EP0221475A2
Expired / Lapsed
EP
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An apparatus for cancelling television fading interference
Assignee: Toshiba Corp
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Filing: 1986-10-24
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Granted: —
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Expires: 2006-10-24
Abstract
Abstract A television fading interference-cancelling apparatus (100) includes two sets of TV antennas (11; 12), a subtracter (14), and adder (13), a variable gain/phase controller (16; 17; 18) and digital fading cancelling means (20; 30; 40; 50). The digital fading cancelling means includes at least a fading signal component remover (30) and a maximum value detector (40). The fading signal component remover (30) receives a subtraction signal (Δ) from the subtracter (13) and digitally averages this signal (Δ) to remove the fading signal components contained therein. Then the maximum value detector (40) detects a frequency signal having a maximum value by selecting the digitally averaged signals. This frequency signal is used in the variable gain/phase controller (16; 17; 18) to control the gain and phase shift of a desired TV signal without having adverse influences by the fading interference signals.
Inventors
- 👤 Seiji Patent Division Isobe
- 👤 Makoto Patent Division Kaijima
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 14:57
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/14; H04N5/21; H04N5/211
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
310 words
An apparatus (100) for cancelling television fading interference characterized by comprising: first antenna means (11) for receiving a desired television (TV) signal to derive a first television (TV) output signal; second antenna means (12) positioned apart from the first antenna means (11) by a predetermined distance (d) and directed to the same direction as the first antenna means (11), for receiving said desired TV signal to derive a second television (TV) output signal: first adder means (13) for adding the first TV output signal to the second TV output signal to derive a summation signal (ε); subtracter means (14) for subtracting the first TV output signal from the second TV output signal to derive a subtraction signal (Δ) containing a plurality of fading interference signals; signal searching means (20) for searching said subtraction signal (Δ) to detect said plurality of fading interference signals in a digital form; fading signal component removing means (30) for removing fading signal components from said plurality of fading interference digital signals by digitally averaging said plurality of fading interference digital signals to derive a plurality of fading-less interference digital signals; maximum value detector means (40) for detecting a maximum value from said plurality of fading-less interference digital signals to derive single digital data having said maximum value; frequency signal generating means (50) for generating an analog frequency signal corresponding to said single digital interference data having the maximum value; gain/phase controlling means (16; 17; 18) for controlling an amplitude and a phase of said subtraction signal (Δ) supplied from said subtraction means (14), based upon said single digital interference data having the maximum value to derive a gain/phase-controlled subtraction signal (Δ'); and second adder means (15) for adding said gain/phase-controlled subtraction signal (Δ') to said summation signal (ε) so as to derive said desired TV signal without having adverse influences by said fading interference signals.
Claim 2
Independent Claim
310 words
An apparatus (100) for cancelling television fading interference characterized by comprising: first antenna means (11) for receiving a desired television (TV) signal to derive a first television (TV) output signal; second antenna means (12) positioned apart from the first antenna means (11) by a predetermined distance (d) and directed to the same direction as the first antenna means (11), for receiving said desired TV signal to derive a second television (TV) output signal: first adder means (13) for adding the first TV output signal to the second TV output signal to derive a summation signal (ε); subtracter means (14) for subtracting the first TV output signal from the second TV output signal to derive a subtraction signal (Δ) containing a plurality of fading interference signals; signal searching means (20) for searching said subtraction signal (Δ) to detect said plurality of fading interference signals in a digital form; fading signal component removing means (30) for removing fading signal components from said plurality of fading interference digital signals by digitally averaging said plurality of fading interference digital signals to derive a plurality of fading-less interference digital signals; maximum value detector means (40) for detecting a maximum value from said plurality of fading-less interference digital signals to derive single digital data having said maximum value; frequency signal generating means (50) for generating an analog frequency signal corresponding to said single digital interference data having the maximum value; gain/phase controlling means (16; 17; 18) for controlling an amplitude and a phase of said subtraction signal (Δ) supplied from said subtraction means (14), based upon said single digital interference data having the maximum value to derive a gain/phase-controlled subtraction signal (Δ'); and second adder means (15) for adding said gain/phase-controlled subtraction signal (Δ') to said summation signal (ε) so as to derive said desired TV signal without having adverse influences by said fading interference signals.
