Besballtalk Office Phone System

Ethernet Time Clock

Synchronous And Asynchronous Clocking

A wide range of timing solutions are available, including crystal oscillators (XO), voltage-controlled crystal oscillators (VCXO), and clocks. No one size fits all strategy applies when it comes to component selection. Picking the right device for a particular application is dependent on a number of factors, including whether or not the clocks must be synchronized to an externally provided reference clock, the system architecture of the processor and high speed serial data transmission ICs, and the frequency and jitter requirements of the end application. In high performance applications, low jitter and low phase noise are critical given that they have a direct impact on the bit-error rate in high speed serial data transmission applications and the signal-to-noise ratio of analog to digital data converters.

Hardware design in high performance applications such as networking, wireless RF transmission, broadcast video and test and measurement is becoming increasingly complex as hardware designers grapple with the need to support a growing number of standards, protocols, and specifications within a single hardware design. A few examples illustrate this trend. The latest networking gear is being designed to support not only SONET/SDH and Ethernet, but also high-definition video transmission. Next generation wireless infrastructure equipment is being designed to support both WiMAX and LTE (Long-Term Evolution). Broadcast video equipment, which spans a wide variety of functions including image capture, encoding, decoding, processing and video transport, must support NTSC and PAL standards to ensure worldwide compatibility. As the lines between traditionally different types of equipment become increasingly blurred, a separate challenge arises. Designing the most efficient timing architecture is paramount in these applications to minimize design time and BOM cost.

Asynchronous Clocking

The simplest clock generation source is an oscillator (XO), which generates a single output frequency for a single component. XOs are oftentimes used in asynchronous applications. Each oscillator provides a local reference to maintain two independent clock domains. System operation requires XO frequencies be close but not identical. This architecture is ideal for burst-mode traffic applications. Continuous communication requires bit or packet stuffing and FIFO management to prevent overflow/underflow conditions. Video processing equipment and 10/100/1000BaseT Ethernet are examples of applications that use asynchronous clocking. XO selection should be based on the frequency, jitter and stability requirements of the end application.

Synchronous Clocking

Synchronous clocking is most often used in applications that require continuous communication. Network latency and variability in latency must be minimized. To accomplish this, applications including SONET/SDH, Synchronous Ethernet (SyncE), wireless backhaul, and video transport require that the source and destination operate at the same frequency. On the transmit side, the clocks that provide timing for the transmit path of the high speed SerDes are locked to a highly accurate reference clock. Both primary and secondary reference clocks are supplied from a centralized timing source (e.g. GPS). A PLL is used to lock to this backplane reference, attenuate jitter on the clock signal to remove unwanted noise, and provide a low jitter output clock to the PHY. On the receive side, a Clock and Data Recovery (CDR) unit is used to recover the system clock. This CDR may be an external component or integrated within the PHY depending on the application. A XO may be used to center the CDR to provide fast acquisition and lock. The recovered clock passes through another PLL to divide the clock frequency down to a lower rate. Local timing can either be synchronized to this clock or to another local clock that is synchronized to a centralized timing source. Synchronization to the source ensures clock synchronization across all nodes in the network. Depending on system requirements, the PLLs used in this application may require a low loop bandwidth to filter unwanted clock jitter from the clock signal.

About the Author

Silicon Labs - Clock Generators and Optocouplers.

Clock 1100 - barcode time recorder - Ethernet $391.99 Wasp Clock 1100 - Barcode time recorder - Ethernet

Pyramid TimeTrax Pro TT950EK Ethernet Time Clock & Recorder $480.99 0% 1 Each 50 50 Employee - Upgradable to 6000 TimeTrax Pro TT950EK Ethernet Time Clock & Recorder Software Media 50 x Employee Badges 50' Cable Mounting Brackets Instruction Manual Being Ethernet-ready allows multi-terminal capability that will grow with your business. Simply hook the TimeTrax Pro Ethernet time and attendance system up to any networked Ethernet jack. Employees can swipe in and swipe out from any of the unlimited number of Pyramid TimeTrax Ethernet terminals available, regardless of technology. Ethernet LAN and WAN is compatible with multi-time zone functionality. Easy-to-use system includes variable pay periods, multiple employee groups and export to most payroll systems. Time clock offers a "point and click" punch, payroll editing plus many standard reports and allows many options including synchronized wall clocks and bell/horn systems. Kit includes a swipe terminal, software, 50 employee badges, 50' cable, mounting brackets, and an instruction manual. Time recorder is expandable to 6,000 employees. Automatic System Blue Clock In Clock Out Magnetic Strip Network No Payroll Export Pyramid Pyramid Technologies, Inc Silver TT950EK TimeTrax Pro TimeTrax Pro TT950EK Ethernet Time Clock & Recorder Wall-mountable Yes www.pyramidtechnologies.com

