APPLICATION NOTE – IRIG-B REDUNDANCY
7Pages

APPLICATION NOTE – IRIG-B REDUNDANCY IRIG-B Redundancy Goal • to test the redundancy of the system thanks to the IRIG-B point-to-point distribution Requirements • 1x MXS-EVO • 2x ETS-EVO • Oscilloscope ETS-EVO #1 Electrical link Optical link Equipment MXS-EVO MXS-EVO is a multi-output generator for high stability Time & Frequency signals, aimed to synchronization of systems and devices in many areas like Broadcast, Defence, Space, Telecommunication etc. The unit has 12 programmable outputs designed to make the equipment adaptable to di_erent situation and meet user’s needs. Furthermore it has an Ethernet interface for Time Protocol Synchronization (NTP or PTPv2 Grandmaster Clock). The unit is also capable of two (1 input and 1 output) optical ST connectors designed for IRIG B. MXS-EVO can get external reference input from GPS receiver, E1/T1, PPS, 1 to 10 MHz analogue, IRIG-B Time code, PTPv2 IEEE 1588-2008, in order to have maximum reliability that is completed by dual independent Power Sup

APPLICATION NOTE – IRIG-B REDUNDANCY Internal high stability OCXO aging rate of ± 1*10-10/day 12 channels GPS receiver with automatic tracking and timing error management New generation DPLL fast lock with holdover Multi reference inputs: o GPS o E1 (G.703/9) or T1 o PPS o 1, 2, 2.048, 5, 10 MHz o IRIG-B Time Code o PTPv2 (IEEE 1588-2008) 1x Fast-Ethernet interface for NTP and/or PTP synchronization 1x Optical multimode I/O via ST connectors 12x programmable outputs configurable between: o PPS o IRIG B DCLS o IRIG B AM o E1 (G.703/9) / T1 with SSM o 2.048 MHz (G.703/13) o 10 MHz (Low Phase...

APPLICATION NOTE – IRIG-B REDUNDANCY ETS-EVO ETS-EVO is a very flexible solution to generate ultra-stable Time (PPS, Time Codes, NTP/PTP Serial Time Telegrams, etc…) and Frequency (10 MHz Low Noise and 2.048 MHz square wave output). The unit is a multi reference input equipment that can accept various reference inputs from (GPS, NTP/PTP as well as IRIG B Time Code both Electrical and Optical). ETS-EVO has Event Time input capability via Dry Contacts. Furthermore the unit can be easily remotely managed via SNMP or a user friendly GUI on a web interface. Internal high stability OCXO aging...

APPLICATION NOTE – IRIG-B REDUNDANCY Test cases The configuration of the equipment is really simple. It is just needed to put the various devices in • automatic switch mode • automatic IRIG-B input selection In this way the default configuration makes the ETS-EVO to be directly disciplined by the GPS antennas and the MXS-EVO by the IRIG-B input (either electrical or optical) from the two ETSEVO. In case of an antenna failure on a ETS-EVO the other ETS-EVO would still propagate the time via the IRIG-B link. So the system is fully redundant and the time on the various devices is always...

APPLICATION NOTE – IRIG-B REDUNDANCY Test #2 In this test we want to check the IRIG-B accuracy and coherence on the three devices With an oscilloscope is possible to compare the output signals from the three devices. The IRIG-B signal carries information about date and time, as shown in the following table. It is quite easy to recognize the time passing by triggering a PPS and observing the first few bits indicating the seconds.

APPLICATION NOTE – IRIG-B REDUNDANCY The above picture represents the time 8 seconds. Test #3 In this test we want to check the NTP accuracy and coherence on the three devices 1. We need to setup a NTP daemon1 2. And add a line for every device (MXS-EVO and ETS-EVO). It is also a good idea to specify an external public NTP server in order to compare the time stamp with an external source. ## ntpd.conf server ntp1.ien.it server ntp2.ien.it server 192.168.200.14 server 192.168.200.15 server 192.168.200.16 3. Ask the timing information with ntpq –c peer remote refid st t when poll reach delay...

APPLICATION NOTE – IRIG-B REDUNDANCY Conclusions IRIG-B is just one of the many timing protocols implemented in our devices. We have prepared other papers where we have presented a few methods for synchronizing remote devices via an Ethernet connection, both in frequency (SyncE) and time (PTP), with precision ranging from nanoseconds (SyncE and PTP) to milliseconds (NTP). This paper is meant to be used as a starting point to implement a fully redundant system and to show how it can be done with a few simple point-to-point connections. The overall achievable accuracy is ±100 ns and this...