Inquisitive Mind – Dec 2017

A series of monthly knowledgeable and intelligent articles with links to interesting blogs entries, tools, and anything that interests an inquisitive mind. The Amazing $1 microcontroller: Very detailed and thorough blog article on specs, tools, environment about minimal costing micro-controllers from Atmel, Cypress, Freescale, Microchip, NXP, Renesas (my favorite), ST etc IP Header checksum: If you have ever tried to understand the TCP/IP protocols then you would have definitely stumbled upon the checksum field that is the part of protocol headers like TCP, IP. Roman10 and GeekStuff explain the IP header checksum in detail. Jobs and Demand for AI experts,  There are … (Continue Reading)

Stock Valuation and Technical Analysis

Stock Valuation for Engineers

As engineers we keep ourselves too busy (and occupied) in creating something useful and valuable for the society and the world at large, while we see people earn insane amounts of money by investing in stocks and buying shares of the same companies where people like us word hard to make it profitable and innovative. Sure, we get our salary, awards and satisfaction (and hopefully some ESOP), however, we should not lack in financial knowledge, especially the technical analysis, that is required to know which stock is valuable (at current level) and may invest some loose change (or certain amount … (Continue Reading)

Phase difference

What is Plesiochronous

In this short article and your next 2 minutes, you are going to learn “What is Plesiochronous” and (be careful – once you know it you cannot un-know it), you can brag about this concept (and this seemingly-complicated word) to your friends (and foes). So, what is it? What does Plesiochronous really mean and what is it used for? It is related to TIME (you guessed it right, due to the word “chronos”), but what is so special? If you have been following this website, we have talked in detail about “time and clock synchronization” in a series of articles, … (Continue Reading)

Testing the Quality of Clock Synchronization

Measures of synchronicity – Accuracy of Time

Although it is just easier to buy the equipment available to test the synchronism of two independent systems, we discuss here the measures of synchronicity – Accuracy of Time. The reader would thus be able to choose among the available products in market and appreciate them better (after having gone through the Synchronization basics and timing-protocols and the technology-comparison etc). Two measures of quality of any single oscillator and clock are Jitter and Wander. And measures of synchronization achieved between two different clocks or oscillators, through whatever means, are TiE, MTIE, TDEV etc. These are explained further. Quality of an … (Continue Reading)

Comparison - SyncE, NTP, GPS, IEEE-1588

Comparison – SyncE, NTP, GPS, IEEE-1588

We, now have enough information to compare various synchronization methods after we went through the clock synchronization basics and the Synchronous Ethernet (SyncE), IEEE-1588 technologies. In this section we would look at various factors through which we can have a comparison – SyncE, NTP, GPS, IEEE-1588 and evaluate these technologies: Network Load: Sync-E works at the physical layer and is independent of congestion or network load. It would work whether traffic is present or the link is idle. Also, except for 10-pps ESMC messages, Sync-E does not load the network in order to achieve synchronization. Even the accuracy achieved is … (Continue Reading)

1588 Software Design and Multi-core

IEEE-1588 Software Design and Multi-core

From a high level, IEEE-1588 software design and multi-core design and implementations consist of time-stamping hardware, protocol parsing software and filtering and clock correcting algorithm. The prior article mainly dealt with how the time-stamps were exchanged between master and its various slaves while the next article would deal with the related algorithms. This section deals with how all this gets tied together as a complete system and solution that achieves synchronization. In order to keep the operating-system and stack latencies from adding up, it is beneficial to time-stamp the packets as close to the hardware as possible i.e. when a … (Continue Reading)

IEEE-1588 v2 Clock Recovery

IEEE-1588 synchronization

In continuation of time-synchronization article series, conceptually, IEEE-1588 synchronization is as simple as if you were asking the time from somebody and (s)he replying after looking at his/her watch. You would then correct your watch accordingly. This is simply: Time to be set = Time told + some delay But this simplicity just ends here. Let us look at some of the issues we would face in the above scheme: To be very precise, you might want to calculate the exact delay it took him/her to tell you the time. In addition compensate for the time it would take you … (Continue Reading)

SyncE ESMC Packet Format

Synchronous Ethernet (SyncE)

In simple terms, Synchronous Ethernet extends the use of a PLL (Phase locked loop) clock to transmit data. At a very crude level, this, and only this, is the whole conceptual working of Synchronous Ethernet. At the physical layer, two Ethernet peer nodes are already synchronized through a PLL for the RX (receiving) end. A PLL works by using a negative feedback loop to lock. Just the way we tune a guitar: listening to a tuning-fork, plucking the string, comparing the sound and correcting the tension. In Ethernet, the receiving node monitors the incoming bits, compares their alignment and timing with … (Continue Reading)

Synchronization in Networks

(Continuing from the previous post: “Clock Synchronization in Telecommunication Networks“…) Like layers in a network, time synchronization consists of two basic layers: Phase synchronization; and Frequency Synchronization (Read more about Synchronous / Asynchronous / Isochronous / Plesiochronous) It is extremely easy to grasp this concept by considering the day-to-day questions: Why do you always make me wait? It means the other person’s watch is behind (or your watch is ahead) of agreed-upon time. A 4 ‘o clock in other person’s watch might translate to 4:10 pm in yours. This is a phase error and requires phase synchronization. Is my watch/clock … (Continue Reading)

Time Synchronization in Telecommunication Networks

Ques: How do we synchronize the clocks across nodes in a telecom network? Answer: Instead of relying on nodes “keeping” their own sense of time, the time is “distributed” across the network hierarchy. Two promising solutions: Synchronous Ethernet and IEEE 1588 are presented in this article as well as their “combination” to deal with the synchronization challenge. Ultimately, the synchronization achieved is measurable both qualitatively and quantitatively using various tools and methods that are further discussed. The new-age network deployments It is a fact that the service providers have huge investment in legacy TDM, SONET/SDH, ATM network and equipment, however, … (Continue Reading)