Binary code digital signals

Pardon Our Interruption. As you were browsing electronics-tutorials. ws something about your browser made us think you were a bot. There are a few reasons this might happen: You're a power user moving through this website with super-human speed. You've disabled JavaScript in your web browser. A third-party browser plugin, such as Ghostery or NoScript, is preventing JavaScript from running. Additional information is available in this support article. To request an unblock, please fill out the form below and we will review it as soon as possible. CHAPTER 2 — Analog and Binary Signals. Everyone knows that computers are "digital" and that they use "binary" numbers. You probably have some idea of what these terms mean. But we need to be clear about their precise meaning and to be clear about why computers are digital. Binary signals Analog signals Advantages of Binary Bits Noisy signals. Study these topics carefully if you want to know what is really going on with computers. wiseGEEK: What Is a Digital Signal?

A digital signal is a way of transmitting data that converts the data to discrete values, usually based on the binary code that computer systems work upon, which consists of packets of information coded as strings of ones and zeros. Using digital signaling allows for an accurate and nearly identical copying of certain types of information like numbers, letters, or the individual pixel colors that make up images, and this information can be stored without long-term degradation of its quality. Where digital signal conversion occurs from what is originally an analog signal, however, such as with music or other natural wave forms, the end result is only an approximation of the original analog signal and some quality in digital format may be lost. While analog signals are based upon natural processes that utilize the electromagnetic wave forms by which electricity and light are transmitted, digital signal processing requires a digital signal converter. A modulator-demodulator (modem) is such a device. It receives analog signals either from air wave transmissions or telephone lines, and converts them to digital signals that a computer or modern digital television can display as useful information. Analog signal transmission has been a common form of transmission in technology since the 1800s, but, as of 2007, it is estimated that over 94% of stored and transmitted information has become digital world wide. This is up from only 3% for digital storage in 1993, and the reasons given for switching to digital signal transmissions is often one of capacity and noise. Analog signals can only be transmitted within a defined range for wavelengths, and, when the signal reaches outside this range or is interfered with by other analog signals along similar wavelengths, distortions and noise can degrade the value of the signal. Since digital signals are based upon a discrete onoff transmission principle, they have far less susceptibility to corruption over long distances.

A digital signal can also be broken up into separate packets of information known as computer bytes and sent individually to a destination where they are reassembled. This allows for a much more efficient means of transmitting data along randomized networks such as that of the Internet, and it also increases the speed of data transmission over all. One of the main drawbacks to a digital TV signal or digital cable signal, for instance, is that it is an artificial reproduction of the original data, whereas an analog signal starts out as an exact copy of the original. As a digital signal is translated by multiple devices, encoded as analog and decoded as digital, and reassembled at the end point, quality in the reproduction can be lost. This is due to the fact that digital signals are often copies of copies of copies, and, in the process, approximations must be made by technology to replicate what the original signal was. Wireless digital transmissions can also be corrupted by other wireless activity in the area or radio signals that interfere with them, though this tends to be less of a problem than signal corruption in over the air analog transmissions. 2) @talentryto - That's what my mother always says. However, think of all of the channels that you couldn't get with the old system! 1) Though digital signals are the modern way of transmitting information, I still think that the analog system was much easier to use. Sometimes I miss not being able to get television programs without a digital box. Related wiseGEEK articles. Prior to 2009, televisions in the U. S. could receive analog TV signals, but now only digital signals are used and special adapters are needed for old-style televisions. Since a digital TV signal is so much smaller, it can do many things that an analog signal can’t. Data moves over networks in small pieces called packets. Cable and satellite providers generally provide a decoder box to their subscribers for a small monthly fee.

Binary code digital signals Get via App Store Read this post in our app! How is binary converted to electrical signals? I'm just starting off in electronics and am already fascinated. Having played with an Arduino these past few days I'm aware that binary is a representation of different voltages - such as +5V representing 1 and GND representing 0 . I've been trying to discover how, at a physical level, the microcontroller converts the binary to these voltages. I cant seem to find a description anywhere. Can anyone share their knowledge or point me to a placegood book that describes how this works? I want to restate part of KellenJB's answer in a slightly different way: There is no conversion from binary 1's and 0's to voltages like 5 V and 0 V. The microcontroller, or any physical circuit, just operates on the voltages. Those voltages are "converted" to binary 1's and 0's in our heads when we form a simplified model in our minds about how the circuit is working. There isn't really a "conversion" that takes place. Binary 1s and 0s is just a virtual representation of the underlying voltages.

In fact, in many systems a high voltage might mean 0 while a low voltage means 1. There are some reasons why this is done, but probably more then you care to dive into this early on. To understand what is happening in the logic, it is probably best to look into the transistor. A transistor can be used for many things, but at a simple level you can treat it as a switch. Conceptually you can think of it just like your light switch on the wall, but instead of being controlled by physically moving the switch it is controlled by the change in current. You could treat the light being on as a 1 and the light off being a 0. Now you can start to combine these switches in varying sets to create different logic elements (like AND, OR, NOR, etc). I know my answer isn't horribly detailed, but I hope it will answer your question. If you need more explanation I will be willing to add more detail, just don't want to overwhelm you. The short answer is it doesn't "convert", the voltages are the binary (or a representation of it). Just like if you write a number on some paper the marks are a representation of the number, or count on an abacus the stone positions are a representation of a number. Binary is a number system, just like decimal (or octal, hexadecimal, etc) While decimal (base-10) has 10 symbols (0123456789) binary (base-2) only has two (01) The sequence 10 in any base means the base to the first power, so in decimal 10 means 10^1 = 10, and in binary it means 2^1 = 2. Following on, 100 in decimal means 10^2 = 100, and in binary it means 2^2 = 4. And so on. To represent decimal using electronics would be possible but complicated, so they chose binary which can be represented by simple 0 and 1 (or onoff) There were variations on this, like ternary (3 states) systems and of course analogue computing. Before transistors, there were mechanical punch card machines (google knows plenty, some very interesting reading if you have the time) The earliest binary digital computers were made with real switches (electronic relays). The Zuse Z3 (1941) is an example: After this vacuum tubes were used instead of relays (could switch faster with no moving mechanical parts), which performed the switching instead of relays.

