KR100667151B1 - Digital ultra-narrowband terminating system using direct-conversion and its multiple-band transmission and receiving apparatus - Google Patents

Abstract

The present invention uses a direct conversion scheme that can improve the performance and maintenance of the terminal by using the DSP technology while satisfying the frequency ultra-narrow banding condition of 6.25 kHz or less, using the DSP technology, and enables low-power driving and light weight of the terminal. A digital ultra narrowband terminal system and a multiband transmitting / receiving apparatus thereof, which perform baseband digital signal processing, voice call implementation, channel encoding and decoding, analog radio frequency (RF) signal processing, and modulation / modulation signal processing through digital wireless communication. A digital signal processing module; Frequency synthesizing means for generating a frequency for direct transmission and reception frequency conversion under the control of the digital signal processing module; Switching means for selecting a reception band of a radio frequency (RF) signal received through a multiband antenna or a transmission band of a radio frequency signal transmitted according to a switch adjustment signal of the digital signal processing module; Multi-band receiving means, under control of the digital signal processing module, for directly frequency converting a reception frequency selected by the switching means into a baseband in-phase (I) and quadrature (Q) signal; And multi-band transmission means for directly converting baseband I and Q signals into a transmission frequency band and transmitting the same through the switching means.

Digital ultra narrowband terminal, direct conversion method, multiband, dual band, DSP

Description

Digital ultra-narrowband terminating system using a direct conversion method and its multi-band transmitting and receiving device {Digital ultra-narrowband terminating system using direct-conversion and its multiple-band transmission and receiving apparatus}             

1 is a configuration example of a conventional FM and digital narrowband terminal,

2 is a block diagram of an embodiment of a direct conversion digital ultra narrowband terminal system according to the present invention;

3 is a diagram illustrating an embodiment of a speech signal flow in a direct conversion type digital ultra narrowband terminal system according to the present invention;

4 is a configuration diagram of an apparatus for transmitting and receiving a multiband in a direct conversion type digital ultra narrowband terminal system according to the present invention.

* Explanation of symbols on the main parts of the drawing

20: DSP module 21: microprocessor

22: RF transceiver 23: power supply

The present invention relates to a digital ultra narrowband terminal system using a direct conversion method and a multi-band transmission and reception apparatus thereof, and more particularly, to control and drive signals of terminals using DSP technology while satisfying a frequency ultra narrowband condition of 6.25 kHz or less. The present invention relates to a digital ultra narrow-band terminal system and a multi-band transmitting / receiving apparatus thereof using a direct conversion method capable of improving and maintaining terminal performance, and easily driving and reducing terminal power.

A simple radio station is a system widely used in construction sites, large discount stores, resorts, and gas delivery for simple business communication within a certain area. Currently, the domestic radio station has a shortage of designated frequencies in comparison to these user demands. As a result, communication quality deterioration and communication failure due to interference are intensifying. In order to improve the frequency shortage caused by the proliferation of the spectrum, the development of frequency ultra narrowband technology is in progress to maximize the utilization efficiency per unit frequency channel (25kHz → 12.5kHz → 6.25kHz).

These improvements include analog single-side band (SSB) technology and digital multiple access technology, which have four to five times the frequency utilization efficiency or equivalent frequency utilization efficiency compared to the FM method using the existing 25KHz channel. .

Currently, developed countries have completed the establishment of frequency narrowband banding plans since 2005 through the establishment of technology for ultra narrowband banding, and digital methods such as Association of Public Safety Communication Officials (APCO) Project 25 and Terrestrial Trunked Radio (TETRA) rather than analog single-sideband technology. Through the transition, we are promoting technology development and commercialization in two directions: providing high quality service through the interworking with other commercial mobile wireless systems and integrating the national public safety net.

For reference, looking at the domestic frequency super narrow banding technology, the UHF band (335.4 ~ 470 MHz) was narrowed to 12.5 kHz at the end of December 1996, some of the VHF band (138 ~ 174 MHz) narrowed at the end of December 2004 Although it is scheduled to end banding, it takes about 63% of all simple radio stations, and the 220MHz band, which has serious interference, is a technical standard of 25kHz. It is in a state not provided.

