CN109347499B - Method for analyzing interference mechanism of radio frequency front end of communication receiver - Google Patents

Method for analyzing interference mechanism of radio frequency front end of communication receiver Download PDF

Info

Publication number
CN109347499B
CN109347499B CN201811155760.4A CN201811155760A CN109347499B CN 109347499 B CN109347499 B CN 109347499B CN 201811155760 A CN201811155760 A CN 201811155760A CN 109347499 B CN109347499 B CN 109347499B
Authority
CN
China
Prior art keywords
interference
signal
receiver
frequency
radio frequency
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201811155760.4A
Other languages
Chinese (zh)
Other versions
CN109347499A (en
Inventor
孟进
赵治华
王青
李毅
何方敏
唐健
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Naval University of Engineering PLA
Original Assignee
Naval University of Engineering PLA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Naval University of Engineering PLA filed Critical Naval University of Engineering PLA
Priority to CN201811155760.4A priority Critical patent/CN109347499B/en
Publication of CN109347499A publication Critical patent/CN109347499A/en
Application granted granted Critical
Publication of CN109347499B publication Critical patent/CN109347499B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06—Receivers
    • H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
    • H04B1/1027—Means associated with receiver for limiting or suppressing noise or interference assessing signal quality or detecting noise/interference for the received signal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B17/00—Monitoring; Testing
    • H04B17/20—Monitoring; Testing of receivers
    • H04B17/29—Performance testing

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Noise Elimination (AREA)

Abstract

The invention provides a method for analyzing an interference mechanism of a radio frequency front end of a communication receiver, which is characterized in that a nonlinear mathematical model of the communication receiver under the interference action is established according to a radio frequency front end circuit of the receiver, the interference action mechanism and the interference characteristic are found out, different interference types formed under different frequency relation conditions of a useful signal and an interference signal are analyzed, and an interference generating condition and a quantitative analysis method of strongest interference in each type are obtained. And calculating to obtain a maximum interference signal which does not influence the reception of the useful signal by utilizing the analysis result and the minimum signal-to-noise ratio requirement of the receiver, and finally obtaining the quantitative suppression requirement of the interference signal by combining the actual interference signal size to realize the quantitative design of the interference cancellation device index. The invention not only can accurately clarify the action mechanism of different interference types formed under the simultaneous action of the useful signal and the interference signal, but also can accurately calculate the interference suppression requirement, and can realize the quantitative suppression design of the co-location interference of the communication system.

