Home » Archives for March 2011
Study gives 4G data performance high marks
Handsets operating on 4G cellular networks offer significant improvement in data transfer performance compared to their 3G predecessors, according to a study evaluating the performance of smartphones available from U.S. national carriers conducted by consulting firm Metrico Wireless Inc. More Here.
ZTE claims 10-Tbps data transmission record
Chinese telecommunications equipment company ZTE Corp. claims to have broken the world record for a single-channel data transmission with a rate of 10 terabits per second over 640-kilometers of optical fiber. This is the equivalent of sending 160 high definition movies every second. More here.
Six ways to manage a side hustle without going insane
A side hustle is anything you are doing outside of your full-time job (like building a business or a blog around something you are passionate about), and often involves an entrepreneurial enterprise of some sort. In this article Jenny Blake shares some tips with you to help you keep things together during the exciting pursuit of what you love
U.K. readies for auction of 4G spectrum
Ofcom, the U.K. government's regulatory body for telecommunications, has announced plans for an auction of radio spectrum for 4G mobile services in the U.K. It has announced a consultation procedure as it decides the detailed rules for the auction which is expected to take place in the first quarter of 2012. More here.
Altair, Alcatel-Lucent okay LTE chipset
Mobile communications chip company Altair Semiconductor Ltd. has announced that a combination of its FourGee 4G-LTE chipset and Alcatel-Lucent infrastructure has completed a three-month field trial with a U.S. wireless carrier and is now commercially available. More here
Accelerate product development through codevelopment of Hardware and Software
Rising product complexity and intense market pressures present major challenges to designers of electronic systems. To stay competitive, tight coordination between processes used by hardware and software engineers is critical to optimize product quality. This is especially true while controlling costs and meeting tight timelines.
This whitepaper discusses key elements of development and explores how the use of shared processes between hardware and software disciplines enable teams to develop products more quickly. Once shared processes are established, common tools can drive the next level of efficiency. It also highlights how how IBM has successfully used these techniques across a 25,000+ user base to significantly reduce development costs, increase reuse, and improve quality.
This paper is sponsored by IBM
This whitepaper discusses key elements of development and explores how the use of shared processes between hardware and software disciplines enable teams to develop products more quickly. Once shared processes are established, common tools can drive the next level of efficiency. It also highlights how how IBM has successfully used these techniques across a 25,000+ user base to significantly reduce development costs, increase reuse, and improve quality.
This paper is sponsored by IBM
Moisture Barriers for Flexible Electronics
Defects on plastic substrates such as pinholes, cracks and grain boundaries cause a 'pore effect', where oxygen and water molecules are able to seep through and penetrate through the plastic barrier and into the active material. For applications such as flexible OLED displays, organic solar cells, or even electrophoretic displays, sensitivity to oxygen and moisture compromises device lifetime significantly. This means that in order to achieve adequate lifetime for flexible devices that would make viable commercial products, the pathway for oxygen and moisture down into the active layers must be blocked.
Tera-Barrier Films is a portfolio company of Exploit Technologies Pte. Ltd. (ETPL), the commercialisation arm of Singapore's Agency for Science, Technology and Research (A*STAR) and Applied Ventures, LLC, the venture capital arm of Applied Materials, Inc. as of August 2009. The company was incubated by Exploit-Technologies Pte. Ltd. as a Flagship programme for two years prior to spin-off.
Current barrier technologies focus on reducing these defects by using alternate organic and inorganic multilayers coated on plastic. In contrast, Tera-Barrier has taken an innovative approach to resolve the 'pore effect' by literally plugging the defects in the barrier oxide films using nanoparticles. This reduces the number of barrier layers needed in the construction of the barrier film down to two layers in this unique nanoengineered barrier stack. Tera-Barrier's barrier stack consists of barrier oxide layers and nanoparticulate sealing layers. The nanoparticles used in the barrier film have a dual function - not only sealing the defect but also actively reacting with and retaining the moisture and oxygen.