Looking at the configuration of a conventional FM and digital narrowband terminal with reference to Figure 1 as follows.

1 is a conventional VHF (Very High Frequency) and UHF (Ultra High Frequency) band terminal proposed for the conventional analog frequency modulation (FM) method and 12.5kHz constant-envelope 4-level frequency modulation (C4FM) digital method, Using the heterodyne receiver structure, it consists of a reception pre-end, 1 ^st IF (Intermediate Frequency) stage, 2 ^nd IF stage, analog baseband (I & Q) and frequency synthesizer.

The frequency conversion of the input signal was converted to 45.15MHz in the VHF band (138 to 174MHz) and 73.35MHz in the UHF and 800MHz bands through HSI (High Side Injection), and then the final frequency conversion to 450kHz. .

The transmitter simplifies the configuration of the transmitter by performing direct-modulation, ie, direct frequency conversion, using the constant amplitude characteristics of the FM modulation.

In general, receivers of land mobile radio (LMR) terminals use a heterodyne scheme as shown in FIG. 1.

However, in view of the recent demands of operators and users for multi-band services and multi-mode services according to the expansion of the use frequency band and various services, a change in the form of a terminal for providing such a multi-band / multi-mode service is required. Lose.

Nevertheless, according to the conventional narrowband terminal, many filters are required because the heterodyne method is used to maintain the frequency selectivity and sensitivity, and the specification is difficult, so that it is difficult to integrate with other devices. RF miniaturization and low cost required in terms of wireless mobile communication system for the mode was impossible.

The present invention has been proposed to solve the above problems, while satisfying the frequency ultra narrowband condition of 6.25 kHz or less, by using DSP technology to process the signal control and driving of the terminal using the terminal technology, the terminal performance is improved and easy to maintain and the terminal low power Disclosure of the Invention It is an object of the present invention to provide a digital ultra narrow-band terminal system and a multi-band transmitting / receiving apparatus thereof using a direct conversion method capable of driving and reducing weight.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

The present invention for achieving the above object, in the digital ultra narrowband terminal system, baseband digital signal processing, voice call implementation, channel encoding and decoding, analog radio frequency (RF) signal processing and modulation and demodulation signal processing through digital wireless communication A digital signal processing module performing a function; Frequency synthesizing means for generating a frequency for direct transmission and reception frequency conversion under the control of the digital signal processing module; Switching means for selecting a reception band of a radio frequency (RF) signal received through a multiband antenna or a transmission band of a radio frequency signal transmitted according to a switch adjustment signal of the digital signal processing module; Multi-band receiving means, under control of the digital signal processing module, for directly frequency converting a reception frequency selected by the switching means into a baseband in-phase (I) and quadrature (Q) signal; And multi-band transmission means for directly converting baseband I and Q signals into a transmission frequency band and transmitting the signal through the switching means, wherein the reception means includes multiplexes for filtering and amplifying the RF signal selected by the switching means. Band reception preposition means; I / Q demodulation means for directly frequency converting the frequency input from said reception preposition means into a baseband in-phase (I) / quad phase (Q) signal using the frequency input from said frequency synthesizing means; And filtering the baseband I and Q signals which are directly frequency-converted through the I / Q demodulation means, and then specifying the filtered baseband I and Q signals according to the voltage gain adjustment signal of the digital signal processing module. Filtering and voltage gain amplifying means for amplifying the signal to a digital signal processing module to amplify it to a level, wherein the transmitting means transmits the baseband I and Q signals filtered using the frequency inputted from the frequency synthesizing means. Modulation means for directly converting to a; And multi-band transmission pre-transmission means for filtering and amplifying the baseband I and Q signals directly converted by the modulation means to transmit to the switching means.

