Data transmission occurs between transmitter and receiver over some transmission medium, Transmission media may be classified as guided or unguided, Below are the few terminology which are used in the transmission system.
Guided Media: The transmission signal are guided along a physical path for example coaxial cable or optical fiber. These kind of transmission media are known as guided media.
Unguided Media: It provides a mean for transmitting electromagnetic waves but do not guide them. For example propagation through air or vacuum.
Direct Link: It refers to the transmission path between two devices in which signal propagate directly from transmitter to receiver with intermediate devices.
Point to Point Transmission: A guided transmission medium is point-to-point if it provides a direct link between two devices and those are the only two devices sharing the medium.
Multipoint Guided Transmission: In multipoint guided transmission more than two devices share the same medium.
Bit Rate: In telecommunications and computing, bit rate (sometimes written bit rate,data rate) is the number of bits that are conveyed or processed per unit of time. The bit rate is quantified using the bits per second (bitis or bps) unit, often in conjunction with an SI prefix such as kilo-(kbit/s or kbps), mega-(Mbit/s or Mbps), giga-(Gbit/s or Gbps) or tera-(Tbit/s or Tbps).
Bandwidth: In addition to frequency domain representation of signal (spectrum). It is often desirable to express quantitatively the range of frequencies over which the power or energy density spectrum of the signal is concentrated. This quantitative measure is called the bandwidth of a signal.. Signal bandwidth is calculated as the difference between the highest (significant) frequency and the lowest (significant) frequency in the signal spectrum.
Signal Strength: In telecommunications, particularly in radio, signal strength refers to the magnitude of the electric field at a reference point that is a significant distance from the transmitting antenna. It may also be referred to as received signal level or field strength. High-powered transmissions, such as those used in broadcasting, are expressed in dB-millivolts per meter (dBmV/m). For very low-power systems, such as mobile phones, signal strength is usually expressed in dB-microvolts per meter (dBuV/m) or in decibels above a reference level of one milliwatt (dBm). In broadcasting terminology, 1 mV/m is 1000 uV/m or 60 dBu.
SNR: In analog and digital communications, signal-to-noise ratio, often written S/N or SNR, is a measure of signal strength relative to background noise. The ratio is usually measured in decibels (dB).
If the incoming signal strength in microvolt is Vs, and the noise level, also in microvolt, is Vn, then the signal-to-noise ratio, S/N, in decibels is given by the formula
SIN = 20 logio (Vs/Vn)
In simple words signal strength
SRN = Signal power/Noise power
