KR20120133674A - Apparatus for up-converting multichannel digital radio frequency - Google Patents

Abstract

PURPOSE: An apparatus for up-converting a multichannel digital radio frequency is provided to prevent changes of a device value due to temperature changes or secular changes by comprising the device with a digital device having high reliability. CONSTITUTION: A plurality of digital modulators(100) perform digital modulation for a plurality of digital signals. A DAC(300) receives a digital signal from the plurality of digital modulators. The DAC converts the digital signal to a broadband radio frequency signals having respective different frequencies. The digital modulator comprises a receiving part which converts the received digital signal to an I signal and a Q signal and a pulse shaping filter which limits a frequency band of the I signal and the Q signal. The digital modulator comprises a first interpolation part performing the interpolation for the I signal and the Q signal, a numerical control oscillator, and a quadrature modulator which comprises a multiplier and an adder and modulates for the Q signal and the I signal. [Reference numerals] (100) First digital modulator; (200) Second interpolation part; (300) DAC; (AA) First digital signal; (BB) Second digital signal; (CC) n-th digital signal; (DD) Second digital modulator; (EE) n-th digital modulator; (FF) RF

Description

Multi-Channel Digital Radio Frequency Upconversion Unit {APPARATUS FOR UP-CONVERTING MULTICHANNEL DIGITAL RADIO FREQUENCY}

The present invention relates to a multichannel digital radio frequency upconversion device. More specifically, the present invention relates to a multi-channel digital radio frequency up-conversion device for upgrading a multi-channel digital signal to the frequency of a wideband RF signal in order to modulate and transmit the multi-channel digital signal into a radio frequency (RF) signal. will be.

A broadband wireless transmission system includes a modulator for modulating a transmission signal to an intermediate frequency (IF) of a radio frequency, and an up converter for receiving the intermediate frequency and then upgrading it to a desired radio frequency (RF). The intermediate frequency is used in various ways such as 36MHz, 44MHz, 70MHz depending on the characteristics of the wireless system. Generally, 36MHz and 44MHz are used for video transmission, and various intermediate frequencies such as 70MHz and 140MHz are used for other wireless communication systems.

The transmission of terrestrial TV and cable TV, military communication, and satellite communication use a very wide frequency band. Especially, terrestrial TV and cable TV use 50-860MHz, and the bandwidth reaches tens of octaves. A device that takes an intermediate frequency and converts the frequency into an arbitrary frequency within a frequency range of tens of octaves is called a wideband upconversion device.

1 is a block diagram showing the configuration of a conventional analog radio frequency upconversion device.

Conventional analogue radio frequency up-conversion device is a super heterodyne system, and includes an analog mixer 12, a fixed voltage controlled oscillator 14, a wideband voltage controlled oscillator 15, and an analog filter 16, and the like. It is composed.

In order to transmit a digital signal to a radio frequency band, it is converted into an analog IF signal, which is mixed with a signal oscillated through the fixed voltage controlled oscillator 14 and converted into a second IF signal, which is converted into a second IF signal. Is mixed with the wideband voltage controlled oscillator 15, converted back to any wideband RF signal and sent out.

When converting a multi-channel digital signal into a radio frequency band having a different frequency at a time by using a conventional analog radio frequency upconversion device, the configuration as shown in FIG. 2 should be used. Such a configuration uses a lot of analog devices. There is a problem that the price increases.

In addition, such an analog radio frequency upconversion device is vulnerable to ambient noise and difficult to integrate. In addition, there is a problem that can affect the performance of the equipment by changing the characteristics due to the change in the value of the device according to the error, temperature change and secular variation of the device value. In addition, analog devices require many adjustments in production, which makes it difficult to mass-produce, expensive, and requires periodic inspection and maintenance.

The present invention has been made to solve the above problems,

The first object of the present invention is to configure the device of the radio frequency up-conversion device as a digital device of high reliability to prevent the change of device value due to temperature change or secular variation, to enable mass production of the frequency up converter, It is to provide a multi-channel digital radio frequency upconversion device that can implement a kind of modulator at a low price.