In particular, the present invention provides a receiving device of a super narrow band terminal, comprising: control means for adjusting a switch for selecting a reception band, adjusting a voltage gain, and adjusting frequency channel information; Switching means for selecting a reception band of a radio frequency (RF) signal received through a multi-band antenna according to a switch adjustment signal of the control means, respectively; Multi-band reception pre-transmission means for passing only signals of a corresponding reception band in the RF signal selected by the switching means and suppressing and amplifying out-of-band signals; Frequency synthesizing means for generating a frequency for direct conversion of a received frequency in accordance with the frequency channel information adjustment signal of the control means; I / Q demodulation means for directly frequency converting the output signal of the reception preamble into a baseband in-phase (I) / quad phase (Q) signal according to the frequency for the direct conversion of the reception frequency; And filtering the baseband I and Q signals directly frequency-converted through the I / Q demodulation means, and then filtering the filtered baseband I and Q signals according to the voltage gain adjustment signal of the control means. Filtering and voltage gain amplifying means for amplifying and transmitting the amplified circuit to an analog-to-digital converter of the control means.

In addition, the present invention provides a transmitting device of a super narrow band terminal, comprising: control means for monitoring a state of a modulation means, adjusting switch for selecting a transmission band, frequency channel information, inter-path magnitude and phase; Filtering means for filtering baseband modulated in-phase (I) and quadrature (Q) signals respectively applied from the control means; Frequency synthesizing means for generating a frequency for direct transmission frequency conversion in accordance with the frequency channel information adjustment signal of the control means; Modulation for directly converting the filtered baseband I and Q signals to a transmission frequency band according to the frequency generated by the frequency synthesizing means and adjusting the output power according to the inter-path magnitude and phase adjustment signal of the control means Way; Multi-band transmission pre-transmission means for filtering only signals in the corresponding transmission frequency bands from baseband I and Q signals directly converted by the modulation means, and then transmitting them at the maximum output voltage under the control of the modulation means; And switching means for selecting a transmission radio frequency signal input from said transmission preposition means according to a switch adjustment signal of said control means.

The present invention can simultaneously service the VHF band (138 ~ 174MHz) and 220MHz band, which occupies 77% of the domestic simple radio station while satisfying the frequency ultra-narrow banding conditions of 6.25kHz or less, the frequency for low power driving and light weight of the terminal The conversion uses a direct conversion method, and the terminal signal control and driving according to the digitization is made using DSP signal processing technology to improve the performance and maintenance of the terminal. In addition, the present invention improves the power efficiency of the terminal transmitter through the transmission radiation mask standard using the Cartesian Feedback Loop (CFL) linearization method due to the digital linear modulation scheme for ultra narrow bandwidth.

In addition, the 6.25kHz digital ultra narrowband terminal system is currently commercialized, and the structure of the terminal for the multi-band service using the direct transmission / reception scheme proposed by the present invention has not been proposed, but the structure and function of the present invention It can be used for the design and implementation of the terminal of the digital super narrowband frequency common system and the ultra narrowband terminal (including the RF transceiver) for the multiband service, and can be applied to the terminal system having the small size, low cost, and light weight of the LMR terminals in the future. .

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. There will be. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of an embodiment of a direct conversion type digital ultra narrowband terminal system according to the present invention.

Digital ultra narrowband terminal using the direct conversion method according to the present invention is composed of a DSP (Digital Signal Processor) module 20, microprocessor 21, RF transceiver 22, power supply unit 230 and the like.

Specifically, as illustrated in FIG. 2, the direct conversion digital ultra narrowband terminal system according to the present invention includes a power supply unit 23 and baseband digital signal processing, voice call implementation, and channel through digital wireless communication. DSP module 20 and terminal RF interface for performing encoding and decoding, analog radio frequency (RF) signal processing and modulation and demodulation signal processing, and checking the operating state of the RF transceiver 22 through the microprocessor 21. A microprocessor 21 for transmitting or adjusting a signal, and a multi-band RF transceiver 22 for directly converting a transmission / reception frequency using a direct conversion scheme.

Signal flow for the digital terminal voice call is shown in FIG.