The result is a moisture barrier performance of better than 10-6 g/m2.day which satisfies even the most stringent requirements for flexible organic device substrates. The barrier film also has a lag time of more than 2,300 hours at 60 ⁰C and 90% RH (i.e. the time required for moisture to pass through the barrier film under those conditions).
It's also important to point out that the barrier layer on its own is not an adequate way to keep oxygen and moisture away from the active materials. Moisture ingress can also occur from the side of the device if it is not adequately sealed. This leads to specific requirements in water vapour transmission rates for the sealants used in electronic devices.
Two of the main companies developing these types of adhesives are Henkel and DELO, Henkel focused mainly on thermally-cured solutions while DELO is focused on UV-cured adhesives.
A trade-off becomes apparent when trying to find the right balance of permeation rates and flexibility. The adhesives that are characterised by the best performance in terms of water vapour transmission are more rigid and would compromise the overall flexibility of the final device. This means that in order to manufacture devices of a given flexibility, permeation performance needs to be sacrificed. Hence, a lot of research and development effort is focused into the development of systems that would lead to a good balance between permeation performance and flexibility.
For more in-depth presentations from Henkel, DELO and Terra Barrier as well as breakthroughs in other materials, manufacturing and novel devices, don't miss the opportunity to attend Printed Electronics/Photovoltaics Europe, in Dusseldorf, Germany on the 5th and 6th of April 2011.
For more information, visit the website www.idtechex.com/dusseldorf
Tera-Barrier Films is a portfolio company of Exploit Technologies Pte. Ltd. (ETPL), the commercialisation arm of Singapore's Agency for Science, Technology and Research (A*STAR) and Applied Ventures, LLC, the venture capital arm of Applied Materials, Inc. as of August 2009. The company was incubated by Exploit-Technologies Pte. Ltd. as a Flagship programme for two years prior to spin-off.
Current barrier technologies focus on reducing these defects by using alternate organic and inorganic multilayers coated on plastic. In contrast, Tera-Barrier has taken an innovative approach to resolve the 'pore effect' by literally plugging the defects in the barrier oxide films using nanoparticles. This reduces the number of barrier layers needed in the construction of the barrier film down to two layers in this unique nanoengineered barrier stack. Tera-Barrier's barrier stack consists of barrier oxide layers and nanoparticulate sealing layers. The nanoparticles used in the barrier film have a dual function - not only sealing the defect but also actively reacting with and retaining the moisture and oxygen.
The result is a moisture barrier performance of better than 10-6 g/m2.day which satisfies even the most stringent requirements for flexible organic device substrates. The barrier film also has a lag time of more than 2,300 hours at 60 ⁰C and 90% RH (i.e. the time required for moisture to pass through the barrier film under those conditions).
It's also important to point out that the barrier layer on its own is not an adequate way to keep oxygen and moisture away from the active materials. Moisture ingress can also occur from the side of the device if it is not adequately sealed. This leads to specific requirements in water vapour transmission rates for the sealants used in electronic devices.
Two of the main companies developing these types of adhesives are Henkel and DELO, Henkel focused mainly on thermally-cured solutions while DELO is focused on UV-cured adhesives.
A trade-off becomes apparent when trying to find the right balance of permeation rates and flexibility. The adhesives that are characterised by the best performance in terms of water vapour transmission are more rigid and would compromise the overall flexibility of the final device. This means that in order to manufacture devices of a given flexibility, permeation performance needs to be sacrificed. Hence, a lot of research and development effort is focused into the development of systems that would lead to a good balance between permeation performance and flexibility.
For more in-depth presentations from Henkel, DELO and Terra Barrier as well as breakthroughs in other materials, manufacturing and novel devices, don't miss the opportunity to attend Printed Electronics/Photovoltaics Europe, in Dusseldorf, Germany on the 5th and 6th of April 2011.
For more information, visit the website www.idtechex.com/dusseldorf
Best known modelling practices for gigabit serial design - Live Webcast
This presentation will go over some of the common issues encountered when setting up performing circuit simulation of high speed serial designs. Topics will include s-parameter passivity and causality, frequency sampling and bandwidth and how they relate to simulation accuracy, model concatenation, and correlation between the time and frequency domains.
