CN112615633A - Radio frequency front-end circuit of broadband multi-channel direction finder - Google Patents
Radio frequency front-end circuit of broadband multi-channel direction finder Download PDFInfo
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- CN112615633A CN112615633A CN202011468605.5A CN202011468605A CN112615633A CN 112615633 A CN112615633 A CN 112615633A CN 202011468605 A CN202011468605 A CN 202011468605A CN 112615633 A CN112615633 A CN 112615633A
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Abstract
The invention provides a radio frequency front-end circuit of a broadband multi-channel direction finder, which comprises the following components: the correction switch and power division module is used for accessing an external radio frequency signal and a correction signal and gating the radio frequency signal or the correction signal to the 3-path receiving channel assembly; the receiving channel module is used for receiving the radio frequency signal, carrying out frequency conversion processing on the signal and outputting an intermediate frequency signal with a bandwidth of 40 MHz; the local vibration source is used for providing local vibration signals for signal down-conversion; a reference clock for providing a clock signal; the power supply module is used for providing power for the correction switch and power division module, the receiving channel module, the local vibration source and the reference clock; the receiving channel module is used for realizing superheterodyne secondary frequency conversion through switching between a low noise mode and a conventional mode so as to achieve the purpose of optimizing a noise coefficient.
Description
Technical Field
The invention belongs to the technical field of communication, and particularly relates to a radio frequency front-end circuit of a broadband multi-channel direction finder.
Background
Radio direction finding devices use antennas to find beacons or signal sources, direction finding antennas being an important component of radio direction finding devices.
The broadband receiver is a key component in a communication system, and along with the rapid development of communication technology and the numerous and diverse modern modulation systems, the congestion degree of a wireless frequency spectrum is increased day by day, and increasingly rigorous requirements are provided for the performances and indexes of the receiver in the aspects of linearity, dynamic range, sensitivity, anti-interference capability, adaptability and the like.
For the radio frequency front end of the direction-finding equipment, indexes such as gain, noise coefficient, phase noise, frequency stability and the like have important influence on a receiving system. The signal capacity is increased, the utilization rate of the wireless frequency spectrum is improved, and increasingly strict requirements are put forward on the performance and indexes of equipment in the aspects of linearity, anti-interference capability, adaptability and the like. The devices for realizing the frequency conversion and amplification functions are all nonlinear devices, and can generate interference signals such as harmonic signals, intermodulation signals and the like. At the same time, a large number of signals of different frequency bands exist in space. These signals generate interference signals through intermodulation, frequency multiplication, etc., and the interference signals affect the demodulation accuracy.
Disclosure of Invention
In view of this, the present invention provides a radio frequency front end circuit of a wideband multi-channel direction finder, so as to solve the technical problem of low signal purity existing in the prior art.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
a wideband multi-channel direction finder rf front-end circuit, comprising:
the correction switch and power division module is used for accessing an external radio frequency signal and a correction signal and gating the radio frequency signal or the correction signal to the 3-path receiving channel assembly;
the receiving channel module is used for receiving the radio frequency signal, carrying out frequency conversion processing on the signal and outputting an intermediate frequency signal with a bandwidth of 40 MHz;
the local vibration source is used for providing local vibration signals for signal down-conversion;
a reference clock for providing a clock signal;
the power supply module is used for providing power for the correction switch and power division module, the receiving channel module, the local vibration source and the reference clock;
the receiving channel module is used for realizing superheterodyne secondary frequency conversion through switching between a low noise mode and a conventional mode so as to achieve the purpose of optimizing a noise coefficient.
Further, the receiving channel module includes:
the switching and gain selection unit is used for switching a low noise mode and a conventional mode and carrying out selectable gain on signals;
a multi-layer dielectric filtering unit for lossless multi-layer dielectric filtering of the gain-selectable signal.
Further, the switching and gain unit includes:
a switching component for switching between a low noise mode and a normal mode;
a filter for filtering a signal in a low noise mode;
the low-noise amplifier is used for amplifying the filtered signal;
a selectable gain for implementing a selectable gain on the signal in the low noise mode and the normal mode.
