Synchronization Explained - National Instruments
This dating method is also known as “Archaeological Dating” or “Historical Chronology”. The various methods of relative dating are;. 1. Synchronism. Dec 22, In synchronization studies to date, the action of each individual is mathematically A synchronization method for node transmission time was. Dating and synchronizing paleoclimatic records over the last interglacial to the synchronization of climate records . method has limitations when considering.
So far, there has been considerable research attention on the working principles behind synchronization phenomena in nature and, as a result, various models and theoretical investigation have been developed to apply synchronization principles to various mobile communication systems. In this article, we present an exploration of synchronization phenomena in nature.
Some representative models on synchronization are investigated and its working principles are analyzed. In addition, we survey some key applications inspired by synchronization principles for the future mobile communication systems.
The characteristics and limitations of the applications inspired by synchronization in nature are evaluated in the context of the use of nature-inspired technologies. Finally, we provide the discussion of further research challenges for developing the advanced application of natural synchronization phenomena in the future mobile communication systems.
Introduction The inclination of living entities, ranging from animals to humans, to synchronize with each other is the most common tendency in the universe [ 1 ]. Thousands of fireflies synchronously illuminate, while geese fly at the same speed in formation. Applause at concert halls merges to produce a harmonized sound in time, and the menstrual periods of women who closely interact for a long time also synchronize.
Thousands of cardiac pacemaker cells in the heart fire in synchronization to sustain life. Inanimate objects, such as particles and planets, synchronize as well.
Laser beams are created when trillions of atoms oscillating in sync emit photons of the same phase and frequency. Moreover, only one side of the moon can be viewed because the orbital and rotational periods of the moon are synchronized by the gravitational pull between the earth and moon. As shown in the above examples, synchronization occurs with both conscious living organisms and inanimate objects without consciousness.
A key aspect of this phenomenon is that it does not involve a leader who directs the behavior, nor does it require the obtaining of clues from the surrounding environment. Rather, the entities synchronize in a certain rhythm. Fireflies, flocks of birds, schools of fish, and pacemaker cells are all modeled as populations of oscillators [ 3 ]. An oscillator is an entity that continues to repeat itself in a regular time interval. If more than one oscillator influences another oscillator through a physical or chemical process, they are considered to be connected.
Fireflies communicate through light, birds in a flock identify their respective position using their sight, and pacemaker cells transmit electric currents to each other. Reference Clock Synchronization To understand how reference clock synchronization works for oversample clock timed devices, you need to know about the timing and synchronization circuitry on these devices. The delta-sigma ADCs used on these devices require a free-running oversample clock to drive their ADC conversion process.
The ADC produces a new sample after a certain number of oversample clock periods have elapsed.
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The number of clock periods required to produce a new sample is called the oversample rate. Diagram of Oversample Clock Timed Devices To offer users flexibility in choosing their sample rates, these devices feature agile direct digital synthesis DDS clock generator circuitry that can generate the required ADC oversample clock for a wide range of desired sampling rates.
Reference clock synchronization for these devices works in two stages: Reset the DDS clock generator, clock divider, and ADCs on all the devices such that the sample clocks on all the devices are synchronized.
Start the acquisition synchronous to the sample clocks on all the devices. Before jumping into the complicated details of how this all works, remember to keep the following in mind: NI-DAQmx automatically handles everything required to perform reference clock synchronization on supported devices anytime you create a multidevice task.
Even if you are an advanced user trying to manually control this synchronization process, you should probably use the NI-DAQmx programming examples as a starting point for your application. Figure 13 shows how you perform the first stage of reference clock synchronization. At this point, all the devices simultaneously begin the process of resetting their DDS clock generator circuits, clock divider circuits, and ADCs. To line up multiple devices with different reset times, add another SyncPulse.
ResetDelay value to faster devices to align them with slower devices. In addition, you can synchronize devices running at different rates by modifying the SyncClk. The SyncClk is a clock signal used when sending triggers between devices. Triggers are sent on one SyncClk edge and received on the next SyncClk edge. The SyncClk is set to run at the same rate on all devices even if those devices are running at different sample clock rates. If all devices are running at the same rate, then the SyncClk.
Lock all devices to a common reference clock and send a synchronization pulse to all slave devices. Note that this example also sets an extra parameter called MinDelayToStart. This is just a software feature to ensure that the master device waits long enough after sending the sync pulse before attempting to start the acquisition. You can synchronize devices running at different rates by modifying the SyncClk.
Now that Stage 1 sample clock synchronization is complete, Stage 2 starting the acquisition is simply a matter of sending out a start trigger synchronous to the sync clocks on all devices. Stage 2 begins with the master sending out a start trigger.
This start trigger is output synchronously to the sync clock, which was previously synchronized on all the devices. After all the devices receive the start trigger, they wait for their next internal sync clock. At this point, all devices begin generating their sample clocks at essentially the same time.