Referring to voice communication, first, an analog signal input through a microphone (MIC) 201 is converted into a 64 kbps digital signal through a pulse code modulator (PCM) (8 kHz) 202, so that the bandwidth of the normal voice (4 kHz) The data sampled at twice the speed of 8 kHz is transferred to the speech coder (vocoder) 203 using 8 bit resolution.

At this time, the transmitted data is converted into a digital signal of 4.4kbps through the voice compression process through an AMBE Vocoder chip 203 to conform to the P25 voice standard. The generated data is inserted into a frame and error correction code into 9.6 kbps, and then converted into Coherent Quaternary Phase Shift Keying (CQPSK) through Field Programmable Gate Array (FPLD) (205). Is modulated. The modulated digital signal is converted into an analog signal through a digital to analog converter (206) and then through a signal line (232) to a transmitter (CFL ASIC chip) 221 of the RF transceiver 22. ) Is amplified and wirelessly transmitted through the antenna 224.

On the contrary, the voice signal received through the antenna 224 is applied to the receiver 222 of the RF transceiver 220 to be directly frequency-converted to the baseband, and then through the signal line 233 to the analog-to-digital converter ( A / D Converter 207 converts to a digital signal, then FPGA 205 performs a CQPSK demodulation process and decodes the FEC decoder and speech decoder of speech encoder 203, followed by a pulse code modulator (PCM) 208. The voice is output to the speaker 209 through the.

The DSP module 20 includes a microphone 201, a speaker 209, a pulse code modulator (PCM) 202, 208, a speech coder (AMBE vocoder chip) 203, an FPGA (CPLD) 205, a DSP chip 204 A baseband digital signal processing function (204, 205), AMBE for digital radio communication, including a flash memory (210), a digital / analog converter (206) and an analog / digital converter (207). (Advanced Multi-band Excitation) Voice Call Implementation via Vocoder Chip 203, Channel Encoding and Decoding Functions (203 to 205), Analog RF Signal Processing and Modulation and Demodulation Signal Processing Functions (205) and Signal Lines (232, 233) A function 204 of checking an operating state of the RF transceiver 22 is performed through the microprocessor 21 through 234.

The microprocessor 21 transmits or adjusts the terminal RF interface signal through the signal line 231, and additionally performs functions for a user interface (UI) and a man machine interface (MMI) external to the terminal.

The RF transceiver 22 includes a transmitter 221 including a Cartesian Feedback Loop (CFL) linearization scheme, a receiver 222, a frequency synthesizer (PLL) 223, an antenna 224, and the like. All use direct conversion.

The transmitter 221 performs a frequency-converted transmit signal amplification function, transmit signal filtering, and a spurious signal suppression function, and the receiver 222 performs low noise amplification and filtering of a received signal, and an automatic gain control (AGC) adjustment voltage signal 231. It performs reception gain control, channel out-of-band signal filtering, and converts the received RF signal into an analog baseband signal. The frequency synthesizer (PLL) 223 generates an RF transmit / receive frequency and tunes a channel frequency. ) Perform the function.

The power supply unit 230 supplies power to each module through signal lines 235 and 236 using a single + 7.5V power supply.

4 is a configuration diagram of an apparatus for transmitting and receiving a multiband in a direct conversion type digital ultra narrowband terminal system according to the present invention.

As shown in FIG. 4, the multi-band transceiver of the direct conversion digital super narrowband terminal system includes two antenna terminals for transmitting and receiving signals of a corresponding band, a switch 403 for band selection, and transmission / reception selection of a selected band. Receive pre-end (RxFE) 410,415 and transmit pre-end (TxFE) 441,446, common I / Q demodulator 420, frequency synthesizer (PLL) 432 and Cartesian Feedback Loop (CFL), respectively. 439), the structure is simple and inexpensive by reducing the number of RF components required by using the direct conversion method instead of the general heterodyne method, and also improves the power efficiency characteristics of the transmitter using the CFL 439. It is possible to drive.