Claim 3
Dependent Claim
121 words
An apparatus (100) as claimed in claim 1, characterized in that said signal searching means (20) includes: an oscillator (21) for oscillating an oscillation signal having a center frequency (f c ) with respect to said desired TV signal; a sweep signal generator (25) for generating a sweeping signal having a predetermined frequency range (± Δf); a first voltage controlled oscillator (22) for producing mixing signals (f c ± Δf) by sweeping said oscillation signal having said frequency (f c ) within said predetermined frequency range (± Δf), based upon said sweeping signal; and a frequency converter (23) for frequency-converting said subtraction signal (Δ) by mixing said mixing signals (f c ± Δf) therewith to obtain said digital fading interference signals.
Claim 4
Dependent Claim
42 words
An apparatus (100) as claimed in claim 2, characterized in that said frequency converter (23) is constructed of a mixer (231), a low pass filter (232), a sample/hold circuit (233) and an analog-to-digital converter (234), said circuits being series-connected to each other.
Claim 5
Dependent Claim
24 words
An apparatus (100) as claimed in claim 1, characterized in that said fading signal component remover (30) is constructed by a digital filter (300).
Claim 6
Dependent Claim
97 words
An apparatus (100) as claimed in claim 4, characterized in that said digital filter (300) includes: a memory (310) for storing said digital fading interference signals derived from said signal searching means (20); and a digitally averaging circuit (316; 318) for successively adding said digital fading interference signals read out from said memory (310) within a predetermined data number to derive summed fading interference signal component data, and for dividing said summed fading interference signal component data by said predetermined data number so as to derive digitally-averaged fading interference signals, thereby producing said fading-less interference digital signals.
Claim 7
Dependent Claim
84 words
An apparatus (100) as claimed in claim 5, characterized in that said digitally averaging circuit includes: a digital adder (316) for successively adding said digital fading interference signals read out from said memory (310) within said predetermined data number to derive said summed fading interference signal component data; and a first latch (318) for latching said summed fading interference signal component data so as to take out a predetermined digit from said summed fading interference signal component data as said digitally-averaged fading interference signals.
Claim 8
Dependent Claim
126 words
An apparatus (100) as claimed in claim 1, characterized in that said maximum value detector means (40) includes: a buffer (404) for temporarily storing said digitally-averaged fading interference signals derived from said fading signal component remover means (30): a second latch (406) for latching said fading interference signals buffered in the buffer (404); and a comparator (402) having a first input (A) to receive said fading interference signals from said second latch (406) and a second input (B) to receive said fading interference signals directly from said fading signal component remover means (30), for comparing said fading interference signals of the first input (A) with said fading interference signals of the second input (B) so as to derive said single digital data having said maximum value.
Claim 9
Dependent Claim
82 words
An apparatus (100) as claimed in claim 2, characterized in that said frequency signal generating means (50) includes: a frequency memory (54) for storing said single digital interference data having the maximum value sent from said maximum value detector means (40); and a second voltage-controlled oscillator (52) for producing said analog frequency signal by processing said single digital interference data stored in the frequency memory (54) and said oscillation signal having said center frequency (f c ) derived from said oscillator (21).
Claim 10
Dependent Claim
53 words
An apparatus (100) as claimed in claim 1, characterized in that said gain/phase controlling means is constructed of a variable gain amplifier (16), a variable phase shifter (17) series-connected to the variable gain amplifier (16), and a gain/phase controller (18) coupled to said variable gain amplifier (16) and said variable phase shifter (17).
Claim 11
Dependent Claim
27 words
An apparatus (100) as claimed in claim 1, characterized in that said predetermined distance (d) is substantially equal to a wavelength (λ) of said desired TV signal.
References Cited (Backward Citations)
No citation records indexed.
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