KR20030075438A - Transmitting and Receiving Apparatus with Only One Oscillator in Radio Transmission System - Google Patents

Abstract

PURPOSE: A transmitting and receiving device using one local oscillator in a wireless transmission system is provided to reduce the size of a system by composing a transmitter and a receiver as one module and sharing the local oscillator. CONSTITUTION: One local oscillator(407) is used in a frequency up-conversion and a primary frequency down-conversion, for oscillating a local signal. A frequency up-converter(402) mixes a transmission signal with an IF(Intermediate Frequency) band, which is modulated in a modulator(401), with the local signal from the local oscillator(407), for up-converting the IF band into an RF(Radio Frequency) band. An amplifier(403) amplifies the voltage level of the transmission signal received from the frequency up-converter(402), as a voltage level suitable for long-distance transmission. A low noise amplifier(404) amplifies a receiving signal. A primary frequency down-converter(405) mixes the receiving signal received from the low noise amplifier(404) with the local signal from the local oscillator(407), for performing the primary frequency down-conversion. A frequency synthesizer(409) synthesizes the local signal used in a secondary frequency down-conversion. A secondary frequency down-converter(406) mixes the receiving signal down-converted in the primary frequency down-converter(405) with the local signal from the frequency synthesizer(409), for performing the second frequency down-conversion.

Description

Transmitting and Receiving Apparatus with Only One Oscillator in Radio Transmission System}

The present invention relates to a transmission and reception apparatus using one local oscillator, and more particularly, to make a transmitter and a receiver of a wireless transmission system into one module to oscillate the transmitter and the receiver using only one local oscillator. It relates to a transmitting and receiving device.

A method mainly used for transmitting and receiving signals at a transmitter and a receiver in a general wireless transmission system is a heterodyne method. In the heterodyne system, a transmitter modulates an input baseband signal into an intermediate frequency (IF) signal, converts the intermediate frequency signal into a radio frequency (RF) signal, and transmits the same through a transmitting antenna. The receiver converts the radio frequency signal received from the receiving antenna into an intermediate frequency signal and then converts the intermediate frequency (IF) signal into a baseband signal.

In the conventional wireless transmission system, a local oscillator is used by separating a transmitter and a receiver.

1 is a block diagram of a transmitter and a receiver of a conventional wireless transmission system to which a heterodyne scheme is applied.

As shown in FIG. 1, a transmitter 100 of a conventional wireless transmission system using a heterodyne method converts a transmission signal of an intermediate frequency (70 MHz) input from a modulator 101 into a radio frequency (8 GHz) signal. A local frequency (8 GHz) transmitter for transmitting a local signal (8 GHz) which is used to transmit a local frequency (8 GHz) according to a local signal (8 GHz) from the local oscillator (104) for the transmitter. And a amplifier 103 for amplifying the voltage of the transmission signal received from the frequency riser 102.

That is, the frequency riser 102 mixes the transmission signal (transmission data) of the intermediate frequency (70 MHz) input from the modulator 101 with the radio frequency signal (8 GHz) oscillated by the local oscillator 104, thereby radio frequency (8 MHz). The signal is raised to a radio frequency and sent to the amplifier 103 so as to be amplified and transmitted through the transmit antenna.

On the other hand, the receiver 110 is a low-noise amplifier 105 for amplifying the voltage of the signal received through the receiving antenna with low noise, and the received signal of the radio frequency (8 GHz) received through the receiving antenna to the intermediate frequency (70MNz) signal A local oscillator 108 for oscillating a local signal (8 GHz) used for converting a signal to a local signal, and a frequency of a received signal input from the low noise amplifier 105 to a local signal from the local oscillator 108 for the receiver. And a frequency lowering unit 106 for lowering the intermediate frequency according to (8 GHz) and outputting the result to the demodulator 107.

That is, in order for the frequency lowering of the low noise amplified radio frequency (8 GHz) signal received through the receiving antenna, the frequency lowering unit 106 receives the local signal (8 GHz) input from the local oscillator 108 and the received radio frequency (8 GHz). The signal is mixed to output an intermediate frequency (70 MHz) signal.

2 is an overall conceptual diagram of a conventional wireless transmission system.

As shown in FIG. 2, since the general wireless transmission system is bidirectional (send and receive) rather than unidirectional, the number of local oscillators used in the conventional wireless transmission system is four in total, two for transmission and one for reception. Able to know.

Therefore, the conventional wireless transmission system has a large volume of the whole system, the reliability and stability of the high frequency local oscillator is inferior, and the supply and demand of materials is difficult.

In addition, in the conventional wireless transmission system, since the local oscillators have a slight frequency deviation, the frequency deviation caused by the use of two or more local oscillators is further weighted. There was an increasing problem.

The present invention has been proposed to solve the above problems, to provide a local signal for the frequency rise and frequency down by configuring a transmitter and a receiver used in a communication system such as a wireless transmission system as one module It is an object of the present invention to provide a transmitter and receiver using a single local oscillator that can reduce the size of the system and simplify the structure by sharing the local oscillator used, and can reduce the amount of adjustment work by more than half.

