KR100525847B1 - Digital TV On Channel Repeater with Digital Adaptive Correction - Google Patents

Abstract

The present invention relates to a digital TV co-channel repeater having a digital distortion compensation function, in particular an RF receiving antenna; A DTV RF receiver composed of two BPFs, an amplifier, a blender and a local oscillator; A DTV RF transmitter composed of a mixer unit, HPA and BPF; A digital TV co-channel repeater comprising an RF transmitting antenna, comprising: an A / D converter, an I / Q demodulator, an adaptive compensator, a digital filter, an I / Q modulator, between the DTV RF receiver and the DTV RF transmitter; In order to implement a system that receives a signal from the main transmitter and retransmits it at the same frequency in order to supplement the shadow area in the digital TV transmission service area by installing a signal processing unit including a D / A conversion unit, In order to recover the noise ratio (S / N), an adaptive compensator using digital filter and digital signal processing technology is introduced to compensate for channel distortion of the received RF signal, linear and nonlinear distortion of the transmitter, and distortion of the RF couple signal. It is possible to improve the S / N of the output signal, and to build and control a system that can expand the service area.

Description

Digital TV On Channel Repeater with Digital Distortion Compensation

The present invention relates to a digital TV co-channel repeater having a digital distortion compensation function. More particularly, the present invention relates to a digital TV co-channel repeater. A new co-channel repeater system invented to reduce signal delay time.

In general, the configuration of a digital co-channel repeater system in a digital TV broadcasting network is as follows.

First, FIG. 1 is a schematic diagram of a general co-channel relay system. IF 1 shows compressed MPEG TS (transport stream) data transmitted from a studio to a ST (Studio to Transmitter) link. A VSB modulator (1) of the US Advanced Television Systems Committee (ATSC) DTV that modulates a VSB (Vestigial Side Band) signal in the (Intermediate Frequency; 44 MHz) band, and a modulated IF signal is transmitted to a radio frequency (RF) channel. After up-converting, it is via a high power amplifier to a DTV transmitter (Tx) (2) that transmits DTV RF signals to service areas within a few tens of kilometers with a high power of several kW or more. A main transmission station configured;

A reception antenna (3) for receiving an RF signal of a main transmission station and a DTV RF receiver (Rx) (4) for converting the received signal into a signal of an RF, IF band or baseband through a frequency selection circuit and a demodulation circuit; A signal processor (5) for performing signal processing for retransmission through a band pass filter (BPF) or digital demodulation, and a retransmitted RF (Radio Frequency) channel (same frequency as originally received) DTV RF transmitter (6), which converts to and then amplifies to the desired output via a high power amplifier, and the transmit channel is the same as the receive RF channel, but the output is usually very small and the main service area is covered by the main station signal. In a form limited to some regions, the repeater consists of a transmitting antenna (7) for transmitting the amplified signal through a transmitting antenna arranged in the repeater so as not to interfere with the receiving unit.

Secondly, Figure 2 shows a schematic diagram of a simple repeater that receives a conventional RF signal and transmits the signal after it is amplified, which is a radio signal (RF) receiving antenna (3), a band pass filter (BPF), and a high power amplifier. (HPA) 62, a BPF 63, and an RF transmitting antenna 7, which amplify the RF signal received from the RF receiving antenna 3 as it is, and then transmit the same.

Third, FIG. 3 shows a schematic diagram of a simple repeater for receiving a conventional RF signal, converting it to IF, converting it back to RF, and amplifying and transmitting the RF signal, which is an RF receiving antenna 3, a BPF 41, and an amplifier 42. ), Mixer 43 and local oscillator 45 for IF conversion, IF BPF 44, mixer 61, HPA 62, BPF 63, RF transmission antenna 7 ), And converts the RF signal received from the RF receiving antenna into IF and then converts it into RF and then amplifies and transmits the RF signal.

Fourthly, FIG. 4 shows a configuration of a regenerative repeater which receives a conventional RF signal, completely demodulates it, modulates it, and then transmits the converted RF signal. This is an RF receiving antenna 3, a BPF 41, and an amplifier 42. , Mixer 43 and local oscillator 45, IF BPF 44, VSB demodulator 51, VSB modulator 52, mixer 61, HPA 62 for conversion to intermediate frequency signal IF , BPF (63), RF transmission antenna (7), the RF signal received by using a VSB demodulator to fully error correction demodulated to TS (Transport Stream) level, and then remodulated and sent through the VSB modulator to be.