Lathem Time Touchscreen Time Clock, Silver/Black. Each $448.64 Manufacturer: Lathem Time. Each. PC600 Touchscreen Time Clock offers state-of-the-art Windows CE embedded Ethernet time clock, a full-color touchscreen interface and a proximity badge reader. Full-color screen allows tips, transfers and edits. 50-employee

Wasp 1100 Additional Barcode Time Clock $357.99 1100 1100 Additional Barcode Time Clock 633808550035 1100 Additional Time Clock AC Power Adapter Ethernet Cable Expand your bar code based time and attendance system Easily added to your system via Ethernet (LAN) connectivity Ideal solution for entering chronological data for tracking when employees arrive, take lunch and depart Automatic System Durable LCD Magnetic Strip Power Adapter Wall-mountable Wasp Wasp Barcode Technologies www.waspbarcode.com

Time Clock $24.99 H. Armstrong Roberts Time Clock - Photographic Print

Retirement Time Clock $9.99 Includes (1) time clock.

Dart Time Wall Clock $80 Dart Time Wall Clock

Tee Time Wall Clock $92 Tee Time Wall Clock

CLOCK,PROXIMTY TIME,BKSLV $313.99 CLOCK,PROXIMTY TIME,BKSLV

Lathem PC600 Table Clock $356.99 PC600 Touchscreen Time Clock offers state-of-the-art Windows CE embedded Ethernet time clock, a full-color touchscreen interface and a proximity badge reader. Full-color screen allows tips, transfers and edits. 50-employee capacity can be expanded easily to support up to 500. Time clock can even be accessed over the Internet. System includes 15 proximity badges (additional badges sold separately) and powerful PayClock software for editing, reporting and exporting to popular payroll applications such as QuickBooks. Gray Lathem Lathem Time Company PC600 PC600 Touchscrren Table Clock PC600-KIT Table Clock www.lathem.com

Tell Time Owl Clock $59.99 Tell Time Owl Clock - Wall Decal

Cisco System Clock Module w/ Ethernet + Lec Back Card Igxscmrf $850 Cisco System Clock Module w/ Ethernet + Lec Back Card Igxscmrf

IP PoE 4 Digit 4 Inch Clock $309.57 - Valcom IP Clock- 4 Digit digital readout- 4 Inches- Easy to install via RJ-45 connection- IP ClocksPower over Ethernet (IEEE 802.3af)- No master clock required - set automatically by NTP (Network Time Protocol)- 10/100BaseT Ethernet compatible- DHCP or

The Clock $33.95 ">From the mid 1700s in Edinburgh until today ... "The Clock "winds its way through time and tides. Through the centuries it stands, a sentinel in many a home, some grand, some not so grand. Always it stands and keeps time for the owner. It keeps watch in more ways than one. Some owners are proud of the clock and keep it front and center, while others are ambivalent towards it and hardly notice its presence. Still it ticks and tocks its way through the ocean of time that two centuries avail. It was built as a pass into the Hammermen Society of Edinburgh; the boy genius craftsman that gave it birth could never have imagined the journey it went on ... neither can you >Many stories boast truth. They describe themselves as "based on a real-life incident." The story of the clock is indeed is based on a very true story. >Author James Leslie Payne is a broadcast executive in radio and television. He lives on Canada's West Coast with his wife, a golden retriever named Billy, and the Sentinel-yes, the Sentinel. It turns out that's the latest stop on its incredible journey-one that Payne is eager to share with you. >Turn your collar to the cold winds of time; let's begin the journey of "The Clock." >"

Tigger Time Clock World Wall Clock by CafePress $15 A Clock With The Saying 'Whats The Time? Tigger Time' World Wall Clock Decorate any room in your home or office with our 10 inch wall clock. Black plastic case. Requires 1 AA battery included.

metric Clock Metric time Wall Clock by CafePress $15 metric time clock Metric time Wall Clock Decorate any room in your home or office with our 10 inch wall clock. Black plastic case. Requires 1 AA battery included.

Big Time Teaching Clock $23.49 Geared for teaching time our Big Time Teaching Clock is great for demonstration! Hidden gears maintain correct hour and minute relationships.

Pyramid Technologies TTEZEK Time Trax EZ Ethernet Time amp; Attendance System 5 7/10 x 5 x 2 $487.5 Automated time and attendance system is quick and simple to use. Ethernetreadyjust plug into any networked jack and go. Accommodates 50; can be expanded up to 6 000 employees. Mix and match any Pyramid Ethernet terminal time within the same network. Software exports hours directly to most major payroll providers. Includes EZ terminal swipe badges software power supply cables mounting bracket and instruction manual. Silver and blue. Time Clock Type: Electronic; Number of Employees: 50; Imprint Style: N/A; Minute Increments: N/A.