It is a second object of the present invention to provide a multi-channel digital radio frequency upconversion device capable of miniaturizing a wireless communication and broadcasting device using a wideband frequency.

A third object of the present invention is to provide a multi-channel digital radio frequency up-conversion device capable of transmitting various signals, including digital TV signals and the like, more quietly than when using an analog device.

In accordance with an embodiment of the present invention, a multichannel digital radio frequency upconversion device is provided.

A plurality of digital modulators each receiving a plurality of digital signals and performing digital modulation; And a DAC receiving digital signals from the plurality of digital modulators and converting the digital signals into wideband RF signals having different frequencies from each other.

The digital modulator may include a receiver configured to convert the received digital signal into an I signal and a Q signal; A pulse shaping filter receiving I and Q signals from the receiver and limiting frequency bands of the I and Q signals; A first interpolation unit performing interpolation to increase the sampling rates of the I and Q signals; And a quadrature modulator configured to receive the I and Q signals from the first interpolation unit, a numerically controlled oscillator for oscillating a cosine signal and a sine signal, and a multiplier and an adder for modulating the I and Q signals. It may include.

The multi-channel digital radio frequency upconversion device receives a plurality of digital signals from the plurality of digital modulators, performs interpolation to increase the sampling rate of the digital signals, synthesizes the plurality of digital signals, and delivers the digital signals to the DAC. It may further include a two interpolation unit.

In accordance with another embodiment of the present invention, a multichannel digital radio frequency upconversion device is provided.

A plurality of digital modulators, each receiving a plurality of analog IF signals, converting the signal into a digital signal, and performing digital modulation on the digital signal; And a DAC receiving digital signals from the plurality of digital modulators and converting the digital signals into wideband RF signals having different frequencies from each other.

The digital modulator includes: an ADC for converting the analog IF signal into a digital signal; A quadrature demodulator receiving the digital signal from the ADC, demodulating the signal into an I signal and a Q signal, and reducing their frequencies to convert to a baseband digital signal; An LPF receiving I and Q signals from the quadrature demodulator and removing their harmonics; A first interpolation unit performing interpolation to increase the sampling rates of the I and Q signals; And a quadrature modulator configured to receive the I and Q signals from the first interpolation unit, a numerically controlled oscillator for oscillating a cosine signal and a sine signal, and a multiplier and an adder for modulating the I and Q signals. It may include.

The multi-channel digital radio frequency upconversion device receives a plurality of digital signals from the plurality of digital modulators, performs interpolation to increase the sampling rate of the digital signals, synthesizes the plurality of digital signals, and delivers the digital signals to the DAC. It may further include a two interpolation unit.

The multi-channel digital RF upconversion device according to an embodiment of the present invention has the following effects.

(1) The device of the radio frequency upconversion device is composed of high reliability digital device to prevent the change of device value due to temperature change or secular variation, to enable mass production of frequency upconverter, and to provide various kinds of modulators. It can be implemented at a low price.

(2) Minimize the development of wireless communication and broadcasting equipment using broadband frequencies.

(3) Various signals, including digital TV signals, can be transmitted more quietly than when using analog devices.

1 is a block diagram showing the configuration of a conventional analog radio frequency upconversion device.
2 is a diagram illustrating an apparatus for upconverting a multi-channel digital radio frequency using a conventional analog radio frequency upconversion device.
3 is a block diagram illustrating a configuration of a multi-channel digital radio frequency upconversion device according to an embodiment of the present invention.
4 is a block diagram illustrating a configuration of a digital modulator of a multi-channel digital radio frequency upconversion device according to an embodiment of the present invention.
FIG. 5 is a block diagram illustrating a configuration of a digital modulator of a multi-channel digital radio frequency upconversion device according to another embodiment of the present invention.

Hereinafter, the present invention will be described in detail through exemplary embodiments with reference to the accompanying drawings, and the present invention is not limited thereto. In addition, detailed descriptions of well-known functions and configurations that may blur the gist of the present invention will be omitted.

3 is a block diagram illustrating a configuration of a multi-channel digital radio frequency upconversion device according to an embodiment of the present invention.