Among the above-described systems, a system for receiving and amplifying and retransmitting an RF signal (ie, FIG. 2) passes the RF signal received from the RF receiving antenna 3 through the BPF 41 to remove the adjacent channel signal, and then removes the HPA. In this case, the amplified signal includes the channel noise included in the received signal, and removes the adjacent channel signal generated by the HPA from the amplified signal with the channel filter 63 and then the RF transmission antenna (7). I send it out)

In addition, the system that receives the RF signal, converts it to IF, and then converts it back to RF and transmits the RF signal (that is, FIG. 3), passes the RF signal received from the RF receiving antenna 3 through the BPF 41 to transmit an adjacent channel signal. After the removal, convert the signal to IF using the mixer 43 and the local oscillator 45, remove the out-of-band signal using the BPF 44 for IF, and then convert the signal to the RF using the mixer 61. The signal is amplified by the HPA, and then passed through the channel filter 63 and then transmitted to the RF transmission antenna 7.

In addition, the system for demodulating and remodulating the data level after receiving the RF signal (ie, FIG. 4) passes the RF signal received from the RF receiving antenna 3 through the BPF 41 to remove the adjacent channel signal, and then the mixer ( 43) and the local oscillator 45 are converted to IF and then demodulated by the VSB decoder 51 to the baseband MPEG TS signal, and then remodulated by the VSB modulator 52 and then the mixer unit 61. Converts the modulated IF signal into an RF signal, and then amplifies it in the HPA 62, and then removes the out-of-band signal using the channel filter 63, and then transmits the RF signal in the RF transmission antenna 7. .

However, in the above-described conventional embodiments, a system for receiving and amplifying and retransmitting an RF signal cannot transmit a signal having a higher quality than the received RF signal, and a signal deterioration occurs during conversion so that the distortion of the received signal remains intact. In addition to the transmission, there is a problem that the signal distortion may occur severely when the transmitted signal is input to the receiving antenna.

In addition, a system for receiving an RF signal, converting it to IF, and then converting it to RF again can effectively remove a signal of an adjacent channel, and thus may output higher than a system for receiving and amplifying and retransmitting an RF signal. It is not possible to send a higher quality signal than the RF signal that is, there is a problem that the signal degradation may occur during the conversion process, the signal distortion may occur strongly when the transmitted signal is input to the receiving antenna.

In addition, the system that demodulates and remodulates the data level after receiving the RF signal completely demodulates the received analog signal to the TS stream and then remodulates the signal, so that the S / N of the transmission signal is very high. Since the signal and the retransmitted signal are different signals, if the terrestrial isolation of the receiving area and the transmitting station is not good, the two signals are not only operated with perfect noise, but also have a high carrier to noise (CN) ratio of 15 dB or more. have.

The present invention has been made to solve such a conventional problem, the channel error component caused by the signal transmission from the transmitting station to the relay station or the signal of the feedback signal generated when the signal retransmitted at the transmitting end of the repeater is input again to the receiving end of the repeater Distortion and signal distortion generated inside the repeater can be corrected, and the repeater has less time delay than the repeater which includes all the signal demodulation and demodulation functions, and the repeater is installed in comparison with the repeater which includes all the signal demodulation functions. The purpose is to provide a digital TV co-channel repeater with a digital distortion compensation function to freely set the region.

The above object of the present invention, the RF receiving antenna; A DTV RF receiver consisting of two BPFs, an amplifier, a mixer and a local oscillator; A DTV RF transmitter composed of a mixer unit, HPA and BPF; A digital TV co-channel repeater comprising an RF transmitting antenna, comprising: an A / D converter, an I / Q demodulator, an adaptive compensator, a digital filter, an I / Q modulator, between the DTV RF receiver and the DTV RF transmitter; This can be achieved by additionally providing a signal processing section comprising a D / A conversion section.

Therefore, digital filter and digital signal processing technology to recover the low S / N of the input signal when implementing a system that receives the signal of the main transmitter and retransmits it at the same frequency to compensate for the shadow area in the digital TV transmission service area. By adopting the adaptive compensator, the channel distortion of the received RF signal, the linear distortion of the transmitting end, the distortion of the RF couple signal can be compensated for, and the S / N of the output signal can be improved, so that the service area can be expanded. You can build and control the system.

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

FIG. 5 is a diagram showing the overall system configuration of the repeater of the present invention, and FIG. 6 is a detailed block diagram of the digital filter unit in the present invention.