The ENIAC is an example of an early computer made with vacuum tubes. Then in the 60's transistors arrived and soon after ICs. The transistors perform the same function that the relaysvalves had in earlier machines, but were a lot smaller, faster and consumed less power. The actual theory behind the basic way binary computer circuits work hasn't changed at all, just like we haven't changed the way we manipulate numbers in mathematics - algorithms improve but the basic rules remain the same. So if you know how binary works, and you have a simple circuit capable of storing either a 1 or 0 as two different voltage levels (e. g. 5V and 0v), and other simple circuits that can perform simple logical functions like AND and OR, then you can combine them all to do more complex stuff. Since all these binary circuits are just switches at the most fundamental, you can achieve the same thing with anything that can alternate between two states like mechanicalrelayvalvetransistor?. To give an example of storing a number in binary, lets say we have 8 switches (what type they are isn't important) A 1 is represented by 5V and a 0 is represented by 0V. We want to store the number 123. In decimal it is 123 = (1 X 10^2) + (2 * 10^1) + (3 x 10^0) In binary it is 01111011 = (0 x 2^7) + (1 x 2^6) + (1 x 2^5) + (1 x 2^4) + (1 x 2^3) + (0 x 2^2) + (1 x 2^1) + (1 x 2^0) So all we do is set switches 0,1,3,4,5,6 to 5V and switches 7 and 2 to 0V. This "stores" the number 123 in binary. This setup would be known as a "register". If you want to know more about how the switches are combined to form more complex circuits get yourself a good book on digital logic or ask google. This site doesn't seem to be too bad to start with. The program you are running is using voltages that represent ones and zeros. Everything about that digital part is voltages either close to ground or close to the supply voltage (5V in your example).

When you load a processor register with 0xFF lets say you are creating 8 separate 5Volt signals somewhere in the chip. When you then store that register value in a control register that is related to the output ports, the output pins on the device the 5V signals in the processors register then cause other 5V signals to be created that are connected to the external pins of the device. The voltages are just a way of representing the binary. It is a quite efficient and practical conversion that allows for binary logic to be implemented using different transistor configurations. The way binary logic is usually implemented electronically is by using CMOS ( en. wikipedia. orgwikiCMOS ) technology, in which two MOS transistors are set up in a complementary pair to form a CMOS gate. There are other electronic implementations of binary logic though, using TTL ( en. wikipedia. orgwikiTransistor–transistor_logic ) for example, or relays. But you could use anything really, paper, paper robot goats: robives. comcategoryproduct_tagslogic_goats . The electronical CMOS implementation just happens to be an efficient and practical one. Out of these simple CMOS gates, you can build more complicated logic gates: NAND and NOR, the standard gate being NOT, are the basic ones. Out of these, you can build everything that is binary logic, an adder, a register file, memory.

Out of these you can build an ALU, all the way up to a complete microprocessor. If you want more information, you can read a book about digital logic, I happen to own and like this one: A nice practical way for understanding how a CPU is built is just to build one yourself, using VHDL and a FPGA. You can get cheap FPGA development boards and the software is usually free (for a restricted license). I have a few by digilent which are quite affordable: Simply put, in a given range (usually from 5 to 12 volts) the most significant bit is 0 in the first half of that range and 1 in the other. The next most significant bit is calculated by further dividing that half in two and so on until all the bits have been calculated. Therefore, binary is just about increasing and decreasing voltages that are measured periodically. Here's a simplified example. In the range from 1V to 256V, let's translate (analog) 137 to binary (numeric) using pseudocode: Binary code digital signals Get via App Store Read this post in our app! How electrical signals converted into Digital (binary 1 0) I already ask this question in yahoo and in Microsoft. they say that : did I mean to say how to convert analog signals to digital signals. and they suggest me the theory of AD converter So, here is my question : the electricity that we use in our daily life to operate computers, refrigerators, televisions etc = ANALOG SIGNAL . because I want to know how this electricity is converted into digital signals.

1. if electricity = analog signal, then ok I already got the answer(AD converter) if electricity ≠ analog signal, then suggest me any book where from I learn this mechanism step by step to convert it to digital signals if electricity ≠ analog signal, can I convert this electricity directly to digital, without converting it first to analog signal. Your question assumes that there are somehow two kinds of electricity, analog and digital. This is not the case. The difference between analog and digital is how we humans interpret an electrical signal. Electricity is electricity, it does not care how we interpret it. For an analog signal we interpret its level value (voltage, or sometimes current) as conveying information with infinite resolution: in the ideal world 1.00000 Volt and 1.00001 Volt convey different information (the latter could mean for instance that the measured temperature is 0.1 degree higher). For a digital signal we interpret its level as conveying just one bit of information. For instance, below 2.5V (but ideally 0V) it conveys a 0, above 2.5V (ideally 5V) it conveys a 1. An analog signal can clearly convey much more information with just the level on one wire. A digital signal on the other hand has the very important property that a little noise on the line does not affect the information in an ideal signal: 0V (ideal 0 signal level) + 1V noise => 1V, which is still recognizable as a 0 level. This means that a digital signal can be transported, storedretrieved and processed without loss of information . It turns out that it is much easier and cheaper to create a digital circuit that handlestoretransmit let's say 20 bits (which together can represent. 1*10^6 different values) than to create an analog circuit that can do things with an analog signal with an accuracy of 1*10-6. Hence the trend to do everything digital. That brings us back to your question of AD conversion. Our real world is inherently analog, and so are (nearly?) all our sensors that interface with the real world.