The weak RF signal received through each antenna is filtered through the low pass filters 401 and 402 and then by the DSP module 452 through the adjustment terminal signal line 451 at the switch 403 to Band 1 (VHF band, 138). ~ 174MHz) and one of the band 2 band (220MHz band). That is, the DSP module 452 uses two adjustment bits to transmit a "10" signal for Band 1 reception (Rx), "11" for transmission (Tx), and "2" for Band 2 reception. The 00 " signal is applied to the switch 403 through the adjustment terminal signal line 451 in the case of transmission.

The multi-band receiver of the direct conversion digital ultra narrowband terminal system includes a pre-selection band for filtering and low noise amplification for each band [Band 1 (VHF band, 138-174 MHz), Band 2 band (220 MHz band)]. Receive pre-end (RxFE) (410,415) consisting of pass filters (411, 416), low noise amplifiers (412, 413, 417, 418), and band pass filters (414, 419) for removing video signals, and a common I / Q demodulator 420 and I / Q, respectively. Automatic Gain Control (AGC) 422,426 for the path of < RTI ID = 0.0 >

In more detail, as shown in FIG. 4, the multi-band receiving apparatus of the direct conversion type digital ultra narrowband terminal system includes a DSP module for adjusting switch adjustment, voltage gain adjustment, and frequency channel information for selecting a reception band. 452 and a switch 403 for selecting a reception band of the RF signal received and filtered through the multiband antenna according to the switch adjustment signal of the DSP module 452, and a reception band in the switched RF signal ( In the switched RF signal and the first pre-receive stage (Band 1 RxFE) 410 for passing only signals in the VHF band, 138 to 174 MHz, and suppressing and amplifying signals outside the reception band (VHF band, 138 to 174 MHz). Adjusting the frequency channel information of the second pre-receive stage (Band 2 RxFE) 415 and the DSP module 452 to pass only signals in the reception band (220 MHz band) and suppress and amplify signals outside the reception band (220 MHz band).According to the signal, the frequency synthesizer 432 for generating a frequency for direct conversion of the reception frequency, and the output signal of the first and second reception pre-ends (410, 415) in accordance with the frequency for the direct conversion of the baseband baseband I / Q demodulator 420 for directly frequency-converting the in-phase / quad-phase (Q) quadrature-phase (I) signal of the signal, and the frequency-directed basis directly through the I / Q demodulator 420. Low-pass filters 421 and 425 for filtering the I and Q signals in the band and the DSP module 452 by amplifying the filtered baseband I and Q signals to a predetermined level according to the voltage gain adjustment signal of the DSP module 452. Voltage Gain Amplifier (VGA) 422,426 for transmitting to an analog-to-digital converter (ADC).

The weak RF signal received through each antenna is filtered through the low pass filters 401 and 402 and then selects one band through the adjustment signal 451 of the switch 403 by the DSP module 452. For example, when a receiver of Band 1 is selected, that is, when an adjustment signal of "10" is applied, a band (for example, VHF band (138 to 174 MHz) through the band pass filter 411 of the reception pre-end 410. After passing through the signal, the out-of-band signal is suppressed, and then amplified low noise through the low noise amplifiers 412 and 413, and then passed through the image signal removing filter 414. This signal is directly frequency-converted into a baseband signal by an I / Q demodulator 420 consisting of an AGC, I / Q mixer and frequency divider, filtered through a low pass filter (421, 425) and then a VGA (Voltage Gain Amplifier) ( After being amplified to a constant level through 422 and 426, a baseband signal is transmitted to the analog-to-digital converter (ADC) of the DSP module 452 through the signal lines 423 and 427.

Here, the DSP module 452 adjusts the operating voltages of the VGAs 422 and 426 through the signal lines 424 and 428 to supply constant power to the analog-to-digital converters (ADCs) of the DSP module 452. This allows demodulation of the desired signal with minimal distortion without overloading the demodulation.

On the other hand, when the receiver of Band 2 is selected, the same operation as described above.

