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The short answer is compression. It also depends on what types of signals you are referring to. I will talk about cable because its easier.
Think of it as space on a line, a Analog tv signal for 1 channel takes up 6 Mhz of space. ------
A digital signal is "compressed" now its the same picture but it only takes up .75 Mhz of space or -
So because the information is compressed into smaller spaces you can fit 4 channels of digitally compressed TV into the space required for 1 analog channel.
That's the short and skinny on that.
What else can I help you with?
Does the connection between your home and the end office local loop use an analog or digital signal?
It depends. It's true, the standard POTS (plain old telephone service) is delivered over an analog loop. However, you may have a service known as DSL, it is even in the name (Digital Subscriber Line) digital. It uses the *unheard* areas (25kHz+) of the line to carry digital signal. So a line can be both analog and digital! Also, DSL can be provided on what's called a "dry loop" which is using a pair of copper (typically what would carry POTS service, but isn't connected to the PSTN.) That being said, it can be Analog, Digital or both: Analog and Digital.
What are analog and digital signals?
Analog radio signals cause characteristic changes, or modulations, in the radio waves that carry them: amplitude modulation (AM) and frequency modulation (FM). An old technology compared to newer digital signals such as satellite and high definition radio, differences that distinguish analog radio from digital radio include signal characteristics, sound clarity and cost.Type of Signal Transmission1. Carrier waves -- invisible forms of electricity and magnetism that travel wirelessly from radio broadcasting stations to radio receivers -- transmit AM, FM and digital HD radio programs. Digital signals transmit via pulses or digits of binary code, a language based on the numbers 0 and 1, before decoding.Clarity of Sound2. FM analog radio signals encounter interference when large objects such as mountains or buildings enter the intended path of travel, and cannot bend, unlike AM analog signals. An interrupted analog signal results in a crackling, unclear radio station. Digital radio signals generally don't experience interference errors, although bad weather can severely affect satellite stations.Cost3. Most perks have a catch. Satellite radio plays very few commercials, but there's a subscription fee and you must buy a satellite specific receiver. While free, traditional AM/FM radio and HD radio include commercial advertisements. To hear HD radio, you need a specific HD receiver. Digital HD receivers can play both analog and HD radio stations, but traditional analog receivers can stream only AM/FM stations.
Is HD broadcast the same as digital broadcast?
All HD broadcasts are digital. Not all digital broadcasts are HD. "Digital" is simply a way of coding TV pictures onto a radio wave so that your TV can receive the radio wave and turn it back into a TV picture. The old method was called "analog." Digital is more efficient than analog and allows a lot more information to be carried on the radio wave. Since the wave can now carry more information, some TV stations are choosing to use that extra information for a high definition (HD) picture rather than a standard definition (SD) picture. In fact, there is so much extra room with a digital signal that most TV stations can now show several different programs at once! Most channels will now have several sub-channels. For example, instead of having just Channel 7, you might have Channel 7.1, 7.2, 7.3, and so on -- each with a different program. An HD signal takes up a lot of room, so TV stations that broadcast an HD signal have less room to add additional sub-channels. What is happening with the digital transition is that all analog TV broadcasts will be turned off. Only digital broadcasts will remain on the air. Each TV station decides what it will do with its digital signal. It can use the digital signal to broadcast one HD sub-channel and a few SD sub-channels or it can broadcast a lot of digital SD sub-channels. Most TV stations will choose to broadcast at least one HD sub-channel.
What is SDTV?
SDTV stands for Standard Definition Television. It refers to TV that isn't HDTV (High-Definition Television). In the US, SDTV is 525 line with NTSC color encoding or 480 lines if the signal is digital. The figure of 480 refers to the number of active lines that make up the image. Note that the analog signal with 525 lines has blank lines at the beginning and end of each image, so the active area is still around 480 lines, plus or minus a few lines. In Europe, SDTV is 625 line with PAL color encoding, or 576 lines if the signal is digital. As with the US signal, the number 576 refers to the number of active lines making up the image. Whether or not the signal is digital, the resolution is identical. Digital signals will be component or RGB based and don't use NTSC or PAL encoding. Component signals however still carry the same information as PAL or NTSC signals. Component, whether digital or analog will normally provide significantly better image quality than either PAL or NTSC analog signals. In comparison, HDTV resolution uses 720 lines or 1080 lines for the image, so providing more detail.
What the conversion from analog to digital mean?
