KR101325454B1 - Apparatus and method for selecting tv channel - Google Patents

Abstract

The present invention provides a pilot detector for measuring a pilot frequency for a plurality of TV channels received from a TV channel antenna and a pilot power associated with the pilot frequency, and calculating the intermodulation frequency based on the pilot frequency and the pilot power. An apparatus for selecting a TV channel including a channel selector for selecting an available TV channel group from the plurality of TV channels using an intermodulation frequency.

Description

TV channel selection device and method {APPARATUS AND METHOD FOR SELECTING TV CHANNEL}

The present invention relates to an apparatus and method for selecting TV channels.

Radio Awareness (CR) refers to a technology that automatically finds unused frequencies according to region and time to enable desired communication.

In other words, it finds an idle spectrum that is scattered in various widths and the time occupied continuously varies, and determines the frequency bandwidth, output, modulation method, etc. suitable for the environment, and recycles it.

The wireless recognition (CR) communication system refers to a communication system that wants to use an idle spectrum by detecting a spectrum in use, and detects the existence of a TV signal by detecting the spectrum of the entire TV signal, and searches for an empty available channel. There is a problem that the speed of searching for available channels is slow.

In addition, there is a problem in that the influence of the intermodulation interference signal inevitably generated between a plurality of TV channels.

One embodiment of the present invention is to provide an apparatus and method for selecting a TV channel capable of selecting an optimal channel while avoiding an interference signal caused by intermodulation between TV channels when there are a plurality of TV channels. .

TV channel selection apparatus according to an embodiment of the present invention is a pilot detector for measuring a pilot frequency and a pilot power associated with the pilot frequency for a plurality of TV channels received from a TV channel antenna, and the pilot frequency and the pilot power And a channel selector configured to calculate an intermodulation frequency based on the intermodulation frequency and to select an available TV channel group from the plurality of TV channels using the intermodulation frequency.

According to an embodiment of the present invention, a method of selecting a TV channel includes measuring a pilot frequency and a pilot power associated with the pilot frequency for a plurality of TV channels received from a TV channel antenna, based on the pilot frequency and the pilot power. Calculating an intermodulation frequency, and selecting an available TV channel group from the plurality of TV channels using the intermodulation frequency.

According to an embodiment of the present invention, it is possible to select a TV channel that minimizes interference due to intermodulation between two or more TV channels.

According to an embodiment of the present invention, the presence of a TV signal can be detected using only a pilot signal to select an available TV channel at a higher speed.

1 is a view showing a pilot signal used in the apparatus and method for TV channel selection according to an embodiment of the present invention.
2 is a block diagram of a wireless cognitive communication system including a TV channel selection apparatus according to an embodiment of the present invention.
3 is a flowchart illustrating a method for selecting a TV channel according to an embodiment of the present invention.
4 is a flowchart illustrating a method for selecting a TV channel according to another embodiment of the present invention.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing a pilot signal used in the apparatus and method for TV channel selection according to an embodiment of the present invention.

A pilot signal is a signal in a communication system that allows a receiver to perform timing and frequency synchronization, and to evaluate and track a desired channel for subsequent demodulation and decoding of information data. For reference, it can be seen that the pilot signal 110 exhibits a higher power density than the center frequency 130 of the TV channel and other TV signals.

An embodiment of the present invention relates to a TV channel selection device having a function of measuring power for each TV channel in a TV frequency band, by using a pilot signal having a higher power density than other TV signals such as a video signal and an audio signal. You can select an empty TV channel.

Several pilot schemes can be used in a communication system, and these schemes generally adopt a scheme of transmitting a known sequence in a known time period. A receiver that knows only the sequence or the sequence and time period in advance can use this information to perform the various functions.

2 is a block diagram of a wireless cognitive communication system including a TV channel selection apparatus 230 according to an embodiment of the present invention. The wireless cognitive communication system includes a TV channel antenna 210, a switch 220, a TV channel selector 230, a phase-lock-loop 240, and a mixer 250, 260.

Referring to FIG. 2, the TV channel selection apparatus 230 according to an embodiment of the present invention includes a pilot detector 233 and a channel selector 236.