That is, when a receiver of Band 2 is selected, that is, when an adjustment signal of "00" is applied, a signal in a band (for example, 220 MHz band) is passed through the band pass filter 416 of the reception pre-end 415. In addition, the out-of-band signal is suppressed and then amplified low noise through the low noise amplifiers 417 and 418 and then passed through the image signal removal filter 419. This signal is directly frequency-converted into a baseband signal by an I / Q demodulator 420 consisting of an AGC, I / Q mixer and frequency divider, filtered through a low pass filter (421, 425) and then a VGA (Voltage Gain Amplifier) ( After being amplified to a constant level through 422 and 426, a baseband signal is transmitted to the analog-to-digital converter (ADC) of the DSP module 452 through the signal lines 423 and 427.

Here, the DSP module 452 adjusts the operating voltages of the VGAs 422 and 426 through the signal lines 424 and 428 to supply constant power to the analog-to-digital converters (ADCs) of the DSP module 452. This allows demodulation of the desired signal with minimal distortion without overloading the demodulation.

The frequency synthesizer (PLL) 432 used a dual-PLL synthesizer for direct transmission / reception frequency conversion, and the reception VCO (Voltage Controlled Oscillator) output frequency 433 minimizes the effects of direct conversion (DC- offset, LO leakage, etc.) to generate twice the frequency, applied to the LO (Local Oscillator) terminal of the I / Q demodulator 420, and then based on the RF input frequency through the internal divider (/ 2) circuit. Convert directly to band.

In order to prevent the injection-pulling phenomenon due to the direct conversion method, the transmission VCO frequency 434 also uses a frequency four times or two times the frequency used in the present invention (four times in the present invention). The reference clock frequency uses a 19.2 MHz Voltage Controlled TCXO (VCTCXO) 431, and the clock component of this output frequency operates as a modem portion reference frequency (19.2 MHz) of the DSP module 452 via the signal line 430.

Here, the signal line "429" is a connection line for driving and controlling the frequency synthesizer 432 by the DSP module 452, and adjusts frequency channel information and the like.

On the other hand, the multi-band transmission apparatus of the direct conversion digital ultra narrow band terminal system, the band pass filter (442, 447), the drive amplifier for filtering the signals applied to the CFL (439) for each band and the maximum power amplification of the transmission signal 443,448, TxFE 441,446 consisting of power amplifiers 444,449 and directional couplers 445,450, and common CFLs 439 and LPFs 436,438 for the respective paths of I / Q. do.

In more detail, as shown in FIG. 4, the multi-band transmission apparatus of the direct conversion type digital ultra narrowband terminal system monitors the state of the CFL 439, switches for selecting transmission bands, and frequency channel information. , A low pass filter for filtering the baseband modulated in-phase (I) and quadrature (Q) signals applied from the DSP module 452 and the DSP module 452 for adjusting the magnitude and phase between paths, respectively. 436,438, a frequency synthesizer 432 for generating a frequency for direct transmission frequency conversion according to the frequency channel information adjustment signal of the DSP module 452, and a filtered basis for the frequency for direct transmission frequency conversion CFL 439 for directly converting the I and Q signals of the band to the transmission frequency band and adjusting the output power according to the inter-path magnitude and phase adjustment signal of the DSP module 452, and the directly converted baseband I, Q First transmit pre-transmission for transmitting only signals in the transmission band (VHF band, 138-174MHz) and suppressing signals outside the transmission band (VHF band, 138-174MHz) at maximum output voltage under the control of the CFL 439 Band 1 TxFE 441 and I / Q signals in the directly converted baseband pass only signals in the transmission band (220 MHz band) and suppress signals outside the transmission band (220 MHz band) to adjust the CFL 439. The transmission band is selected in accordance with the switch 1 TxFE (446) and the switch adjustment signal of the DSP module 452 to transmit at the maximum output voltage. And a switch 403, a low pass filter 401, 402, and a dual band antenna for transmitting the signals through the antenna of the corresponding transmission band after filtering the output signals.

The multi-band transmitter of the direct conversion type digital ultra narrowband terminal system also has a case where an adjustment signal of “11” is applied to the transmitter of Band 1 as in the case of the receiver.

The baseband modulated I and Q signals applied from the DSP module 452 through the signal lines 435 and 437 are applied to the lowpass filter and the frequency uplinker (modulator) in the CFL 439 and then directly converted to the transmission frequency band. . The converted signal is filtered through only the bandpass filter 442 and then transmitted to the maximum output voltage through the driving amplifier 443 and the power amplifier 444.