Description

Method for analyzing interference mechanism of radio frequency front end of communication receiver
Technical Field
The invention relates to the technical field of electromagnetic compatibility analysis design, in particular to a method for analyzing an interference mechanism of a radio frequency front end of a communication receiver.
Background
The independent platforms such as ships, war chariot, fighter plane, etc. are equipped with various devices such as communication, radar, electronic warfare, etc., and the common point of the devices is that the devices need to complete the transmission or reception of signals by means of antennas, resulting in dense antennas on the platforms and insufficient mutual space isolation. The transmitting antenna transmits a high-power signal to a far-end receiver, the receiver receives a weak communication signal from a far end, and a local transmitting signal is a useless signal for the local receiver and is a strong co-location interference signal. When the distance between the transmitting antenna and the receiving antenna is close, although the difference between the frequency of the transmitted signal and the frequency of the received signal is far, because a strong interference signal generated by the transmitter enters the receiver through space radiation, a front end circuit of the receiver is saturated or the sensitivity of the receiver is reduced, the receiver cannot normally work, and the electromagnetic compatibility problem of a communication system is caused.
An effective method for solving the electromagnetic compatibility problem adopts a radiation interference self-adaptive cancellation technology, and the basic principle is that a reference signal is extracted at a transmitting end, a cancellation signal which is equal to the interference signal in size and opposite to the interference signal is generated through a self-adaptive control algorithm, and the cancellation signal is positively and negatively cancelled with the interference signal at the front end of a receiver, so that the interference is eliminated. For example, the multi-channel interference cancellation device (patent number: ZL201518001239.6) invented by the applicant can simultaneously cancel the co-location coupling interference of the co-platform multi-channel transmitter to the receiver, and ensure the simultaneous compatible operation of the transceiver system.
The interference of the transceiver in the communication system is caused by a plurality of factors, and an interference action mechanism model and an analysis method must be studied in depth to thoroughly solve the problem of interference elimination. Previous studies have not modeled receiver systems containing both useful and interfering signals, and have failed to accurately reveal the mechanisms of action of different types of interference. The quantitative suppression design of the co-location radiated interference of the communication system can be realized only if the quantitative corresponding relation between the interference suppression ratio and the received signal-to-noise ratio is correctly established.
Disclosure of Invention
The invention aims to provide a method for analyzing an interference mechanism of a radio frequency front end of a communication receiver aiming at the defects of the prior art, and the quantitative design of the indexes of an interference cancellation device is realized.
The invention provides a method for analyzing an interference mechanism of a radio frequency front end of a signal receiver, which comprises the following steps: analyzing different interference types formed under different frequency relation conditions when a useful signal and an interference signal are input at the radio frequency front end of the communication receiver, so as to obtain the generating conditions of co-frequency interference, harmonic interference, intermodulation interference and an analyzing method; and calculating to obtain a maximum interference signal which does not influence the reception of the useful signal by utilizing the analysis result and the minimum signal-to-noise ratio requirement of the receiver, and finally obtaining the quantitative suppression requirement of the interference signal by combining the actual interference signal size to realize the quantitative design of the interference cancellation device index.
The invention adopts the following steps to analyze:
setting the input signal of the radio frequency front end of the communication receiver as VinThe output signal is VoutUsing a third order nonlinear model (a)1、a2、a3Third order linear factors, respectively) to describe the rf front-end characteristics of a communication receiver, can be expressed as:
Figure BDA0001818925080000031
if the input signal VinFrom frequency ωSAmplitude of VSAnd two of the useful signal
Frequency of omega respectivelyI1And ωI2Respectively having an amplitude of VI1And VI2The interference signal components of (a), namely:
Vin＝Vscosωst+VI1cosω11t+VI2cosω12t
then the signal V is outputoutCan be expressed as a number of times,
Vout＝a1(Vscosωst+VI1cosωI1t+VI2cosωI2t)+a2(Vscosωst+VI1cosωI1t+VI2cosωI2t)2+a3(VScosωSt+VI1cosωI1t+VI2cosωI2t)3
the minimum requirement of signal-to-noise ratio for ensuring the communication receiving quality is SNR, the original amplitude of an interference signal is V, and the residual amplitude of the interference when the SNR is expected to reach is VreThen the interference suppression requirement is:
RdB＝20log(V)-20log(Vre)
specifically to each type of interference, the co-channel interference suppression requirements are:
Figure BDA0001818925080000032
the harmonic interference rejection requirements are:
Figure BDA0001818925080000033
the intermodulation interference rejection requirements are:
Figure BDA0001818925080000034
the intermodulation interference suppression requirements are:
Figure BDA0001818925080000041
the modeling method for describing the front-end circuit of the receiver by adopting the third-order nonlinear model can accurately clarify the action mechanism of different interference types formed under the simultaneous action of the useful signal and the interference signal. The invention establishes the quantitative corresponding relation between the interference suppression ratio and the receiving signal-to-noise ratio, can accurately analyze the relation between the interference suppression requirement and the interference signal amplitude and the relation between the interference suppression requirement and the useful signal amplitude by utilizing the established mathematical model, can realize the co-site interference quantitative suppression design of a communication system, and provides quantitative design input for key technical indexes such as the interference cancellation ratio, the dynamic range and the like of the radiation interference self-adaptive cancellation device.
Drawings
FIG. 1 is a diagram of an exemplary communication receiver front end circuit in accordance with the present invention
FIG. 2 is a block diagram of a third-order nonlinear model implemented in the present invention
FIG. 3 is a graph of the quantitative relationship between the RF interference suppression requirement and the amplitude of the desired received signal
FIG. 4 is a graph of the quantitative relationship between the RF interference rejection requirement and the interfering signal amplitude
Fig. 5 is a graph showing the quantitative relationship between the rf interference suppression requirement and the linearity of the front-end circuitry of the receiver.
Detailed Description
The invention will be further described in detail with reference to the following drawings and specific examples, which are not intended to limit the invention, but are for clear understanding.
Taking Amplitude Modulation (AM) communication as an example, let the received useful signal be:
νu(t)＝[Au+m(t)]cosωut
wherein A isuIs the amplitude, ωuM (t) is a modulation signal, which is a carrier frequency.
Taking two amplitude modulated interferers of the same parameters as an example, two amplitude modulated transmitter signals causing co-site interference can be understood as follows:
vi1(t)＝[Ai1+mi1(t)]cosωi1t，vi2(t)＝[Ai2+mi2(t)]cosωi2t
the receiver input signal may be represented as:
vin(t)＝[Au+m(t)]cosωut+[Ai1+mi1(t)]cosωi1t+[Ai2+mi2(t)]cosωi2t
let Vu＝Au+m(t)，Vi1＝Ai1+mi1(t)，Vi2＝Ai2+mi2(t), the output signal of the front-end circuit of the communication receiver (fig. 1) is:
Figure BDA0001818925080000051
as can be seen from the above equation, the nonlinear effect of the receiver produces new frequency components. The newly generated frequency components produce different interference effects due to the difference between the frequency of the interference signal and the frequency of the useful signal, and are analyzed below.
(1) Same frequency interference
When the interference signal frequency and the useful signal frequency satisfy | ωI-ωSWhen the value is greater than 2 pi.delta f, the delta f is the 'audio' band-pass filtering bandwidth of the receiver, and the receiver can be interfered. The co-channel interference does not need to cause the nonlinearity of the receiver, and is directly demodulated by the receiver, and the threshold for generating the interference is very low. The corresponding output signal-to-noise ratio is as follows:
Figure BDA0001818925080000061
(2) harmonic interference
When the frequency of the interference signal and the frequency of the useful signal satisfy | N · ωI-ωSProduced when | is less than 2 π Δ f. Harmonic interference is the stronger of the receiver nonlinear interference, and the interference threshold is lower. In general, a receiver is designed in a symmetrical sampling mode, even-order nonlinear coefficients can be greatly reduced, and even-order harmonic interference can be ignored. Only odd-order harmonic interference is considered, wherein the third-order harmonic interference is strongest, and the corresponding output signal-to-noise ratio is as follows:
Figure BDA0001818925080000062
usually has a1＞＞a3The above formula can be simplified as:
Figure BDA0001818925080000063
(3) intermodulation interference
When the interference signal frequency and the useful signal frequency satisfy
Figure BDA0001818925080000071
The time is generated, wherein the third-order intermodulation interference is strongest, and the three-order intermodulation interference is two items in total, and the corresponding output signal-to-noise ratios are respectively as follows:
Figure BDA0001818925080000072
Figure BDA0001818925080000073
when V isI1＝VI2＝VIWhen, and usually has a1＞＞a3The above formula can be simplified as:
Figure BDA0001818925080000074
(4) intermodulation interference
