Dual-carrier interphone

Abstract

The invention provides a dual-carrier interphone. The dual-carrier interphone comprises a receiver link and a transmitter link, the receiver link consists of an antenna matching network, a first electric tuning filter, a low noise amplifier, a second electric tuning filter, a frequency mixer, an intermediate frequency amplifier, an intermediate frequency demodulation chip and a baseband chip which are connected in sequence; a transmitter link adopts single-carrier transmission or dual-carrier transmission, and the single-carrier transmission is realized through a baseband chip, a TCVCXO crystal oscillator, a phase-locked loop chip, a transmission VCO, a pre-amplifier, an attenuator, a pre-amplifier, a driving-stage amplifier, an excitation-stage amplifier and an antenna matching network which are connected in sequence; on the basis, the dual-carrier transmission switches the output of the receiving VCO to a channel of the pre-amplifier, and controls the transmitting VCO and the receiving VCO to transmit simultaneously. According to the invention, one-channel transmission or two-channel transmission is realized by adopting one transmission link, simultaneous two-channel simultaneous talkback can be realized, and the call efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of intercoms, and in particular to a dual-carrier intercom. Background Art

[0002] When traditional walkie-talkies need to notify users on two or more channels, they need to switch to channel 2 for repeated intercom after speaking on channel 1, which cannot meet the application requirements of cross-channel intercoms. In addition, traditional walkie-talkies use current APC control, but current control of dual-carrier output cannot accurately control power, and the power will increase rapidly before transmission, which can easily damage the power amplifier tube. Summary of the invention

[0003] In order to solve the above-mentioned deficiencies in the prior art, an object of the present invention is to provide a dual-carrier walkie-talkie to overcome the defects in the prior art.

[0004] In order to achieve the above-mentioned object, the present invention provides a dual-carrier intercom, which includes a receiver link and a transmitter link; wherein the receiver link is composed of an antenna matching network, a first electrically tuned filter, a low noise amplifier, a second electrically tuned filter, a mixer, an intermediate frequency filter, an intermediate frequency amplifier, an intermediate frequency demodulation chip and a baseband chip connected in sequence; wherein the carrier signal received by the antenna is filtered out of part of the out-of-band electromagnetic wave signal through the antenna matching network, and then enters the first electrically tuned filter, the first electrically tuned filter pre-selects a working carrier signal, and outputs it to the low noise amplifier; the low noise amplifier selects the pre-selected working carrier signal The carrier signal is amplified and enters the second electrically tuned filter. The second electrically tuned filter filters out the clutter and carrier filtering generated by the low noise amplifier in the carrier signal to reduce useless signals, and then enters the mixer; the mixer performs difference frequency on the carrier signal and the local oscillator signal from the second electrically tuned filter and generates an intermediate frequency. The intermediate frequency is passed through the intermediate frequency filter to suppress the adjacent channel signal. The useful signal is filtered by the intermediate frequency filter and amplified by the intermediate frequency compensation of the intermediate frequency amplifier, and then sent to the intermediate frequency demodulation chip for the second difference frequency demodulation to obtain the modulated signal; the demodulated modulated signal is sent to the baseband chip by the baseband signal to decode and output the received audio voice information;

[0005] The transmitter link is single-carrier transmission or dual-carrier transmission; wherein, the single-carrier transmission includes: the voice signal collected by the microphone (MIC) is encoded by the baseband chip and modulated on the TCVCXO crystal oscillator, the TCVCXO crystal oscillator modulates the encoded voice signal and sends it to the transmitting VCO through the phase-locked loop chip; the phase-locked loop chip controls the transmitting VCO to lock at the target frequency when performing single-carrier transmission according to the data requirements of the control chip, and modulates the 4FSK data signal or analog audio on the transmitting VCO for transmission; the transmitting VCO locks the modulated voice signal to the target carrier and generates the first carrier to perform single-carrier transmission, and the single carrier is then amplified by the pre-amplifier, attenuator, pre-amplifier, driver amplifier, and excitation amplifier in sequence, and then sent to the antenna matching network, and then radiated outward by the antenna;