Analog phone lines. Analog signals. Digital security. Digital PBX. Analog-to-digital adapters. What does it all mean? In the telecom world, understanding analog versus digital isn't as simple as comparing one technology to another. It depends on what product-and in some cases, which product feature-you happen to be talking about. Analog at a glanceAs a technology, analog is the process of taking an audio or video signal (in most cases, the human voice) and translating it into electronic pulses. Digital on the other hand is breaking the signal into a binary format where the audio or video data is represented by a series of "1"s and "0"s. Simple enough when it's the device-analog or digital phone, fax, modem, or likewise-that does all the converting for you. Is one technology better than the other? Analog technology has been around for decades. It's not that complicated a concept and it's fairly inexpensive to use. That's why we can buy a $20 telephone or watch a few TV stations with the use of a well-placed antenna. The trouble is, analog signals have size limitations as to how much data they can carry. So with our $20 phones and inexpensive TVs, we only get so much. Enter digitalThe newer of the two, digital technology breaks your voice (or television) signal into binary code-a series of 1s and 0s-transfers it to the other end where another device (phone, modem or TV) takes all the numbers and reassembles them into the original signal. The beauty of digital is that it knows what it should be when it reaches the end of the transmission. That way, it can correct any errors that may have occurred in the data transfer. What does all that mean to you? Clarity. In most cases, you'll get distortion-free conversations and clearer TV pictures. You'll get more, too. The nature of digital technology allows it to cram lots of those 1s and 0s together into the same space an analog signal uses. Like your button-rich phone at work or your 200-plus digital cable service, that means more features can be crammed into the digital signal. Compare your simple home phone with the one you may have at the office. At home you have mute, redial, and maybe a few speed-dial buttons. Your phone at work is loaded with function keys, call transfer buttons, and even voice mail. Now, before audiophiles start yelling at me through their PC screens, yes, analog can deliver better sound quality than digital…for now. Digital offers better clarity, but analog gives you richer quality. But like any new technology, digital has a few shortcomings. Since devices are constantly translating, coding, and reassembling your voice, you won't get the same rich sound quality as you do with analog. And for now, digital is still relatively expensive. But slowly, digital-like the VCR or the CD-is coming down in cost and coming out in everything from cell phones to satellite dishes. When you're shopping in the telecom world, you often see products touted as "all digital." Or warnings such as "analog lines only." What does it mean? The basic analog and digital technologies vary a bit in definition depending on how they're implemented. Read on. Phone linesAnalog lines, also referred to as POTS (Plain Old Telephone Service), support standard phones, fax machines, and modems. These are the lines typically found in your home or small office. Digital lines are found in large, corporate phone systems. How do you tell if the phone line is analog or digital? Look at the back of the telephone connected to it. If you see "complies with part 68, FCC Rules" and a Ringer Equivalence Number (REN), then the phone and the line are analog. Also, look at the phone's dialpad. Are there multiple function keys? Do you need to dial "9" for an outside line? These are indicators that the phone and the line are digital. A word of caution. Though digital lines carry lower voltages than analog lines, they still pose a threat to your analog equipment. If you're thinking of connecting your phone, modem, or fax machine to your office's digital phone system, DON'T! At the very least, your equipment may not function properly. In the worst case, you could zap your communications tools into oblivion. How? Let's say you connect your home analog phone to your office's digital line. When you lift the receiver, the phone tries to draw an electrical current to operate. Typically this is regulated by the phone company's central office. Since the typical proprietary digital phone system has no facilities to regulate the current being drawn through it, your analog phone can draw too much current-so much that it either fries itself or in rare cases, damages the phone system's line card. What to do? There are digital-to-analog adapters that not only let you use analog equipment in a digital environment, but also safeguard against frying the internal circuitry of your phone, fax, modem, or laptop. Some adapters manufactured by Konexx come designed to work with one specific piece of office equipment: phone, modem, laptop, or teleconferencer. Simply connect the adapter in between your digital line and your analog device. That's it. Or you can try a universal digital-to-analog adapter such as Hello Direct's LineStein®. It works with any analog communications device. Plus, it's battery powered so you're not running extra cords all over your office. Cordless phonesThe very nature of digital technology-breaking a signal into binary code and recreating it on the receiving end-gives you clear, distortion-free cordless calls. Cordless phones with digital technology are also able to encrypt all those 1s and 0s during transmission so your conversation is safe from eavesdroppers. Plus, more power can be applied to digital signals and thus, you'll enjoy longer range on your cordless phone conversations. The advantage to analog cordless products? Well, they're a bit cheaper. And the sound quality is richer. So unless you need digital security, why not save a few bucks and go with an analog phone? After all, in home or small office environments where you may be the only cordless user, you won't have any interference issues. Keep in mind, when talking about digital and analog cordless phones, you're talking about the signals being transferred between the handset and its base. The phones themselves are still analog devices that can only be used on analog lines. Also, the range of your cordless phone-analog or digital-will always depend on the environment. Cellular phonesPerhaps the most effective use of the digital versus analog technology is in the booming cellular market. With new phone activations increasing exponentially, the limits of analog are quickly being realized. Digital cellular lets significantly more people use their phones within a single coverage area. More data can be sent and received simultaneously by each phone user. Plus, transmissions are more resistant to static and signal fading. And with the all-in-one phones out now-phone, pager, voice mail, internet access-digital phones offer more features than their analog predecessors. Analog's sound quality is still superior-as some users with dual-transmission phones will manually switch to analog for better sound when they're not concerned with a crowded coverage area-but digital is quickly becoming the norm in the cellular market. What to buy?The first thing to consider when buying analog or digital equipment is where you'll be using it. If you're buying for a proprietary PBX phone system, you'll need to get the digital phone designed for that particular system. Need to connect a conferencer on your digital system? Opt for a digital-to-analog adapter. Shopping for home office equipment? Most everything you'll consider is analog. Want an all-in-one cellular phone-paging, voice mail, web? A digital cellular phone will deliver it all. In fact, the only head-scratcher may be your cordless phone purchase. Looking for security and distortion-free conversations in your small office? Go with a digital 900 MHz or 2.4 GHz cordless phone. Using a cordless at home? An analog phone will give you the richest sound quality and usually enough range.