When the frequencies of two paths of interference signals meet the absolute value of N1·ωI1-N2·ωI2If | < 2 π Δ f, the third-order intermodulation interference is strongest, and the corresponding output SNR is:
Figure BDA0001818925080000075
when V isI1＝VI2＝VIWhen, and usually has a1＞＞a3The above formula can be simplified as:
Figure BDA0001818925080000076
in order to make the error rate of the useful signal output by the receiver within the allowable range, it is necessary to make the output of the receiver have a certain signal-to-noise ratio (e.g. SNR is 20dB), so as to ensure the communication reception quality. The original amplitude of the interference signal is set as V, and the residual amplitude of the interference when the signal-to-noise ratio SNR is expected to be reached is set as VreThen the interference suppression requirement can be defined as:
RdB＝20log(V)-20log(Vre)
specifically to each type of interference, the co-channel interference suppression requirement can be quantitatively calculated as:
Figure BDA0001818925080000081
the harmonic interference rejection requirements are:
Figure BDA0001818925080000082
the intermodulation interference rejection requirements are:
Figure BDA0001818925080000083
the intermodulation interference suppression requirements are:
Figure BDA0001818925080000084
figure 3 shows the quantitative relationship between the radio frequency interference rejection requirement and the amplitude of the desired received signal. For same-frequency interference, the interference suppression requirement is reduced by 10dB every time a useful signal is increased by 10 dB; for third-order harmonic interference and third-order intermodulation interference, the interference suppression requirement is reduced by 10dB every time a useful signal is increased by 30 dB; for the third-order intermodulation interference, the size of a useful signal is increased, and the interference suppression requirement cannot be reduced.
Fig. 4 shows the quantitative relationship between the radio frequency interference suppression requirement and the interfering signal amplitude. For co-channel interference, harmonic interference, intermodulation interference and intermodulation interference, the interference rejection requirement increases by 10dB for every 10dB increase in the interfering signal.
Fig. 5 shows a quantitative relationship between the requirements for radio frequency interference suppression and the linearity of the front-end circuitry of the receiver. For same frequency interference, the linearity is increased, and the requirement for reducing interference suppression is not influenced; for harmonic interference and intermodulation interference, the interference rejection requirement is reduced by 3.33dB for every 10dB increase in linearity; for intermodulation interference, the interference suppression requirement is reduced by 5dB for every 10dB increase in linearity.
The technical effects of the present invention are illustrated by examples. Assuming that the transmitting power of the communication station is 60dBm and the isolation of the transmitting and receiving antennas is 30dB, the interference power is 60-30 dBm, i.e. 137dB μ V. The amplitude of the useful signal is respectively 60dB mu V and 0dB mu V for calculation. The linearity of the receiver is set to 10 (poor receiver performance and heavy nonlinearity) and 100 (good receiver performance and light nonlinearity). In order to make the output signal-to-noise ratio of the receiver 20dB, the same frequency interference, harmonic interference, intermodulation interference and intermodulation interference rejection requirements can be calculated as shown in table 1 using the present invention.
TABLE 1 quantitative suppression requirement for various types of interference
Figure BDA0001818925080000091
Figure BDA0001818925080000101
In actual communication, the transceiver stations of the common platform can not work at the same frequency, and the same frequency interference can not occur. The radiated interference cancellation technique can suppress harmonic interference, intermodulation interference and intermodulation interference. As shown in table 1, when the cancellation apparatus is used to suppress the interference of the receiver, in order to ensure the communication quality, it is necessary to achieve an interference cancellation ratio of about 40dB when the desired signal is large (60dB μ V) and an interference cancellation ratio of about 60dB when the desired signal is small (0dB μ V). Therefore, in practical engineering application, the cancellation ratio of the interference cancellation device must reach 40dB-60dB to meet the interference management requirements of independent platform communication systems such as ships, war vehicles and fighters.
The method is also suitable for interference mechanism analysis of a Frequency Modulation (FM) communication mode.
The invention has been described with reference to the detailed drawings of the preferred embodiments. Those skilled in the art can derive numerous variations from the preferred embodiments without departing from the scope of the invention. Accordingly, the preferred embodiments do not limit the scope of the invention. The scope of the invention is defined as the claims.
Those not described in detail in this specification are within the skill of the art.