They produce an analog signal, which we would like to feed into our digital circuits. The circuit that does this is called an Analog-to-Digital-Converter. IIRC there are good explanations on SE of the working of an ADC. if the analog level is higher than some reference point (usually a proportion of the supply voltage of whatever processorintegrated circuit is using the digital signal), it is considered 'digital high', when the analog level gets too low, it is considered 'digital low'. It is merely comparison points, of what should be seen as high and low levels for a digital system. This could be implemented easily with Op-amps used as comparators, with voltage dividers from the supply rail as reference. You can get low voltage digital systems, whose 'high' signal is not actually high enough for other systems to also say that it's 'high'. That is because they might have different comparison levels, or very different voltage supply levels. A->D Converters do not tell you "digital high" or "digital low" they tell you in 'steps' how big the analog signal is detected - like 2V might be represented by the A->D Converter as '200', and 3V could be '300' etc. That is of course very dependant on the analog reference voltage, the converter IC, the resolution of the output (8, 10, 12 bits etc) which tells you the number of steps that the detected analog signal can be broken up into and read by something. "Power" systems can be seen as "Analog" because they are varying in all their interesting properties - there is no one standard for 'powered' and 'not powered' haha! All the signals in nature are analog signals. It needs enormous storage capacity to store an analog signal completely.

So instead of storing all the values, only samples of a signal are stored and these samples can have only predefined values. The value of samples are 'rounded' to nearest 'allowed' value. Such a representation of signal is called digital signal and these predefined set of 'allowed' values are represented by binary values (combination of 1's and 0's). The electricity that we use in our daily life to operate computers, refrigerators, televisions is an analog signal. The output of a micro-phone is an analog signal. The ADC's are used to represent these signals with binary values. Note: Since only samples are taken and values are represented with discrete levels, analog-to-digital conversion leads to loss of some finer details in the signal. But the conversion is usually done with such a precision that the loss of details is under allowed limits or beyond human perception limits. The ADC stuff is useful if you want to describe the signal you receive. If you know you are receiving a numerical signal, and expect it to be 0 or 1, you have much more efficient ways to know if your signal is 0 or 1. You probably know the logical 1 is often 5V, and the 0 0V. Those values depends on the technology you use (most parts on high-end microprocessors now use 1.2V as 1, and 0V as 0), but I will always say "5V" in my answer, for readability. Were does it comes from ? From transistors. Digital electronics uses transistors as commutators.

Transistors either let the current pass, or block it. If you put 5V on the gate of your transistor, it let the current pass, if you put 0V, it blocks the current (some transistors works just the opposite way, some are just different, but it does not matter here). By using 5V in your whole circuit, you become able to switch transistors ON and OFF using other transistors. So, why precisely 5V ? In fact, we don't really need 5V. 4.5V works fine too, 5.5V works fines too, but 10V will probably make your transistor burn, while 2V will make your transistor let some current pass, but resist to it. On the first case, you destroy your circuit, it is obvious it won't work. On the second case, you just can't predict if your output will allow to put the following transistor to either 0 or 1. This lead to logical issues, such as your processor making a subtraction instead of an addition. To sum up, we need binary logic, and we make electronics behave as logical systems. We have just chosen some parts of the analog characteristics that allow us to do logic, and avoid to make transistors be between passing and blocking state, as it makes no sense in binary logic. I think the aspect that you trying to understand, and most people don't think about, is what is meant by "analog" or "Analogue"? It really means "analogous" -> adjective (often analogous to) comparable in certain respects. This means it is a representative in electrical terms (voltage, current) of a real world "signal". If you are designing a sound system you don't actually work with sound, you use a transducer (a microphone) to convert to an electrical signal, manipulate it in the electrical domain and then convert it back when you need to hear it this is done through another transducer (a speaker). The distinction in the electrical domain is whether the signal is continuous or discrete. the former, confusingly is simply called "analog" in common usage, and the later is called digital, again in common usage. There are systems, relatively rare now, that use pneumatics to control pneumatic systems, and in some cases those had discrete control ("digital") and continuous control. They are air controlling air, with no "analogous" step in between.