This webcast is Hosted by EDN and Sponsored by ANSYS.
Register Now - Click Here
Presenter:
Daniel Dvorscak,
Senior Application Engineer,ANSYS, Inc.
Date: March 25, 2011
Time: 3:00 PM ET / 12:00 PM PT
This webcast is Hosted by EDN and Sponsored by ANSYS.
Register Now - Click Here
Presenter:
Daniel Dvorscak,
Senior Application Engineer,ANSYS, Inc.
Date: March 25, 2011
Time: 3:00 PM ET / 12:00 PM PT
Intel's new 4G acquisition is Sysdsoft
Intel has made a purchase to bolster its 4G wireless platform, buying Egypt-based Sysdsoft, a maker of 4G software stacks. Sysdsoft has been more closely associated with MIPS than Intel architectures, having created an LTE protocol stack for the MIPS/Android platform, with which the processor core maker hopes to penetrate the mobile sector. It may have to look for a new ally now, with Intel taking over most of the assets of the privately held Egyptian company, and hiring about 100 of its engineers and computer scientists.
Printed Electronics - Europe is Different
Printed electronics is one of the most important new enabling technologies. It will have a major impact on most business activities from publishing and security printing to health care, automotive, military and consumer packaged goods sectors. It is now recognized that commercialization can and should take place in very disparate applications, contrasting with the rather narrow view of possibilities in the past.
However, the regions of the world see printed electronics differently. For example, the USA focuses on the military applications among others. For example, Dr Brian Fuchs of the US Army describes printing processes and novel ink development for armament applications. He notes that,
"Through the advancement of materials printing, superior capabilities can be added to military assets".
Also in the USA, the now Taiwanese-owned E-Ink has recently progressed to colour versions of its electrophoretic displays, interestingly seeing them as useful for textbooks first.
East Asia wishes to use printed electronics to reinforce its dominance in electronic displays such as flat panel television screens and e-readers - for that is where most of the leading brands are made - and generally in consumer electronics and photovoltaics.
Broad approach in Europe
Europe has interest in a very wide range of potential applications, with consumer packaged goods being just one of many applicational sectors prioritized. Peter Johansson of In-Core Systems of France develops vision inspection for the typical roll-to-roll coating manufacturing processes employed. He has practical experience of metal film coating for batteries for electric cars, for example. Flexible Electronics Concepts in the UK has major contracts to make innovative designs of smart label and smart packaging for both the electrical and consumer packaged goods industries.
Leader in paper electronics
It is in Europe where most of the successes in printing electronic and electrical components onto paper takes place. Professor Arved Huebler of Chemnitz University of Technology Institute for Print and Media Technology in Germany puts it this way,
"Printed electronics is the upcoming big innovation for the traditional paper based print media market - with a strong economic impact. This ten years old statement is still very true, but do we need another ten years for finding the killer application? For a lot of reasons, mass printed photovoltaics on paper could become a hot candidate, outpacing the trusty old printed RFID vision."
Security printing
Security printer De La Rue of the UK is about to reveal, "Power into Paper - a New Paradigm". The European Commission FACESS project is progressing a basic building block of printed electronics that puts organic photovoltaics, printed rechargeable lithium-ion batteries and associated electronics all on one small piece of flexible polymer film, with paper a possibility later.
The USA, Europe and East Asia are all working hard on printed Organic Light Emitting Diode technology for lighting and signage and on rechargeable laminar batteries. Many of these are now at the tipping point of commercial production. Gary R. Johnson President and CEO of Blue Spark Technologies in the USA, which prints disposable batteries for interactive media - modernizing paper magazines, point of sale and so on - observes that,
"Exciting applications for printed electronics lie in interactive packaging, ubiquitous sensor networks for health care, RFID and other areas. Today, the value proposition is mainly based on the value of uniquely thin, flat, flexible product forms not otherwise achievable. Moreover, as yet, they are still partly based on traditional silicon and other technologies, such as silicon chips, with a clear roadmap to fully printing components such as printed transistors and OLEDS."
