ES2324693B1 - METHOD AND APPLIANCE FOR THE IDENTIFICATION AND DIAGNOSIS OF INTERFERENCES IN RF SIGNALS, IN PARTICULAR TELEVISION SIGNALS. - Google Patents

Abstract

Method and apparatus for identification and diagnosis of interference in RF signals, in particular Television signals.

Method for the identification and diagnosis of interference in analogue or digital television signals, in those for each frequency, frequency range (1, 2, 3, 4) or carrier wave (P_ {1} to P_ {9}, ...), there is an optimal level default of a spectrum control variable (D, A), in function of time (spectrum), such as intensity, the irradiated power, the MER, the BER, etc. At each level or value of the spectrum control variable (n_ {0}, n_ {1}, ..., n_ {4}) a respective standard determined value is associated (c_ {0}, c_ {1}, ..., c_ {4}) of a certain visible characteristic of control. For each instant of time (t) and for each frequency or frequency range (1, 2, 3, 4), or for each carrier wave (P_ {1} to P_ {9}, ...), the value of the previous one is plotted Visible characteristic determined. The presence of a interference (D ', D' ', A') is determined when a discontinuity in the value of the previous visible characteristic determined, appearing a new value (c_ {5}, c_ {6}, c_ {7}) different from the standard set due value (c_ {1}, c_ {1}, c_ {0 '}).

Description

Method and apparatus for identification and diagnosis of interference in RF signals, in particular Television signals.

Technical sector of the invention

The present invention belongs to the sector Telecommunications technician, more specifically to the broadcasting of analog and digital TV signals. In In particular, the invention relates to a method for identification and diagnosis of interference in RF signals (radio frequency), in particular television signals, either in digital (DTT, etc.) or analog (PAL, etc.) encoding.

More specifically, the present invention relates to a method for the identification and diagnosis of interference in RF signals, in particular television signals, whether analog or digital, in which for each frequency, or frequency band or range or signal modulated, there is a predetermined optimal value of a control variable (D, A), as a function of time and frequency (spectrum), such as intensity, irradiated power, MER (" Modulation Error Ratio ", or modulation error ratio, in English), the BER (" Bit Error Ratio "), etc.,

Background of the invention

The emergence of digital terrestrial television, DVB-T, has involved a number of important Advantages: greater spectral efficiency with higher TV services, greater robustness of the television signal, more efficient use of the radiated power, improvement in network planning transmission, etc.

The ability to correct errors Received by the receiver is another of the undoubted advantages of terrestrial digital television according to the standard DVB-T

However, the complexity of the received signal for reception systems and the emergence of the concept of "digital cliff" makes new methods necessary of measure that ensure quality in a reception facility of digital terrestrial television.

So far, with analog television, the installer technicians were able to interpret phenomena electrical based on the measurements made on the signal of television and for the purposes of these phenomena on the image: signal reflections, high noise levels, impulsive noise due to machinery, etc. This intuitive diagnosis allowed act on the origin of the phenomenon and thus ensure the quality of the installation.

With digital terrestrial television DVB-T, the electrical phenomena that usually disturb the television signal, are corrected by the own receiving system Additionally, the characteristics of the new digital terrestrial television signal make new ones appear electrical and disturbing phenomena unknown so far. In this scenario, the installer cannot know that disturbing phenomena exist in the TV installation, nor act to eliminate them, since the system itself corrects errors received by hiding these phenomena, with which the reception facility in a poor quality situation, close to the "digital cliff."

The present invention seeks to create tools of diagnosis on the signals received in an installation of DVB-T digital terrestrial television in order to Detect which phenomena interfere with the television signal.

In Fig. 1 the typical broadcast spectrum of digital television signals (curve "D") is shown, in the band or interval 2. This can be simplified according to a "step" whose height is an emission level or measurement of another emission characteristic, such as intensity, radiated power, MER (" Modulation Error Ratio ", or modulation error ratio, in English), or other control signal. The signal represented is, for example, a TV (video) signal encoded by the DVB-T (" Digital Video Broadcast-Terrestrial " standard, known as DTT in Spanish).

