Commentary
Set-Top Box Lexicon: The Signal: Digital and Analog
- by Jane Clarke , March 11, 2011
CIMM's Set-Top Box Data Lexicon is a compilation of terms and definitions associated with Set-Top Box data and its measurement. This Word-A-Week column highlights a term and definition from the Lexicon to help forge a common language for Set-Top Box data usage and expedite the roll-out of the data for its many industry applications.
In a prior column we delineated the difference between Analog and Digital Set-Top Boxes. In this column we talk about Analog and Digital transmission signals. The Analog signal has been around for years. It has been our standard transmission of television since its inception. But the landscape has changed dramatically with new transmission capabilities that have opened up new possibilities in not only signal delivery but also signal return path. There was "Analog" but there is arguably no more powerfully generic term in the realm of Set-Top Box Data as "Digital"; Hardware has gone "Digital," Software has become "Digital." But what does this mean?
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Digital capability is at the core of the existence of Set-Top Box data for a myriad of industry uses and Digital Compression is the road that took us to Digital capability. It is safe to say that without Digital capability there would be no Set-Top Box data at this time.
Here are terms and definitions related to Analog and Digital Signals and the advent of Digital technology via Digital Compression:
Analog Signal
See also: Digital Cable, Digital Signal
CIMM DEFINITION : In telecommunications, analog refers to a transmission standard that uses variable frequencies and amplitudes of electrical impulses to emulate the audio waveform of sound. A traditional form of telecommunications transmission in a constant variable wave, rather than in packet-based (or digital) form. (Source: CableLabs)
2 : An older version of a TV signal or the Set-Top Box that transmits programs in the lowest television definition in use today - 480i format. Data is transmitted only in one direction - to the household or viewers. There is usually no "back channel" or "return path" transmission where data or usage is transmitted back to the headend or operator.
3 : A continuous electronic signal that carries information in the form of a continuously variable waves unlike digital signals which are made up of discrete pulses. (Source: Nielsen)
4 : Refers to the way cable broadcasts are transmitted directly from the television wall cable to the television. It is one method by which television signals are transmitted since Low Power TV stations still transmit analog signals.
5 : Type of cable signal that normally does not allow back channel. With a STB or DVR, return path data collection may become possible. (Source: TIVO)
NOTE - In addition to the lack of a return path, analog STBs provide no consistent mechanism for the download or execution of software and thus cannot provide any interactivity, including IPGs and EBIF. (Source: FourthWall Media). Therefore you can't serve a household targeted ad via an analog signal. (Source: Visible World).
Digital
See also: Analog Signal
CIMM DEFINITION : (1) In communications and computer technology, digital refers to a method of encoding information using a binary system made up of zeroes and ones. In communications technology this takes the form of two very different electrical voltages, several volts positive and negative, to represent the two values. This substantial difference in voltages for each state makes it unlikely that minor fluctuations in voltage due to electro-magnetic interference will change the way a signal is interpreted when received. (2) Information that is encoded into bits and bytes, or packets (0s and 1s, computer binary language). Generally perceived to be an advanced communication form offering clearer signals and increased transmission capacity. (Source: CableLabs)
Digital Signal
See also: Digital Cable
CIMM DEFINITION : A signal that has a limited number of discrete states prior to transmission. This may be contrasted with an analog signal which varies in a continuous manner and may be said to have an infinite number of states. (Source: CableLabs)
Digital Compression
CIMM DEFINITION : An engineering technique for converting a cable TV signal into a digital format which may then be processed in a manner that requires a smaller portion of spectrum for its transmission. This compressed format allows many channels to be carried in the bandwidth normally required for one signal. This format can also be easily stored and manipulated. (Source: CableLabs)
2 : An encoding process that saves storage space and enables more channels, networks and other content to be delivered to the Set-Top Box. An encoding / decoding process that minimizes data storage and transmission sizes in STB collection engines.
Please refer to the CIMM Lexicon online at http://www.cimm-us.org/lexicon.htm for additional information on these and other terms.
It is quite unfortunate that more time is still being spent on the issue of changing signal from Analog to digital or vice versa. The bare fact is that any information in its continuous form could be referred to as analog and when it is broken into bits and pieces or seconds or minutes(digits) to be regrouped by the help of the Modem, is all what these long debates are going on.
The matter now bothers on software and not hardware in order for the various format or signals to be synchronized to enhance easy transmission and reception.
To cite Professors J.C.C. Nelson and Desmond McLernon and others at the Institute of Electronic and Electrical Engineering (IEEE) at the Leeds University 1997/98 and 2000) during Technology and Communications lectures, this issue is resolved through quantization, whereby the analog signal is plotted on a graph for the binary numbers to be sample picked to serve as the digital system.
It must also be noted that any information in its bits and pieces or seconds and minutes would not be coherent as they would be disjointed and would not make sense.
One would be tempted to believe that in the quest to avoid using the term analog in transmission and receiving information, especially film and video plus write ups get bugged up and at the end they either streak get choked and reception is poor. in the early hours of the day when President Obama was speaking on the japan earth quake, there were intermittent breaks that did not allow for easy hearing or viewing.
It is high time some of the arguments being put forward forcefully are revised to make room for some works that had been carried out and perfected in the past.
We should also be guided by the works of Clerk Maxwell on Electromagnetism, when it comes to transmission and reception of signals. When postulated in his papers in 1863 that of the three forms of transmission Conduction, convention and radiation or electromagnetic, the first two need a medium to be able to transmit while the third does not need a medium.
Interestingly, it was only Heinrich Hertz who to some extent understood Maxwell and therefore a similar process to come out with the Herzian waves-Hertz (187) that is used to measure power transmission.
I will come at a later stage to explain how and why there is no need to mount large and huge transmitters and dishes across countries in the name of transmission and receiving signals, while in actual fact they only add up to cost and do not add or improve upon the actual form of transmission or reception.
Hope readers would take sober reflection on the issues raised and try to brood over them in the rush to come out with gadgets and boxes in the name of manufacturing.
I am transmitting from Accra Ghana using a mobile chip fixed into USB stick with a software that cannot be said to be among the best.
Let's make good use of technological advancement as pioneered by Prof. Morse (Morse Code), Marconi and others in the areas of telegraph, radio, diode and Triode vacuum tubes in the case of John Fleming (1904 Diode) and Lee Forests (1907 Audion Triode or Triode)