows a quantity of sync intervals: “n sync intervals”, where n = 1,2,4,8,16,32 (when n=1 it will say “1
sync interval”).
5. Time of Day
Time of Day is an essential part of the DXD-8 design. In a PTP network, the devices all need to know the Time of Day, i.e. year,
month, day, hour and seconds, even nanoseconds, to achieve frequency and phase synchronization. At the heart of the DXD-8
is the Main Time of Day Clock (TOD) & Reference Frame Generator. This is where System Time is generated and where the
references generated by the DXD-8 are aligned with the PTP epoch.
As shown on the diagram above, some of the reference sources include time and rate information. GPS and PTP for example
carry precise time and date information as well as frequency. However, traditional reference signals, such as video sync or
word clock, only carry the frequency information. When selecting one of those as reference (BNC inputs), the time information
needs to be added from another source. The DXD-8 offers several options.
IEEE-1588
ETHERNET
PTP
INT
OCXO
ANT
GPS
ETHERNET
UNIVERSAL OUTPUTS
1
2
BNC OUT 1 & 2
BNC OUT 3 & 4
BNC OUT 5 & 6
BNC OUT 7 & 8
5
6
7
8
SYNC
SYNC
SYNC
SYNC
3
4
• WC
• AES
• VID
• 10 MHz
• 1PPS
• WC
• AES
• VID
• 10 MHz
• 1PPS
• WC
• AES
• VID
• 10 MHz
• 1PPS
• WC
• AES
• VID
• 10 MHz
• 1PPS
SYNC
TIME SOURCES
(POSITION)
INT
TCXO
REFERENCE SOURCES
(RATE)
SYNC
TIME
SELECT
REFERENCE
SELECT
ETHERNET
BNC IN B
WC
AES
VID
10MHz
BNC IN A
WC
AES
VID
10MHz
NTP
INTERNAL
TIME OF DAY
CLOCK
&
REFERENCE
FRAME
GENERATOR
DXD-8 DIAGRAM
INT
RTC
ETHERNET
PTP
(BMCA)
ANT
GPS
PTP
(BMCA)
Rate & Position
Rate Only
Position Only