Note that internal to both the master and slave devices there is a sample clock that is running behind the scenes. Data associated with this sample clock is not acquired and the sample clock signal is not output to other devices until the start trigger event has occurred. This is represented on the waveforms by the dashed lines for the sample clock signal prior to the start trigger occurring.
After the master sends out a start trigger, all devices begin their sample clocks at the same time. Newer PXI Express-based devices support reference clock synchronization. You may have multiple oversample clock timed devices in this scheme, all of which are synchronized via reference clock synchronization. You synchronize sample clock timed devices by exporting a sample clock signal from the oversample clock timed devices to the sample clock timed devices via the PXI Express backplane.
In this case, the sample clock timed devices are using the sample clock synchronization method described earlier. One of these devices then generates a sample clock that is routed via the PXI Express backplane trigger lines to one or more sample clock timed slave devices. The amount of skew between the slaves depends on the skew in the backplane routing delays.
The NI-DAQmx code required to route this sample clock to the sample clock timed slave devices is exactly the same as the sample clock synchronization code shown previously. The top task contains the oversample clock timed master device that generates the sample clock, and the bottom task contains the sample clock timed slave devices receiving this sample clock.
In this case, the top task contains the oversample clock timed master device that generates the sample clock, and the bottom task contains the sample clock timed slave devices receiving this sample clock. Pros Allows synchronization across different types of devices No drift between the devices Sample clock timed devices have greater skew and uncertainty between them due to backplane routing delays Sample clock timed devices cannot run faster than the sample clock provided by the oversample clock timed devices Table 6.
This method allows synchronization across different types of devices.
Chronological dating - Wikipedia
Share Triggers Across Sample Clock Timed and Oversample Timed Devices You can use this same technique to synchronize oversample clock and sample clock timed devices as described previously. One advantage of using this technique is that you can separate your devices into two groups: You can then use reference clock synchronization within each group to achieve tight synchronization within the group.
This process repeats in the following years also. The formation of rings is affected by drought and prosperous seasons. In the years with unfavourable weather the growth rings will be unusually narrow. On the other hand, during years with exceptionally large amounts of rain the tree will form much wider growth rings.
Most of the trees in a give area show the same variability in the width of the growth rings because of the conditions they all endured. Thus there is co-relation between the rings of one tree to that of another. Further, one can correlate with one another growth rings of different trees of same region, and by counting backwards co-relating the inner rings of younger trees with the outer rings of older trees we can reconstruct a sequence of dates.
By comparing a sample with these calendars or charts we can estimate the age of that sample. Thus it is possible to know the age of the wood used for making furniture or in the construction work. The main disadvantage with the system is that, we require a sample showing at least 20 growth rings to make an objective estimation of its age.
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Hence smaller samples cannot be dated. This method can date the sample upto the time of cutting the tree, but not the date when it was actually brought into use. This method is based on the fact that the magnetic field of the earth is changing constantly in direction and proporationate intensity, and that these changes lead to measurable records.
The magnetism present in the clay is nullified once the pottery, bricks or klins are heated above degree centigrade. This implanted magnetism can be measured and the date of its firing estimated. The dating of ancient pottery by Thermoluminiscence measurements was suggested by Farrington Daniels of the University of Wisconsin in America Thermoluminescence is the release in the form of light of stored energy from a substance when it is heated. All ceramic material contain certain amounts of radioactive impurities uranium, thorium, potassium.
When the ceramic is heated the radioactive energy present in the clay till then is lost, and fresh energy acquired gradually depending on the time of its existence. The thermoluminescence observed is a measure of the total dose of radiation to which the ceramic has been exposed since the last previous heating, i. The glow emitted is directly proportional to the radiation it received multiplied by the years.
It is present in nearly every mineral. During rock formation, especially lava, tuffs, pumice, etc. Virtually all argon that had accumulated in the parent material will escape. The process of radio-active decay of potassium continues and the argon accumulated again which when measured will give a clue as to the age of the rock. The application of this method to archaeology depends on locating the widespread distribution of localities that have recently in the last half-million years experienced volcanic activity forming layers over the culture-bearing deposits.
The city of Pompeii in Italy is a good example of the destruction caused by volcanic activity. This method is more useful in dating the prehistoric sites. The starting phase of the Palaeolithic period in India is pushed back by atleast one million years from the earlier dating of about 5 lakh years B.
This unique example comes from a sit known as Bori in Maharashtra, where it was found that a layer yielding flake tools is overlain by a layer of volcanic ash. When this ash was subjected to Potassium-Argon dating it yielded a date of 1. Initially this method was developed to date the meteorites and other extra-terristrial objects, but it is now being applied to archaeological purposes as well.