According to this, there is provided an RF receiving antenna 3 for receiving an RF signal transmitted from a main transmitting station; The BPF 41 removes an adjacent channel signal from the RF signal received through the antenna 3, and the amplifier 42 amplifies the output signal of the BPF 41 to a predetermined level. A mixer 43 for mixing the output signal and the output signal of the local oscillator 45 and converting them into an intermediate frequency signal IF, and an IF BPF 44 for removing adjacent channel signals in the signal output through the mixer 43. DTV RF receiver (4) consisting of; Included in the mixer unit 61 under the control of the local oscillator 45 and converting the IF signal into an RF signal, the HPA 62 for amplifying the output signal of the mixer unit 61 to a high output and the amplified RF signal. A DTV RF transmitter 6 comprising an RF channel BPF 63 for canceling out-of-band signals; In the digital TV co-channel repeater composed of an RF transmitting antenna (7) for transmitting the RF signal output from the DTV RF transmitter (6),

An A / D converter 53 for converting an IF signal input from the IF BPF 44 into a digital signal between the DTV RF receiver 4 and the DTV RF transmitter 6; An I / Q demodulator 54 for demodulating the digital IF signal output from the baseband to the baseband, a demodulated outgoing signal output from the DTV RF transmitter 6, and a digital filter through operations of an adaptive equalizer and a microprocessor. Channel characteristics among the output signals of the I / Q demodulator 54 under the control of the adaptive compensator 58 and the adaptive compensator 58 that calculates the filter coefficient and the look up table (LUT) of the unit 55. Digital filter unit 55 to remove errors by compensating for the error and compensate for nonlinear distortion components of transmitter HPA 62, and I / Q modulator 56 to modulate the error-corrected signal through the digital filter unit 55. ) And a D / A converter 57 for converting a digitally modulated signal through the I / Q modulator 56 into an analog IF signal. And a signal processor (5), characterized in that the additional installation.

In this case, the digital filter unit 55 may include a reference data generator 551 for generating reference data for compensating for nonlinear distortion, a signal output from the I / Q demodulator 54, and a reference data generator 551. MUX (Multiplexer) 552 to select any one of the reference signal output from the signal, under the control of the adaptive compensation unit 58 to correct the channel characteristics of the output signal of the I / Q demodulator 54 A digital filter 553 for eliminating an error, a complex multiplier 555 for compensating for the nonlinear distortion of the signal input from the digital filter 553, and outputting it to the I / Q modulator 56; and the complex multiplier ( It is characterized by comprising a LUT 554 for storing the coefficient value of 555.

Referring to the operation and effect of the system of the present invention configured as described above are as follows.

First, the RF signal transmitted from the main transmission station is received by the DTV RF receiver 4 through the RF reception antenna 3 and the adjacent channel signal included in the RF signal is removed through the BPF 41.

This RF signal is then amplified to a predetermined level by the amplifier 42, then mixed with the output signal of the local oscillator 45 by the mixer 43, converted into IF, and then again by the IF BPF 44 by the IF signal. Adjacent channel signals in the network are removed.

Subsequently, the analog IF signal output from the DTV RF receiver 4 is first input into the A / D converter 53 of the signal processor 5 and converted into a digital signal to prevent signal distortion that may occur in the future. do.

The converted digital signal is demodulated by the IQ demodulator 54, the signal distortion component is removed by the digital filter unit 55, and then modulated by the IQ modulator 56, and then the D / A conversion unit ( 57) generates an analog IF signal.

In this case, the MUX 552 in the digital filter unit 55 may include any one of reference data for nonlinear distortion compensation provided by the reference data generator 551 and a signal output from the I / Q demodulator 54. Since it is selected and provided to the digital filter 553, the digital filter 553 is controlled by the adaptive compensator 58 and the linear characteristic is removed by correcting the channel characteristics among the output signals of the I / Q demodulator 54. The multiplier 555 processes the nonlinear distortion of the transmitter in the complex multiplier 555 and outputs the result to the I / Q modulator 56. The coefficient value of the complex multiplier 555 is LUT ( 554).

Meanwhile, the analog IF signal output from the D / A converter 57 in the signal processor 5 is an RF signal through the mixer 61 under the control of the local oscillator 45 in the DTV RF transmitter 6. After conversion to the A, it is amplified to high power through the HPA (62), and then the adjacent channel signal contained in the RF signal through the RF channel BPF (63) is removed and then transmitted to the air through the RF transmitting antenna (7) .

At the same time, the RF signal output from the DTV RF transmitter 6 is fed back through the adaptive compensator 58 in the signal processor 5 to compensate for the distortion of the RF signal, distortion of the transmitter, distortion of the RF couple signal, and the like. The filter coefficient and the nonlinear component of the transmitter are measured by the reference data generator, and the LUT for compensating for the compensation is calculated and re-input to the digital filter unit 55, so that the channel distortion, linear and Nonlinear distortion and oscillation distortion caused by RF coupling are compensated for.

In this case, the linear distortion is a distortion of the RF receiving end 4 of the repeater, a distortion of the RF transmitting end 6 of the repeater, channel distortion such as frequency fading when receiving a signal transmitted to the transmitting station at the repeater, and a signal transmitted from the transmitting end of the repeater. Is caused by oscillation (feedback distortion), etc., caused by leaking back into the receiving end of the repeater (coupling of the signal). Nonlinear distortion is caused by the nonlinear nature of the high output amplifiers in the transmitter.

