"A",
"B",
"C",
"D",
"E",
"F",
"G",
"H",
"I",
"J",
"K",
"L",
"M",
"N",
"O",
"P",
"Q",
"R",
"S",
"T",
"U",
"V",
"W",
"X",
"Y",
"Z"
INTERFERENCE: See EMI. [EMI Components]
INTERFERENCE PARAMETERS: Equipment and propagation characteristics necessary for the proper
evaluation of a given EMI situation.
INTERFERENCE/SIGNAL RATIO: See I/S Ratio.
INTERFERENCE THRESHOLD: The level of interference normally expressed in terms of the I/S (interference/
signal) ratio at which performance degradation in a system first occurs as a result of EMI.
INTERFEROMETER: When two widely spaced antennas are arrayed together, they form an interferometer. The radiation pattern consists of many lobes, each having a narrow beam-width. This antenna can provide good spatial selectivity if the lobe-to-lobe ambiguity can be solved such as using amplitude comparison between the two elements.
INTERMEDIATE FREQUENCY (IF): A lower frequency to which an rf echo is converted for ease of
amplification.
INTERMODULATION: The production, in a nonlinear element (such as a receiver mixer), of frequencies corresponding to the sums and differences of the fundamentals and harmonics of two or more frequencies which are transmitted through the element; or, the modulation of the components of a complex wave by each other, producing frequencies equal to the sums and differences of integral multiples of the component frequencies of the complex wave.
INTERSYSTEM EMC: EMC between the external electro-magnetic environment (EME) and an aircraft with it's installed systems. Generally, only system BIT must operate properly on the carrier deck while all system functions must operate properly in the operational EME.
INTRASYSTEM EMC: EMC between systems installed on an aircraft, exclusive of an external environment.
INVERSE CON SCAN: One method of confusing a radar operator or fire control radar system is to provide erroneous target bearings. This is accomplished by first sensing the radar antenna scan rate and then modulating repeater amplifier gain so the weak portion of the radar signal is amplified by the jammer, while the strong portion is not, so the weapons systems will fire at some bearing other than the true target bearing. The angle deception technique is used to break lock on CONSCAN radars.
INVERSE GAIN: Amplification, inverse modulation, and re-radiation of a radar's pulse train at the rotation rate of the radar scan. Deceives a conical scanning radar in angle.
ISOTROPIC ANTENNA: A hypothetical antenna which radiates or receives energy equally in all directions. [Antenna Dictionary]
I/S RATIO (INTERFERENCE-TO-SIGNAL RATIO) (ISR): The ratio of electromagnetic interference level to
desired signal level that exists at a specified point in a receiving system. The ratio, normally expressed in dB, is employed as a tool in prediction of electronic receiving system performance degradation for a wide range of interference receiver input levels. Performance evaluations compare actual I/S ratios to minimum acceptable criteria.
