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DXD/PTP/GPS User Manual (rev 2.10)

Page 11

9. Time Menus 

9.1 TIME STANDARDS (MENU 7.1) 

The following time standards are available on the DXD-8 in addition to the local time: 

TAI

: International Atomic Time, an atomic coordinated time that has been measuring time continuously since 1955 with 

no leap seconds. It is used as a base by other standards such as UTC. 

UTC

: Coordinated Universal Time is the time zone ‘0’ from which all other time zones are calculated. It is based on 

TAI and since 1972 has had leap seconds every year or so, depending on the earth’s rotation. 

GPS

: Global Positioning System time is used by the atomic clocks in the GPS satellites. It is continuous time (no leap 

seconds) measured from the GPS time zero point of midnight January 5, 1980. It is 19 seconds behind TAI. 

Loran

: Long Range Navigation time based on atomic clocks. Like GPS, it is continuous time with no leap seconds 

measured from the time zero point of midnight January 1st, 1958. 

Local

: Local time is based on UTC and can have adjustments for time zone and Daylight Saving (menu 7.1). 

Menu 7.1 lets you pick which of these time standards will be used to display the following DXD times: 

System Time

, the main Time Of Day clock at the heart of the DXD 

RTC

, Real Time Clock, a constantly running, battery-backed-up clock inside the DXD 

Grandmaster

, time received on the Ethernet port from the PTP Grandmaster 

GPS

, time received from the GPS receiver (

optional

To avoid confusion, it is recommended to use one standard for all DXD times. The default value is TAI. But some users may 
prefer to use Local Time instead while others may even prefer different standards for different times. 

Be aware that, even though the time source may give Time Of Day, it may not correspond to the time indicated on a 
wall clock as it would depend on the standard used or even on the accuracy and settings of the source time. 

There are 2 other Local Time parameters in menu 7.1: 

Time Zone

: can be adjusted in hours and minutes with a positive or 

negative value, relative to UTC (or GMT) 

Daylight Saving

: can be adjusted in hours and minutes (typically 1 hr). 

DST can only be set manually. 

At the bottom of this page a ‘hint’ message appears for setting the time zone 
properly: NY -5, Tokyo +9. 

9.2 REAL TIME CLOCK (MENU 7.2) 

Menu 7.2 lets you set several parameters of the RTC (Real Time Clock), the DXD internal back up clock described in chapter 8 
above. 

Set Time: YYYY/MM/DD 

and

 HH:MM:SS

: These fields let you enter manually a date and a time that will become 

the current date and time of the RTC when the [

ENTER

] key is pressed. 

System Time Jam From RT Clock

: With ‘Press ENTER to Jam’ selected, the Main TOD Clock (System Time) will 

Jam from the internal RTC Time when the [

ENTER

] key is pressed. 

Note that depending on the offset between the 2 clocks, this action will most certainly create a certain amount of 
‘sync shock’ as all the outputs are locked to the System Time. 

Auto Update RT Clock

: When this function is turned on, the RTC is automatically updated with the date & time 

information from GPS. This update occurs within a second of when the feature is turned on, then every 1.2 hr. Options 
are “From GPS” or “Off”. 

This field does not appear if the DXD/GPS card is not installed. 

At the bottom of this page the RTC Time is displayed along with the Time Standard set up in menu 7.1 

Содержание DXD/GPS

Страница 1: ...k DXD OCXO OCXO option for the DXD Universal Clock Operations manual Version 2 10 January 2021 All materials herein Brainstorm Electronics Inc Brainstorm Electronics reserves the right to change or mo...

Страница 2: ...6 GPS Menus 8 6 1 SATELLITES SELECTION MENU 6 1 8 6 2 GPS SETTINGS MENU 6 2 8 6 3 ADVANCED GPS SETTINGS MENU 6 3 8 7 DXD OCXO 9 8 Time of Day 9 8 1 RTC Real Time Clock 10 8 2 Time Jam 10 8 2 1 TIME JA...

Страница 3: ...9 15 Typical PTP use 20 15 1 HYBRID SYNC GENERATOR ACCEPTING MULTIPLE REFERENCES 20 15 2 DISTRIBUTED PTP VS INDIVIDUAL GRANDMASTERS WITH GNSS 21 16 Guidelines for con fi guring PTP Precision Time Prot...

Страница 4: ...a series of 4 numbers separated by periods This key is only valid for the DXD 8 with the serial number used when you placed the order Note that PTP is optional on the DXD 8 only A feature key is not r...

Страница 5: ...ng LOCAL REF WHEN GM When PTP Mode is selected if GPS is available this fields enables GPS to be set as the reference when the DXD 8 is the Grandmaster Enabling this field will announce the DXD 8 as G...