In the same Fig. 1 it has been represented, in the curve "A" in the frequency range 4, the spectrum of broadcasting an analog TV signal in PAL format (Line Alternated in Phase), in which the spectrum adopts a sinuous form with maximum and minimum of the control characteristic depending on the frequency. In this case, this PAL signal has been represented in a frequency range 4.

The quality in the transmission of both signals it implies the conservation of their respective spectrum throughout the weather. However, it is known that interference occurs continuous or temporary impulses "that affect these spectra of transmission and ultimately, to the quality of the signal seen in the receivers These interferences are phenomena that create sudden changes in the current of the conductor that carries the TV signal, and may be caused by transients of household electrical appliances, ignition of automobile engines nearby, atmospheric phenomena of character electromagnetic, etc. Its consequence is the known effects of fog, snow, double image, stripes, etc., on analog TV and video signal lags, momentary loss of sound or freezing of the image in DTT, etc. And in general, all interference that affects the level, MER or BER, etc.

The current technique for detection of interference or any type of problem that may affect the correct reception of analog TV signals is based on the on-screen behavior analysis of the analog signal received in the presence of interference. But this procedure It is discarded when it comes to digital signals.

The purpose of the present invention is provide a method to detect and characterize these interference in order to anticipate and correct them in advance

Explanation of the invention.

To this end, according to a first aspect, the object of the invention is a method for the identification and diagnosis of interference in RF signals, in particular television signals, whether analog or digital, again concept, which in its essence is characterized because it includes the phases of:

associate with each level or value of the variable of spectrum control (n_ {0}, n_ {1}, ..., n_ {4}) a respective standard determined value (c_ {0}, c_ {1}, ..., c_ {4}) of a certain visible characteristic of control,

graph, for each moment of time (t) and for each frequency or frequency range (1, 2, 3, 4), the value of the previous visible characteristic determined, and

determine the presence of an interference (D ', D' ', A') when there is a discontinuity in the value of the previous visible characteristic determined, appearing a new value (c_ {5}, c_ {6}, c_ {7}) different from the value certain standard due (c_ {1}, c_ {1}, c_ {0}).

According to another feature of the invention, the method comprises the later phase of associating the new value different produced in interference to a type of interference particular.

According to the preferred embodiment of the invention, said control visible certain characteristic is a color (c_ {0}, c_ {1}, ..., c_ {4}) of the visible spectrum associated to the level or value (n_ {0}, n_ {1}, ..., n_ {4}) of the control variable, so that the phase of determining the interference is made when there is a discontinuity in the color.

Specifically, it is expected that this color is a "grayscale" color.

The plot operation can be performed representing on a coordinate axis the frequency channels of the TV frequency band, the carrier waves of the spectrum of digital TV broadcast.

The spectrum control variable from which graph the level can be the signal strength, the power of the signal, the MER or the BER of the carriers.

In a second aspect, the invention has for object the apparatus for the implementation of a method as described above, for the identification and diagnosis of interference in analog or digital signals from TV, radio or data.

This representation of "3D" measurements that use a color code for the "z" dimension (depth), allows to reveal the interfering content on the signal of interest, highlighting the intensity of the interference and its duration.

This analysis is performed in the domain of time and frequency in a case and in the behavior of carriers transmitted within the channel itself, in the case of be COFDM modulations.

In this way, the method of the invention is focused on discovering the causes of interference, transient or no, on the signal of interest, which may affect the quality of the signal. This can be done on the basis of analyzing the patterns of colors that appear on the screen when the method of applying the present invention

In this way, and having associated a color specific to a particular anomaly or interference of the spectrum, simply observing a scheme like that of Figs. 3, 7 or 8, it you can appreciate in a very intuitive way the presence of a interference and even identify such interference (a transients of a household electrical appliance, the ignition of a car engine, a particular atmospheric phenomenon or even the existence of magnetic defects in electrical installations in homes, which otherwise could not be identified, etc.).

Brief description of the drawings

The description of the preferred embodiments of the present invention, for whose best understanding is accompanied by some drawings, given merely by way of descriptive and non-limiting example, in which:

Fig. 1, is the flat representation of the typical spectra of transmission of a digital TV signal and of an analog TV signal;

Fig. 2 is a view showing several possible variations of the previous signals, to illustrate possible variations of the spectra due to interference;

Fig. 3 shows an exemplary embodiment of a secondary spectrum of the signals of Fig. 2 which, according to the invention serves to identify interference produced;

Fig. 4 is a representation of the spectrum of a digital television signal like that of Fig. 1, although with a somewhat greater detail;

Fig. 5 is a detail view of the spectrum of Fig. 4, in which, for purposes of clarity, only a few carriers have been represented, specifically nine carrier waves;

Fig. 6 a view showing a representation in three coordinates of an example of MER values for multiple carrier waves, as a function of time, when represents, in the "z" coordinate, the value of the MER according with qualitative criteria associated with a corresponding variation of color, in that it is significant in height, and therefore of the value of the MER for each moment of time and for each wave carrier;

Fig. 7 is a two-dimensional representation of Fig. 6, in which the value of the MER is represented only For the color; Y

Fig. 8 is a schematic view showing an analyzer whose display shows the representation two-dimensional of Fig. 7.

Detailed description of the drawings

In these drawings you can see the operating mode of the method of the present invention, for the identification and diagnosis of interference in RF signals, in particular Television signals, whether analog or digital. In these signals, for each frequency, frequency range (1, 2, 3, 4) or carrier wave (P1 to P9, ...), there is an optimal level default of a spectrum control variable (D, A), in function of time (spectrum), such as intensity, the irradiated power, the MER, the BER, etc.,

The typical broadcast spectrum of digital television signals (curve D), in the band or interval 2, is shown in Fig. 1. This can be simplified according to a "step" whose height is an emission or measurement level of another characteristic. of emission, such as intensity, radiated power, MER (" Modulation Error Ratio ", or modulation error ratio, in English), or other control signal. The signal represented is, for example, a TV (video) signal encoded by the DVB-T (" Digital Video Broadcast-Terrestrial " standard, known as DTT in Spanish).

A representation of the D spectrum of the digital television signal of Fig. 1 is shown in Fig. 4, although in a somewhat greater detail, while Fig. 5 is a view, even in greater detail of the D spectrum of Fig. 4, in which, for the sake of clarity, only a few carriers have been represented, namely nine carrier waves P_ {1} to P_ {{}}. The detailed appearance of the spectrum of a DTT TV signal in the plain or " plateau " will be shown, with a "representative" average value of level n_ {1}.

In the same Fig. 1 above it has been represented, in the curve A in the frequency range 4, the spectrum of broadcasting an analog TV signal in PAL format (Line Alternated in Phase), in which the spectrum adopts a sinuous form with maximum n_ {2}, n_ {3}, n_ {4} and minimum n '0, n' '0 of the control characteristic as a function of frequency. In this case, this PAL signal has been represented in a range of frequencies 4.

Outside the zones of the intervals of frequency of DTT and PAL signals, the spectrum adopts a value "basal" n_ {0} which can be zero or not.

According to the method of the invention, it is associated with each level or value of the spectrum control variable (n_ {0}, n_ {1}, ..., n_ {4}) a respective standard determined value (c_ {0}, c_ {1}, ..., c_ {4}) of a given color or of a Gray grayscale. For every moment of time (t) and for each frequency, frequency range (1, 2, 3, 4) or carrier wave number, each point of this two-dimensional space, It is represented with the color or gray of the associated scale. The "frequency ranges" may be such that each of they define a corresponding "carrier wave" of emission of TV signals (explained above in relation to Fig. 4 and 5, and later with Figs. 6 and 7).

When interference occurs (D ', D' ', A '), according to the method, a discontinuity of the color or of the gray of this two-dimensional representation, appearing a new color or gray value (c_ {5}, c_ {6}, c_ {7}) different from standard set due value (c_ {1}, c_ {1}, c_ {0}), easily visible or configurable, for the purpose of Perform a numerical or computerized diagnosis.

In Fig. 2 several possible ones are shown variations of the previous signals, to illustrate possible spectral variations due to interference, in successive moments of time t = 0, t_ {1}, t_ {2} and t_ {3}. It is shown the spectrum of the control level variable ("n"), for each time value (for example separated a sampling time or system clock frequency).

The equivalent spectrum is illustrated in Fig. 3 to that of Fig. 2 but seen "from above". Each level has been represented by a gray scale color correspondent:

one

For t = 0 the curve DA appears, which is, by example, the nominal one, or represented in Fig. 1, lacking interferences or anomalies, with the color scheme (below above) c_ {0} c_ {1} c_ {0} c_ {2} c '_ {c} {3} c' '_ {0} c_ {4}.

For t = t_ {1} in Fig. 2 a curve D'A, in which, in the digital part D 'there is a color discontinuity for the frequency band of the interval 1, associated with the decrease to level d5 with respect to at the "nominal" level n_ {1}, to which a new value corresponds of gray c_ {5}, different (lighter) from c_ {1}, which is the one would correspond to the digital TV signal D exempt from interference The analog signal A remains unchanged, so that the colors for t = t_ {1} match those of t = 0.

For t = t_ {2} in Fig. 2 a curve D''A ', in which, in the digital part D' 'a new one is produced discontinuity, specifically a new decrease to d6 with respect to at the "nominal" level n_ {1}, and in analog part A 'of frequency range 3 a spurious peak occurs "d_ {7}", above the value of the "nominal" level n '0 that would correspond to the frequency f' 0 (see Fig. 1) in question.

In Fig. 3, for d6 a new value corresponds gray c_ {6}, different from c_ {1} and also from c_ {5}, easily distinguishable in the graphic representation of Fig. 3. To the peak "d_ {7}", it corresponds to a darker gray c_ {7} that the gray c '0 that would correspond to the value n' 0 of "normal" at the frequency f '0. Which is also visible clearly in Fig. 3.

Finally, for t = t_ {3} in Fig. 2 returns to appear the DA curve, lacking interference or anomalies, and in the representation of Fig. 3 again shows the scheme of colors or grays without discontinuities or "without interference", with identical color scheme c_ {0} c_ {1} c_ {0} c_ {2} c '0 c_ 3 c' '0 c 4 {which for t = 0.

According to the method, the new value is associated different from the color or gray produced in the interference, at a type of particular interference. Therefore if they are parameterized color values, by remote analysis of they can diagnose what is the interference that has produced the corresponding variation in the value of the levels (intensity, irradiated power, MER, BER, etc.).

In Figures 1 to 3 the case in which the graphic representation is done by frequency channels of TV frequency band.

However, there are alternative modes of spectrum representation. For example, when it comes to signal Digital TV (DTT or DVB-T), the operation of graphing is done by carrier waves of the emission spectrum of Digital TV, as can be seen in Figs 6 and 7.

For each carrier wave p_ {i} of # i (in the Figs. 4 to 8 only a few carrier waves are represented p_ {i}, p_ {{}}, p_ {{{}}}, p_ {{}}, p_ {{}}, p_ {{}}, p_ {{}}, p_ {8}, p_ {9}, among the thousands of them that incorporates a digital signal) is associated with a value of MER, calculated in a way In itself known and conventional. MER is a measure of the quality of the signal. For a correct view of the signal on the monitor in the TV monitor, the MER must be equal to or greater than a minimum value predetermined, which is associated, according to the present invention, a gray value "minimum MER" (Fig. 6). At lower values of MER is associated with other gray values ("bad MER"), for darker example, and higher values are associated with others corresponding gray values ("acceptable MER"; "MER good "), for example successively clearer as improves the MER.