Certainly , Europe is looking at a far broader range of printed components than is pursued in East Asia. To take one example, Professor Werner Jillek of the Georg Simon Ohm University of Applied Sciences in Germany finds that Inkjet printing of nano-particles is a novel technology for manufacturing electronic devices. With silver inks, conductive lines are printed which after a sintering process exhibit sufficient conductivity for various applications. As a demonstrator, the double-sided layout pattern of an FM radio is printed with discrete components attached by conductive glue. In addition, resistors are integrated by inkjet printing as well, using dispersed carbon nanotubes. The sheet resistance can easily be adjusted by repeated printing and the saturation settings in graphic programs.
Whereas laminar lithium-ion rechargeable batteries are made by many companies in North America, Dr Kari Ronka VTT Finland has recently claimed to be printed them. Such truly solid state batteries are the future vision for both large traction batteries and small laminar batteries.
David Lussey of Peratech in the USA is involved in "Quantum Tunnelling Composites (QTC) in Textile and Film Touch-screens, Controls and Sensors" In a printable electronic ink form QTC now allows the construction of sensors, switches, touch controls and touch-screens without the need for air gaps or stand-offs. Over in Europe, Bayer MaterialScience AG has created what it calls a "New dimension for touch screen applications with fidelity haptics using dielectric actuators".
Commercialization must now be the priority
Raghu Das CEO of IDTechEx notes that, "Certainly Europe now has a huge variety of printed electronic technologies - organic, inorganic and composite - and a rapidly broadening vision of how widely they can be applied. Newly printed components are announced al the time. However, the Europeans must work to commercialise as effectively as the Americans and East Asians. That is why our forthcoming event Printed Electronics Europe strongly emphasises commercialisation. It benchmarks best practice from outside Europe in aspects where the Europeans are laggards. This year, we even have an End User Forum - something more appropriate to Europe's needs than peer reviewed academic papers."
The largest event on the subject
All the organizations mentioned above will be presenting at Printed Electronics Europe in Düsseldorf Germany which takes place April 5-6 (www.IDTechEx.com/peEUROPE). Another annual IDTechEx event is Printed Electronics USA which takes place at the end of the year. Both have streams on the new flexible photovoltaics in the two day conference and exhibition and they have optional masterclasses and visits to local centers of excellence on the day before and the day after and both have an awards dinner. These events vie for the title of world's largest event on the subject each year.
However, the regions of the world see printed electronics differently. For example, the USA focuses on the military applications among others. For example, Dr Brian Fuchs of the US Army describes printing processes and novel ink development for armament applications. He notes that,
"Through the advancement of materials printing, superior capabilities can be added to military assets".
Also in the USA, the now Taiwanese-owned E-Ink has recently progressed to colour versions of its electrophoretic displays, interestingly seeing them as useful for textbooks first.
East Asia wishes to use printed electronics to reinforce its dominance in electronic displays such as flat panel television screens and e-readers - for that is where most of the leading brands are made - and generally in consumer electronics and photovoltaics.
Broad approach in Europe
Europe has interest in a very wide range of potential applications, with consumer packaged goods being just one of many applicational sectors prioritized. Peter Johansson of In-Core Systems of France develops vision inspection for the typical roll-to-roll coating manufacturing processes employed. He has practical experience of metal film coating for batteries for electric cars, for example. Flexible Electronics Concepts in the UK has major contracts to make innovative designs of smart label and smart packaging for both the electrical and consumer packaged goods industries.
Leader in paper electronics
It is in Europe where most of the successes in printing electronic and electrical components onto paper takes place. Professor Arved Huebler of Chemnitz University of Technology Institute for Print and Media Technology in Germany puts it this way,
"Printed electronics is the upcoming big innovation for the traditional paper based print media market - with a strong economic impact. This ten years old statement is still very true, but do we need another ten years for finding the killer application? For a lot of reasons, mass printed photovoltaics on paper could become a hot candidate, outpacing the trusty old printed RFID vision."
