| Noise Figure: |
A measure of the noisiness of an amplifier. Noise factor is defined as input signal-to-noise ratio to output signal-to-noise ratio. Noise figure is noise factor expressed in dB. The lowest possible value for a matched system is 3 dB. The ratio of the actual noise power generated at the input of an amplifier to that which would be generated in an ideal resistor. The lower the noise figure, the better the performance. |
| NTSC: |
National Television Systems Committee. An industry-wide engineering group which, during 1950-1953, developed the color television specification now established in the United States. The National Television Standards Committee which created the standard for North American TV broadcasts. |
| PAL(Phase Alternation Line): |
A video standard used in many parts of the world. Phase Alternate Line. The European color TV format which evolved from the American NTSC standard. Passband : The band of frequencies that a circuit passes with little attentuation. |
| Passive: |
An electronic device alters or controls a signal but does not contain any transistor stage for amplification, oscillation or modulation. |
| Path Loss: |
The attenuation that a signal undergoes in traveling over a path between two points. Path loss varies inversely as the square of the distance traveled. Pay-Per-View : Pay-per-view is a method of purchasing programming on a per-program basis. |
| Polarization: |
The direction of the electric vector of the radiated signal. |
| Preamplifier: |
An amplifier, usually mast mounted, used prior to the main amplifier to increase weak signals. The preamplifier establishes the noise figure of the system. The first amplification stage. In an SMATV system, it is the amplifier mounted adjacent to an antenna to increase a weak signal prior to its processing at the headend. Radio Frequency : The approximately 10 kHz to 100 GHz electromagnetic band of frequencies used for man-made communication. |
| Raster: |
The random pattern of illumination seen on a television screen when no video signal is present. |
| Reference Signal: |
A highly stable signal used as a standard against which other variable signals may be compared and adjusted. |
| Repeater: |
A device, usually remote, which receives a signal transmitted from an external sources, amplifies this signal and retransmits it, usually at a different frequency. It enables transmitted signals to travel great distances. Communications satellites are very sophisticated repeaters. A device that receives and re-broadcasts signals to extend the range of an original broadcast facility. |
| Return Loss: |
The ratio of the total power, transferred and reflected (and also "incident" power) to the reflected power alone, when expressed in decibels, is called the return loss. The return loss expresses the relative strength of a signal traveling "backwards" through a transmission system, to that travelling in the "desired" direction. A ratio of the amount of reflected signal to the total available signal entering a device expressed in decibels. |
| Reverse Isolation: |
An amplifier is used between the antenna or cable company input and the modulator combiner to isolate the signal. This will prevent the picture produced from your modulator from leaking out to other peoples TV's. |
| Roll: |
A loss of vertical sychronization which causes the picture to move up or down on receiver or monitor. |
| S.N.R. (Signal to Noise Ratio): |
A ratio between desired signal and unwanted noise, expressed in decibels. This term is used extensively in broadcasting and video. The ratio of signal power to noise power in a specified bandwidth, usually expressed in decibels. |
| Scrambling: |
A method of altering the identity of a video or audio signal in order to prevent its reception by persons not having authorized decoders. |
| Sidebands: |
The signals falling in the band of frequencies on either side of a carrier resulting from the process of modulation. |
| Signal Strength: |
The intensity of the television signal measured in volts, millivolts, microvolts, or dB, using 0 dB as a reference. Equal to 1000 microvolts in RF systems; generally 1 volt in video systems. |
| Snow: |
Heavy random noise. Video noise or sparklies caused by an insufficient signal-to-noise input ratio to a television set or monitor. |
| Spacing: |
Length of a cable between amplifiers based on the amount of grain required to overcome cable losses in dB at the highest TV channel carried in a system; TX Converter Channel or (920) MHz (NTSC). |
| Splitter: |
A device that takes a signal and splits it into two or more identical but lower power signals. |