Automobiles use mechanical systems to control mechanical systems (springs, shock absorbers etc.). In some cases you can directly convert from the real world signal (sound, light etc.) directly in the digital domain (discrete electrical signalling). Simple examples might be a contact closure that is temperature sensitive to control a furnace (power on off), to more complex, like an image sensor that detects individual photons and counts them (at that level you could consider light to be in discrete units already - since the term is so loosely applied - you could consider it to be digital already). Here is a write up on why the distinction between analog and digital is perhaps not significant is certain areas. It's just simply "what is the easiest representation that allows a problems to be solved" Diagram the System to Transmit Binary Data. Signals and Systems For Dummies. The various blocks of a digital communication system are a hybrid of discrete-time signal generation and filtering, continuous-time signal processing at baseband frequencies, and continuous-time radio frequency (RF) up and down conversion. Start with the signal. A digital communications signal at baseband takes the form.

where a k is a bit sequence that’s been translated from binary 01 values to +– 1 values, p ( t ) is a pulse shape, and A is an amplitude scale factor. The bit duration is T h , so the serial bit rate is R b = 1 T b bps. The index k runs over the duration of the digital message sequence. Common pulse shapes include rectangular (RECT), raised cosine (RC), and square root raised cosine (SRC). In the continuous-time domain, the RECT pulse is just. In the business of line codes for digital signaling, x bb ( t ) under the RECT pulse is known as nonreturn-to-zero (NRZ) because the waveform never sits at zero. It’s also common practice to generate x bb ( t ) first in the discrete-time domain, using the equivalent pulse shape sequence p n to create x bb n and then using a digital-to-analog converter (DAC) to convert the sequence to a continuous time signal. For wireless communications, you need to place the baseband signal on a carrier frequency, similar to AM. Because cosine and sine function carriers are orthogonal (in a vector sense, the information carrier by the sine and cosine carriers are at right angles, so they don’t interfere with each other), the typical formulation is to put one baseband signal on cos(2 πf c t ) and a second signal on sin(2 πf c t ). Binary phase-shift keying (BPSK) is used, which has x I ( t ) = x bb ( t ) with RECT, RC, or SRC pulse shaping, and x Q ( t ) = 0. The block diagram, shown later, is developed for the general case. The name BPSK comes about because with NRZ line coding, x I ( t )cos(2 πf c t ) is the carrier signal at either 0 degrees or 180 degrees as a result of the +– 1 data multiplication. Check out the waveform and spectra. Using the custom function NRZ_bits() , written in Python (see ssd. py ), the figure shows x I ( t ) (a discrete-time simulation) and the power spectrum.

The slow spectral roll-off when using the RECT pulse results in poor spectral efficiency. You can resolve this with the RC and SRC pulse shapes. Use pulse shapes to increase spectral efficiency. To limit the bandwidth of the RECT spectrum, you can pass the signal through a low-pass filter (such as a low-pass Butterworth, Chebyshev, and so on). Doing so results in intersymbol interference (ISI), which means that signal energy from adjacent bits smear into the bit of interest, raising the probability of creating a bit error when the signal is received in a noise background. So what do you do? Nyquist pulse shaping to the rescue! The RC pulse shape ensures that no ISI occurs. The bit energy still spreads across multiple symbols, but there’s a timing location once per bit (symbol) period that has zero ISI! The occupied spectral bandwidth is given by (1 + α) R b , where 0 < α ≤ 1 is the excess bandwidth factor. Note α &rarr 0 gives the most compact spectrum but is impractical to implement. Typical α values found in use today range from 0.25 to 0.5. The spectral efficiency for BPSK with α = 0.5 is 1.5 bpsHz.

You must consider power efficiency in digital communications. The idea is to get by, using as little power as possible while maintaining a low probability of making bit errors. Additive noise and interference from other users is the primary cause of bit errors. Additive noise comes about because the received signal strength is usually just above the noise floor (power efficiency). A matched filter at the receiver ensures that you can reduce the noise yet not overly distort the signal. Nyquist to the rescue again: You can minimize the probability of making a bit error if you distribute the RC pulse shape between the transmitter and receiver matched filter. You can do this by using the SRC filter. The transmitter pulse shape is SRC, and the receiver matched filter is identical. The SRC pulse has the same parameter α for controlling the signal bandwidth. Discrete-time implementation of the SRC pulse shapes is the way to go. The mathematical description of the SRC pulse is as follows: N s is the number of samples per bit (symbol), sinc( x ) = sin( πx ) ( πx ), and 0 < α ≤ 1 is known as the excess bandwidth factor .

A small but significant detail is that the SRC pulse has infinite duration. It’s also symmetrical about n = 0. Complete the block diagram. Check out the complete transceiver block diagram for implementing pulse-shaped BPSK as well as general IQ modulation. (GRAC)Networking - Chapter 5. . Linear process and produces frequencies that are the sum and difference of the carrier signal and the components of the modulating signal (how is this linear though? it produces a sine wave, doesn't it?) Involves altering one or more characteristics of a carrier frequency to represent binary data. Two binary values are represented by two different amplitudes of the carrier frequency. Suspectible to sudden gain changes and is a rather inefficient modulation technique. Used to transmit digital data over an optical fiber. Digital data, analog signaling: ASK (amplitude shift keying), FSK (frequency shift keying), PSK (phase shift keying) Analog data, analog signaling: Amplitude modulation (AM), Frequency modulation (FM), Phase modulation (PM) Frequency modulation and phase modulation are special cases of angle modulation. As opposed to amplitude modulation - includes a cos term and is therefore nonlinear, and will produce a wide range of frequencies.

Shows ratio of data rate R to transmission bandwidth. Measures efficiency with which bandwidth can be used to transmit data. Also known as modulating signal. Analog data in electric form can be transmitted as baseband signals easily and cheaply. For unguided transmission, it is virtually impossible to transmit baseband signals. All biphase techniques require at least one transition bit per time and may have two, so maximum modulation rate is twice that for NRZ - bandwidth required is correspondingly higher. Two pros: synchronization (biphase codes are known as self-clocking codes), and no dc component. Binary 1 is represented by a positive or negative pulse - the binary 1 pulses must alternate in polarity. Pros: no loss in synchronization if a long string of 1s occur (long string of 0s still a problem) since 1s alternate in voltage from positive to negative, there is no net dc component bandwidth is considerably less than NRZ pulse alternative property provides a means for error detection. An increase in SNR decreases bit error rate. An increase in bandwidth allows an increase in data rate (more in chapter 6) Modulates analog data to produce an analog signal in a different frequency band, which can be utilized on an analog transmission system. In all cases of ASK, PSK, FSK, the resulting signal occupies a bandwidth centered on the carrier frequency. The frequency of the carrier signal is chosen to be compatible with the transmission medium being used. Three characteristics of carrier signal: amplitude, frequency, and phase.