Security printing
Security printer De La Rue of the UK is about to reveal, "Power into Paper - a New Paradigm". The European Commission FACESS project is progressing a basic building block of printed electronics that puts organic photovoltaics, printed rechargeable lithium-ion batteries and associated electronics all on one small piece of flexible polymer film, with paper a possibility later.
The USA, Europe and East Asia are all working hard on printed Organic Light Emitting Diode technology for lighting and signage and on rechargeable laminar batteries. Many of these are now at the tipping point of commercial production. Gary R. Johnson President and CEO of Blue Spark Technologies in the USA, which prints disposable batteries for interactive media - modernizing paper magazines, point of sale and so on - observes that,
"Exciting applications for printed electronics lie in interactive packaging, ubiquitous sensor networks for health care, RFID and other areas. Today, the value proposition is mainly based on the value of uniquely thin, flat, flexible product forms not otherwise achievable. Moreover, as yet, they are still partly based on traditional silicon and other technologies, such as silicon chips, with a clear roadmap to fully printing components such as printed transistors and OLEDS."
Certainly , Europe is looking at a far broader range of printed components than is pursued in East Asia. To take one example, Professor Werner Jillek of the Georg Simon Ohm University of Applied Sciences in Germany finds that Inkjet printing of nano-particles is a novel technology for manufacturing electronic devices. With silver inks, conductive lines are printed which after a sintering process exhibit sufficient conductivity for various applications. As a demonstrator, the double-sided layout pattern of an FM radio is printed with discrete components attached by conductive glue. In addition, resistors are integrated by inkjet printing as well, using dispersed carbon nanotubes. The sheet resistance can easily be adjusted by repeated printing and the saturation settings in graphic programs.
Whereas laminar lithium-ion rechargeable batteries are made by many companies in North America, Dr Kari Ronka VTT Finland has recently claimed to be printed them. Such truly solid state batteries are the future vision for both large traction batteries and small laminar batteries.
David Lussey of Peratech in the USA is involved in "Quantum Tunnelling Composites (QTC) in Textile and Film Touch-screens, Controls and Sensors" In a printable electronic ink form QTC now allows the construction of sensors, switches, touch controls and touch-screens without the need for air gaps or stand-offs. Over in Europe, Bayer MaterialScience AG has created what it calls a "New dimension for touch screen applications with fidelity haptics using dielectric actuators".
Commercialization must now be the priority
Raghu Das CEO of IDTechEx notes that, "Certainly Europe now has a huge variety of printed electronic technologies - organic, inorganic and composite - and a rapidly broadening vision of how widely they can be applied. Newly printed components are announced al the time. However, the Europeans must work to commercialise as effectively as the Americans and East Asians. That is why our forthcoming event Printed Electronics Europe strongly emphasises commercialisation. It benchmarks best practice from outside Europe in aspects where the Europeans are laggards. This year, we even have an End User Forum - something more appropriate to Europe's needs than peer reviewed academic papers."
The largest event on the subject
All the organizations mentioned above will be presenting at Printed Electronics Europe in Düsseldorf Germany which takes place April 5-6 (www.IDTechEx.com/peEUROPE). Another annual IDTechEx event is Printed Electronics USA which takes place at the end of the year. Both have streams on the new flexible photovoltaics in the two day conference and exhibition and they have optional masterclasses and visits to local centers of excellence on the day before and the day after and both have an awards dinner. These events vie for the title of world's largest event on the subject each year.
Infineon's work in progress - The story for our time
How massive restructuring has created a novel business model at the semiconductor stalwart. If there has been a constant at Infineon, it has been change. From a division of giant Siemens, to a broad-line integrated semiconductor device manufacturer (IDM), to an IDM without a DRAM business, to a bankruptcy candidate, to a fabless powerhouse in smart-phone silicon, to what may be an entirely new model for a semiconductor company, Infineon has illustrated the maxim that a company's only real intellectual equity is its ability to change. In conversation with EDN, Infineon CEO Peter Bauer sketched out a fascinating trajectory.