In addition, the present invention, by using the same local oscillator in the transmitter and receiver using a method of determining the frequency of the frequency synthesizer using the deviation of the frequency difference of the GO / RETURN per channel per frequency band in the wireless transmission system It is an object of the present invention to provide a transmission / reception device using one local oscillator to reduce frequency deviation.

1 is a block diagram of a conventional wireless transmission system to which the heterodyne method is applied.

2 is an overall conceptual diagram of a conventional wireless transmission system.

3 is a conceptual diagram of an embodiment of a wireless transmission system according to the present invention;

4 is a block diagram of an embodiment of a transmission and reception apparatus using one local oscillator according to the present invention.

5 is a diagram illustrating an embodiment of a frequency down conversion process according to the present invention;

* Explanation of symbols for the main parts of the drawings

101, 401: modulator 102, 402: frequency riser

103, 403: amplifier 104, 108, 407: local oscillator

105, 404: low noise amplifier 106, 405, 406: frequency down

107, 408: demodulator

According to an aspect of the present invention, there is provided a transmission / reception apparatus using one local oscillator, comprising: one local oscillation means for oscillating a local signal commonly used for frequency rising conversion and primary frequency falling conversion; A frequency raising means for mixing up the transmission signal of the modulated intermediate frequency band for transmission with the local signal from the local oscillation means and upconverting the radio frequency band; Amplifying means for amplifying a transmission signal received from the frequency raising means; Low noise amplifying means for amplifying the received signal; First frequency lowering means for first-order down converting the received signal input from the low noise amplifying means by mixing with the local signal from the local oscillating means; Frequency synthesizing means for synthesizing a local signal for use in secondary frequency downconversion; And second frequency lowering means for mixing the first frequency down-converted received signal with a local signal from the frequency synthesizing means to perform second down conversion.

In addition, the present invention is characterized in that it further comprises an automatic gain control means for maintaining a constant power level of the received signal of the first frequency down conversion in the primary frequency down means.

In addition, the present invention is characterized in that it further comprises an automatic gain control means for maintaining a constant power level of the received signal converted by the secondary frequency down conversion in the secondary frequency down means.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the wireless transmission system proposed in the present invention, the frequency band of the transmit / receive signal is assumed to be 8 GHz, but the frequency of the local oscillator signal of the local oscillator and the local oscillator signal input to the secondary frequency dropper are different depending on the frequency band of the transmit / receive signal.

3 is a conceptual diagram of an embodiment of a wireless transmission system according to the present invention.

As shown in Fig. 3, the wireless transmission system according to the present invention is configured to provide local signals to both the transmitter and the receiver with only one local oscillator. Detailed configuration and operation thereof will be described with reference to FIG. 4.

4 is a diagram illustrating an embodiment of a transmission and reception apparatus using one local oscillator according to the present invention.

As shown in FIG. 4, a transmission / reception apparatus using one local oscillator according to the present invention includes one local oscillator 407 for oscillating a local signal commonly used for frequency rising conversion and primary frequency falling conversion. A frequency riser 402 for up-converting the transmission signal (transmission data) of the intermediate frequency band modulated by the modulator 401 with the local signal from the local oscillator 407 to a radio frequency band, and the frequency riser 402. An amplifier 403 for amplifying the voltage level of the transmission signal received from the signal to a voltage level suitable for long-distance transmission, a low noise amplifier 404 for low noise amplifying the received signal, and a received signal received from the low noise amplifier 404 A first frequency down converter 405 and a second frequency for mixing down with the local signal from the local oscillator 407 to perform the first down conversion. A frequency synthesizer 409 for synthesizing a local signal used for the strong conversion, and a received signal down-converted by the primary frequency reducer 405 by mixing with a local signal from the frequency synthesizer 409 to lower the secondary And a secondary frequency down converter 406 for converting.

Hereinafter, referring to FIG. 4, operation of each component of a transceiver using one local oscillator according to the present invention will be described.

First, referring to the operation of the transmitter, a radio frequency by mixing the transmission signal (transmission data) of the intermediate frequency (70 MHz) output from the modulator 401 with the local signal (8 GHz) of the local oscillator 407 in the frequency riser 402. When the signal is raised to a signal of (8 GHz) and input to the amplifier 403, the amplifier 403 amplifies the voltage of the received signal to a voltage level suitable for long-distance transmission and transmits it through the transmission antenna.

Next, referring to the operation of the receiver, the received signal received through the receiving antenna is amplified with low noise in the low noise amplifier 404, the primary frequency down 405 is received with the local signal (8GHz) of the local oscillator 407 The signal is mixed down to convert the received signal to a first intermediate frequency, and the second frequency down converter 406 converts the signal down-converted to the first intermediate frequency in the primary frequency down converter 405 from the frequency synthesizer 409. After mixing with the local signal of the down-conversion to the second intermediate frequency (70MHz) and transmits to the demodulator 408.

Therefore, since the radio frequency signal received at the receiving antenna is frequency-descent converted over the first and second orders, the radio frequency signal has two intermediate frequencies during the frequency conversion process.