The pilot detector 233 measures a pilot frequency and a pilot power associated with a pilot frequency for a plurality of TV channels received through the switch 220 from the TV channel antenna 210 when the wireless cognitive communication system is in a reception mode.

In this case, the pilot frequency refers to the center frequency of the pilot channel, the pilot power refers to the power of the pilot channel, and the measurement of the pilot frequency and the pilot power may be performed in a measurement time period of T seconds in the TV channel band.

The channel selector 236 calculates the intermodulation frequency based on the pilot frequency and the pilot power measured by the pilot detector 233, and selects an available TV channel group from the plurality of TV channels using the intermodulation frequency. .

In addition, the channel selector 236 may determine effective pilot frequencies of the TV channel based on the pilot frequency and the pilot power, and calculate the intermodulation frequency according to the determined effective pilot frequencies.

The effective pilot frequencies represent the channel currently in use, in which case the pilot power corresponding to that pilot frequency will appear above a certain threshold. The effective pilot frequencies may be pilot frequencies corresponding to pilot power above a first threshold (eg, −114 dBm).

The intermodulation frequency may be calculated using center frequencies determined according to the pilot power.

To this end, the channel selector 236 compares the pilot power for each effective pilot frequency, selects the center frequencies of the first pilot frequency having the largest pilot power and the second pilot frequencies, which are the next highest order, and the center frequencies of the TV channel. Can be determined.

In this case, the intermodulation frequency may be calculated by substituting the calculated center frequency of the first pilot frequency and the second pilot frequency into the following equation.

[Mathematical Expression]

Intermodulation Frequency = 2Fa-b or 2Fb-a

Here, Fa is the center frequency of the TV channel with the largest pilot power and Fb is the center frequency of the TV channel with next-order pilot power immediately after the maximum pilot power.

The channel selector 236 may select a TV channel in which interference is minimized by an intermodulation frequency among the plurality of TV channels as an available TV channel group.

Here, the intermodulation frequency refers to a frequency at which interference is likely to occur due to interference, and a channel having minimal interference between TV channels can be selected by excluding a TV channel corresponding to the intermodulation frequency from the available TV channel group.

In addition, the channel selector 236 calculates a TV channel of a frequency band including the intermodulation frequency, and when the power measurement at the intermodulation frequency is lower than a preset second threshold, the calculated TV channel is available. You can register with

In this case, even if the intermodulation occurs, the power is low and there is a low possibility that the problem of interference actually occurs. Therefore, even a TV channel in the frequency band including the intermodulation frequency can be registered as an available TV channel group.

For the same reason, the channel selector 236 measures the power value at the intermodulation frequency, and if the measured power value is lower than the preset second threshold, the TV channel of the frequency band including the intermodulation frequency is available. You can register as a channel group.

Operation of the radio-cognitive communication system including the TV channel selection device as described above is as follows.

In the reception mode from the antenna 210 through the transmission / reception switch 220, the pilot power and frequency are measured through the pilot detector 233 and transmitted to the channel selector 236.

The channel selector 236 may be equipped with an operation or a control method according to an embodiment of the present invention in the form of a program.

When a TV channel is selected from the group of available TV channels selected by the channel selector 236, the oscillation frequency of the phase-lock loop 240 is adjusted to the center frequency of the selected TV channel and transmitted to two transmission / reception mixers 250 and 260. Communication can be performed.

3 is a flowchart illustrating a method for selecting a TV channel according to an embodiment of the present invention. Hereinafter, the functions performed in each step will be described in detail.

Referring to FIG. 3, in the method of selecting a TV channel according to an exemplary embodiment of the present invention, a method of measuring a pilot frequency and a pilot power (310), determining an effective pilot frequency (330), and calculating an intermodulation frequency are performed. 350, and selecting 370 an available TV channel group.

Step 310 measures the pilot frequency and the pilot power associated with the pilot frequency for the plurality of TV channels received from the TV channel antenna.

In this case, the pilot frequency and the pilot power may be measured by the pilot detector 233 in a measurement time period of T seconds in the TV channel band, where the pilot frequency is the center frequency of the pilot channel and the pilot power is the power of the pilot channel. do.

In operation 330, the channel selector 236 determines effective pilot frequencies of the TV channel based on the pilot frequency and the pilot power measured in operation 310.