Referring to FIG. 3, the multi-channel digital radio frequency upconversion device according to an embodiment of the present invention includes a plurality of digital modulators 100, a second interpolation unit 200, and a DAC 300.

The plurality of digital signals, the first digital signal and the second digital signal to the n-th digital signal, are respectively received by the first digital modulator and the second digital modulator to the n-th digital modulator of the plurality of digital modulators 100.

The plurality of digital modulators 100 performs digital modulation on the received digital signal and transmits the digital modulator to the second interpolation unit 200.

The second interpolation unit 200 performs interpolation to increase the sampling rate of the digital signals received from the plurality of digital modulators 100, synthesizes the plurality of digital signals, and then synthesizes the plurality of digital signals. The DAC 300 converts the digital signal into wideband RF signals having different frequencies from each other and transmits the same. Since the sampling frequency of the high-speed DAC 300 is very high, in the case of a TV channel having a bandwidth of 6 ~ 8Mhz, it is possible to up-convert a plurality of channels at a time to a desired RF frequency.

4 is a block diagram showing the configuration of the digital modulator 100 of the multi-channel digital radio frequency up-conversion device according to an embodiment of the present invention.

Referring to FIG. 4, the digital modulator 100 includes a receiver 110, a pulse shaping filter 120, a first interpolation unit 130, and a quadrature modulator 140.

The receiver 110 receives the baseband digital signal and converts the baseband digital signal into an in-phase signal (hereinafter referred to as I signal) and a quadrature signal (hereinafter referred to as Q signal).

Digital signals are converted into I and Q signals and quadrature modulated. This modulation method is called in-phase / quadrature (I / Q) modulation. I / Q modulation is a method of transmitting two separate channels of information, where the carrier signal is shifted to produce two carriers in a sin and cosine version. Two modulation inputs are applied to two separate modulators, each of which is fed a signed or cosine carrier. The outputs of the two modulators are logarithmically summed and the result is one signal to be transmitted containing I and Q information. Upon receipt, the composite signals I and Q are processed and extracted by a receiver using carrier replicas (sign and cosine).

Modulation of the digital signal to the I signal and the Q signal can be used in a variety of ways within a range apparent to those skilled in the art.

The digital pulse shaping filter 120 is essentially used in a digital communication system, and converts a symbol of an input signal into a shape of a specific waveform to limit a frequency band.

The digital signal passing through the pulse shaping filter 120 passes through the first interpolation unit 130 that performs interpolation to increase the sampling rate of the digital signal.

Since the digital signal must be modulated with a high frequency RF signal, the quadrature modulator 140 is composed of a numerically controlled oscillator (NCO), two multipliers and an adder, and a cosine signal in the numerically controlled oscillator. And oscillate a sin signal, and perform modulation of the I signal and the Q signal.

The numerically controlled oscillator 240 corresponds to the voltage controlled oscillator 14 in the analog domain and is an oscillator used in the digital domain. Referring to the operation of the voltage controlled oscillator 14, the input of the voltage controlled oscillator 14 is a voltage, the output is the frequency of the oscillator. The whole unit of the voltage controlled oscillator 14 is output / input and becomes rad / v. As the input voltage increases, the output frequency increases, and this characteristic is used for PLL. In the digital domain, a device having the same characteristics as the voltage controlled oscillator 14 in the analog domain is referred to as a numerically controlled oscillator in the sense that a multibit number is used as an input instead of a voltage.

As described above with reference to FIG. 3, the digital signals passing through the quadrature modulator 140 are interpolated by the second interpolation unit 200 to increase the sampling rate, synthesized, and finally synthesized through the DAC 300. Each frequency is converted into a high frequency RF signal and transmitted.

In order to process wideband RF signals of 50 to 860 MHz used in the digital TV field in the digital domain, the DAC 300 may use an ultrafast DAC 300 having a conversion frequency of 2 GHz.

FIG. 5 is a block diagram illustrating a configuration of a digital modulator 100 of a multi-channel digital radio frequency upconversion device according to another embodiment of the present invention.