At this time, if there is an automatic gain controller between the primary frequency lowering unit 405 and the secondary frequency lowering unit 406 although not shown in the figure, the voltage level of the received signal can be demodulated by the demodulator 408. As a result, the system can be implemented with higher performance. In another embodiment, the automatic gain controller may be positioned next to the secondary frequency down converter 406.

FIG. 5 is a diagram illustrating an example of a frequency down conversion process according to the present invention. FIG.

As shown in FIG. 5, converting a radio frequency signal received by a receiving antenna into a 221.614 MHz signal is referred to as a first frequency down conversion, and converting a first frequency down converted 221.614 MHz signal into a 70 MHz signal. This is called the differential frequency falling transform.

The frequency of the signal used for the second frequency down conversion is obtained by using a transmission (GO) and a reception (RETURN) frequency table recommended by the International Telecommunication Union-Radiocommunication Sector (ITU-R). Table 1 below shows a frequency table indicating a transmission (GO) and a reception (RETURN) frequency in the 8 MHz band, which is an oscillation frequency.

Referring to Table 1, a method of generating a frequency down-converted signal, taking the case of channel 1 as an example, is as follows.

Since the frequency of the signal received through the receiving antenna is 8.431634 MHz, the signal output by mixing with the signal of the local oscillator, which is the frequency of 8.210020 MHz, that is, the frequency of the signal output from the primary frequency dropper becomes 221.614 MHz. This signal is mixed with a signal at 291.614 MHz to descend to a baseband signal at 70 MHz.

In other words, when the frequency down conversion is performed first, a signal of 221.614 MHz is generated, and when the signal is mixed with the 291.614 MHz signal for the second frequency down conversion, it becomes a 70 MHz signal.

At this time, the generation of the 291.614MHz signal is due to the frequency difference between the transmission signals and the reception signals of the respective channels of Table 1 is always 151.614MHz. That is, the frequency difference between the transmission local transmitter signals and the reception local oscillator signals of each channel of Table 1 is always 291.614 MHz.

channel Transmit (GHz) Receive (GHz) Channel 1 signal 8.280020 8.431634 Local oscillator signal 8.210020 8.501634 Channel 2 signal 8.291682 8.443296 Local oscillator signal 8.221682 8.513296 Channel 3 signal 8.303344 8.454958 Local oscillator signal 8.233344 8.524958 Channel 4 signal 8.315006 8.466620 Local oscillator signal 8.245006 8.536620 Channel 5 signal 8.326668 8.478282 Local oscillator signal 8.256668 8.548282 Channel 6 signal 8.338330 8.489944 Local oscillator signal 8.268330 8.559944

In the above description, the radio frequency of the 8 GHz band has been described as an example. However, the frequency in the same manner as described above using the difference in the transmission (GO) and the receiving (RETURN) frequency for each channel is constant for frequencies other than 8 GHz. The descent conversion can be performed. That is, in the present invention, the frequency of the frequency synthesizer is determined and used using the deviation caused by the frequency difference of GO / RETURN per channel for each frequency band.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the art without departing from the technical spirit of the present invention. It will be clear to those of ordinary knowledge.

The present invention as described above, the system by configuring a transmitter and a receiver used in a communication system such as a wireless transmission system as a single module to share a local oscillator used for supplying a local signal for frequency rise and frequency fall In addition to reducing the size and simplifying the structure, there is an effect of reducing the amount of adjustment work by more than half.

In addition, the present invention, by using the same local oscillator in the transmitter and receiver using a method of determining the frequency of the frequency synthesizer using the deviation of the frequency difference of the GO / RETURN per channel per frequency band in the wireless transmission system There is an effect that can reduce the frequency deviation.

Claims (4)

In the transmission and reception apparatus using one local oscillator in a wireless transmission system, One local oscillating means for oscillating a local signal commonly used for frequency rising conversion and primary frequency falling conversion; A frequency raising means for mixing up the transmission signal of the modulated intermediate frequency band for transmission with the local signal from the local oscillation means and upconverting the radio frequency band; Amplifying means for amplifying a transmission signal received from the frequency raising means; Low noise amplifying means for amplifying the received signal; First frequency lowering means for first-order down converting the received signal input from the low noise amplifying means by mixing with the local signal from the local oscillating means; Frequency synthesizing means for synthesizing a local signal for use in secondary frequency downconversion; And Secondary frequency dropping means for mixing the primary frequency down-converted received signal with a local signal from the frequency synthesizing means to perform secondary downconversion Transmitting and receiving device using one local oscillator in a wireless transmission system comprising a. The method of claim 1, Automatic gain control means for maintaining a constant power level of the first frequency down-converted received signal by the primary frequency lowering means Transmitting and receiving device using one local oscillator in a wireless transmission system further comprising. The method of claim 1, Automatic gain control means for maintaining a constant power level of the second frequency down conversion received signal by the second frequency down means; Transmitting and receiving device using one local oscillator in a wireless transmission system further comprising. The method according to any one of claims 1 to 3, The frequency synthesizing means, Transmitter and receiver using a single local oscillator in a wireless transmission system, characterized in that the frequency determined by using the deviation according to the frequency difference per channel recommended by the International Standardization Organization synthesized and supplied as a local signal to the secondary frequency lowering means .