Further, the switch assembly includes: BW118 chips arranged oppositely.
Further, the selectable gain device is an HM639 gain chip.
Further, the switching and gain unit further includes:
and the adjustable filtering power supply is used for providing an adjustable and stable power supply for the low-noise amplifier.
Further, the multilayer dielectric filter unit includes:
the frequency mixer is used for mixing the intermediate frequency signal and the local oscillator signal to obtain a mixing signal;
at least two filtering and amplifying units connected in series, the filtering and amplifying units comprising: a filter and a radio frequency amplifier connected in series.
Further, the filtering and amplifying unit further includes: the filter comprises a first filter capacitor and a second filter capacitor, wherein the first filter capacitor is in short connection with the input end of the filter, and the second filter capacitor is electrically connected with the output end of the filter.
Compared with the prior art, the radio frequency front-end circuit of the broadband multi-channel direction finder has the following advantages:
the radio frequency front-end circuit of the broadband multi-channel direction finder realizes superheterodyne secondary frequency conversion by switching between a low noise mode and a conventional mode by setting a receiving channel module so as to achieve the aim of optimizing a noise coefficient. In addition, the selective gain of the denoised signal can be realized through the selectable gain module. And the signals can be amplified after being filtered by the multi-layer medium filtering unit, so that the index requirement of the next stage is met. Because the switching and gain selecting unit and the multilayer medium filtering unit adopt superheterodyne secondary frequency conversion, interference signals generated by modes of intermodulation, frequency multiplication and the like are avoided, and the accuracy of demodulation is influenced by the interference signals. In order to eliminate or reduce interference signals, filtering technology is required to filter radio frequency signals and variable frequency link signals during reasonable frequency spectrum processing, so that the purity of the signals is improved.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 is a schematic structural diagram of a radio frequency front-end circuit of a broadband multi-channel direction finder according to an embodiment of the present invention;
fig. 2 is a schematic circuit diagram of a switching and gain selecting unit in a radio frequency front-end circuit of a wideband multi-channel direction finder according to an embodiment of the present invention;
fig. 3 is a schematic circuit diagram of a multi-layer dielectric filter unit in a radio frequency front-end circuit of a wideband multi-channel direction finder according to an embodiment of the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.
The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
Fig. 1 is a schematic structural diagram of a radio frequency front end circuit of a wideband multi-channel direction finder according to an embodiment of the present invention, and referring to fig. 1, the radio frequency front end circuit of the wideband multi-channel direction finder includes:
the correction switch and power division module is used for accessing an external radio frequency signal and a correction signal and gating the radio frequency signal or the correction signal to the 3-path receiving channel assembly;
the receiving channel module is used for receiving the radio frequency signal, carrying out frequency conversion processing on the signal and outputting an intermediate frequency signal with a bandwidth of 40 MHz;
the local vibration source is used for providing local vibration signals for signal down-conversion;
a reference clock for providing a clock signal;
the power supply module is used for providing power for the correction switch and power division module, the receiving channel module, the local vibration source and the reference clock;
the receiving channel module is used for realizing superheterodyne secondary frequency conversion through switching between a low noise mode and a conventional mode so as to achieve the purpose of optimizing a noise coefficient.
In this embodiment, the calibration switch and the power dividing unit are responsible for selecting a receiver signal source, performing power division and outputting of the calibration signal, where the receiver signal source may be a received signal from an antenna, or may be a calibration signal after power division. The antenna receiving signal comes from an external radio frequency signal interface, the correction signal comes from the correction source module, and the other path of correction signal is output outwards.
The correction source module provides comb spectrum correction signals with the bandwidth interval of 100kHz and the bandwidth of 40MHz in the range of broadband radio frequency signals and provides a sampling master clock of 102.4 MHz.