At this time, the CFL 439 is to improve the linearity of the power amplifier 444. The directional coupler 445 samples a part of the output power and the frequency downlink (demodulator) in the CFL 439 through the signal line 452. In this case, the DSP module 452 adjusts the magnitude and phase of the two paths through the signal line 440 to improve the IMD (Inter-modulation Distortion) characteristic by about -30 dBc.

The signal line 454 forming an interface between the CFL 439 and the DSP module 452 is a terminal for checking whether the state of the CFL 439 is high or abnormal.

On the other hand, the operation in the case that the transmitting terminal of the band 2, that is, the adjustment signal of "01" is applied as follows.

The baseband modulated I and Q signals applied from the DSP module 452 through the signal lines 435 and 437 are applied to the lowpass filter and the frequency uplinker (modulator) in the CFL 439 and then directly converted to the transmission frequency band. . The converted signal is filtered through only the bandpass filter 447 and then transmitted only at the maximum output voltage through the driving amplifier 448 and the power amplifier 449.

At this time, the CFL 439 is to improve the linearity of the power amplifier 449. The CFL 439 samples a part of the output power through the directional coupler 450 and samples the frequency downlink (demodulator) in the CFL 439 through the signal line 453. ), The DSP module 452 adjusts the magnitude and phase of the two paths through the signal line 440 to improve the IMD (Inter-modulation Distortion) characteristic by about -30 dBc.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

The present invention as described above has the effect of simultaneously serving the VHF band (138 ~ 174MHz) and 220MHz band while satisfying the frequency ultra-narrow banding conditions of 6.25kHz or less.

In particular, the present invention can not only increase the power efficiency of the transmitter by using the CFL linearization technique for improving the linearity of the transmitter according to the super narrow band through the direct conversion scheme and the digital linear modulation, but also due to the reduction of parts used and the linearization scheme. Low power driving and light weight are possible, and the terminal signal control and driving according to the digitization use the DSP signal processing technology, thereby improving the terminal performance and easy maintenance.

Claims (10)

