Glossary

L.O. Stability (Local Oscillator Frequency Stability) The variance in the frequency of the Local oscillator with time, temperature, voltage, humidity or vibration.

MHz (MegaHertz) Mega which is 106 [i.e. 950 MHz =950 million Hertz (Hz)].

MTBF Mean Time Between Failure estimated lifetime of unit.

PLL (Phase Locked Loop) A type of oscillator that uses digital circuits and a precision reference signal to accurately control the frequency of the conversion oscillator. An LNB that incorporates a PLL oscillator has the characteristics of very low levels of phase noise and high levels of frequency stability.

PPM (Parts Per Million) A unit of measure used to express the frequency stability of an oscillator. In Ku-band 1ppm represents a frequency change of 10 kHz when the conversion oscillator is 10.0 GHz.

SCPC (Single Channel Per Carrier) A satellite transmission system that employs a separate carrier for each channel, as opposed to frequency division multiplexing that combines many channels on a single carrier.

Transmitter (BUC Block upconverter) A device that converts L-band signal (950 to 1450 Mhz) into a RF transmit power signal via a waveguide interface.

TCXO (Temperature Compensated Crystal Oscillator) An oscillator circuit, such as would be used as a local oscillator or a reference in a PLL LNB, that has been designed so that the frequency change with temperature is as small as possible.

VSAT (Very Small Aperture Terminal) This is normally a two way satellite transmission system.

VSWR (Voltage Standing Wave Ratio) Can best be described as waves coming into the L.O. Frequency shore from the ocean. Desirable VSWR waves come in smoothly and the energy used in the LNB that is used as the bases for the down conversion to the L-Band is dissipated into the sand. This desirable VSWR is called “primary incident” and results in a low VSWR

Amplifier A device used to increase the level of a signal. Baseband The band of frequencies containing the information, prior to modulation (and subsequent to demodulation). dB (decibel) A term that expresses the ratio of power levels used to indicate gains or losses of signals. Decibels relative to one watt, milliwatt and millivolt are abbreviated as dBW, dBm and dBmV, respectively.

Downconverter A device that takes a block of frequency and converts it to a lower frequency.The lower the noise temperature, the better the performance.

Downlink The equipment used to receive the signals from a satellite.

DRO (Dielectric Resonator or Dielectrically Stabilized Oscillator) Highly stable oscillator circuit employed by LNBs.

External reference The signal that is supplied to an LNB via the center conductor of the IF cable. The reference frequency is normally 10 MHz and is used to accurately phase lock the conversion oscillator in the LNB to the wanted frequency.

Gain The amount of amplification of input to output power often expressed as a multiplicative factor or in decibels.

GHz (GigaHertz) which is 109 [i.e. 2.5 GHz would be 2.5 billion hertz (Hz)].

L-band The microwave frequency band between approximately 900 MHz to 2000 MHz.

LNB (Low Noise Block Downconverter) An LNA and block downconverter enclosed in a single housing. The output of an LNB is an IF signal at L-Band [nominally 950 to 1450 MHz].

L.O. Frequency (Local Oscillator Frequency) The frequency setting of the oscillator used in the LNB that is used as the bases for the down conversion to the L-Band output frequency. The Local oscillator frequency is added or subtracted from the input frequency to obtain the output frequency.

Events

  • AUVSI 2014

    May 12 - 15, 2014

    Orange County Convention Center, Orlando, Florida

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