Such a repeater of the present invention, in addition to the ATSC DTV repeater, digital audio broadcasting (DAB), digital multimedia broadcasting (DMB, Digital Multimedia Broadcasting), European DTV transmission standard (DVB-T), Japanese DTV transmission standard ( It is applicable to digital broadcast transmission systems that require most co-channel relays such as ISDB-T).

As described above, according to the present invention, a signal error of a feedback signal generated when a channel error component generated while a signal is transmitted from a transmitting station to a relay station or a signal retransmitted at the transmitting end of the repeater is input to the receiving end, a signal distortion generated inside the repeater, and the like. Compared to a repeater that includes all the signal demodulation and demodulation functions, the delay of the repeater is very small, and the repeater installation region can be freely set.

1 is a schematic diagram of a general co-channel relay system.

2 is a block diagram of a simple repeater for receiving a conventional RF signal and transmitting it as it is after signal amplification.

3 is a schematic diagram of a simple repeater for receiving a conventional RF signal, passing through a filter after IF conversion, converting it back to RF, and amplifying and transmitting the RF signal.

4 is a configuration diagram of a repeater for receiving and fully demodulating a conventional RF signal and transmitting the RF signal after RF conversion.

5 is an overall system configuration of the repeater of the present invention.

Figure 6 is a detailed block diagram of a digital filter unit in the present invention.

Explanation of symbols on main parts of drawing

1: DTV modulator 2: DTV RF transmitter

3: RF receiving antenna 4: DTV RF receiver

5: signal processor 6: DTV RF transmitter

7: RF transmitting antenna 41,44: BPF

42: amplifier 43: blender

45: local oscillator 51: VSB modulator

52: VSB demodulator 53: A / D converter

54: I / Q demodulation section 55: digital filter section

56: I / Q modulator 57: D / A converter

58: adaptive compensator 61: mixer

62: HPA 63: RF channel BPF

551: reference signal generator 552: MUX

553: Digital Filter 554: LUT (Look-Up Table)

555: Complex Multiplier

Claims (2)

An RF receiving antenna 3 for receiving an RF signal transmitted from a main transmitting station; The BPF 41 removes an adjacent channel signal from the RF signal received through the antenna 3, and the amplifier 42 amplifies the output signal of the BPF 41 to a predetermined level. A mixer 43 for mixing the output signal and the output signal of the local oscillator 45 and converting them into an intermediate frequency signal IF, and an IF BPF 44 for removing adjacent channel signals in the signal output through the mixer 43. DTV RF receiver (4) consisting of; Included in the mixer unit 61 under the control of the local oscillator 45 and converting the IF signal into an RF signal, the HPA 62 for amplifying the output signal of the mixer unit 61 to a high output and the amplified RF signal. A DTV RF transmitter 6 comprising an RF channel BPF 63 for canceling out-of-band signals; In the digital TV co-channel repeater composed of an RF transmitting antenna (7) for transmitting the RF signal output from the DTV RF transmitter (6), An A / D converter 53 for converting an IF signal input from the IF BPF 44 into a digital signal between the DTV RF receiver 4 and the DTV RF transmitter 6; An I / Q demodulator 54 for demodulating the digital IF signal output from the baseband to the baseband, a demodulated outgoing signal output from the DTV RF transmitter 6, and a digital filter through operations of an adaptive equalizer and a microprocessor. Channel characteristics among the output signals of the I / Q demodulator 54 under the control of the adaptive compensator 58 and the adaptive compensator 58 that calculates the filter coefficient and the look up table (LUT) of the unit 55. Digital filter unit 55 for eliminating errors by compensating for error and compensating for linear and nonlinear distortion components of transmitter HPA 62, and an I / Q modulator for modulating an error corrected signal through the digital filter unit 55. And a D / A converter 57 for converting a digitally modulated signal into an analog IF signal through the I / Q modulator 56. A digital TV co-channel repeater having a digital distortion compensation function, characterized in that an additional signal processor (5) is provided. The method according to claim 1, The digital filter unit 55 outputs a reference data generator 551 for generating reference data for compensating for nonlinear distortion, a signal output from the I / Q demodulator 54, and a reference data generator 551. Digital to remove the linear error by correcting the channel characteristics of the output signal of the I / Q demodulator 54 under the control of the MUX 552, the adaptive compensation unit 58 to select any one of the reference signal to be A complex multiplier 555 for compensating for the nonlinear distortion of the signal input from the filter 553 and the digital filter 553 to the I / Q modulator 56, and a coefficient value of the complex multiplier 555 Digital TV co-channel repeater with a digital distortion compensation function, characterized in that consisting of a LUT (554) for storing the.