Step 330 is a process of searching for TV channels currently in use by using a pilot signal of a TV frequency band, and the effective pilot frequency indicates pilot power above a certain threshold, that is, a channel currently in use.

Here, the effective pilot frequencies of the TV channel may be determined based on the pilot frequency and the pilot power, and the pilot frequency corresponding to the pilot power that is greater than or equal to the first threshold (eg, −114 dBm) may be determined as the effective pilot frequency.

Step 350 calculates the intermodulation frequency based on the pilot frequency and the pilot power. In this case, the intermodulation frequency may be calculated according to the power of the effective pilot frequencies determined in operation 330, and may also be performed by the channel selector 236.

In addition, step 350 may be performed by determining center frequencies of a TV channel according to pilot power and calculating intermodulation frequencies using the determined center frequencies.

In this case, the center frequencies of the TV channels are compared with the pilot power for each effective pilot frequency to select the center frequencies of the first pilot frequency having the largest pilot power and the second pilot frequency having the next highest order, and are determined as these two center frequencies. Can be.

Here, the large pilot power of the effective pilot frequency means that the interference between TV channels is likely to occur as much, and thus, the remaining channels except for the channel having a high possibility of interference are used later.

When the first pilot frequency and the second pilot frequency are determined through the above process, the intermodulation frequency may be calculated by the above-described equation.

Step 370 selects an available TV channel group from the plurality of TV channels using the intermodulation frequency calculated in step 350. The available TV channel group includes usable empty TV channels, and among the plurality of TV channels, TV channels whose interference is minimized by the intermodulation frequency may be selected as the available TV channel group.

In step 370, a TV channel of a frequency band including an intermodulation frequency is calculated to select an available TV channel group, and when the power measurement at the intermodulation frequency is lower than a second preset threshold, the calculated TV channel is available. Can be selected as a channel group.

In operation 370, when the power measured at the intermodulation frequency is measured to be lower than the preset second threshold, the TV channel in the frequency band including the intermodulation frequency may be selected as an available TV channel group.

A random process for minimizing interference may be used as a method of selecting a TV channel to be used among the available TV channel groups selected in step 370, and the operation of step 370 may be performed by the channel selector 236. .

A random process that minimizes interference is as follows.

If two of the ten TV channels are in use and two channels are produced that are likely to cause intermodulation by the channel being used, then six except ten of the ten TV channels that are in use or highly likely to be intermodulated One of the one channel may be selected at random.

4 is a flowchart illustrating a method for selecting a TV channel according to another embodiment of the present invention.

In order to select a channel of the radio recognition communication system in the TV frequency band, the pilot detector 233 measures the pilot power and the pilot frequency, which are narrowband signals in the TV band (410).

Thereafter, the channel selector 236 determines the effective pilot frequency based on the threshold (415), compares the power of the effective pilot frequency (420), and determines whether the number of powers of the effective pilot frequency is two or more. (425).

For example, if there are L total TV channels, if there are zero effective pilot channels, the group of available TV channels is L total TV channels; if there is one valid pilot channel, one TV channel corresponding to a valid pilot channel L-1 channels except for are selected as available TV channel groups.

If there are N valid pilot channels, the number of available TV channel groups is L-N.

As described above, when the number of available TV channel groups is L-N, the center frequency of the TV channel is determined using the channel having the largest effective pilot channel power and the next two largest TV channels (430).

That is, the two pilot frequencies F1 and F2 are selected in the largest order among the N pilot frequencies, and the center frequencies Fa and Fb of the TV channels corresponding thereto are selected. At this time, by comparing the power of the pilot for each pilot frequency, it is possible to select the center frequency of the two TV channels mapped to the largest pilot and the next order pilot.

The intermodulation frequency is generated by substituting the center frequency determined in operation 430 into the equation described with reference to FIG. 2 (435).

If the intermodulation frequency generated in step 435 belongs to the frequency band of the group of available TV channels composed of LNs, a TV channel including the intermodulation frequency is calculated (440) to narrowband smaller than the TV signal bandwidth at the frequency of the intermodulation. Measure the power with.

Thereafter, if the measured channel power measured at the two intermodulation frequencies calculated in [Equation] is lower than the predetermined threshold (445), the TV channel corresponding to the intermodulation frequency is available. Leave at (450).

