Installing a Ntp Server Using a Radio Reference Source
Network Time Protocol (NTP) is one of the Internet’s oldest protocols still used, invented by Dr David Mills from the University of Delaware, it has been in utilized since 1985. NTP is a protocol designed to synchronize the clocks on computers and networks across the Internet or Local Area Networks (LANs).
NTP (version 4) can maintain time over the public Internet to within 10 milliseconds (1/100th of a second) and can perform even better over LANs with accuracies of 200 microseconds (1/5000th of a second) under ideal conditions.
NTP works within the TCP/IP suite and relies on UDP, a less complex form of NTP exists called Simple Network Time Protocol (SNTP) that does not require the storing of information about previous communications, needed by NTP. It is used in some devices and applications where high accuracy timing is not as important.
Time synchronisation with NTP is relatively simple, it synchronises time with reference to a reliable clock source. This source could be relative (a computer’s internal clock or the time on a wrist-watch) or absolute (A UTC – Universal Coordinated Time – clock source that is accurate as is humanely possible).
It is strongly recommended by Microsoft and others, that external based timing should be used rather than Internet based, as these can’t be authenticated. Specialist NTP servers are available that can synchronise time on networks using either the MSF (or equivalent) or GPS signal.
Atomic clocks are the most absolute time-keeping devices; however, they are extremely expensive and are generally only to be found in large-scale physics laboratories. However, NTP can synchronise networks to an atomic clock by using either the Global Positioning system (GPS) network or specialist radio transmission (MSF in Britain).
The MSF national time and frequency radio transmissions used to synchronise an NTP server is broadcast by the National Physics Laboratory in Cumbria which serves as the United Kingdom’s national time reference, there are also similar systems in Colorado, US (WWVB) and in Frankfurt, Germany (DCF-77).
A radio based NTP time server usually consists of a rack-mountable time server, and an antenna, consisting of a ferrite bar inside a plastic enclosure, which receives the radio time and frequency broadcast. The antenna should always be mounted horizontally at a right angle toward the transmission for optimum signal strength. Data is sent in pulses, 60 a second. These signals provides UTC time to an accuracy of 100 microseconds, however, the radio signal has a finite range and is vulnerable to interference.
A radio referenced NTP servers is easily installed and can provide an organization with a precise time reference enabling the synchronization of entire networks
About the Author
Richard N Williams is a technical author and a specialist in the telecommunications and network time synchronisation industry helping to develop dedicated time server products; ethernet clocks, GPS time servers, NTP servers, digital wall clocks, atomic clock servers and SNTP time servers. Please visit us for more information about NTP products and NTP servers
Absolute Radio from UK received in Austria
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5 Things to Consider When Purchasing New DJ Speakers by Erland Schulze
For a DJ to wow the audience, they need to have a high quality sound system. Only by choosing the right DJ speakers can the DJ hope to envelope the crowd with sound and create the club/venue ambiance that will help them build a name for themselves. But buying the right speakers isn’t easy. Professional audio equipment comes in many different shapes and sizes, and which DJ speakers to choose depends a great deal on your budget and your needs.
DJ Speaker Considerations
•Cost/Quality Trade Off
Most DJs don’t operate on a high budget when they’re first starting out, so you may need your first speakers to be cost efficient. Depending on the venues, you may be able to afford more harmonic distortion or impedance than someone producing music or playing in a quieter location, which should help you buy professional audio that meets your budget. However, it’s important to remember that the better the speakers the better the sound, and buying low quality speakers for the sake of saving money may not always be in your best interests.
•Size
When you’re playing music with loud bass – especially if you are in a large and crowded venue – you may need speakers with large drivers that can handle the depth of the bass on each track. While some smaller professional speakers are made with enough power to mimic the volume of larger speakers, larger speakers have more reliability and are a better choice for filling a crowded room or outdoor venue. If you only play smaller venues, large DJ speakers will still handle more bass, but smaller drivers may still be sufficient.
•Active/Passive
You have the option of choosing either an active speaker or a passive speaker. Active speakers are more expensive, but may provide you with more value. They are equipped with their own power and amps to help create a quality sound, while passive speakers require you to buy that hardware separately. Active speakers are more popular, but some DJs prefer passive speakers because they allow you to have more control over the additional audio equipment.
•Venue(s)
Your expected venues can affect your choice in professional DJ speakers. If you expect to play mostly outdoors, you need loudspeakers that can reach a large audience. If you expect to play primarily in clubs and smaller locations, these larger speakers may be overkill. It’s difficult to know exactly where you expect to play, but you should try your best to match your speakers to the venues you plan to use.
•Complementary Parts
Speakers are not the only types of professional audio equipment you are going to purchase. As such, you
should make sure that you’re choosing speakers that work well with the equipment you already have on hand. You will need to make sure your speakers can handle the same ohm load as your receiver, make sure that your power source is creating enough power for your speakers, etc. An audio system only works as well as each piece of equipment works with each other.
Choosing the Right Professional DJ Equipment
While there any many considerations for choosing the best audio equipment for your needs, the most important quality of these speakers is that you approve of the quality sound. You are the one in charge of the audio, and it’s important that you enjoy every note coming from the speakers you choose. Only then will you be able to create the music your audience will love to hear.
If you are in the business of professional audio and video, you must have the right equipment. You can find the quality professional equipment you need at SJ Media Systems.
Article Source: http://www.earticlesonline.com/Article/5-Things-to-Consider-When-Purchasing-New-DJ-Speakers/1195312