Claims (1)

1. A method for analyzing interference mechanism of radio frequency front end of communication receiver is characterized by comprising the following steps: analyzing useful signals and interference signals input by the radio frequency front end of the communication receiver, and forming different interference types under different frequency relation conditions, so as to obtain the generating conditions of co-channel interference, harmonic interference, intermodulation interference and an analyzing method; calculating to obtain a maximum interference signal which does not influence the reception of a useful signal by using the analysis result and the minimum signal-to-noise ratio requirement of the receiver, and finally obtaining the quantitative inhibition requirement of the interference signal by combining the actual interference signal size;
setting the input signal of the radio frequency front end of the communication receiver asV inThe output signal isV outDescribing the radio frequency front end characteristic of the communication receiver by adopting a third-order nonlinear model as follows:
Figure 256085DEST_PATH_IMAGE001
wherein the content of the first and second substances,a 1、a 2、a 3respectively, three-order linear factors;
if the input signal isV inFrom a frequency of
Figure 705101DEST_PATH_IMAGE002
With a magnitude ofV SRespectively of two frequencies
Figure 750417DEST_PATH_IMAGE003
And
Figure 552151DEST_PATH_IMAGE004
respectively has an amplitude of
Figure 569786DEST_PATH_IMAGE005
And
Figure 923406DEST_PATH_IMAGE006
of interfering signals, i.e.：
Figure 331385DEST_PATH_IMAGE007
Then output the signalV outCan be expressed as:
Figure 232083DEST_PATH_IMAGE008
let the original amplitude of the interfering signal beV；The signal-to-noise ratio desired to achieve the reception quality of the communication isSNRResidual amplitude of time interference isV re，
Figure 166541DEST_PATH_IMAGE009
A band pass filter bandwidth for the receiver audio;
the interference suppression requirements are:
Figure 363167DEST_PATH_IMAGE010
；
when the interference signal frequency and the useful signal frequency satisfy
Figure 524021DEST_PATH_IMAGE011
Co-channel interference is generated, and the output signal-to-noise ratio SNR is as follows:
Figure 526612DEST_PATH_IMAGE012
the interference suppression requirements are:
Figure 456522DEST_PATH_IMAGE013
when the interference signal frequency and the useful signal frequency satisfy
Figure 588164DEST_PATH_IMAGE014
Harmonic interference is generated, and the output signal-to-noise ratio is as follows:
Figure 95368DEST_PATH_IMAGE015
the interference suppression requirements are:
Figure 573754DEST_PATH_IMAGE016
when the interference signal frequency and the useful signal frequency satisfy
Figure 623750DEST_PATH_IMAGE017
Intermodulation interference is generated, and the output signal-to-noise ratio is as follows:
Figure 224496DEST_PATH_IMAGE018
Figure 156679DEST_PATH_IMAGE019
the interference suppression requirements are:
Figure 140554DEST_PATH_IMAGE020
when the frequencies of two paths of interference signals meet
Figure 904110DEST_PATH_IMAGE021
And generating intermodulation interference, wherein the output signal-to-noise ratio is as follows:
Figure 879020DEST_PATH_IMAGE022
the interference suppression requirements are:
Figure 970604DEST_PATH_IMAGE023
。
CN201811155760.4A 2018-09-30 2018-09-30 Method for analyzing interference mechanism of radio frequency front end of communication receiver Active CN109347499B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201811155760.4A CN109347499B (en) 2018-09-30 2018-09-30 Method for analyzing interference mechanism of radio frequency front end of communication receiver

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201811155760.4A CN109347499B (en) 2018-09-30 2018-09-30 Method for analyzing interference mechanism of radio frequency front end of communication receiver

Publications (2)

Publication Number Publication Date
CN109347499A CN109347499A (en) 2019-02-15
CN109347499B true CN109347499B (en) 2022-03-29