If the channel power measured at the intermodulation frequency is higher than a preset threshold (eg, -114 dBm), the TV channel corresponding to the intermodulation frequency is excluded from the available TV channel group (460). That is, a TV channel including the two intermodulation frequencies is not selected as an available TV channel group.

If the power measured at the intermodulation frequency is lower than the threshold, even if the TV channel having the intermodulation is registered to the available TV channel group (450), the radio-cognitive communication system may randomly select the TV channel among the available TV channel group ( 455).

The methods according to the present invention can be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. This is possible.

Therefore, the scope of the present invention should not be construed as being limited to the embodiments described, but should be determined by equivalents to the appended claims, as well as the appended claims.

210: antenna
220: transmission module
230: receiving module
240: phase lock loop
250, 260: transmission and reception mixer

Claims (15)

A pilot detector for measuring a pilot frequency for a plurality of TV channels received from a TV channel antenna and a pilot power associated with the pilot frequency; And
Determine effective pilot frequencies of the TV channel based on the pilot frequency and the pilot power, calculate a intermodulation frequency according to the determined powers of the effective pilot frequencies, and use the intermodulation frequency among the plurality of TV channels. Channel selector to select a group of available TV channels
TV channel selection device comprising a. delete The method of claim 1,
The channel selector
And determining a pilot frequency corresponding to a pilot power that is greater than or equal to a preset threshold as the effective pilot frequency. The method of claim 1, wherein the channel selector
And determining center frequencies according to the pilot power, and calculating the intermodulation frequency using the determined center frequencies. The method of claim 4, wherein the channel selector,
Compare the pilot power for each effective pilot frequency;
And comparing the center frequencies of the first pilot frequency with the largest pilot power and the second pilot frequencies with the next highest pilot power to determine the center frequencies of the TV channel. 5. The method of claim 4,
And the intermodulation frequency is calculated according to the following equation.
[Mathematical Expression]
Intermodulation Frequency = 2Fa-Fb or 2Fb-Fa
(Where Fa is the center frequency of the TV channel with the largest pilot power and Fb is the center frequency of the TV channel with next-order pilot power immediately after the maximum pilot power.) The method of claim 1, wherein the channel selector
And selecting a TV channel in which the interference is minimized by the intermodulation frequency among the plurality of TV channels as the available TV channel group. The method of claim 1, wherein the channel selector,
Calculating the TV channel in a frequency band including the intermodulation frequency,
And register the calculated TV channel as the available TV channel group when the power measurement at the intermodulation frequency is lower than a preset threshold. The method of claim 1, wherein the channel selector,
Measure the power at the intermodulation frequency,
And registering the TV channel in the frequency band including the intermodulation frequency as the available TV channel group when the measured power is lower than a preset threshold. The method of claim 1, wherein the channel selector,
And selecting the TV channel through a random process of minimizing interference among the available TV channel groups. Measuring a pilot frequency for a plurality of TV channels received from a TV channel antenna and a pilot power associated with the pilot frequency;
Determining effective pilot frequencies of the TV channel based on the pilot frequency and the pilot power;
Calculating a intermodulation frequency according to the determined powers of the effective pilot frequencies; And
Selecting an available TV channel group from the plurality of TV channels using the intermodulation frequency
TV channel selection method comprising a. delete The method of claim 11, wherein calculating the intermodulation frequency comprises:
Determining center frequencies in accordance with the pilot power; And
Calculating the intermodulation frequency using the determined center frequencies
TV channel selection method comprising a. The method of claim 13, wherein determining center frequencies according to the pilot power comprises:
Comparing the pilot power for each effective pilot frequency; And
As a result of the comparison, determining the center frequencies of the first pilot frequency having the largest pilot power and the center frequencies of the second pilot frequency, which are the next highest order, as the center frequencies of the TV channel.
TV channel selection method comprising a. 15. The method of claim 14,
The intermodulation frequency is calculated according to the following equation.
[Mathematical Expression]
Intermodulation Frequency = 2Fa-Fb or 2Fb-Fa
(Where Fa is the center frequency of the TV channel with the largest pilot power and Fb is the center frequency of the TV channel with next-order pilot power immediately after the maximum pilot power.)

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