Spiral Clock small Time Wall Clock by CafePress $15 If you want to know the time, ask a dervish... Time Wall Clock Decorate any room in your home or office with our 10 inch wall clock. Black plastic case. Requires 1 AA battery included.

It's Bocce Time Clock Sports Wall Clock by CafePress $15 It's Bocce Time Clock decorated with red and green bocce balls and a yellow pallino with the text IT'S BOCCE TIME in the center. Sports Wall Clock Decorate any room in your home or office with our 10 inch wall clock. Black plastic case. Requires 1 AA battery included.

Time To Train Clock Wall Clock by CafePress $15 Having problems remembering to train? Now you will NEVER FORGET This clock tells you EXACTLY what time it is... IT'S TIME TO TRAIN Wall Clock Decorate any room in your home or office with our 10 inch wall clock. Black plastic case. Requires 1 AA battery included.

PC1128 Juggling Time Clock in Brushed $319.99 Nova Lighting Juggling Time Clock is sleek smooth silver pendulum clock Can be mounted anywhere for a contemporary look A clean contemporary clock uses glass and aluminum and is hand crafted and hand finished no two pieces a like

Time to Meditate Wall Clock by CafePress $15 It's time to meditate bag clock Wall Clock Decorate any room in your home or office with our 10 inch wall clock. Black plastic case. Requires 1 AA battery included.

11624 Time Lines Clock in Brushed $399.99 Time Lines Clock is modern wall clock with fluorescent lighting Background light illuminates roman numerals See-though mirror creates infinity effect

Poker time clock Humor Wall Clock by CafePress $15 Because it's always poker time Humor Wall Clock Decorate any room in your home or office with our 10 inch wall clock. Black plastic case. Requires 1 AA battery included.

WC20 Stretching Time Clock in Brushed $399.99 See things from a slightly different perspective with the Stretching Time Clock that stretches time and space The Stretching Time Clock features a whimsically-warped brushed aluminum frame with oversized Roman numerals on a contrasting face Shiny sil...

Time-ish Clock Funny Wall Clock by CafePress $15 A humorous clock for people to whom time does not matter Perfect for the office, college dorm, or any slackers home. Funny Wall Clock Decorate any room in your home or office with our 10 inch wall clock. Black plastic case. Requires 1 AA battery included.

AudioVox / CLOCK RADIO AUTO TIME SET / RC141 $37.33 AudioVox - CLOCK RADIO AUTO TIME SET - RC141

AudioVox / CLOCK RADIO AUTO TIME SYNC / RC150I $58.96 AudioVox - CLOCK RADIO AUTO TIME SYNC - RC150I

Time for pizza Clock Pizza Wall Clock by CafePress $15 Pizza Clock Pizza Wall Clock Decorate any room in your home or office with our 10 inch wall clock. Black plastic case. Requires 1 AA battery included.

Telly The Teaching Time Clock $29.95 Award Winner InformationClock-Watching Fun! A real working clock with both analog and digital displays, Telly the Teaching Time Clock helps kids learn to tell time with two fun and friendly quiz modes. In beginner mode, kids move the hands and Telly announces the time and displays it on the LED. In advanced mode, Telly asks kids to set the hands to a certain time. Includes a night-light and carry handle. Batteries included. For 1-2 players. 11" high. Multiple Award Winner, including Parents' Choice. Ages 3+.

IFC1824 Endless Time Clock in Brushed $369.99 Time may sometimes stand still but this wall clock keeps perfect time while the infinity lights seem endless Battery operated clock and lights are AC powered Best display is on curves pedestal

Geneva Clock Table Clock $12.99 3480AT Battery Digital Dual Time Display Geneva Clock Geneva Clock Co. Quartz Solar Powered Table Clock Square Table Clock with Blue Backlight www.genevaclockco.com

First Time Gear Clock $14.99 Many great inventors spent their childhoods dismantling telephones and radios, much to their parent's dismay. However, it's important to know that most of the time they were just curious, which is a good thing! There are great jewels to discover, and we should embrace that neverending curiosity! The First Time Gear Clock is the perfect way to get started on the right foot, or hand (we have endless puns). This educational kit comes disassembled with easy to follow, color-coded instructions. Seeing the fascinating inner-workings of a clock is not only fun, but will also teach about the scientific nature of objects like it. Each small piece of the clock serves a purpose and learning those mechanics will help cognitive development as well. And knowing the time is always beneficial! Don't wait to get your children started on this! After all, we know you have the patience of a saint ; )