95
The Decibel
The decibel (dB) provides a means of representing large power
ratios as manageable, small numbers, and allows the overall gains
and losses in a module or a network to be calculated by addition
and subtraction, rather than by multiplication and division.
The original unit is the Bel (named after Alexander Graham Bell).
The decibel is one-tenth of a Bel. The power ratio of two power
measurements is calculated as follows:
Ratio of power P1 to power P2, in dB:
The power ratio of two voltage measurements is calculated as follows:
Power ratio of voltage V1 to voltage V2, in dB:
Voltage Confusion
dBmV and dBµV expressions of power contain an upper case V.
This does not mean they are expressions of voltage. They are
expressions of power. When all the power scales (dBm, dBmV and
dBµV) are laid next to each other, it is easy to see that each track
on a dB for dB basis.
Basic Cable Theory Useful Technical Data
Содержание AMM-806
Страница 86: ...79 TVCB PC Installation ...
Страница 93: ...86 SMI Installation Torque Patterns 1 Start Here 2 3 4 5 6 1 Start Here 2 3 4 4 PORT 8 PORT ...
Страница 125: ...118 Fiber Optics Fiber Loss vs Path Length Single Mode 1550 nm ...
Страница 156: ...149 Cable TV Channel Format NTSC NTSC Composite Video Waveform ...
Страница 157: ...150 US Frequency Spectrum ...
Страница 158: ...151 FCC Aeronautical Band Frequencies Used for Communication and Navigation ...
Страница 171: ...164 F C x 32 Temperature Conversion Nomograph C F FAHRENHEIT F CELSIUS C 9 5 C F 32 5 9 KELVIN K K C 273 ...
Страница 175: ...168 Common CATV Symbols ...
Страница 176: ...169 Common CATV Symbols ...
Страница 177: ...170 Digital L Band Distribution Symbols ...
Страница 178: ...171 Digital L Band Distribution Symbols ...
Страница 183: ...176 Typical Cable Attenuation Chart in dB 100 Feet 68 F 20 C ...
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Страница 188: ...181 Signal to Interference Limits Non Coherent Carriers ...
Страница 190: ...183 Heterodyne Modulator Analog ...
Страница 191: ...184 Heterodyne Processor Analog ...
Страница 213: ...206 Multiplexers ...
Страница 215: ...208 Antenna Stacking Methods to Increase Received Signal Level NOTE Refer to Antenna Spacing Chart for dimensions ...
Страница 216: ...209 Antenna Spacing Mounting Channelized Antennas on the Same Mast NOTE Refer to Antenna Spacing Chart for dimensions ...
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