Tracking

tracking

(1) The recording of an event. See tracking cookie and e-mail tracker.

(2) In desktop publishing, the consistent letterspacing of text. Tracking is used to expand or contract the amount of text on a page by expanding or reducing the amount of space between letters. It differs from kerning in that it is applied to an entire font or to a range of text, whereas kerning refers to certain letter pairs.

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tracking [′trak·iŋ]

(electricity)

A leakage or fault path created across the surface of an insulating material when a high-voltage current slowly but steadily forms a carbonized path.

(electronics)

The condition in which all tuned circuits in a receiver accurately follow the frequency indicated by the tuning dial over the entire tuning range.

(engineering)

A motion given to the major lobe of a radar or radio antenna such that some preassigned moving target in space is always within the major lobe.

The process of following the movements of an object; may be accomplished by keeping the reticle of an optical system or a radar beam on the object, by plotting its bearing and distance at frequent intervals, or by a combination of techniques.

(engineering acoustics)

The following of a groove by a phonograph needle.

Maintaining the same ratio of loudness in the two channels of a stereophonic sound system at all settings of the ganged volume control.

(navigation)

Navigation which follows the movements of a craft but does not anticipate future positions.

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(text)

tracking - The spacing between characters in a line of text. This is defined when a font is designed but can often be altered in order to change the appearance of the text or for special effects. Tracking should not be confused with kerning which deals with the spacing between certain pairs of characters. See also leading.

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Tracking 

the maintenance of the coordinated variation of the resonant frequencies of oscillatory circuits of, for example, a superheterodyne receiver, that are tuned by means of a single control knob. When a superheterodyne receiver is tuned to a certain signal, the resonant frequency f_rad of the input circuit and the radio-frequency amplifier is set equal to the frequency f_sig of the received signal, and the resonant frequency f_osc of the local oscillator is adjusted so that the intermediate frequency (usually equal to the difference between f_rad and f_osc) coincides with the resonant frequency of the intermediate-frequency amplifier.

Figure 1. Schematic of an input and radio-frequency amplifier circuit and of the local oscillator circuit: (L) and (L_osc) inductance coils of the circuits; (C) variable capacitors; (C₁), (C₂), and (C₃) padder capacitors; (f_rad) and (f_osc) resonant frequencies of the circuits; the broken line indicates that the capacitance of the capacitors is varied by a single tuning knob

Tracking is generally accomplished by employing identical variable capacitors in all tunable circuits and by using additional fixed capacitors, called padders, in the local oscillator circuit, which must have a frequency different from f_rad (see Figure 1). In this case, the relations between the angle of rotation of the tuning knob and f_rad and between the angle of rotation and f_osc are not exactly those required—that is, the tracking is only approximate. Nonetheless, the tracking is still sufficiently accurate. In the receivers of the mid-1970’s, the variable capacitors used are either capacitors with mechanically varied capacitance or varactors (varicaps).

REFERENCES

Radiopriemnye ustroistva. Edited by V. I. Siforov. Moscow, 1974.
Chistiakov, N. I., and V. M. Sidorov. Radiopriemnye ustroistva. Moscow, 1974.

V. M. SIDOROV