The receiving channel assembly and the local vibration source realize amplitude limiting, preselection, frequency conversion, filtering and gain control of broadband radio frequency signals, and output intermediate frequency signals with 76.8MHz frequency points and 40MHz bandwidth. The local oscillator module provides an initial secondary local oscillator signal to the local oscillator power division module. The external reference source or the internal constant-temperature crystal oscillator provides a 10MHz reference clock output, and the automatic switching capability of the internal reference source and the external reference source is provided, and the external reference source has priority. Meanwhile, reference sources of 10MHz and 40MHz are provided to the external interface and the correction source module, respectively. The local oscillator power division module divides the power of the first local oscillator and the second local oscillator on the premise that the output of the first local oscillator and the second local oscillator is greater than or equal to 0dBm and then sends the divided power to a receiving channel and a correction source.
The correction switch module is used for accessing an external radio frequency signal and a correction signal and gating the radio frequency signal or the correction signal to the 3-path receiving channel assembly.
The correction switch module enables the correction signals after the three paths of power division and the three paths of radio frequency signals to be output through the 2-to-1 radio frequency switch respectively, and sends the correction signals and the three paths of radio frequency signals to the receiving channel. The correction switch module is arranged at the first-stage input of the equipment, the insertion loss of the correction switch module directly affects the noise coefficient index of the equipment, and key parameters such as the insertion loss and a second-order intercept point are comprehensively considered to select an integrated switch chip to build an SPDT switch group. The technical indexes of the correction switch module are as follows:
a) frequency range: 30MHz to 8 GHz;
b) port standing wave: less than or equal to 1.5(50 omega impedance matching);
c) correcting the switching time of the switch: less than or equal to 50 us;
d) insertion loss: less than or equal to 1dB (signal branch) and less than or equal to 2dB (correction branch without distribution loss).
The module consists of a one-to-four active power division module and 4 single-pole double-throw Switches (SPDT), and realizes the functions of correcting input → correcting output on-off, correcting input → radio frequency output on-off and antenna input → radio frequency output on-off.
In order to ensure that the correction input → the radio frequency output three paths are corrected simultaneously, a one-to-four power divider is adopted, and 1 path is reserved for standby. The frequency range is 30 MHz-8000 MHz, and the resistance power dividing network is adopted to ensure good power dividing characteristic, because the resistance power dividing insertion loss is large, in order to ensure the gain, an amplifier with high saturation point output is required to be added, and the requirement of ensuring the output of 1dB compression point while meeting the gain is met.
In order to ensure that the correction paths work independently and have higher isolation, an SPDT absorption type switch can be adopted, and the switch adopts a structural form of combining series connection and parallel connection of PIN tubes. When the correction path works, the corresponding switch is opened, and other paths are cut off, so that the isolation can be effectively realized.
The two correction paths of correction input → correction output and antenna input → radio frequency output adopt the mode of direct connection of a switch, the PIN tube switch with low loss and high isolation can meet the system requirement, and in addition, the PIN tube has large power tolerance and can meet the requirement of outputting a 1dB compression point.
Correspondingly, the power module provides power for the above devices, and the local vibration source provides a corresponding local vibration source for the receiving channel module to perform frequency mixing.
In the embodiment, the noise coefficient is optimized mainly through the receiving channel module, and the system requirement is met.
Specifically, the receiving channel module includes:
the switching and gain selection unit is used for switching a low noise mode and a conventional mode and carrying out selectable gain on signals;
a multi-layer dielectric filtering unit for lossless multi-layer dielectric filtering of the gain-selectable signal.
Fig. 2 is a schematic circuit diagram of a switching and gain selecting unit in a radio frequency front-end circuit of a wideband multi-channel direction finder according to an embodiment of the present invention, referring to fig. 2, the switching and gain selecting unit includes:
a switching component for switching between a low noise mode and a normal mode; a filter for filtering a signal in a low noise mode; the low-noise amplifier is used for amplifying the filtered signal; a selectable gain for implementing a selectable gain on the signal in the low noise mode and the normal mode.
In this embodiment, the switch assembly includes: BW118 chips arranged oppositely. The selectable gain device is an HM639 gain chip.
