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| Carries information in the form of a continuous wave. In networking analog signals are most often generated by electrical current |
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| The size, shape and other characteristics that describe the analog signal and information it carries |
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| A smoothly oscillating curve that is the result of calculating the sine of the angles between zero and 360 degrees and plotting the results |
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| The height(or depth) of the wave from the midpoint between the top and the bottom of the waveform |
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| One complete oscillation of an analog signal |
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| The number of complete cycles per second in the wave, measured in hertz |
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| A description of where a wave's cycle begins in relationship to a fixed point |
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| The distance between to successive peaks in wave form |
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| Has only two values a binary 1=on and a binary 0=off |
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| A high frequency oscillating signal is used as a base, or carrier, for information. Then a lower frequency data signal is superimposed over the carrier waveform. |
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| When the signal reaches its destination, the receiver decodes the signal, removing the data from the carrier |
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| Is software or hardware that codes and decodes data to and from analog format. |
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| Digital to Analog Conversion |
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| Analog to Digital Conversion |
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| Synchronous Communications |
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| A byte is sent in a standardized time interval where the receiver assumes that one byte is transmitted every interval.The devices must start and stop their reckoning of these intervals at the same time |
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| Asynchronous Communications |
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| Special start and stop bit patterns are inserted between a byte of data. By watching for these patterns the receiver can distinguish between the bytes of data |
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| Are Digital Transmissions Modulated? |
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| No they are not modulated over a carrier. Data is converted into a digital waveform using "on-off keying," or "Manchester Encoding" |
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| Is a digital transmission encoding scheme in which a change in voltage from one state to another within a predetermined interval is symbolized by a 1. No voltage change is symbolized by a 0. The sender must syncronize its clock with the sender by watching for the 1's |
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| Is a way to overcoming the limitations of on-off keying. It represents the transition from positive to ground with a 0 and from negative to positive voltage IN THE MIDDLE OF THE BIT PERIOD it designate a 1 |
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| Bits are transmitted ONE PER CLOCK CYCLE over a single tranmission medium |
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| Multiple bits are transmitted over multiple transmission lines. Multiple bits even multiple bytes are transmitted per clock cycle |
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| DIGITAL SIGNALS are sent via a DC pulse over a single UNMULTIPLEXED signal channel(Uses TDM) |
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| ANALOG SIGNALS are used to send data over a transmission medium using a portion of the bandwidth. Signals are wave of electromagnetic or optical energy.(Uses FDM) |
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