Is PCM is an example of analog to digital?
No, Pulse Code Modulation is a communication method used to carry digital data but is not part of any analog to digital conversion. PCM is often used to carry audio data as a digital stream and therefore is the encoding used as the signal is first converted to a digital format.
What is the term for a device that converts digital data from a computer into analog signals and back again?
The devices are known very simply as analog to digital converters and digital to analog converters. They are frequently shorted to A-D and D-A converters. A complete analog to digital converter will not only convert the analog signal into a set of numbers, it will also format the digital data ready to deliver to the next step in the signal chain. In television, this means generating a fairly complex stream of data that will carry not only the picture but audio and other data as well. Digital to analog converters reverse the process and use the incoming data to generate an analog signal. In television, well know examples are the digital set top boxes. They receive digital data from an antenna and convert the numbers into analog audio and video signals.
Does the connection between your home and the end office local loop use an analog or digital signal?
It depends. It's true, the standard POTS (plain old telephone service) is delivered over an analog loop. However, you may have a service known as DSL, it is even in the name (Digital Subscriber Line) digital. It uses the *unheard* areas (25kHz+) of the line to carry digital signal. So a line can be both analog and digital! Also, DSL can be provided on what's called a "dry loop" which is using a pair of copper (typically what would carry POTS service, but isn't connected to the PSTN.) That being said, it can be Analog, Digital or both: Analog and Digital.
What is digital signal?
There are many forms of digital signals PWM, PAM, and more Basically is a signal that carry information to be extracted to its original form.
What method of signal transmission uses radio waves to carry signals?
The analog method of signal transmission uses radio waves to carry signals. Digital transmission involves the use of satellites to transmit signals.
Digital signal in free space?
Electromagnetic radiation (radio waves, light) travels in free space. This radiation can be encoded to carry either analog information or digital information. An example of analog-encoded radiation is that emitted by an AM radio station. Examples of digitally-encoded radiation are a wireless home computer network and the next generation of television broadcasting.
Advantage of digital signal?
Higher immunity to noise, storage of digital signal is cheap and easy, its representation is only using two levels as opposed to infinite levels for analog
What similarities between analog and digital signals?
ANALOG:continuous,rate of transmission is slow,less reliable 2 transmit,more noise,interference is more DIGITAL:non continuous,rate of transmission is fast,more reliable 2 transmit,less noise,interference is less
Does S-Video carry sound and pictures?
No, S-video carries only a video signal. You will require an additional connection to transport audio, either analog or digital.
What video types support or carries both analog and digital signals?
Analog and digital video signals don't mix well so there are few interfaces that handle both. HDMI is purely digital and has no capacity to carry analog signals. RCA, phono or scart connections are analog with no provision to carry digital video. In broadcast studios, 75 ohm co-ax cable is used almost exclusively to carry video. The same cables will carry analog video or digital video depending on what they are connected to. The decision to make broadcast digital signal run on the same cable as analog video has greatly smoothed the transition to digital broadcasting. As far as domestic video is concerned, the only dual standard interface that is recognized is the DVI connector. Primarily a computer display interface, it carries digital video but will also handle analog VGA signals on the same cable. Furthermore, the two signals can be carried simultaneously and can be the same or different images. As the digital video component of a DVI interface is compatible with the video component of HDMI, it can carry broadcast signals as well as computer display data so it can be described as a video cable. Note that although DVI and HDMI are compatible, DVI does not carry the audio element of the signal whereas the HDMI interface does.
What is the difference between a modem and a codec?
* Codec is for coding analog data into digital form and decoding it back. The digital data coded by Codec are samples of analog waves. * Modem is for modulating digital data into analog form and demodulating it back. The analog symbols carry digital data.
What is the difference between analog and digital in very simple English?
Analog signals represent values with a continuously variable level. The signal has an infinite number of possible levels. Because the signal is infinitely variable, it can be affected by outside interference as well as by the circuits that carry and process the signal. These are the sources of noise and distortion. A system that handles analog information must be able to operate at the highest frequency that the signal will use. For audio, that is typically 20KHz and for video, in the region of 10MHz. A digital signal represents values in discrete steps and is often shown as a numeric value. The signal has a limited number of steps and there is no way to represent any intermediate values. The limitation in the number of steps is in itself a source of distortion but the nature of digital signals is that they are resistant to distortion and noise so the signal will not be degraded further. As the number of possible values increases, so the distortion caused by digitizing the signal will reduce. A digital system typically has to operate at far higher frequencies than its analog counterpart. Using audio signals as an example, a typical digital signal will capture a 16 bit value 44000 times each second. The frequency response of circuits handling the data will need to be in the region of 700KHz rather than the 20KHz for an analog signal.