The device used for converting analog data into digital form for transmission, and subsequently recovering the original analog data from the digital. The rate at which data elements are transmitted. Don't confuse data rate with modulation rate. Bit confused about this? Come back later. Is one of two principal techniques used in codecs. One of the most popular alternatives to PCM. Analog input is approximated by a staircase function that moves up or down by one quantization level at each sampling interval. Output of delta modulation process can be represented as a single binary digit for each sample. When information to be transmitted is represented in terms of the changes between successive signal elements rather than the signal elements themselves. May be more reliable to detect a transition in the presence of noise rather than to compare a value to a threshold. 0 = transition at beginning of interval. 1 = no transition at beginning of interval. Is a type of biphase technique: overcomes the limitations of NRZ codes.

Minimum size signal element is a pulse of one-half the duration of a bit interval. A binary 0 is represented by sending a signal burst of the same phase as the previous signal burst sent. A binary 1 is represented by sending a signal burst of opposite phase to the preceding one. Is in the same ballpark, in terms of efficiency, as ASK, FSK, and PSK. Conversion to digital signaling allows the use of the more efficient digital switching techniques. A special case of angle modulation. FM requires greater bandwidth than AM. Increase in m(t) (modulation??) should increase transmitted bandwidth but does not increase the average power level of the FM signal. Resulting signal occupies a bandwidth centered on the carrier frequency. Most common form is BFSK, where the two binary values are represented by two different frequencies near the carrier frequency. Each signaling element is one bit. Successive violations are of alternate polarity so that no dc component is introduced.

Is a scrambling technique commonly used in long-distance transmission services. Transition in the middle of each bit period. Midbit transition serves as clocking mechanism and also as data. 0 = transition from high to low in middle of interval. 1 = transition from low to high in middle of interval. Classified under the biphase set of coding techniques that overcomes the limitations of NRZ codes. Each signaling element is less than one bit. All modulation techniques involve operation on one or more of the three fundamental frequency domain parameters: amplitude, frequency, and phase. For analog data & signal: common use of modulation is to shift the bandwidth of a baseband signal to another portion of the spectrum so multiple signals (each at a different position on the spectrum) can share the same transmission medium. Process of combining an input signal m(t) and a carrier at frequency f(c) to produce a signal s(t) whose bandwidth is usually centered on f(c) Don't confuse it with data rate.

Rate at which signal level is changed. Rate at which signal elements are transmitted. Rate at which signal elements are generated. Is expressed in baud (signal elements per second) One way of characteristizing modulation rate is to determine the average number of transitions per bit time. A category of encoding techniques that addresses some of the deficiencies of the NRZ codes. But is not as efficient as NRZ coding - the receiver of multilevel binary signals has to distinguish between three levels instead of just two. The bit error rate for NRZ codes, at a given signal-to-noise ratio, is significantly less than that for multilevel binary. Most common, and easiest, way to transmit digital signals is to use two different voltage levels for two binary digits. The NRZ codes are the easiest to engineer and make efficient use of bandwidth. Most of the energy in these codes is between dc and half the bit rate. Main limitations are the presence of a dc component and the lack of synchronization capability. 0 = no transition at beginning of interval, 1 = transition at beginning of interval. Variation of NRZ.

Maintains a constant voltage pulse for the duration of a bit time. Data are encoded as the presence of absence of a signal transition at the beginning of the bit time. Is an example of differential encoding. Problem with long string of 0's - output is a constant voltage over time and any drift between the clocks of transmitter and receiver will result in loss of synchronization. Problem: can lose sense of polarity of the signal. On multidrop twisted-pair line, if the leads from an attached device to the twisted pair are accidentally inverted, all the 1s and 0s for NRZ-L will be inverted. Problem with long string of 1s and 0s - constant voltage, loss of synchronization. Each signaling element is one bit. Common for asynchronous tranmission. Phase modulation is a special case of angle modulation.

The phase is proportional to the modulating signal. The phase of the carrier signal is shifted to represent data. There is binary phase shift keying (use two phases to represent two binary digits) and differential phase shift keying (phase shift is with reference to the previous bit transmitted rather than some constant reference signal) 0 = positive or negative level, alternating for successive zeroes. 1 = no line signal. Most recent preceding 0 bit has negative voltage. No loss of synchronization if a long string of 0s occur. Since the 0 signals alternate in voltage from positive to negative, there is no net dc component. Bandwidth of signal is less than that for NRZ codes. To convert to digital - each of these analog samples must be assigned a binary code. Don't quite understand it. Simplest technique to digitize analog data. Involves sampling the analog data periodically and quantizing the samples. A principal technique used in codecs. Based on the sampling theorem (if a signal is sampled at regular intervals of time and at a rate higher than twice the highest signal frequency, then the samples contain all the information of the original signal. The original signal may be reconstructed from these samples) Popular analog signaling technique.