[0006] The dual-carrier transmission includes: two voice signals collected by the MIC are encoded by the baseband chip and then modulated on the TCVCXO crystal oscillator, the TCVCXO crystal oscillator modulates the two encoded voice signals and sends them to the transmitting VCO and the receiving VCO respectively through the phase-locked loop chip; the transmitting VCO generates a first carrier of the target channel frequency for transmission, and at the same time as the first carrier is transmitted, the receiving VCO generates a second carrier of the target channel frequency for transmission;

[0007] The control chip switches the receiving VCO output to the channel of the pre-amplifier of the transmitter link through the phase-locked loop chip; the phase-locked loop chip controls the transmitting VCO and the receiving VCO to transmit simultaneously when dual-carrier transmission is performed according to the control of the control chip; the first carrier and the second carrier are sent to the antenna matching network in turn through the pre-amplifier, attenuator, pre-amplifier, drive-stage amplifier, and excitation-stage amplifier, and then radiated outward by the antenna.

[0008] Through the above technical scheme, a control chip is connected to a phase-locked loop chip, the phase-locked loop chip is connected to the transmitting VCO and the receiving VCO, and the transmitting VCO and the receiving VCO are both connected to the pre-amplifier. When dual-carrier transmission is performed, the control chip controls the output of the receiving VCO to switch to the pre-amplifier of the transmitter link, so that the transmitting VCO and the receiving VCO can transmit the carrier at the same time, or when single-carrier transmission is performed, the transmitting VCO transmits the carrier, and the single-carrier or dual-carrier realizes one channel transmission or two-channel transmission on a transmission link composed of a pre-amplifier, an attenuator, a pre-amplifier, a driving stage, and an excitation stage. It is possible to directly talk to users of two channels without repeating the content of the talk, thereby improving the call efficiency and solving the application requirements of cross-channel talk.

[0009] As a further explanation of the dual-carrier walkie-talkie described in the present invention, preferably, the transmitter link also includes APC power control, and the APC power control includes using a mean detector to detect the carrier signal after amplification by the microstrip coupled excitation stage, and amplifying the level of the carrier signal and sending it to the APC controller; the APC controller compares the level of the amplified carrier signal with the reference level and controls the attenuator; the mean detector, APC controller and attenuator are continuously and repeatedly detected, compared and controlled attenuation, so that the total transmission power of the single carrier transmission or dual carrier transmission of the transmitter link is maintained at 5W.

[0010] Through the above technical solution, directional coupling detection and mean detection are adopted, and the detection-comparison-attenuation are repeated in a continuous cycle to ensure that the total power of single-carrier and dual-carrier transmission remains unchanged, and is always stable at 5W transmission. The power amplifier tube will not be damaged due to the increase in the number of carriers, which solves the problem that the traditional current-type APC control method cannot achieve the same total power of multi-carriers and is easy to damage the power amplifier tube.

[0011] As a further illustration of the dual-carrier intercom described in the present invention, preferably, the mean detector is connected to the coupling circuit, and the coupling circuit is coupled to the excitation stage amplifier to obtain the carrier signal amplified by the microstrip coupling excitation stage; wherein the coupling circuit includes a first resistor, a second resistor, a third resistor, a capacitor and a fourth resistor; the mean detector is respectively connected to one end of the first resistor and the first end of the second resistor, the other end of the second resistor is respectively connected to one end of the third resistor and one end of the capacitor, the other end of the capacitor is connected to the fourth resistor, and the other ends of the first resistor, the third resistor and the fourth resistor are all grounded.

[0012] Through the above technical solution, the carrier signal after amplification by the excitation stage is obtained through the coupling circuit and transmitted to the mean detector for detection, thereby ensuring that the total power during single-carrier and dual-carrier transmission remains unchanged.