Referring to fig. 1, the radio frequency signal output by the calibration switch and the power division module enters the BW118 chip after being filtered by the filter capacitor, and enters a low noise mode when a pin 15 of the BW118 chip is enabled, the radio frequency signal filtered by the capacitor is filtered by the filter and amplified by the low noise amplifier, and the low noise amplifier can output a corresponding voltage through the configured adjustable filter power supply, so that the purpose of adjusting and amplifying according to the output voltage of the power supply is achieved. And the opposite BW118 chip is entered again, 16 pins of the opposite BW118 chip are enabled, the opposite BW118 chip is entered into an HM639 gain chip, level signals are input to the HM639 gain chip through D0-D3 pins, the selection gain is realized, and after the selection gain is finished, the signals are amplified again through a low-noise amplifier, so that the output signals meet the corresponding gain requirements.
And in the case that the pin of the BW118 chip 15 is in the disabled state, the normal mode is entered, that is, the selection gain is realized by entering the selectable gain device through the opposite BW118 chip without passing through the above-mentioned filter and low noise amplifier, and the amplification is performed through the subsequent low noise amplifier.
The adjustable filtering power supply realizes voltage adjustability and filtering through the sliding rheostat, the RC filter and the LC filter.
The amplified signal is input into a multilayer medium filter unit, a frequency mixer adopts a high local frequency mixing scheme, the receiving frequency range is 30 MHz-8000 MHz, the corresponding local frequency is 9490 MHz-17460 MHz, and the corresponding intermediate frequency is 9460 MHz. Three medium filters are arranged at the intermediate frequency, the BW-1dB bandwidth of each medium filter is larger than 100MHz to meet the bandwidth requirement of 40MHz, a first-stage gain compensation amplifier is arranged in the middle of the three-stage medium filter to compensate the signal power loss caused by the loss of the medium filter, and the signal power entering the second mixer is ensured to meet the dynamic requirement of the system. Meanwhile, in order to meet the requirement of 0-60 dB of gain control range, 30dB of radio frequency attenuation and medium frequency attenuation are respectively set, and the two are matched to realize the requirement of 60dB of gain control range of the whole machine. The overall receive circuit normal mode gain is set to 50dB and the low noise mode gain is set to 62 dB.
The multilayer dielectric filter unit includes: the frequency mixer is used for mixing the intermediate frequency signal and the local oscillator signal to obtain a mixing signal; at least two filtering and amplifying units connected in series, the filtering and amplifying units comprising: a filter and a radio frequency amplifier connected in series.
Correspondingly, the filtering and amplifying unit further comprises: the filter comprises a first filter capacitor and a second filter capacitor, wherein the first filter capacitor is in short connection with the input end of the filter, and the second filter capacitor is electrically connected with the output end of the filter. For the purpose of further filtering. Correspondingly, the filtering amplifying unit has the same structure as the adjustable filtering power supply provided above, and is not described herein again.
The radio frequency front-end circuit of the broadband multi-channel direction finder realizes superheterodyne secondary frequency conversion by switching between a low noise mode and a conventional mode by setting a receiving channel module so as to achieve the aim of optimizing a noise coefficient. In addition, the selective gain of the denoised signal can be realized through the selectable gain module. And the signals can be amplified after being filtered by the multi-layer medium filtering unit, so that the index requirement of the next stage is met. Because the switching and gain selecting unit and the multilayer medium filtering unit adopt superheterodyne secondary frequency conversion, interference signals generated by modes of intermodulation, frequency multiplication and the like are avoided, and the accuracy of demodulation is influenced by the interference signals. In order to eliminate or reduce interference signals, filtering technology is required to filter radio frequency signals and variable frequency link signals during reasonable frequency spectrum processing, so that the purity of the signals is improved.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (8)
1. A wideband multi-channel direction finder rf front-end circuit, comprising:
the correction switch and power division module is used for accessing an external radio frequency signal and a correction signal and gating the radio frequency signal or the correction signal to the 3-path receiving channel assembly;
the receiving channel module is used for receiving the radio frequency signal, carrying out frequency conversion processing on the signal and outputting an intermediate frequency signal with a bandwidth of 40 MHz;
the local vibration source is used for providing local vibration signals for signal down-conversion;
a reference clock for providing a clock signal;
the power supply module is used for providing power for the correction switch and power division module, the receiving channel module, the local vibration source and the reference clock;
the receiving channel module is used for realizing superheterodyne secondary frequency conversion through switching between a low noise mode and a conventional mode so as to achieve the purpose of optimizing a noise coefficient.