"Today, the competition is not between companies. It is between countries. For instance, China is investing, I believe the figure is, $20 billion in electric cars. But in Germany, even more than in the USA, the notion of subsidy is disliked. The government believes in the operation of free markets. Perhaps the future is coming down to differences in industrial policies. - Peter Bauer, CEO - Infineon Technologies AG"
"Today, the competition is not between companies. It is between countries. For instance, China is investing, I believe the figure is, $20 billion in electric cars. But in Germany, even more than in the USA, the notion of subsidy is disliked. The government believes in the operation of free markets. Perhaps the future is coming down to differences in industrial policies. - Peter Bauer, CEO - Infineon Technologies AG"
Interview Question on Power Analysis
Your task is to do power analysis for a circuit that sends out a one-clock-cycle pulse on the done signal once every 16 clock cycles(done is ’0’ for 15 clock cycles, then ’1’ for one cycle, then repeat with 15 cycles of ’0’ followed by a ’1’, etc). You have been asked to consider three different types of counters: 1. Binary counter, 2. Gray-code counter, and 3. One-hot counter. (The table below
shows the values from 0 to 15 for the different encoding schemes) What is the relative amount of power consumption for the different options?
Additional Info:
Your implementation technology is an FPGA where each cell has a programmable combinational circuit and a flip-flop. The combinational circuit has 4 inputs and 1 output. The capacitive load of the combinational circuit is twice that of the flip-flop.
1. You may neglect power associated with clocks.
2. You may assume that all counters:
(a) are implemented on the same fabrication process
(b) run at the same clock speed
(c) have negligible leakage and short-circuit currents
Encoding:
The columns below represent, Decimal Gray One-Hot Binary in order
0 0000 0000000000000001 0000
1 0001 0000000000000010 0001
2 0011 0000000000000100 0010
3 0010 0000000000001000 0011
4 0110 0000000000010000 0100
5 0111 0000000000100000 0101
6 0101 0000000001000000 0110
7 0100 0000000010000000 0111
8 1100 0000000100000000 1000
9 1101 0000001000000000 1001
10 1111 0000010000000000 1010
11 1110 0000100000000000 1011
12 1010 0001000000000000 1100
13 1011 0010000000000000 1101
14 1001 0100000000000000 1110
15 1000 1000000000000000 1111
This question is asked widely in interviews worldwide with varying levels of difficulty. Please start discussing.
Tip: Capacitance is dependent upon the number of signals, and whether a signal is combinational or a flop.
shows the values from 0 to 15 for the different encoding schemes) What is the relative amount of power consumption for the different options?
Additional Info:
Your implementation technology is an FPGA where each cell has a programmable combinational circuit and a flip-flop. The combinational circuit has 4 inputs and 1 output. The capacitive load of the combinational circuit is twice that of the flip-flop.
1. You may neglect power associated with clocks.
2. You may assume that all counters:
(a) are implemented on the same fabrication process
(b) run at the same clock speed
(c) have negligible leakage and short-circuit currents
Encoding:
The columns below represent, Decimal Gray One-Hot Binary in order
0 0000 0000000000000001 0000
1 0001 0000000000000010 0001
2 0011 0000000000000100 0010
3 0010 0000000000001000 0011
4 0110 0000000000010000 0100
5 0111 0000000000100000 0101
6 0101 0000000001000000 0110
7 0100 0000000010000000 0111
8 1100 0000000100000000 1000
9 1101 0000001000000000 1001
10 1111 0000010000000000 1010
11 1110 0000100000000000 1011
12 1010 0001000000000000 1100
13 1011 0010000000000000 1101
14 1001 0100000000000000 1110
15 1000 1000000000000000 1111
This question is asked widely in interviews worldwide with varying levels of difficulty. Please start discussing.
Tip: Capacitance is dependent upon the number of signals, and whether a signal is combinational or a flop.
