Rakon Limited (Corporate Head Office) Phone: +64 (9) 573 5554 Fax: +64 (9) 573 5559 Email: [email protected] Rakon Europe Limited (Europe, Middle East, Africa) Phone: +44 (1522) 883500 Fax: +44 (1522) 883524 Email: [email protected] Rakon Taiwan Representative Office (Asia) Phone: +886 (2) 2759 0259 Fax: +886 (2) 2759 2668 Email: [email protected] Rakon Limited Shenzhen Representative Office (China) Phone: +86 (755) 8283 5991 Fax: +86 (755) 8283 5990 Email: [email protected] Rakon America LLC (Americas) Phone: +1 (847) 930 5100 Fax: +1 (847) 844 3236 Email: [email protected] www.rakon.com Networks are transioning from circuit switched to packet switched to become more efficient, flexible and cost effecve. With me crical services such as audio and real me video being transported through the inherently asynchronous Packet Networks, Timing over Packet technologies such as IEEE1588 is used to support synchronizaon and is becoming prominent. The requirements of Synchronizaon designs posing challenges to tradional methods. Rakon has characterised various types of oscillators under changing environmental condions for the loop me periods relevant to IEEE 1588v2. Rakon presents a wide range of oscillators that economically fit a wide range of applicaon requirements in the IEEE 1588 space. Introduction and Rakon Solutions The local synchronised oscillator is moving from a physical layer based, phase or frequency locked loop, to a me locked system via secondary layer protocols. The non stochasc nature of the Packet Delay Variaons (PDV) force the loop to have smaller bandwidths and thus longer me constants. Oscillators present themselves as high pass filters in the control loop, thus smaller loop bandwidths can mean that the medium term stability performance of an oscillator is important to the overall system performance. Effecvely the oscillator’s stability performance is now dominated by environmental changes during the extended me periods. The oscillator stability over the medium term (minutes to hours) is either poorly characterised or not been accounted for at all, since the stability under these condions is covered indirectly by other oscillator/system specificaons. Medium Term Stability Challenges for Oscillators Used in IEEE 1588v2 Historically there have been only two “oscillator / lock bandwidth” combinaons, namely Stratum 3 and Stratum 3E. For Stratum 3 oscillators, the effect of variable temperature on TDEV and MTIE was likely to be minimal since the oscillator has a lock bandwidth in the 0.1 to 10 Hz range (me constants of 1.6s to 0.02s) and any slow changes in frequency due to, for example, temperature fluctuaons were filtered out. Conversely, with the Stratum 3E oscillator, because of the very high stability required for the variable temperature stability requirement (±5 ppb), small changes in temperature would not affect the TDEV and MTIE even with a 1 millihertz (mHz) lock bandwidth (me constants of 160s. Packet Network Synchronisation Rakon Devices Stability Slope Aging Δt * = 1µs Δt * = 3µs Δt * = 7µs Band Width ROX5242T2 (10 MHz) ±0.2 ppb -20 to 70°C Positive ≤ ±0.07 ppb/day 3 hours 12 hours 36 hours 0.1 mHz ROX3827T3 (10MHz) ±1 ppb -20 to 70°C Positive ≤ ±0.1 ppb/day 1 hour 6 hours 12 hours 0.3 mHz ROX2522S4 (10MHz) ±5 ppb -20 to 70°C ±0.5 ppb/°C ≤ ±0.5 ppb/day 30 minutes 2 hours 4 hours 1 mHz RMO1490B ±10 ppb -40 to 85°C ±2 ppb/°C ≤ ±1 ppb/day 20 minutes 35 minutes 55 minutes 0.05 mHz RFPO45 G.8263 ±20 ppb -40 to 85°C ±2 ppb/°C ≤ ±1 ppb/day 20 minutes 35 minutes 55 minutes 0.05 ~ 3 mHz * Δt: Time to reach phase error limit with ±20°C temperature variation (ΔT) at 10°C/hour Packet Based Synchronization