The multi-channel digital radio frequency up-conversion device according to another embodiment of the present invention is for converting a plurality of analog IF signals, respectively, into wideband RF signals having different frequencies from each other, which is analog-to-digital. The convert 150 includes a quadrature demodulator 160, a low pass filter (LPF) 170, a first interpolation unit 180, and a quadrature modulator 190.

When an analog IF signal is received, the received IF signal is amplified and filtered, and converted into a digital signal through an analog-digital conveter (ADC) 150.

The digital signal is separated into an I signal and a Q signal through the quadrature demodulator 160, and the IF signal is converted into a baseband signal. The converted baseband digital signal is harmonic content is removed via the LPF (170).

Thereafter, as described with reference to FIGS. 3 and 4, the digital signal is converted into a wideband RF signal through the first interpolation unit 180, the quadrature modulator 190, the second interpolation unit 200, and the DAC 300. It is converted and sent out.

The digital radio frequency up-conversion device of the present invention can be used for the digital TV transmitter and the like as described above, and enables the development of a multi-channel modulator and a modulator through high integration of the digital unit, and in particular, It may be used for base station equipment or repeaters for mobile communication.

As mentioned above, although this invention was demonstrated to the said Example, this invention is not limited to this. It will be understood by those skilled in the art that modifications and variations may be made without departing from the spirit and scope of the invention, and that such modifications and variations are also contemplated by the present invention.

12: analog mixer
14: Fixed Voltage Controlled Oscillator
15: Wideband Voltage Controlled Oscillator
16: analog filter
100: digital modulator
110:
120: pulse shaping filter
130, 180: first interpolation unit
140, 190: Quadrature Modulator
150: ADC
160: quadrature demodulator
170: LPF
200: second interpolation unit
300: DAC

Claims (6)

A plurality of digital modulators each receiving a plurality of digital signals and performing digital modulation; And
And a DAC receiving digital signals from the plurality of digital modulators and converting the digital signals into wideband RF signals having different frequencies from each other.
The method of claim 1, wherein the digital modulator,
A receiver for converting the received digital signal into an I signal and a Q signal;
A pulse shaping filter receiving I and Q signals from the receiver and limiting frequency bands of the I and Q signals;
A first interpolation unit performing interpolation to increase the sampling rates of the I and Q signals; And
A numerically controlled oscillator receiving the I signal and the Q signal from the first interpolation unit, and a quadrature modulator including a multiplier and an adder for modulating the I and Q signals; Multi-channel digital radio frequency up-conversion device characterized in that.
The apparatus of claim 1, wherein the multi-channel digital radio frequency upconversion device is
And receiving a plurality of digital signals from the plurality of digital modulators, performing interpolation to increase a sampling rate of the digital signals, and synthesizing the plurality of digital signals, and then transmitting the second interpolation unit to the DAC. Channel digital radio frequency upconversion device.
A plurality of digital modulators, each receiving a plurality of analog IF signals, converting the signal into a digital signal, and performing digital modulation on the digital signal; And
And a DAC receiving digital signals from the plurality of digital modulators and converting the digital signals into wideband RF signals having different frequencies from each other.
The method of claim 4, wherein the digital modulator,
An ADC for converting the analog IF signal into a digital signal;
A quadrature demodulator receiving the digital signal from the ADC, demodulating the signal into an I signal and a Q signal, and reducing their frequencies to convert to a baseband digital signal;
An LPF receiving I and Q signals from the quadrature demodulator and removing their harmonics;
A first interpolation unit performing interpolation to increase the sampling rates of the I and Q signals; And
A numerically controlled oscillator receiving the I signal and the Q signal from the first interpolation unit, and a quadrature modulator including a multiplier and an adder for modulating the I and Q signals; Multi-channel digital radio frequency up-conversion device characterized in that.
The apparatus of claim 4, wherein the multi-channel digital radio frequency upconversion device is
And receiving a plurality of digital signals from the plurality of digital modulators, performing interpolation to increase a sampling rate of the digital signals, and synthesizing the plurality of digital signals, and then transmitting the second interpolation unit to the DAC. Channel digital radio frequency upconversion device.

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