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DXD/PTP/GPS User Manual (rev 2.10) 

6. GPS Menus 

6.1 SATELLITES SELECTION (MENU 6.1) 

The DXD/GPS receiver is a multi-GNSS (Global Navigation Satellite System) timing receiver able to receive concurrently the 
signals of multiple navigation satellite systems. GPS was the first GNSS system deployed but today, other satellite navigation 
systems are in operation such as GLONASS of Russia, Galileo of Europe, BeiDou (Compass) of China. Moreover, SBAS 
(Satellite Based Augmentation System) a network of the geostationary satellite systems (WAAS of United States, EGNOS of 
Europe, MSAS of Japan) is in operation and Japan has started the operation of QZSS (Quasi-Zenith Satellite System). 

Menu 6.1 lets you select which satellite constellations the DXD/GPS will be connecting to from the following selection: 

•GLONASS 
•Galileo 
•QZSS L1C/A 
•SBAS/QZSS L1S 

Note that the 

GPS

 constellation is always enabled.  

If your antenna is multi-GNSS, enabling multiple satellites constellations in this menu will increase the total number of available satellites. 
In environments with limited open space, access to more visible satellites will translate into greater synchronization accuracy. 

6.2 GPS SETTINGS (MENU 6.2) 

•Antenna Cable Delay 

This field in menu 6.2 allows you to compensate for cable delay and other latencies with a range of ± 100 µsec with a 1 
nsec resolution. The default value is 0. 

When designing an antenna system, cable length must be taken into consideration, 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 following formula is used to calculate the cable delay: Tc = L/cv, where L is the cable length in meters; c is the speed 
of light (3.0 x 10

8

 m/s); and v is the velocity factor of the cable expressed as a number less than 1. 

The correct value of v can be found in the cable manufacture’s specifications. 

•Antenna High Gain 

This field gives the option to turn up the LNA gain (Low Noise Amplifier). 

Most installations will use a high-gain active antenna therefore the default value is OFF. However, if using a passive 
antenna or a low-gain active antenna, this should be ON. 

•Estimated Accuracy Threshold 

A value in ns from 20 to 9999 can be entered. ‘No Threshold Test’ is the default value. This is one of the criteria used by 
the DXD to determine if the GPS signal can be used as a reference. The estimated accuracy is indicated on the GPS 
Receiver stays page.  

6.3 ADVANCED GPS SETTINGS (MENU 6.3) 

Menu 6.3 provides additional parameters, referred to as ‘advanced’, as, in most cases, they will not need to be modified and 
are only provided for unusual situations requiring additional adjustments. 

•Survey Sigma Threshold 

Survey Sigma Threshold has a default value of 10. If your DXD/GPS is having difficulties in achieving lock, increase the 
Sigma value. 

•Survey Time Threshold 

Survey Time Threshold is set by default to 24hrs. This survey time restarts each time the DXD is turned on. If you would 
like to achieve lock faster, decrease the Time value. 

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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