Страница 6: ...a quick set up This menu gives you the option to set the timing values to the pro fi le default values 4 4 PORT TIMING MENU 5 4 Announce Interval 3 to 4 1 8sec 16sec Sets the rate at which the master...

Страница 7: ...in your DXD an antenna will need to be connected to the receiver s SMA connector an antenna is not included with the DXD GPS The cable needs an SMA Male connector on the DXD side Ideally the antenna s...

Страница 8: ...sideration as it can not only impact the signal strength but also cause a delay in the signal Under typical conditions however the expected cable delay is negligible in the nanoseconds range The follo...

Страница 9: ...e 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 w...

Страница 10: ...nd wanting all of the cross frame outputs 25 etc to be in correct phase and epoch as well as wordclocks and AES In a primarily legacy application this is the way to increase the number of legacy outpu...

Страница 11: ...to use Local Time instead while others may even prefer different standards for different times Be aware that even though the time source may give Time Of Day it may not correspond to the time indicate...

Страница 12: ...on Jan 1 1970 This process occurs everyday at the same time as set in the DAILY JAM TIME fi eld Daily Jam Time The value entered in the DAILY JAM TIME field is the amount of time after midnight local...

Страница 13: ...to LOCKED GRANDMASTER In case the DXD is or becomes a PTP Salve when locked it changes to LOCKED PTP SLAVE Note that if another source was selected in the reference menu such as Video Sync and the DXD...

Страница 14: ...lock and the Grandmaster in sec Additional times may appear on this page such as Time Code based on the installed options 11 2 2 GPS RECEIVER STATUS PAGE The GPS RECEIVER status page displays the foll...

Страница 15: ...as the ability to clock to a non Dante PTP v2 clock AVB Audio Video Bridging is a set of IEEE standards that facilitate the transport of high performance audio and video on a LAN One of those standard...

Страница 16: ...suited clock is found it will become the Grandmaster 12 6 SYNCHRONIZATION There are several different PTP messages used during synchronization sequenced as follows 1 The grandmaster sends a Sync messa...

Страница 17: ...clocks on a single PTP communication path must use the same method to measure the time delay 12 8 TYPES OF CLOCKS IEEE 1588 de fi nes three different types of clocks Ordinary Clock OC Boundary Clock...

Страница 18: ...ate of the port can change The BMCA determines what unit becomes the Grandmaster If the current Grandmaster disappears or looses GPS another Grandmaster is selected For more on the Grandmaster selecti...

Страница 19: ...it has been set by the operator 14 1 JUMP TO RELOCK When the time difference detected between the external PTP GM and the DXD System Time is above the Jump Threshold value the DXD will jump to the ne...

Страница 20: ...t all equipment could be kept perfectly synchronized But for added fl exibility the DXD s can also be set up to lock to any legacy sync or to PTP as illustrated below These choices are available in th...

Страница 21: ...TP slaves to an external Grandmaster in the second illustration the DXD 8 s are all Grandmaster for their networks and each is locked to GNSS This second solution is particularly useful when distances...

Страница 22: ...ith any other domain number will be ignored menu 5 2 Ports Timing per IEEE 1588 all devices on a PTP domain must have the same value set for these ports timing Announce Interval Announce Receipt Timeo...

Страница 23: ...GMPv2 On larger networks a router is required to manage multicast group membership Switches that support IGMP snooping are also recommended 17 Troubleshooting Error Warning Messages 17 1 PTP NO PORT W...

Страница 24: ...3 Menu 5 1 If PTP was selected TIME JAM BNC INPUT will automatically show in menu 5 1 in blue blue status information The words Time Jam will also appear on the REFERENCE line at the bottom of the ma...

Страница 25: ...the ribbon cable to J23 the GPS connector on the motherboard B J23 is the designator number on both DXD 8 and DXD 16 PCB As always with ribbon cables make sure the connectors are properly oriented do...

Страница 26: ...Including cable loss Low Gain mode FLNA High 3 For best jammer resistance and lower power consumption use 10 dB lower gain than the max gain 18 3 2 RECOMMENDED PASSIVE ANTENNA 1 High Gain mode FLNA Op...

Страница 27: ...TIMEOUT 3 announce intervals SYNC INTERVAL 1 sec log 0 MINIMUM DELAY REQUEST INTERVAL 1 sync interval GLONASS Yes GALLILEO No QZSS LIC A Yes SBAS QZSS LIS SBAS DIF FIX ANTENNA CABLE DELAY 0 ANTENNA H...

Страница 28: ...Page 28 DXD PTP GPS User Manual rev 2 10...

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