[0013] As a further illustration of the dual-carrier intercom of the present invention, preferably, the APC controller controls the step power range of the transmitter link to be 5 to 37 dBm / 1 dB.

[0014] Through the above technical solution, the APC controller controls the transmission power of the transmitter link and can achieve 5~37dBm / 1dB step power control, solving the problem that traditional walkie-talkies can only have high / low power control.

[0015] As a further description of the dual-carrier intercom of the present invention, preferably, the power of the third-order intermodulation of the transmitter link is ≥70dBc.

[0016] Through the above technical solution, the power of the third-order intermodulation of the transmitter link is ≥70dBc, avoiding interference with normal communications at other frequencies.

[0017] As a further description of the dual-carrier intercom of the present invention, preferably, the pre-amplifier adopts an LDMOS radio frequency tube.

[0018] Through the above technical solution, LDMOS RF tube is used to transmit the carrier, and power back-off technology is adopted to better obtain the third-order intermodulation index and avoid interfering with the normal communication of other frequencies.

[0019] As a further illustration of the dual-carrier intercom of the present invention, preferably, the dual-carrier transmission includes dual-carrier simultaneous digital mode transmission and dual-carrier simultaneous analog signal transmission.

[0020] Through the above technical solution, dual-carrier transmission can be used for both dual-carrier simultaneous digital mode transmission and dual-carrier simultaneous analog signal transmission, which solves the application requirements of cross-channel intercom and the problem that traditional walkie-talkies need to switch to channel 2 to repeat the content after the intercom on channel 1 is completed.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1) The present invention sets a control chip connected to a phase-locked loop chip, the phase-locked loop chip is connected to a transmitting VCO and a receiving VCO, and both the transmitting VCO and the receiving VCO are connected to a preamplifier. When dual-carrier transmission is performed, the control chip controls the output of the receiving VCO to switch to the preamplifier, so that the transmitting VCO and the receiving VCO can transmit carriers at the same time, or when single-carrier transmission is performed, the transmitting VCO transmits the carrier, and the single-carrier or dual-carrier realizes one-channel transmission or two-channel transmission on a transmission link composed of a preamplifier, an attenuator, a preamplifier, a driving stage, and an excitation stage. It is possible to directly talk to users of two channels without repeating the content of the talk, thereby improving the call efficiency, solving the application requirements of cross-channel talk, and solving the problem that when a traditional walkie-talkie needs to notify users of two channels or more channels, it needs to switch to the second channel for repeated talk after speaking on the first channel.

[0023] 2) The present invention adopts directional coupling detection and mean detection methods, and repeatedly cycles through detection-comparison-attenuation to ensure that the total power of single-carrier and dual-carrier transmission remains unchanged, and is always stable at 5W transmission. The power amplifier tube will not be damaged due to the increase in the number of carriers, which solves the problem that the traditional current-type APC control method cannot achieve the same total power of multiple carriers and is easy to damage the power amplifier tube.

[0024] 3) The dual-carrier intercom of the present invention can realize dual / multi-channel intercom at the same time, and the call efficiency is high. The mean detection APC control method is adopted, the power stability is high, the TDMA envelope power is flat and stable, the jitter is relatively small, the power supply circuit design is simple, and the charging / discharging time of the transmission link is short when working at 30mS ≤1mS. The traditional current control dual-carrier output cannot accurately control the power; the power will increase quickly before transmission, and the current will be low and large instantly; the envelope flatness will be relatively jittery during TMDA transmission; the charging / discharging time of the transmission link is long when working at 30mS; it will affect the bit error rate of wireless transmission during TMDA intercom.

[0025] 4) The dual-carrier intercom transmission link of the present invention has high requirements for RF devices and high performance requirements for RF devices. It requires the third-order intermodulation index of the overall constant transmission link to be ≥70dBc hard index value, otherwise it will seriously interfere with normal communications at other frequencies.