2. The wideband multi-channel direction finder rf front end circuit of claim 1, wherein the receive channel module comprises:
the switching and gain selection unit is used for switching a low noise mode and a conventional mode and carrying out selectable gain on signals;
a multi-layer dielectric filtering unit for lossless multi-layer dielectric filtering of the gain-selectable signal.
3. The wideband multi-channel direction-finder rf front-end circuit of claim 2, wherein the switching and gain unit comprises:
a switching component for switching between a low noise mode and a normal mode;
a filter for filtering a signal in a low noise mode;
the low-noise amplifier is used for amplifying the filtered signal;
a selectable gain for implementing a selectable gain on the signal in the low noise mode and the normal mode.
4. The wideband multi-channel direction finder radio frequency front end circuit of claim 3, wherein the switch assembly comprises: BW118 chips arranged oppositely.
5. The wideband multi-channel direction finder rf front-end circuit according to claim 3, wherein the selectable gain is an HM639 gain chip.
6. The wideband multi-channel direction-finder rf front-end circuit of claim 3, wherein the switching and gain unit further comprises:
and the adjustable filtering power supply is used for providing an adjustable and stable power supply for the low-noise amplifier.
7. The wideband multi-channel direction finder rf front-end circuit according to claim 2, wherein the multi-layer dielectric filter unit comprises:
the frequency mixer is used for mixing the intermediate frequency signal and the local oscillator signal to obtain a mixing signal;
at least two filtering and amplifying units connected in series, the filtering and amplifying units comprising: a filter and a radio frequency amplifier connected in series.
8. The wideband multi-channel direction-finder rf front-end circuit of claim 7, wherein the filtering amplification unit further comprises: the filter comprises a first filter capacitor and a second filter capacitor, wherein the first filter capacitor is in short connection with the input end of the filter, and the second filter capacitor is electrically connected with the output end of the filter.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011468605.5A CN112615633A (en) | 2020-12-14 | 2020-12-14 | Radio frequency front-end circuit of broadband multi-channel direction finder |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011468605.5A CN112615633A (en) | 2020-12-14 | 2020-12-14 | Radio frequency front-end circuit of broadband multi-channel direction finder |
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| CN112615633A true CN112615633A (en) | 2021-04-06 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113708782A (en) * | 2021-08-27 | 2021-11-26 | 天津光电通信技术有限公司 | MIMO module hardware structure optimization method |
| CN113938138A (en) * | 2021-08-26 | 2022-01-14 | 北京遥测技术研究所 | X-frequency band 8-channel receiving chip of monolithic integrated switch network |
| CN114401019A (en) * | 2021-11-29 | 2022-04-26 | 北京无线电计量测试研究所 | Large-bandwidth high-sensitivity receiving front-end circuit |
-
2020
- 2020-12-14 CN CN202011468605.5A patent/CN112615633A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113938138A (en) * | 2021-08-26 | 2022-01-14 | 北京遥测技术研究所 | X-frequency band 8-channel receiving chip of monolithic integrated switch network |
| CN113708782A (en) * | 2021-08-27 | 2021-11-26 | 天津光电通信技术有限公司 | MIMO module hardware structure optimization method |
| CN114401019A (en) * | 2021-11-29 | 2022-04-26 | 北京无线电计量测试研究所 | Large-bandwidth high-sensitivity receiving front-end circuit |
| CN114401019B (en) * | 2021-11-29 | 2023-09-12 | 北京无线电计量测试研究所 | High-bandwidth high-sensitivity receiving front-end circuit |
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Application publication date: 20210406 |