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  2. 70-centimeter band - Wikipedia

    en.wikipedia.org/wiki/70-centimeter_band

    American radio amateurs may use a maximum of one watt of radiated RF power, on any ham frequency authorized for data emissions, to control RC models. [10] Canadian radio amateurs may use any amateur frequency above 30 MHz for the control of RC models. [11] Plus or minus 5 MHz is a common repeater frequency offset in the 70 cm band.

  3. Amateur radio frequency allocations - Wikipedia

    en.wikipedia.org/wiki/Amateur_radio_frequency...

    The mode requires moderately high power (more than 500 watts) and a fairly large, high-gain antenna because round-trip path loss is on the order of 270 dB for 70 cm signals. Return signals are weak and distorted because of the relative velocities of the transmitting station, Moon and the receiving station.

  4. Ripple tank - Wikipedia

    en.wikipedia.org/wiki/Ripple_tank

    If a small obstacle is placed in the path of the ripples, and a slow frequency is used, there is no shadow area as the ripples refract around it, as shown below on the right. A faster frequency may result in a shadow, as shown below on the right. If a large obstacle is placed in the tank, a shadow area will probably be observed.

  5. Normal mode - Wikipedia

    en.wikipedia.org/wiki/Normal_mode

    This space-dependence is called a normal mode. Usually, for problems with continuous dependence on (x, y, z) there is no single or finite number of normal modes, but there are infinitely many normal modes. If the problem is bounded (i.e. it is defined on a finite section of space) there are countably many normal modes (usually numbered n = 1, 2 ...

  6. Full width at half maximum - Wikipedia

    en.wikipedia.org/wiki/Full_width_at_half_maximum

    The convention of "width" meaning "half maximum" is also widely used in signal processing to define bandwidth as "width of frequency range where less than half the signal's power is attenuated", i.e., the power is at least half the maximum.

  7. Orders of magnitude (frequency) - Wikipedia

    en.wikipedia.org/.../Orders_of_magnitude_(frequency)

    Acoustic – frequency of G −7, the lowest note sung by the singer with the deepest voice in the world, Tim Storms. His vocal cords vibrate 1 time every 5.29 seconds. 10 0: 1 hertz (Hz) 1 to 1.66 Hz: Approximate frequency of an adult human's resting heart beat: 1 Hz: 60 bpm, common tempo in music 2 Hz: 120 bpm, common tempo in music ~7.83 Hz

  8. Wavenumber - Wikipedia

    en.wikipedia.org/wiki/Wavenumber

    It equals the spatial frequency. For example, a wavenumber in inverse centimeters can be converted to a frequency expressed in the unit gigahertz by multiplying by 29.979 2458 cm/ns (the speed of light, in centimeters per nanosecond); [5] conversely, an electromagnetic wave at 29.9792458 GHz has a wavelength of 1 cm in free space.

  9. Pulse-repetition frequency - Wikipedia

    en.wikipedia.org/wiki/Pulse-repetition_frequency

    The pulse-repetition frequency (PRF) is the number of pulses of a repeating signal in a specific time unit. The term is used within a number of technical disciplines, notably radar . In radar, a radio signal of a particular carrier frequency is turned on and off; the term "frequency" refers to the carrier, while the PRF refers to the number of ...