[0026] 5) The dual-carrier intercom of the present invention can realize precision power control and 5-37dBm / 1dB step power control, which solves the problem that traditional intercoms can only perform high / low power control. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the dual-carrier intercom of the present invention. DETAILED DESCRIPTION

[0028] In order to further understand the structure, features and other purposes of the present invention, the preferred embodiments are described in detail with reference to the accompanying drawings as follows. The embodiments described in the drawings are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention.

[0029] In a first embodiment of the present invention, Figure 1 As shown, the present invention provides a dual-carrier intercom, which includes a receiver link 1 and a transmitter link 2.

[0030] The receiver chain 1 is composed of an antenna matching network 11, a first electrically tunable filter 12, a low noise amplifier 13, a second electrically tunable filter 14, a mixer 15, an intermediate frequency filter 19, an intermediate frequency amplifier 16, an intermediate frequency demodulation chip 17 and a baseband chip 18 which are connected in sequence.

[0031] The carrier signal received by the antenna is transmitted to the first electrically tuned filter 12 after filtering out some out-of-band electromagnetic wave signals through the antenna matching network 11. The working carrier signal is pre-selected by the first electrically tuned filter 12 and transmitted to the low noise amplifier 13. The pre-selected working carrier signal is amplified by the low noise amplifier 13 and transmitted to the second electrically tuned filter 14. The second electrically tuned filter 14 filters out the clutter and carrier filtering generated by the low noise amplifier 13 in the carrier signal to reduce useless signals and then enters the mixer 15. The mixer 15 performs a difference frequency on the carrier signal and the local oscillator signal from the second electrically tuned filter 14 to generate an intermediate frequency. The intermediate frequency is suppressed by the intermediate frequency filter 19 for the adjacent channel signal. The useful signal is filtered by the intermediate frequency filter 19 and amplified by the frequency compensation of the intermediate frequency amplifier 16, and then sent to the intermediate frequency demodulation chip 17 for a second difference frequency to demodulate the modulated signal. The demodulated modulated signal is sent to the baseband chip 18 by the baseband signal to decode and output the received audio voice information.

[0032] The transmitter link 2 includes a baseband chip 18, a TCVCXO crystal oscillator 21, a phase-locked loop chip 22, a transmitting VCO 23, a preamplifier 24, an attenuator 25, a preamplifier 26, a driving stage 27, an excitation stage 28 and an antenna matching network 11 connected in sequence to achieve one channel transmission. On this basis, the control chip 3 is connected to the phase-locked loop chip 22, and the phase-locked loop chip 22 is also connected to the receiving VCO 29, and the receiving VCO 29 is connected to the preamplifier 24 to achieve two channels of simultaneous transmission, that is, the receiving VCO 29 and the transmitting VCO 23 provide two carriers for the preamplifier 24 to transmit simultaneously. The receiving VCO 29 is connected to the mixer 15 of the receiver link 1, and when receiving, the receiving VCO 29 provides the mixer 15 with a local oscillator signal.

[0033] When the transmitter link 2 performs single-carrier transmission, the voice signal collected by the microphone (MIC) is encoded by the baseband chip 18 and modulated on the TCVCXO crystal oscillator 21. After the transmitting VCO23 locks the target carrier, the first carrier is generated to perform single-carrier transmission. The single carrier (i.e., the first carrier) is then amplified by the preamplifier 24, the attenuator 25, the preamplifier 26, the driver amplifier 27, and the driver amplifier 28 in sequence, and then sent to the antenna matching network 11 and radiated outward by the antenna. Among them, the phase-locked loop chip 22 locks the transmitting VCO23 to the target frequency according to the data requirements of the control chip 3, and modulates the 4FSK data signal or analog audio on the transmitting VCO23 for transmission.