Is a combination of ASK and PSK - can be considered a logical extension of QPSK. Takes advantage of the fact that it is possible to send two different signals simultaneously on the same carrier frequency, by using two copies of the carrier frequency, one shifted by 90 degrees wrt to the other. Each carrier is ASK modulated - the two independent signals are simultaneously transmitted over the same medium. At the receiver, the two signals are demodulated and the results combined to produce the original binary input. Each signaling element is more than one bit. By quantizing the PAM pulse, the original signal is now only approximated and cannot be recovered exactly - this effect known as quanitizing error or quantizing noise (page 163 explains it better) Tries to address problem of synchronization (with long string of 0s is present, like in pseudoternary) at high data rates. Two scrambling techniques used in long-distance transmission services: B8ZS and HDB3. Design goals: no dc component, no long sequences of zero-level line signals, no reduction in data rate, error-detection capability. Ratio of signal energy per bit to noise density per hertz. This ratio is important because the bit error rate for digital data is a decreasing function of this ratio.

Advantage of EbN0 over SNR is that the latter depends on the bandwidth. Simplest form of digital encoding of digital data is to assign one voltage level to binary one and another to binary zero. More complex encoding schemes are used to improve performance, by altering the spectrum of the signal and providing synchronization capability. A modem converts digital data to an analog signal so it can be transmitted over an analog line. All types involve altering one or more characteristics of a carrier frequency to represent binary data. Analog data are digitized to be able to use digital transmission facilities. Simplest is PCM which involves sampling the analog data periodically and quantizing the samples. Analog data are modulated by a carrier frequency to produce an analog signal in a different frequency band, which can be utilized on an analog transmission system. Binary code digital signals Get via App Store Read this post in our app! How electrical signals converted into Digital (binary 1 0) I already ask this question in yahoo and in Microsoft. they say that : did I mean to say how to convert analog signals to digital signals. and they suggest me the theory of AD converter So, here is my question : the electricity that we use in our daily life to operate computers, refrigerators, televisions etc = ANALOG SIGNAL . because I want to know how this electricity is converted into digital signals. 1. if electricity = analog signal, then ok I already got the answer(AD converter) if electricity ≠ analog signal, then suggest me any book where from I learn this mechanism step by step to convert it to digital signals if electricity ≠ analog signal, can I convert this electricity directly to digital, without converting it first to analog signal.

Your question assumes that there are somehow two kinds of electricity, analog and digital. This is not the case. The difference between analog and digital is how we humans interpret an electrical signal. Electricity is electricity, it does not care how we interpret it. For an analog signal we interpret its level value (voltage, or sometimes current) as conveying information with infinite resolution: in the ideal world 1.00000 Volt and 1.00001 Volt convey different information (the latter could mean for instance that the measured temperature is 0.1 degree higher). For a digital signal we interpret its level as conveying just one bit of information. For instance, below 2.5V (but ideally 0V) it conveys a 0, above 2.5V (ideally 5V) it conveys a 1. An analog signal can clearly convey much more information with just the level on one wire. A digital signal on the other hand has the very important property that a little noise on the line does not affect the information in an ideal signal: 0V (ideal 0 signal level) + 1V noise => 1V, which is still recognizable as a 0 level. This means that a digital signal can be transported, storedretrieved and processed without loss of information . It turns out that it is much easier and cheaper to create a digital circuit that handlestoretransmit let's say 20 bits (which together can represent. 1*10^6 different values) than to create an analog circuit that can do things with an analog signal with an accuracy of 1*10-6. Hence the trend to do everything digital. That brings us back to your question of AD conversion. Our real world is inherently analog, and so are (nearly?

) all our sensors that interface with the real world. They produce an analog signal, which we would like to feed into our digital circuits. The circuit that does this is called an Analog-to-Digital-Converter. IIRC there are good explanations on SE of the working of an ADC. if the analog level is higher than some reference point (usually a proportion of the supply voltage of whatever processorintegrated circuit is using the digital signal), it is considered 'digital high', when the analog level gets too low, it is considered 'digital low'. It is merely comparison points, of what should be seen as high and low levels for a digital system. This could be implemented easily with Op-amps used as comparators, with voltage dividers from the supply rail as reference. You can get low voltage digital systems, whose 'high' signal is not actually high enough for other systems to also say that it's 'high'. That is because they might have different comparison levels, or very different voltage supply levels. A->D Converters do not tell you "digital high" or "digital low" they tell you in 'steps' how big the analog signal is detected - like 2V might be represented by the A->D Converter as '200', and 3V could be '300' etc. That is of course very dependant on the analog reference voltage, the converter IC, the resolution of the output (8, 10, 12 bits etc) which tells you the number of steps that the detected analog signal can be broken up into and read by something.

"Power" systems can be seen as "Analog" because they are varying in all their interesting properties - there is no one standard for 'powered' and 'not powered' haha! All the signals in nature are analog signals. It needs enormous storage capacity to store an analog signal completely. So instead of storing all the values, only samples of a signal are stored and these samples can have only predefined values. The value of samples are 'rounded' to nearest 'allowed' value. Such a representation of signal is called digital signal and these predefined set of 'allowed' values are represented by binary values (combination of 1's and 0's). The electricity that we use in our daily life to operate computers, refrigerators, televisions is an analog signal. The output of a micro-phone is an analog signal. The ADC's are used to represent these signals with binary values. Note: Since only samples are taken and values are represented with discrete levels, analog-to-digital conversion leads to loss of some finer details in the signal. But the conversion is usually done with such a precision that the loss of details is under allowed limits or beyond human perception limits. The ADC stuff is useful if you want to describe the signal you receive. If you know you are receiving a numerical signal, and expect it to be 0 or 1, you have much more efficient ways to know if your signal is 0 or 1. You probably know the logical 1 is often 5V, and the 0 0V. Those values depends on the technology you use (most parts on high-end microprocessors now use 1.2V as 1, and 0V as 0), but I will always say "5V" in my answer, for readability. Were does it comes from ?