Cyclic Redundancy Checking (CRC) - Part 2
Modulo two arithmetic is simple single-bit binary arithmetic with all carries or borrows ignored. Each digit is considered independently. This article talks about how modulo two addition is equivalent to modulo two subtraction, and can be performed using an exclusive OR operation followed by a brief on Polynomial division where remainder forms the CRC checksum.
For example, we can add two binary numbers X and Y as follows:
10101001 (X) + 00111010 (Y) = 10010011 (Z)
From this example the modulo two addition is equivalent to an exclusive OR operation. What is less obvious is that modulo two subtraction gives the same results as an addition.
From the previous example let’s add X and Z:
10101001 (X) + 10010011 (Z) = 00111010 (Y)
In our previous example we have seen how X + Y = Z therefore Y = Z – X, but the example above shows that Z+X = Y also, hence modulo two addition is equivalent to modulo two subtraction, and can be performed using an exclusive OR operation.
In integer division dividing A by B will result in a quotient Q, and a remainder R. Polynomial division is similar except that when A and B are polynomials, the remainder is a polynomial, whose degree is less than B.
The key point here is that any change to the polynomial A causes a change to the remainder R. This behavior forms the basis of the cyclic redundancy checking.
If we consider a polynomial, whose coefficients are zeros and ones (modulo two), this polynomial can be easily represented by its coefficients as binary powers of two.
In terms of cyclic redundancy calculations, the polynomial A would be the binary message string or data and polynomial B would be the generator polynomial. The remainder R would be the cyclic redundancy checksum. If the data changed or became corrupt, then a different remainder would be calculated.
Although the algorithm for cyclic redundancy calculations looks complicated, it only involves shifting and exclusive OR operations. Using modulo two arithmetic, division is just a shift operation and subtraction is an exclusive OR operation.
Cyclic redundancy calculations can therefore be efficiently implemented in hardware, using a shift register modified with XOR gates. The shift register should have the same number of bits as the degree of the generator polynomial and an XOR gate at each bit, where the generator polynomial coefficient is one.
For example, we can add two binary numbers X and Y as follows:
10101001 (X) + 00111010 (Y) = 10010011 (Z)
From this example the modulo two addition is equivalent to an exclusive OR operation. What is less obvious is that modulo two subtraction gives the same results as an addition.
From the previous example let’s add X and Z:
10101001 (X) + 10010011 (Z) = 00111010 (Y)
In our previous example we have seen how X + Y = Z therefore Y = Z – X, but the example above shows that Z+X = Y also, hence modulo two addition is equivalent to modulo two subtraction, and can be performed using an exclusive OR operation.
In integer division dividing A by B will result in a quotient Q, and a remainder R. Polynomial division is similar except that when A and B are polynomials, the remainder is a polynomial, whose degree is less than B.
The key point here is that any change to the polynomial A causes a change to the remainder R. This behavior forms the basis of the cyclic redundancy checking.
If we consider a polynomial, whose coefficients are zeros and ones (modulo two), this polynomial can be easily represented by its coefficients as binary powers of two.
In terms of cyclic redundancy calculations, the polynomial A would be the binary message string or data and polynomial B would be the generator polynomial. The remainder R would be the cyclic redundancy checksum. If the data changed or became corrupt, then a different remainder would be calculated.
Although the algorithm for cyclic redundancy calculations looks complicated, it only involves shifting and exclusive OR operations. Using modulo two arithmetic, division is just a shift operation and subtraction is an exclusive OR operation.
Cyclic redundancy calculations can therefore be efficiently implemented in hardware, using a shift register modified with XOR gates. The shift register should have the same number of bits as the degree of the generator polynomial and an XOR gate at each bit, where the generator polynomial coefficient is one.
Cyclic Redundancy Checking (CRC) - Part 1
Error detection is an important part of communication systems when there is a chance of data getting corrupted. Whether it’s a piece of stored code or a data transmission, you can add a piece of redundant information to validate the data and protect it against corruption. Cyclic redundancy checking is a robust error-checking algorithm, which is commonly used to detect errors either in data transmission or data storage. In this multipart article we explain a few basic principles.