[0034] When the transmitter link 2 performs dual-carrier transmission, the two voice signals collected by the microphone (MIC) are encoded by the baseband chip 18 and modulated on the TCVCXO crystal oscillator 21. The TCVCXO crystal oscillator 21 modulates the two encoded voice signals and sends them to the transmitting VCO23 and the receiving VCO29 respectively through the phase-locked loop chip 22. The first carrier is transmitted by the transmitting VCO23 to generate the target channel frequency, and the second carrier is transmitted by the receiving VCO29 to generate the target channel frequency. The first carrier and the second carrier are transmitted simultaneously, and the control chip 3 controls the output of the receiving VCO29 to switch to the preamplifier 24 of the transmitter link 2. The two carriers (i.e., the first carrier and the second carrier) are amplified by the preamplifier 24, the attenuator 25, the pre-amplifier 26, the booster amplifier 27, and the driver amplifier 28, and then sent to the antenna matching network 11, and radiated outward by the antenna.

[0035] Since intermodulation signals will be generated when two carriers enter the same RF amplifier, the dual-carrier has relatively high requirements for RF, and the third-order intermodulation technical indicators need to be considered. Traditional transmitters using FM RF devices only need to consider the output power of saturated amplification P1dB. In order to obtain better third-order intermodulation indicators, preferably, in this embodiment, the pre-amplifier 24 uses an LDMOS RF tube. Power back-off technology is used, for example: the single-channel output power of the transmitter is 37dBm (5W), the power of each carrier of the dual-channel transmission is approximately 34dBm (2.5W), and the total power is: 2.5×2=5W (37dBm). It is required that the power of the third-order intermodulation of the transmitter link 2 must reach ≥70dBc and meet the emission spurious index ≤-36dBm, otherwise the intermodulation frequency point will seriously interfere with calls at other frequencies.

[0036] In a second embodiment of the present invention, Figure 1 As shown, the transmitter link 2 also includes APC power control. That is, the mean detector 4 is used to detect the carrier signal amplified by the microstrip coupling excitation stage, and the level of the carrier signal is amplified and sent to the APC controller 5; the APC controller 5 compares the level of the amplified carrier signal with the reference level and controls the attenuator 25. The mean detector 4, the APC controller 5 and the attenuator 25 continuously and repeatedly detect, compare and control attenuation, so that the total transmission power of the single carrier transmission or dual carrier transmission of the transmitter link 2 is maintained at 5W.

[0037] This implementation method adopts directional coupling detection and mean detection, and repeatedly cycles through detection-comparison-attenuation to ensure that the total power of single-carrier and dual-carrier transmission remains unchanged and is always stable at 5W transmission, that is, the total power of single-carrier transmission is 5W, and the total power of two-carrier transmission is 5W. The transmission power is maintained at 5W and the power amplifier tube is not damaged due to the increase in the number of carriers. At the same time, it avoids interfering with the normal communication of other frequencies, which solves the problem that the traditional current APC control method cannot achieve the total power of multiple carriers unchanged and is prone to damage to the power amplifier tube.

[0038] In this implementation, preferably, the APC controller 5 controls the transmission power of the transmitter link 2, and can achieve 5-37dBm / 1dB step power control, solving the problem that the traditional walkie-talkie can only control high / low power.

[0039] This implementation adopts the mean detection APC control method, which has great advantages over the traditional current APC control method, including the following advantages: 1) The mean detection APC control method has high power stability; the traditional current APC control method cannot accurately control the power during dual-carrier output, and the power will increase rapidly before transmission, resulting in a phenomenon of instantaneous low current; 2) The mean detection APC control method does not affect the envelope carrier of the 30mS transmission during TDMA (time division multiple access) transmission; the envelope flatness of the traditional current APC control method during TMDA transmission is relatively jittery; 3) The mean detection APC control method has high power stability; the traditional current ... The wave APC control mode has a faster response in the same-frequency transfer of the receive / transmit link electrical control, and the charging / discharging time of the transmitting link is shorter when working at 30mS, ≤1mS; the traditional current APC control mode has a longer charging / discharging time when the transmitting link works at 30mS, which will affect the bit error rate of wireless transmission during TMDA intercom; 4) The mean detection APC control mode has little effect on the power supply control voltage fluctuation. The traditional current APC control circuit has a large control jitter on the power supply system, which seriously affects the adjacent channel power ratio and envelope power charging / discharging jitter and flatness and other performance indicators during TDMA transmission.

[0040] In a third embodiment of the present invention, Figure 1 As shown, the mean detector 4 is connected to the coupling circuit 6, and the coupling circuit 6 is coupled to the drive stage amplifier 28 to obtain the carrier signal amplified by the microstrip coupling drive stage. The coupling circuit 6 includes a first resistor 61, a second resistor 62, a third resistor 63, a capacitor 64 and a fourth resistor 65; the mean detector 4 is respectively connected to one end of the first resistor 61 and the first end of the second resistor 62, the other end of the second resistor 62 is respectively connected to one end of the third resistor 63 and one end of the capacitor 64, the other end of the capacitor 64 is connected to the fourth resistor 65, and the other ends of the first resistor 61, the third resistor 63 and the fourth resistor 65 are all grounded.

[0041] In this implementation, the carrier signal after the excitation stage amplification is obtained through the coupling circuit and transmitted to the mean detector for detection, so as to ensure that the total power remains unchanged when the single carrier and the dual carrier are transmitted. The mean detection total power will not change, whether the total power of the single carrier is 5W; the total power of the dual carrier is also 5W, and the power of each carrier is 2.5W.

[0042] In the fourth embodiment of the present invention, the dual-carrier transmission of the transmitter link 2 can be either dual-carrier simultaneous digital mode transmission or dual-carrier simultaneous analog signal transmission, which solves the application requirements of cross-channel intercom and the problem that traditional walkie-talkies need to switch to channel 2 to repeat the content after the intercom on channel 1 is completed.

[0043] It should be noted that the above invention content and specific implementation methods are intended to demonstrate the practical application of the technical solution provided by the present invention and should not be interpreted as limiting the scope of protection of the present invention. Those skilled in the art can make various modifications, equivalent substitutions or improvements within the spirit and principles of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A dual-carrier intercom, characterized in that: The dual-carrier intercom comprises a receiver link (1) and a transmitter link (2); wherein: The receiver chain (1) is composed of an antenna matching network (11), a first electrically tunable filter (12), a low noise amplifier (13), a second electrically tunable filter (14), a mixer (15), an intermediate frequency filter (19), an intermediate frequency amplifier (16), an intermediate frequency demodulation chip (17) and a baseband chip (18) which are connected in sequence; wherein: The carrier signal received by the antenna passes through an antenna matching network (11) to filter out a portion of the out-of-band electromagnetic wave signal, and then enters a first electrically tunable filter (12). The first electrically tunable filter (12) preselects a working carrier signal and outputs it to a low noise amplifier (13); The low noise amplifier (13) amplifies the pre-selected working carrier signal and enters the second electrically tuned filter (14). The second electrically tuned filter (14) filters out the clutter and carrier wave generated by the low noise amplifier (13) in the carrier signal to reduce useless signals, and then enters the mixer (15); The mixer (15) performs difference frequency on the carrier signal and the local oscillator signal from the second electrically tuned filter (14) and generates an intermediate frequency. The intermediate frequency is passed through an intermediate frequency filter (19) to suppress adjacent channel signals. The useful signal is filtered by the intermediate frequency filter (19) and amplified by the intermediate frequency compensation of the intermediate frequency amplifier (16), and then sent to the intermediate frequency demodulation chip (17) for a second difference frequency demodulation to obtain a modulated signal. The demodulated modulated signal is sent to the baseband chip (18) by the baseband signal to decode and output the received audio and voice information. The transmitter link (2) is a single-carrier transmission or a dual-carrier transmission; wherein, The single carrier transmission comprises: a voice signal collected by the MIC is encoded by a baseband chip (18) and then modulated on a TCVCXO crystal oscillator (21); the TCVCXO crystal oscillator (21) modulates the encoded voice signal and sends it to a transmitting VCO (23) via a phase-locked loop chip (22); the phase-locked loop chip (22) controls the transmitting VCO (23) to lock a target frequency when performing single carrier transmission according to data requirements of the control chip (3), and modulates a 4FSK data signal or analog audio on the transmitting VCO (23) for transmission; the transmitting VCO (23) locks the modulated voice signal to a target carrier and generates a first carrier to perform single carrier transmission; the single carrier is then amplified by a preamplifier (24), an attenuator (25), a preamplifier (26), a driver amplifier (27), and an excitation amplifier (28) in sequence, and then sent to an antenna matching network (11) and radiated outward by the antenna; The dual-carrier transmission comprises: two voice signals collected by the MIC are encoded by a baseband chip (18) and then modulated on a TCVCXO crystal oscillator (21); the TCVCXO crystal oscillator (21) modulates the two encoded voice signals and respectively sends them to a transmitting VCO (23) and a receiving VCO (29) via a phase-locked loop chip (22); the transmitting VCO (23) generates a first carrier of a target channel frequency for transmission, and simultaneously with the transmission of the first carrier, the receiving VCO (29) generates a second carrier of the target channel frequency for transmission; The control chip (3) switches the output of the receiving VCO (29) to the channel of the preamplifier (24) of the transmitter link (2) through the phase-locked loop chip (22); the phase-locked loop chip (22) controls the transmitting VCO (23) and the receiving VCO (29) to transmit simultaneously when dual-carrier transmission is performed according to the control of the control chip (3); the first carrier and the second carrier are sequentially sent to the antenna matching network (11) through the preamplifier (24), the attenuator (25), the preamplifier (26), the driving amplifier (27), and the excitation amplifier (28), and then radiated outward by the antenna.

2. The dual-carrier intercom according to claim 1, characterized in that: The transmitter link (2) also includes an APC power control, which includes using a mean value detector (4) to detect the carrier signal amplified by the microstrip coupled excitation stage, and amplifying the level of the carrier signal and sending it to an APC controller (5); the APC controller (5) compares the level of the amplified carrier signal with a reference level and controls the attenuator (25); and the mean value detector (4), the APC controller (5) and the attenuator (25) are used to repeatedly detect, compare and control attenuation, so that the total transmission power of the single carrier transmission or the dual carrier transmission of the transmitter link (2) is maintained at 5W.

3. The dual-carrier intercom according to claim 2, characterized in that: The mean detector (4) is connected to the coupling circuit (6), and the coupling circuit (6) is coupled to the excitation stage amplifier (28) to obtain a carrier signal amplified by the microstrip coupling excitation stage; wherein, The coupling circuit (6) comprises a first resistor (61), a second resistor (62), a third resistor (63), a capacitor (64) and a fourth resistor (65); the mean value detector (4) is respectively connected to one end of the first resistor (61) and a first end of the second resistor (62); the other end of the second resistor (62) is respectively connected to one end of the third resistor (63) and one end of the capacitor (64); the other end of the capacitor (64) is connected to the fourth resistor (65); and the other ends of the first resistor (61), the third resistor (63) and the fourth resistor (65) are all grounded.

4. The dual-carrier intercom according to claim 2, characterized in that: The APC controller (5) controls the step power range of the transmitter link (2) to be 5-37dBm / 1dB.

5. The dual-carrier intercom according to claim 1, characterized in that: The power of the third-order intermodulation of the transmitter link (2) is ≥70dBc.

6. The dual-carrier intercom according to claim 1, characterized in that: The preamplifier (24) adopts an LDMOS radio frequency tube.

7. The dual-carrier intercom according to claim 1, characterized in that: The dual-carrier transmission includes dual-carrier simultaneous digital mode transmission and dual-carrier simultaneous analog signal transmission.

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