In the digital ultra narrowband terminal system, A digital signal processing module for performing baseband digital signal processing, voice call implementation, channel encoding and decoding, analog radio frequency (RF) signal processing, and demodulation signal processing through digital wireless communication; Frequency synthesizing means for generating a frequency for direct transmission and reception frequency conversion under the control of the digital signal processing module; Switching means for selecting a reception band of a radio frequency (RF) signal received through a multiband antenna or a transmission band of a radio frequency signal transmitted according to a switch adjustment signal of the digital signal processing module; Multi-band receiving means, under control of the digital signal processing module, for directly frequency converting a reception frequency selected by the switching means into a baseband in-phase (I) and quadrature (Q) signal; And It includes a multi-band transmission means for directly converting the baseband I, Q signal to a transmission frequency band and transmitting through the switching means, The receiving means, Multi-band receive preposition means for filtering and amplifying the RF signal selected by the switching means; I / Q demodulation means for directly frequency converting the frequency input from said reception preposition means into a baseband in-phase (I) / quad phase (Q) signal using the frequency input from said frequency synthesizing means; And After filtering the I and Q signals of the baseband directly frequency-converted through the I / Q demodulation means, the I and Q signals of the filtered baseband are adjusted to predetermined levels according to the voltage gain adjustment signal of the digital signal processing module. Filtering and voltage gain amplifying means for amplifying and transferring to the digital signal processing module, The transmitting means, Modulation means for directly converting the filtered baseband I, Q signals to a transmission frequency band using the frequency input from the frequency synthesizing means; And Multi-band transmission pre-transmission means for filtering and amplifying the baseband I, Q signal directly converted by the modulation means to transmit to the switching means Digital ultra narrowband terminal system using a direct conversion method comprising a. delete In the receiving device of a ultra narrowband terminal, Control means for adjusting a switch for selecting a reception band, adjusting a voltage gain, and adjusting frequency channel information; Switching means for selecting a reception band of a radio frequency (RF) signal received through a multi-band antenna according to a switch adjustment signal of the control means, respectively; Multi-band reception pre-transmission means for passing only signals of a corresponding reception band in the RF signal selected by the switching means and suppressing and amplifying out-of-band signals; Frequency synthesizing means for generating a frequency for direct conversion of a received frequency in accordance with the frequency channel information adjustment signal of the control means; I / Q demodulation means for directly frequency converting the output signal of the reception preamble into a baseband in-phase (I) / quad phase (Q) signal according to the frequency for the direct conversion of the reception frequency; And After filtering the I, Q signals of the baseband directly frequency-converted through the I / Q demodulation means, respectively, the I, Q signals of the filtered baseband to the predetermined level according to the voltage gain adjustment signal of the control means. Filtering and voltage gain amplification means for amplifying and transferring the analog / digital converter of the control means. Multi-band receiving apparatus of a direct conversion digital ultra narrowband terminal system comprising a. The method of claim 3, wherein The frequency synthesizing means, I / Q demodulation means by using a multiple phase-locked loop (PLL) synthesizer for direct conversion of reception frequency, and generating twice the frequency of the reception frequency band to minimize the effect of direct conversion of the reception VCO output frequency. Multi-band receiving apparatus of the direct conversion type digital ultra narrowband terminal system, characterized in that applied to. The method according to claim 3 or 4, The reception band is, Multi-band receiving apparatus of the direct conversion type digital ultra narrowband terminal system, characterized in that it comprises a VHF band (138 ~ 174MHz) and 220MHz band. The method of claim 5, The receiving preposition means, Direct conversion method digital, characterized in that the in-band signal is passed through the band pass filter, the out-of-band signal is suppressed and then amplified low noise through a low noise amplifier and then passed to the I / Q demodulation means through the image signal removal filter Multiband receiving apparatus of ultra narrowband terminal system. In the transmission device of a ultra narrowband terminal, Control means for monitoring the state of the modulation means and adjusting switch adjustment for frequency band selection, frequency channel information, interpath magnitude and phase; Filtering means for filtering baseband modulated in-phase (I) and quadrature (Q) signals respectively applied from the control means; Frequency synthesizing means for generating a frequency for direct transmission frequency conversion in accordance with the frequency channel information adjustment signal of the control means; Modulation for directly converting the filtered baseband I and Q signals to a transmission frequency band according to the frequency generated by the frequency synthesizing means and adjusting the output power according to the inter-path magnitude and phase adjustment signal of the control means Way; Multi-band transmission pre-transmission means for filtering only signals in the corresponding transmission frequency bands from baseband I and Q signals directly converted by the modulation means, and then transmitting them at the maximum output voltage under the control of the modulation means; And Switching means for selecting a transmission radio frequency signal input from said transmission preposition means according to a switch adjustment signal of said control means Multi-band transmission apparatus of the direct conversion digital ultra narrowband terminal system comprising a. The method of claim 7, wherein The frequency synthesizing means, The modulation means by generating a multiple phase synchronization loop (PLL) synthesizer for direct conversion of the transmission frequency, and generating a frequency twice or four times the transmission frequency band in order to minimize the effect of the direct conversion of the transmission VCO output frequency. Apparatus for multi-band transmission of the direct conversion type digital ultra narrowband terminal system, characterized in that applied to. The method according to claim 7 or 8, The transmission band is Multi-band transmission apparatus of the direct conversion type digital ultra narrow band terminal system comprising a VHF band (138 ~ 174MHz) and 220MHz band. The method of claim 9, The modulation means, In order to improve the linearity of the power amplifier of the transmission pre-transmission means, the directional coupler of the transmission pre-transmission means by sampling a portion of the output power to the frequency downlink (demodulator) in the modulation means, the two paths in the control means An apparatus for multiband transmission of a direct conversion type digital ultra narrowband terminal system, wherein the intermodulation distortion (IMD) characteristics can be improved by adjusting the magnitude and phase of the liver.

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