Family

ID=65308366

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201811155760.4A Active CN109347499B (en) 2018-09-30 2018-09-30 Method for analyzing interference mechanism of radio frequency front end of communication receiver

Country Status (1)

Country Link
CN (1) CN109347499B (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101793924A (en) * 2009-10-30 2010-08-04 北京航空航天大学 Method for analyzing threshold of radiation intermodulation immunity of radio-frequency receiver
CN102164013A (en) * 2011-04-18 2011-08-24 西安电子科技大学 Electromagnetic compatibility (EMC) comprehensive predictive analysis system and analysis method for co-site interference of radio station
CN102684799A (en) * 2012-04-26 2012-09-19 西安电子科技大学 Spectrum data evaluation method for same-vehicle multi-machine communication system
CN106027176A (en) * 2016-06-29 2016-10-12 中国人民解放军军械工程学院 Receiver in-band dual frequency electromagnetic radiation large signal blocking interference effect prediction method

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101793924A (en) * 2009-10-30 2010-08-04 北京航空航天大学 Method for analyzing threshold of radiation intermodulation immunity of radio-frequency receiver
CN102164013A (en) * 2011-04-18 2011-08-24 西安电子科技大学 Electromagnetic compatibility (EMC) comprehensive predictive analysis system and analysis method for co-site interference of radio station
CN102684799A (en) * 2012-04-26 2012-09-19 西安电子科技大学 Spectrum data evaluation method for same-vehicle multi-machine communication system
CN106027176A (en) * 2016-06-29 2016-10-12 中国人民解放军军械工程学院 Receiver in-band dual frequency electromagnetic radiation large signal blocking interference effect prediction method

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
接收机带内双频阻塞干扰机理建模与验证;王雅平等;《北京理工大学学报》;20180731(第7期);全文 *

Also Published As

Publication number Publication date
CN109347499A (en) 2019-02-15

Similar Documents

Publication Publication Date Title
US9252831B2 (en) Multi-tap adaptive filter for transmit signal leakage cancellation
US8300561B2 (en) Methods and apparatus for canceling distortion in full-duplex transceivers
US9350398B2 (en) Multiple interferer cancellation for communications systems
Korpi et al. Advanced self-interference cancellation and multiantenna techniques for full-duplex radios
US9306618B2 (en) Filter enhancer and method
Faulkner DC offset and IM2 removal in direct conversion receivers
US5905574A (en) Method and apparatus for canceling cross polarization interference
JP6197104B2 (en) Method and apparatus for canceling signal in wireless communication system
US6714775B1 (en) Interference canceller
US20180175907A1 (en) Binary high-power modulator
CN105591656B (en) A kind of gain flatness compensation method of transceiver
US20140064348A1 (en) Digital Post-Distortion Compensation in Telecommunication Systems
Korpi et al. Digital self-interference cancellation under nonideal RF components: Advanced algorithms and measured performance
van Liempd et al. An electrical-balance duplexer for in-band full-duplex with<-85dBm in-band distortion at+ 10dBm TX-power
CN109001693B (en) Method and system for suppressing direct wave of frequency modulation continuous wave radar
CN109412639B (en) Microwave communication same frequency interference protector
US6473596B1 (en) Close proximity transmitter interference limiting
Sadjina et al. A circuit technique for blocker-induced modulated spur cancellation in 4G LTE carrier aggregation transceivers
Ahmed et al. Optimized interference canceling for colocated base station transceivers
CN109347499B (en) Method for analyzing interference mechanism of radio frequency front end of communication receiver
Kiayani et al. Active RF cancellation of nonlinear TX leakage in FDD transceivers
Adles et al. Interferer cancellation in coherent optical RF receivers via optical phase modulation
Zhao et al. Impacts of attenuators on analog self-interference cancellation in full duplex radios
US10164816B2 (en) Device and method for transmitting data
Ahmed et al. An adaptive cancellation system for a colocated receiver and its dynamic range

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant