Shopping on line can be easy, simple and save you lots of money. It can also take a lot of your time, frustrate you, and result in unwanted purchases. Now the same can be said for regular high street shopping, but with the vast opportunity presented by the Internet it will pay you to spend a few minutes reading this and understanding how to better optimize your Time Transfer shopping experience:
1. Compare - without doubt the biggest advantage that the Time Transfer offers shoppers today is the ability to compare thousands of Time Transfer at a time. This is a great thing, but not necessarily all the time! Too much can be daunting at times so take advantage of the great comparison sites and where possible let them do the hard work for you.
2. Research - if it has been said it will be on the internet. Ignorance is no longer a justifiable reason for buying the wrong thing. Take the time to research in detail everything that you could possible want to know about
3. Testimonials - don't know anybody that has bought a Time Transfer? Wrong! If the Time Transfer is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.
4. Questions - Got a question about Time Transfer then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....
5. Reputation - Never heard of the company selling Time Transfer? Don't worry, no reason why you should know every company in the world, but you know someone that does! Use the internet to find out what people are saying about Time Transfer and build up a picture of their reputation for sales, returns, customer service, delivery etc.
6. Returns - still worried that even after all of the above your Time Transfer wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.
7. Feedback - happy with your Time Transfer then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.
8. Security - check for the yellow padlock on the Time Transfer site before you buy, and the s after http:/ /i.e. https:// = a secure site
9. Contact - got a question about Time Transfer, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.
10. Payment - ready to pay for your Time Transfer, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.
Time transfer describes methods for transferring reference clock
synchronization from one point to another, often over long distances. Radio-based navigation systems are frequently used as time transfer systems.
In some cases, multiple measurements are made over a period of time, and exact time synchronization only determined retrospectively.
In particular, time synchronization has been accomplished by using pairs of radio telescope to listen to a pulsar, with the time transfer accomplished by comparing time offsets of the received pulsar signal.
In a one-way time transfer system, one end transmits its current time over some communication channel to one or more receivers. The receivers will, at reception, decode the message, and either just report the time, or adjust a local clock which can provide hold-over time reports in between the reception of messages. The advantage of one-way systems is that they can be technically simple and serve many receivers, as the transmitter is unaware of the receivers. A drawback of the system is that propagation delays of the communication channel remain uncompensated except in some advanced systems. Examples of a one-way time transfer system are the clock on a church or town building and the ringing of their time-indication bells;
Radio clock signals such as
LORAN,
DCF77 and MSF; and finally the Global Positioning System which uses multiple one-way time transfers from different satellites, with positional information and other advanced means of delay compensations to allow receiver compensation of time and position information in real time.
In a two-way time transfer system, the two peers will both transmit, and will also receive each others messages, thus performing two one-way time transfer measurements where the difference of the remote clock compared to the local clock is being noted. The sum of these time differences will become the sum of the delay between the two nodes. It is often assumed that this delay is evenly distributed between the directions between the peers. Under this assumption, the difference between the measured delays divided by two will provide the time difference between the clocks without being affected by propagation delay. The advantage of the two-way time transfer system is that propagation delays gets compensated, but the drawback is that there needs to be means for bi-directional communication (of preferably symmetrical propagation delay) between the directions. Another drawback is that the source of reference needs to be actively measuring slaves, which can become a scale issue. The Two-Way Satellite Time and Frequency Transfer (TWSTFT) system being used in comparison among some time laboratories uses a satellite for a common link between the laboratories. The Network Time Protocol uses packet based messages over an IP network.
See also
References
Time transfer describes methods for transferring reference clock synchronization from one point to another, often over long distances. Radio-based navigation systems are frequently used as time transfer systems.
In some cases, multiple measurements are made over a period of time, and exact time synchronization only determined retrospectively.
In particular, time synchronization has been accomplished by using pairs of radio telescope to listen to a
pulsar, with the time transfer accomplished by comparing time offsets of the received pulsar signal.
In a one-way time transfer system, one end transmits its current time over some communication channel to one or more receivers. The receivers will, at reception, decode the message, and either just report the time, or adjust a local clock which can provide hold-over time reports in between the reception of messages. The advantage of one-way systems is that they can be technically simple and serve many receivers, as the transmitter is unaware of the receivers. A drawback of the system is that propagation delays of the communication channel remain uncompensated except in some advanced systems. Examples of a one-way time transfer system are the clock on a church or town building and the ringing of their time-indication bells;
Radio clock signals such as
LORAN,
DCF77 and
MSF; and finally the Global Positioning System which uses multiple one-way time transfers from different satellites, with positional information and other advanced means of delay compensations to allow receiver compensation of time and position information in real time.
In a two-way time transfer system, the two peers will both transmit, and will also receive each others messages, thus performing two one-way time transfer measurements where the difference of the remote clock compared to the local clock is being noted. The sum of these time differences will become the sum of the delay between the two nodes. It is often assumed that this delay is evenly distributed between the directions between the peers. Under this assumption, the difference between the measured delays divided by two will provide the time difference between the clocks without being affected by propagation delay. The advantage of the two-way time transfer system is that propagation delays gets compensated, but the drawback is that there needs to be means for bi-directional communication (of preferably symmetrical propagation delay) between the directions. Another drawback is that the source of reference needs to be actively measuring slaves, which can become a scale issue. The Two-Way Satellite Time and Frequency Transfer (TWSTFT) system being used in comparison among some time laboratories uses a satellite for a common link between the laboratories. The Network Time Protocol uses packet based messages over an IP network.
See also
- Global Positioning System
- LORAN
- Radio clock
- Watch#Radio-controlled movements
- Atomic clock
- International Earth Rotation and Reference Systems Service
- Network Time Protocol
- Two-Way Satellite Time and Frequency Transfer
- Time signal
References