From transistors. Digital electronics uses transistors as commutators. Transistors either let the current pass, or block it. If you put 5V on the gate of your transistor, it let the current pass, if you put 0V, it blocks the current (some transistors works just the opposite way, some are just different, but it does not matter here). By using 5V in your whole circuit, you become able to switch transistors ON and OFF using other transistors. So, why precisely 5V ? In fact, we don't really need 5V. 4.5V works fine too, 5.5V works fines too, but 10V will probably make your transistor burn, while 2V will make your transistor let some current pass, but resist to it. On the first case, you destroy your circuit, it is obvious it won't work. On the second case, you just can't predict if your output will allow to put the following transistor to either 0 or 1. This lead to logical issues, such as your processor making a subtraction instead of an addition. To sum up, we need binary logic, and we make electronics behave as logical systems. We have just chosen some parts of the analog characteristics that allow us to do logic, and avoid to make transistors be between passing and blocking state, as it makes no sense in binary logic. I think the aspect that you trying to understand, and most people don't think about, is what is meant by "analog" or "Analogue"? It really means "analogous" -> adjective (often analogous to) comparable in certain respects.

This means it is a representative in electrical terms (voltage, current) of a real world "signal". If you are designing a sound system you don't actually work with sound, you use a transducer (a microphone) to convert to an electrical signal, manipulate it in the electrical domain and then convert it back when you need to hear it this is done through another transducer (a speaker). The distinction in the electrical domain is whether the signal is continuous or discrete. the former, confusingly is simply called "analog" in common usage, and the later is called digital, again in common usage. There are systems, relatively rare now, that use pneumatics to control pneumatic systems, and in some cases those had discrete control ("digital") and continuous control. They are air controlling air, with no "analogous" step in between. Automobiles use mechanical systems to control mechanical systems (springs, shock absorbers etc.). In some cases you can directly convert from the real world signal (sound, light etc.) directly in the digital domain (discrete electrical signalling). Simple examples might be a contact closure that is temperature sensitive to control a furnace (power on off), to more complex, like an image sensor that detects individual photons and counts them (at that level you could consider light to be in discrete units already - since the term is so loosely applied - you could consider it to be digital already).

Here is a write up on why the distinction between analog and digital is perhaps not significant is certain areas. It's just simply "what is the easiest representation that allows a problems to be solved" Difference Between | Descriptive Analysis and Comparisons. Key difference: Analog is a linear transmission of signal. In the digital form of transmission, the signal is converted into binary code (0s and 1s) before transmission. Analog and digital are two kinds of processes used for the transmission of electric signals, usually audio or video. Analog is a linear transmission of signal, in which the amplitude varies. In digital, the data is converted into binary code (0s and 1s) before transmission. The translation of data has two distinct amplitudes represent each bit. Analog has been used for decades and is cheaper as compared to digital. VCRs, tape players, and record players are all types of analog devices. They record data in a linear format, i. e. from one point to another.

The devices read the media by scanning the physical data off the media. However, the disadvantage of analog signals is that they have a limitation on the size of the data that can be transmitted at any given point of time. Also, they are prone to signal distortion due to unwanted noise. All natural signals, such as human speech are considered to be analog signals. Therefore, all analog signals must be converted into digital for work on a computer. Computers are digital devices, and hence, perform all calculations using the binary system of 1s and 0s. All digital technology uses the binary system. Digital media is non-linear in nature, which means it can be edited or played back from any point. This is one of the major advantages that digital has over analog. Also, digital is longer lasting than analog, as it does not wear out over time. Also, digital media tends to have better quality over analog as it can compress more data in lesser space. CDs have the sampling rate of 44,000 samples per second. This means that there are 44,000 numbers stored per second of music.

The term, "sampling rate" or "bit rate," refer to how many times per second the digital signal is sampled. However, a disadvantage is that it is prone to losing quality due to the translation of data. Still, the advantages outweigh the disadvantages. For a more detailed comparison see below: Linear transmission of signal. Signal is converted into binary code (0s and 1s) before transmission. Sound, light, temperature, position, or pressure. Computing and electronics. Uses continuous range of values to represent information. Uses discrete or discontinuous values to represent information. Potential for an infinite amount of signal resolution, higher density, simpler technology, cheaper. Easier manipulation, error detection and error correction, improved quality of sound, create effects, does not wear out over time. Might include unwanted sound or noise, signal loss, distortion due to noise, limitation on transmitted data size, wears out over time. Expensive, prone to loss of quality in translation of data. Image Courtesy: burnworld.

com, speckygeek. com. awsome thank u guys . Thu, 07242014 - 18:27. Popular Tags. Newly Added Differences. Most Popular Differences. Most Commented. Copyright © 2017, Difference Between | Descriptive Analysis and Comparisons. Binary code digital signals Get via App Store Read this post in our app! How is binary converted to electrical signals? I'm just starting off in electronics and am already fascinated. Having played with an Arduino these past few days I'm aware that binary is a representation of different voltages - such as +5V representing 1 and GND representing 0 . I've been trying to discover how, at a physical level, the microcontroller converts the binary to these voltages. I cant seem to find a description anywhere.