Fig. 6 is a view showing a representation in three coordinates of an example of MER values for multiple carrier waves, as a function of time "t". In coordinate "z", represents the value of the MER according with the previous qualitative criterion of corresponding variation the color or gray grayscale, in which this is significant of the height, and therefore of the value of the MER for each moment of time and for each carrier wave.

Assuming that the representation of Figs. 4 and 5 is for an instant of time t = 0 and that the MER for nine carriers p_ {{1}}, p_ {{}}, p_ {3}, p_ {{}}, p_ {{}}, p_ {{}}, p_ {7}, p_ {8}, p_ {9}, for t = 0 is "good", in Fig. 6 all carrier waves are graphed with the gray "MER good".

Fig. 7 is a two-dimensional representation of Fig. 6 (view from "above"), in which the value of the MER It is represented only by color. Therefore, for t = 0 and for the nine carriers p 1, p 2, p 3, p 4, p_ {5}, p_ {6}, p_ {7}, p_ {8}, p_ {9}, the gray "MER good".

In the illustrative example shown, the carrier p_ {1} suffers interference between instants t_ {1} and t_ {7}, going through a minimum value of MER for t_ {4}. The variation of the MER is distinguished in the variation in height of the Fig. 6 and in the color variation of Fig. 6 and 7. The carrier p1 also suffers a worsening of the MER between t_ {19} and t_ {23}. Abnormalities or interferences affect p_ {1} and the carrier waves of adjacent frequencies, although with a lower MER variation. The same happens with the carrier wave p5 in between the moments t_ {9} and t_ {11}.

Finally, in Fig. 8 schematic showing an analyzer, oscilloscope or analogous apparatus 5, connected to an antenna 6 receiving a digital TV signal, in which "display" or screen 7 shows the two-dimensional representation of Fig. 7.

Claims (9)

1. Method for identification and diagnosis of interference in radio frequency signals, in particular television signals, whether analog or digital, in which for each frequency, frequency range (1, 2, 3, 4) or wave carrier (P_ {1} to P_ {9}, ...), there is an optimal level default of a spectrum control variable (D, A), in function of time (spectrum), such as intensity, the irradiated power, the MER, the BER, etc., characterized in that it comprises the phases of: associate with each level or value of the variable of spectrum control (n_ {0}, n_ {1}, ..., n_ {4}) a respective standard determined value (c_ {0}, c_ {1}, ..., c_ {4}) of a color (c_ {0}, c_ {1}, ..., c_ {4}) of the visible spectrum associated to the level or value (n_ {0}, n_ {1}, ..., n_ {4}) of the control variable, graph, for each moment of time (t) and for each frequency or frequency range (1, 2, 3, 4), or for each carrier wave (P1 to P9, ...), the associated color, Y determine the presence of an interference (D ', D' ', A') when there is a discontinuity in the value of the previous color, appearing a new value (c_ {5}, c_ {6}, c_ {7}) different from the standard set due value (c_ {1}, c_ {1}, c_ {0}). 2. Method according to claim 1, characterized in that it comprises the subsequent phase of associating the new different value produced in the interference with a particular type of interference. 3. Method according to claim 1, characterized in that said color is a "grayscale" color. 4. Method according to claim 1, characterized in that said plotting operation is performed by frequency channels of the TV frequency band. 5. Method according to claim 1, characterized in that said plotting operation is carried out by carrier waves of the digital TV broadcast spectrum. Method according to claim 1, characterized in that said spectrum control variable of which the level is plotted is the signal strength. Method according to claim 1, characterized in that said spectrum control variable of which the level is plotted is the MER of the carriers. Method according to claim 1, characterized in that said spectrum control variable of which the level is plotted is the BER of the carriers. 9. Apparatus for identification and diagnosis of interference in RF signals, in particular signals analog or digital television, radio or data, for setting in practice of a method according to the preceding claims.