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The algebraic difference between the upper and lower values specified as limiting the range of operation of a measuring instrument. Example: A thermometer intended to measure over the range -40 C + 60 C has a span of 100 C.


A group of associated stations of a radionavigation system. A Loran C chain consists of a master station and two to four secondary stations.


To provide continuous service from one Loran C chain to the next, some stations are operated as members of two chains and radiate signals at both rates. Such a station is faced peri- odically with an impossible requirement to radiate two overlapping pulse groups at the same time. During the time of overlap, the sub- ordinate signal is blanked or suppressed. Blanking is accomplished in one of two ways: priority blanking in which case one rate is always superior or alternate blanking in which case the two rates alternate in the superior and subordinate roll


The specified time interval of a Loran C chain for all stations of the chain to transmit their pulse groups. For each chain a minimum group repetition interval (GRI) is selected of sufficient duration to provide time for each station to transmit its pulse group and additional time between each pulse group so that signals from two or more stations cannot overlap in time anywhere within the coverage area. The GRI is normally stated in terms of tens of microseconds; i.e., the GRI having a duration of 79,900 microseconds is stated as 7900.


In a navigation system, the measure of the accuracy with which the system permits the user to return to a position as defined only in terms of the coordinates peculiar to that system. For example, the distance specified for the repeatable accuracy of a system such as Loran C is the distance between two Loran C positions established using the same stations and time-difference readings at different times. The correlation between the geographical coordinates and the system coordinates may or may not be known.


A correction for additional time (or phase delay) for transmission of a low frequency signal over an all seawater path when the signal transit time is based on the free-space velocity. The Loran C lattices as tabulated in tables or overprinted on the nautical chart normally include compensation for secondary phase factor.


An abbreviated means of identifying an element. i.e. C is the chemical symbol for the element carbon.


A product, material or substance is a controlled product within the meaning of Class C if it meets either of two conditions that causes or contributes to combustion.


1) Affirmative. 2) Sound signal; Affirmative. 3) C flag + three numerals: Course.


Additional Secondary Factor corrections to be applied when plotting Loran C positions on charts to take into account variations in the conductivity of the earth's surface over which the signals pass

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