Can anyone share their knowledge or point me to a placegood book that describes how this works? I want to restate part of KellenJB's answer in a slightly different way: There is no conversion from binary 1's and 0's to voltages like 5 V and 0 V. The microcontroller, or any physical circuit, just operates on the voltages. Those voltages are "converted" to binary 1's and 0's in our heads when we form a simplified model in our minds about how the circuit is working. There isn't really a "conversion" that takes place. Binary 1s and 0s is just a virtual representation of the underlying voltages. In fact, in many systems a high voltage might mean 0 while a low voltage means 1. There are some reasons why this is done, but probably more then you care to dive into this early on. To understand what is happening in the logic, it is probably best to look into the transistor. A transistor can be used for many things, but at a simple level you can treat it as a switch. Conceptually you can think of it just like your light switch on the wall, but instead of being controlled by physically moving the switch it is controlled by the change in current. You could treat the light being on as a 1 and the light off being a 0. Now you can start to combine these switches in varying sets to create different logic elements (like AND, OR, NOR, etc). I know my answer isn't horribly detailed, but I hope it will answer your question. If you need more explanation I will be willing to add more detail, just don't want to overwhelm you. The short answer is it doesn't "convert", the voltages are the binary (or a representation of it). Just like if you write a number on some paper the marks are a representation of the number, or count on an abacus the stone positions are a representation of a number. Binary is a number system, just like decimal (or octal, hexadecimal, etc) While decimal (base-10) has 10 symbols (0123456789) binary (base-2) only has two (01) The sequence 10 in any base means the base to the first power, so in decimal 10 means 10^1 = 10, and in binary it means 2^1 = 2. Following on, 100 in decimal means 10^2 = 100, and in binary it means 2^2 = 4. And so on. To represent decimal using electronics would be possible but complicated, so they chose binary which can be represented by simple 0 and 1 (or onoff) There were variations on this, like ternary (3 states) systems and of course analogue computing.

Before transistors, there were mechanical punch card machines (google knows plenty, some very interesting reading if you have the time) The earliest binary digital computers were made with real switches (electronic relays). The Zuse Z3 (1941) is an example: After this vacuum tubes were used instead of relays (could switch faster with no moving mechanical parts), which performed the switching instead of relays. The ENIAC is an example of an early computer made with vacuum tubes. Then in the 60's transistors arrived and soon after ICs. The transistors perform the same function that the relaysvalves had in earlier machines, but were a lot smaller, faster and consumed less power. The actual theory behind the basic way binary computer circuits work hasn't changed at all, just like we haven't changed the way we manipulate numbers in mathematics - algorithms improve but the basic rules remain the same. So if you know how binary works, and you have a simple circuit capable of storing either a 1 or 0 as two different voltage levels (e. g. 5V and 0v), and other simple circuits that can perform simple logical functions like AND and OR, then you can combine them all to do more complex stuff. Since all these binary circuits are just switches at the most fundamental, you can achieve the same thing with anything that can alternate between two states like mechanicalrelayvalvetransistor?. To give an example of storing a number in binary, lets say we have 8 switches (what type they are isn't important) A 1 is represented by 5V and a 0 is represented by 0V. We want to store the number 123. In decimal it is 123 = (1 X 10^2) + (2 * 10^1) + (3 x 10^0) In binary it is 01111011 = (0 x 2^7) + (1 x 2^6) + (1 x 2^5) + (1 x 2^4) + (1 x 2^3) + (0 x 2^2) + (1 x 2^1) + (1 x 2^0) So all we do is set switches 0,1,3,4,5,6 to 5V and switches 7 and 2 to 0V. This "stores" the number 123 in binary.

This setup would be known as a "register". If you want to know more about how the switches are combined to form more complex circuits get yourself a good book on digital logic or ask google. This site doesn't seem to be too bad to start with. The program you are running is using voltages that represent ones and zeros. Everything about that digital part is voltages either close to ground or close to the supply voltage (5V in your example). When you load a processor register with 0xFF lets say you are creating 8 separate 5Volt signals somewhere in the chip. When you then store that register value in a control register that is related to the output ports, the output pins on the device the 5V signals in the processors register then cause other 5V signals to be created that are connected to the external pins of the device. The voltages are just a way of representing the binary. It is a quite efficient and practical conversion that allows for binary logic to be implemented using different transistor configurations. The way binary logic is usually implemented electronically is by using CMOS ( en. wikipedia. orgwikiCMOS ) technology, in which two MOS transistors are set up in a complementary pair to form a CMOS gate. There are other electronic implementations of binary logic though, using TTL ( en. wikipedia. orgwikiTransistor–transistor_logic ) for example, or relays.

But you could use anything really, paper, paper robot goats: robives. comcategoryproduct_tagslogic_goats . The electronical CMOS implementation just happens to be an efficient and practical one. Out of these simple CMOS gates, you can build more complicated logic gates: NAND and NOR, the standard gate being NOT, are the basic ones. Out of these, you can build everything that is binary logic, an adder, a register file, memory. Out of these you can build an ALU, all the way up to a complete microprocessor. If you want more information, you can read a book about digital logic, I happen to own and like this one: A nice practical way for understanding how a CPU is built is just to build one yourself, using VHDL and a FPGA. You can get cheap FPGA development boards and the software is usually free (for a restricted license). I have a few by digilent which are quite affordable: Simply put, in a given range (usually from 5 to 12 volts) the most significant bit is 0 in the first half of that range and 1 in the other. The next most significant bit is calculated by further dividing that half in two and so on until all the bits have been calculated. Therefore, binary is just about increasing and decreasing voltages that are measured periodically. Here's a simplified example. In the range from 1V to 256V, let's translate (analog) 137 to binary (numeric) using pseudocode: