A de-referenced modem and modulation and demodulation method based on CI-DCSK

Abstract

The present invention discloses a de-referenced modem and modulation and demodulation method based on CI-DCSK, wherein the modem includes a modulator and a demodulator, and the de-referenced modulation and demodulation method is implemented by the modem, wherein the modulation and demodulation method includes: obtaining a DCSK information signal in the current symbol period, completing polarity modulation, and generating a DCSK polarity modulation signal; then completing carrier index modulation, and sending the obtained DCSK polarity modulation signal and DCSK information signal to a demodulator; completing carrier index demodulation, and respectively recovering N discrete sequences with 1 DCSK information signal and N discrete sequences with 1 DCSK polarity modulation signal, and completing decoding output. The technical solution of the present invention can eliminate the system's dependence on a reference signal that does not carry any information, and improve the system's energy efficiency and bit error rate performance.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a de-referenced modem and a modulation and demodulation method based on CI-DCSK. Background Art

[0002] With the rapid development of chaos theory research, chaotic digital modulation technology based on broadband non-periodic chaotic signals has emerged. Chaotic digital modulation uses broadband non-periodic chaotic signals to replace the sinusoidal carrier in traditional digital modulation. As a new type of spread spectrum modulation, chaotic digital modulation not only has similar advantages to other spread spectrum modulation schemes, including anti-interference and anti-multipath fading, but also has its own unique advantages, including: simple generation circuit, excellent autocorrelation characteristics and high sensitivity to initial values, which makes it have good randomness. These characteristics are widely used in spread spectrum communication. In recent years, chaotic digital modulation technology with low interception probability and good anti-fading ability has attracted widespread attention in wireless communication. Among them, the most representative scheme is Differential Chaos Shift Keying (DCSK). This incoherent chaotic digital modulation technology adopts the Transmitted-Reference (TR) method. Half of the time in the TR method is used to transmit a reference signal without data.

[0003] With the rapid development of 5G communication technology, index modulation (IM) technology has aroused great interest. IM technology transmits information by selecting different index numbers instead of directly changing the signal waveform. The main feature of IM technology is that it uses specific indexes of transmission resources to convey information bits, such as antennas, subcarriers, precoding methods, channel path indexes, etc. Compared with traditional modulation transmission systems, IM systems use the index of transmission resources as an additional dimension to transmit information. More importantly, IM can flexibly adapt to various system configurations. Among many index modulation systems, carrier index modulation technology is a more common index modulation technology. However, considering that in the DCSK system based on carrier index, more or less part of the energy is used to send reference signals that do not carry data bits, resulting in reduced energy efficiency. Summary of the invention

[0004] The purpose of the present invention is to provide a de-referenced modem and modulation and demodulation method based on CI-DCSK to solve the problems in the prior art, and to divide all available subcarriers into two equal parts, wherein a subcarrier is selected by an index bit in the first part to send an information signal, and a subcarrier is also selected by an index bit in the second part to send a polarity modulation signal, and then the transmitted information is successfully demodulated at the receiving end with the help of carrier index modulation, thereby improving the energy efficiency and bit error performance of the system.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A de-referenced modem based on CI-DCSK, used to generate a preset number of carrier signals within a symbol period, and equally divide the collected carrier signals into sub-carrier signals for sending DCSK information signals and sub-carrier signals for sending polarity modulation signals, wherein the de-referenced modem includes a modulator and a demodulator, and the modulator modulates the obtained carrier signal and sends it to the demodulator;

[0007] The modulator includes a chaotic signal generator, a pulse shaping filter, a polarity converter, a carrier selector, a carrier multiplier, and a carrier adder;

[0008] The chaotic signal generator is used to generate a discrete chaotic signal sequence within a symbol period, and the obtained discrete chaotic signal sequence is pulsed by a pulse shaping filter to obtain a corresponding DCSK information signal. The polarity converter is used to update the transmitted polarity modulation signal from a unipolar modulation bit to a bipolar modulation bit, and generate a DCSK polarity modulation signal by combining the bipolar modulation bit and the DCSK information signal. A subcarrier signal N1 for transmitting the DCSK information signal and a subcarrier signal N2 for transmitting the DCKS polarity modulation signal are selected by a carrier selector, and all subcarrier signals are sent to a demodulator after passing through a carrier multiplier and a carrier adder in turn;

[0009] The demodulator includes a carrier multiplier, a matching filter, a sampling switch, a DSP chip, a symbol bit converter and a polarity converter;

[0010] The carrier multiplier generates synchronization signals corresponding to the subcarrier signals received in sequence, and the synchronization signals are multiplied with the received subcarrier signals to obtain product signals. The product signals are matched filtered by a matched filter, and the product signals after matched filtering are time-domain sampled by a sampling switch and then sequentially passed through a DSP chip, a symbol bit converter, and a polarity converter to obtain the information signal sent by the modulator.

[0011] Another aspect of the present invention provides a de-referenced modulation and demodulation method based on CI-DCSK, which performs de-referenced modulation and demodulation on a signal to be transmitted within a symbol period, including a transmitting end and a receiving end, wherein the transmitting end is used to modulate the information signal collected within the symbol period through a modulator, and specifically includes the following steps:

[0012] Step A, collecting a preset number of carrier signals within a symbol period, dividing the collected carrier signals into subcarrier signals for sending DCSK information signals and subcarrier signals for sending polarity modulation signals, a chaotic signal generator generating a discrete chaotic signal sequence based on the carrier signals collected within the symbol period, and the discrete chaotic signal sequence undergoes pulse shaping filtering by a pulse shaper to obtain a DCSK information signal;

[0013] Step B: The unipolar modulation bit is used to generate a bipolar modulation bit through a polarity converter, and the bipolar modulation bit is multiplied with the DCSK information signal through a carrier multiplier to obtain a DCSK polarity modulation signal;

[0014] Step C, the carrier selector selects a subcarrier signal N1 for transmitting a DCSK information signal from the subcarrier signals used to send information signals, and selects a subcarrier signal N2 for transmitting a DCSK polarity modulated signal from the subcarrier signals used to send polarity modulated signals. The carrier multiplier sequentially multiplies the DCSK information signal with the subcarrier signal N1, and multiplies the DCSK polarity modulated signal with the subcarrier signal N2. The remaining subcarrier signals that are not selected do not send any information signals. The multiplication results of the carrier multiplier are added by the carrier adder and sent to the receiver.

[0015] Furthermore, the receiving end is used to receive the modulated signal sent by the transmitting end, and demodulate the modulated signal through a demodulator, which specifically includes the following steps:

[0016] Step D, the demodulator receives the signal sent by the modulator, and multiplies the received signal with the corresponding synchronization signal through the carrier multiplier to obtain a product signal, and further obtains the matched filtered product signal through the matched filter;

[0017] Step E: time-domain sampling is performed on the product signal after matched filtering to recover the discrete sequence with DCSK information signal and the discrete sequence with DCSK polarity modulation signal. The discrete sequence with DCSK information signal and the discrete sequence with DCSK polarity modulation signal are used to obtain correlation values ​​through the DSP chip to further obtain polarity modulation bits, and then enter step F;

[0018] Step F: The correlation value and polarity modulation bit obtained by the DSP chip are demodulated in turn by a sign bit converter and a polarity converter to obtain an index bit and a bipolar modulation bit.

[0019] Furthermore, in the aforementioned step E, the DSP chip correlates the two sets of discrete chaotic signal sequences respectively to obtain N*N correlation values, and calculates the absolute value, finds the position of the maximum absolute value, compares the correlation value corresponding to the position with the threshold value, and determines the output bipolar modulation bit according to the threshold value.

[0020] Furthermore, in the aforementioned step F, the sign bit converter converts the row and column values ​​of the found position into binary signals and outputs corresponding index bits; based on the index bits, the polarity converter converts the bipolar binary modulation bits into unipolar binary modulation bits.

[0021] The de-referenced modem and modulation and demodulation method based on CI-DCSK described in the present invention, using the above technical solution compared with the prior art, has the following technical effects:

[0022] The present invention divides the collected subcarrier signals into two parts, selects a subcarrier for sending a DCSK information signal, and selects a subcarrier for sending a DCSK polarity modulation signal. The orthogonality between the DCSK information signal and the DCSK polarity modulation signal is ensured by the orthogonality between different subcarriers. During demodulation, the signals received by the first N subcarriers are correlated with the signals received by the last N subcarriers, and the absolute values ​​are taken to realize information demodulation. The method described in the present invention can avoid sending a reference signal that does not carry any information alone, improve the energy efficiency of the system, and improve the bit error performance of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a structural schematic diagram of a modulator of an exemplary embodiment of the present invention;

[0024] Figure 2 A schematic diagram of the structure of a demodulator of an exemplary embodiment of the present invention;

[0025] Figure 3 The figure is a flowchart of a modulation and demodulation method according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to better understand the technical content of the present invention, specific embodiments are given and described as follows in conjunction with the accompanying drawings.

[0027] Various aspects of the present invention are described in this disclosure with reference to the accompanying drawings, in which many illustrative embodiments are shown. The embodiments of the present disclosure are not necessarily defined to include all aspects of the present invention. It should be understood that the various concepts and embodiments introduced above, as well as those described in more detail below, can be implemented in any of many ways, because the concepts and embodiments disclosed by the present invention are not limited to any implementation. In addition, some aspects disclosed by the present invention can be used alone, or in any appropriate combination with other aspects disclosed by the present invention.

[0028] refer to Figure 1 , Figure 2 , the present invention provides a de-referenced modem based on CI-DCSK, which is used to generate a preset number of carrier signals within a symbol period, and equally divide the collected carrier signals into sub-carrier signals for sending DCSK information signals and sub-carrier signals for sending polarity modulation signals, the de-referenced modem includes a modulator and a demodulator, and the modulator modulates the obtained carrier signal and sends it to the demodulator;

[0029] The modulator includes a chaotic signal generator, a pulse shaping filter, a polarity converter, a carrier selector, a carrier multiplier, and a carrier adder;

[0030] The chaotic signal generator is used to generate a discrete chaotic signal sequence within a symbol period. The obtained discrete chaotic signal sequence is pulsed by a pulse shaping filter to obtain a corresponding DCSK information signal. The polarity converter updates the polarity modulation bit used for transmission from unipolarity to bipolarity, and generates a DCSK polarity modulation signal by combining the bipolar modulation bit and the DCSK information signal. A subcarrier signal N1 for transmitting the DCSK information signal and a subcarrier signal N2 for transmitting the DCKS polarity modulation signal are selected by a carrier selector. All subcarrier signals are sequentially sent to a demodulator after passing through a carrier multiplier and a carrier adder.

[0031] The demodulator includes a carrier multiplier, a matching filter, a sampling switch, a DSP chip, a symbol bit converter and a polarity converter;

[0032] The carrier multiplier generates synchronization signals corresponding to the subcarrier signals received in sequence, and the synchronization signals are multiplied with the received subcarrier signals to obtain product signals. The product signals are matched filtered by a matched filter, and the matched filtered product signals are time-domain sampled by a sampling switch and then sequentially passed through a DSP chip, a symbol bit converter, and a polarity converter to obtain the subcarrier signal sent by the modulator.

[0033] Based on a de-referenced modem provided by the present invention, referring to Figure 3In combination with a modem, the present invention exemplarily provides a de-referenced modulation and demodulation method based on CI-DCSK. In combination with steps A to C, the modulation process specifically includes the following steps:

[0034] Step 1: First, data is collected in the current symbol period. Then, according to the bit signal-to-noise ratio value measured in the channel and the number of available subcarriers 2N, the index selector selects subcarrier N1 for sending DCSK information signals from the 1st to the Nth subcarriers according to index bit 1; the index selector selects subcarrier N2 for sending DCSK polarity modulation signals from the N+1th to the 2Nth subcarriers according to index bit 2, and the remaining 2N-2 subcarriers do not send data bits.

[0035] Step 2: The chaotic signal generator generates a discrete chaotic signal sequence of length β according to the logistic map;

[0036] Step 3: Perform pulse shaping filtering on the discrete chaotic signal sequence generated in step 2 through a raised cosine roll-off filter to obtain the DCSK information signal of step 1;

[0037] Step 4: The modulation bit generates a polarity modulation bit through a polarity converter;

[0038] Step 5: multiplying the DCSK information signal generated in step 3 by the polarity modulation bit generated in step 4 to generate a DCSK polarity modulation signal;

[0039] Step 6: Multiply the DCSK information signal generated in step 3 by the N1th subcarrier selected in step 1;

[0040] Step 7: multiply the DCSK polarity modulated signal generated in step 5 by the N2th subcarrier selected in step 1, and the remaining 2N-2 unselected subcarriers do not send any information signal;

[0041] Step 8: All 2N subcarriers are added together and sent to the demodulator through the antenna.

[0042] In combination with step D to step F, the demodulation process specifically includes the following steps:

[0043] Step 9: The demodulator receives the signal sent in step 9, and multiplies it with 2N synchronized subcarriers with a frequency of respectively to obtain 2N product signals;

[0044] Step 10: Perform matched filtering on the 2N product signals obtained in step 10 respectively, and perform time domain sampling on the filtered 2N product signals. After time domain sampling, the continuous signal will become a discrete sequence. Recover the discrete sequences of the first N channels with 1 DCSK information signal and the discrete sequences of the last N channels with 1 DCSK polarity modulation signal respectively. The discrete sequences of DCSK information signal and DCSK polarity modulation signal recovered here are the discrete sequences of DCSK information signal and DCSK polarity modulation signal in step 3 and step 5 after time domain sampling;

[0045] Step 11: Correlate the first N discrete sequences and the last N discrete sequences in step 11, respectively. The correlation here means storing the first N discrete sequences and the last N discrete sequences into two matrices respectively, and then performing matrix multiplication on the two matrices to finally obtain N*N correlation values;

[0046] Step 12: Take the absolute value of the correlation value in step 12;

[0047] Step 13: Take the maximum value of the absolute values ​​in step 13, convert the abscissa of the maximum value into a binary sequence, which is index bit 1, and convert the ordinate of the maximum value into a binary sequence, which is index bit 2, thereby demodulating the index bit;

[0048] Step 14: Find the correlation value corresponding to the coordinate in step 14 among the N*N correlation values, complete the threshold decision, and output the demodulated polarity modulation bit according to the threshold decision; the demodulation rule is: when the correlation value > threshold value 0, the demodulated polarity modulation bit is "+1", otherwise, the demodulated polarity modulation bit is "-1".

[0049] In the above method, the received signal is respectively transmitted at the receiving end at frequencies f1, ..., f 2N The 2N synchronized subcarriers are multiplied respectively, and the obtained 2N product signals are respectively subjected to matched filtering. The signals output after the 2N matched filtering are sampled in the time domain, and 2N discrete sequences are respectively restored, among which the first N channels contain a discrete sequence of 1 DCSK information signal, and the last N channels contain a discrete sequence of 1 DCSK polarity modulation signal. The first N channels and the last N channels of discrete sequences are correlated respectively to obtain N*N correlation values, and the absolute value is calculated to find the coordinates of the maximum absolute value, and demodulate the index bit; the correlation value corresponding to the coordinate is compared with the threshold 0, and the polarity modulation bit is output according to the threshold judgment.

[0050] On this basis, the present invention proposes a de-referenced modem, which can modulate and demodulate signals using the above method. Specifically, the modulator divides all available subcarriers equally into two parts, wherein the first part selects a subcarrier to transmit a DCSK information signal, the other part selects a subcarrier to transmit a DCSK polarity modulation signal, and the remaining subcarriers do not transmit signals. The demodulator correlates the two received signals respectively, takes the absolute value, and realizes information demodulation based on the absolute value of the correlation value.

[0051] The structure of the modulator in the modem is as follows Figure 1 As shown, it specifically includes: a chaotic signal generator, a pulse shaping filter, a polarity converter, a carrier selector, a 2N-channel carrier multiplier and an adder, and the number of subcarriers available is 2N; the chaotic signal generator generates a discrete chaotic signal sequence, which is subjected to pulse shaping filtering by a pulse shaping filter to obtain a DCSK information signal in the current symbol period; the polarity converter converts the unipolar modulation bit into a bipolar modulation bit, and multiplies it with the DCSK information signal to generate a DCSK polarity modulation signal; the carrier selector selects one subcarrier N1 from the first N subcarriers according to the corresponding index bit to transmit the DCSK information signal, and selects one subcarrier N2 from the last N subcarriers according to the corresponding index bit to transmit the DCSK polarity modulation signal; the 2N-channel carrier multiplier converts the first N channels with frequencies f1,...,f N The N subcarriers of the quartz crystal are multiplied respectively, and the last N subcarriers are multiplied by the frequency f N+1 ,...,f 2N The N subcarriers are multiplied respectively; the adder adds all the subcarriers and sends them.

[0052] The structure of the demodulator in the modem is as follows Figure 2As shown, it includes 2N carrier multipliers, 2N matched filters, 2N sampling switches, DSP chips, symbol bit converters and polarity converters; the 2N carrier multipliers use 2N synchronized subcarriers to multiply the received signals respectively to obtain 2N product signals; the 2N matched filters perform matched filtering on the 2N product signals respectively; the 2N sampling switches perform time domain sampling on the 2N product signals after matched filtering respectively to restore 2N discrete sequences, wherein the first N discrete sequences contain a DCSK information signal, and the last N discrete sequences contain a DCSK polarity modulation signal; the DSP chip correlates the first N discrete sequences and the last N discrete sequences respectively to obtain N*N correlation values, and calculates the absolute value, finds the coordinates of the maximum absolute value, compares the correlation value corresponding to the coordinates with the threshold, and outputs the polarity modulation bit according to the threshold; the index bit converter converts the row and column values ​​of the found coordinates into binary signals and outputs index bits; the polarity converter converts the bipolar modulation bits into unipolar modulation bits.

[0053] As a preferred solution, in order to verify that the reference carrier index-free differential chaotic shift keying modulation and demodulation method provided by the present invention can reduce the bit error rate, the present invention cites a verification example for verification and explanation. The method of this verification example includes the following steps:

[0054] At the transmitting end, the signal is subjected to dereferenced carrier index differential chaotic shift keying modulation, specifically including:

[0055] Step 1: Select the bit signal-to-noise ratio E in the channel b When / N0=10dB, the length β of the discrete chaotic signal sequence within one symbol time is 32, and the number of available subcarriers is 2N=256.

[0056] Step 2: Within one symbol period [0, Tb], the chaotic signal generator outputs a discrete chaotic sequence {x1, x2, ..., x 32}.

[0057] Step 3: Pass the discrete chaotic signal sequence generated in step 2 through a square raised cosine roll-off filter, whose time domain impulse response is h(t), to complete pulse shaping filtering and obtain the DCSK information signal in the current symbol period:

[0058]

[0059] Where, t represents time; T c Indicates chip time.

[0060] Step 4: Use the polarity converter to convert the unipolar modulation bits to be transmitted in the current symbol period into bipolar modulation bits.

[0061] Step 5: Multiply the bipolar modulation bit obtained in step 4 by the DCSK information signal x(t) in the current symbol period generated in step 3 to obtain a DCSK polar modulation signal.

[0062] Step 6: According to index bit 1, the carrier selector selects a subcarrier N1 from the 1st to 128th subcarriers to send a DCSK information signal; according to index bit 2, the carrier selector selects a subcarrier N2 from the 129th to 256th subcarriers to send a DCSK polarity modulation signal.

[0063] Step 7: Combine the DCSK information signal generated in step 3 with the frequency f N1 Multiply the DCSK polar modulated signal generated in step 5 by the subcarrier of frequency f N2 The subcarriers are multiplied.

[0064] Step 8: The unselected 254 channels are respectively allocated to the remaining frequencies f1, ..., f N1-1 ,f N1+1 ,...,f N2-1 ,f N2+1 ,...,f 256 The 254 subcarriers are multiplied.

[0065] Step 9: All 256 signals are added together and transmitted through the antenna.

[0066] At the receiving end, the signal is received and demodulated, including:

[0067] Step 10: The receiver compares the signal received by the antenna with the frequencies f1, f2, ..., f 256 The 256 synchronized subcarriers are multiplied together to obtain 256 product signals.

[0068] Step 11: The 256 product signals obtained in step 10 are matched filtered through 256 filters matched with the square raised cosine roll-off filter used in step 3, and the outputs of the 256 matched filters are time-domain sampled to restore the first 128 discrete sequences with 1 DCSK information signal and the second 128 discrete sequences with 1 DCSK polarity modulation signal.

[0069] Step 12: Correlate the first 128 discrete sequences and the last 128 discrete sequences in step 11 respectively to obtain 128*128 correlation values.

[0070] Step 13: Take the absolute value of the 128*128 correlation values ​​obtained in step 12 and find the coordinates corresponding to the maximum value.

[0071] Step 14: According to the row and column values ​​of the coordinates obtained in step 13, the index bit 1 and the index bit 2 are demodulated respectively through a sign bit converter.

[0072] Step 15: According to the coordinates obtained in step 13, find the corresponding correlation value in the 128*128 correlation values, compare it with the threshold 0, and restore the polarity modulation bit through the polarity converter.

[0073] The present invention uses computer simulation to conduct a transmission test on the reference carrier index differential chaotic shift keying modulation and demodulation method provided by the present invention. In the test, the number of transmitted data bits is 10 6 , the discrete chaotic signal sequence is mapped by the second-order Chebyshev polynomial The chaotic signal sampling frequency is 1MHz, the symbol duration T=32μs, the equivalent number of signal sampling points in each symbol time is 32, the square raised cosine roll-off filter roll-off coefficient α=0.25, and the center frequency interval of all subcarriers satisfies Δf=1.25MHz.

[0074] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. A de-referenced modem based on CI-DCSK, used to generate a preset number of carrier signals within a symbol period, and to divide the collected carrier signals into subcarrier signals for sending DCSK information signals and subcarrier signals for sending polarity modulation signals, characterized in that: The de-referenced modem includes a modulator and a demodulator, wherein the modulator modulates the acquired carrier signal and sends it to the demodulator; The modulator includes a chaotic signal generator, a pulse shaping filter, a polarity converter, a carrier selector, a carrier multiplier, and a carrier adder; The chaotic signal generator is used to generate a discrete chaotic signal sequence within a symbol period, and the obtained discrete chaotic signal sequence is pulsed by a pulse shaping filter to obtain a corresponding DCSK information signal. The polarity converter is used to update the transmitted polarity modulation signal from a unipolar modulation bit to a bipolar modulation bit, and generate a DCSK polarity modulation signal by combining the bipolar modulation bit and the DCSK information signal. A subcarrier signal N1 for transmitting the DCSK information signal and a subcarrier signal N2 for transmitting the DCKS polarity modulation signal are selected by a carrier selector, and all subcarrier signals are sent to a demodulator after passing through a carrier multiplier and a carrier adder in turn; The demodulator includes a carrier multiplier, a matching filter, a sampling switch, a DSP chip, a symbol bit converter and a polarity converter; The carrier multiplier generates synchronization signals corresponding to the subcarrier signals received in sequence, and the synchronization signals are multiplied with the received subcarrier signals to obtain product signals. The product signals are matched filtered by a matched filter, and the product signals after matched filtering are time-domain sampled by a sampling switch and then sequentially passed through a DSP chip, a symbol bit converter, and a polarity converter to obtain the information signal sent by the modulator.

2. A de-referenced modulation and demodulation method based on CI-DCSK, which performs de-referenced modulation and demodulation on a signal to be transmitted within a symbol period, characterized in that: The method comprises a transmitting end and a receiving end. The transmitting end is used to modulate the information signal collected in the symbol period through a modulator, and specifically comprises the following steps: Step A, collecting a preset number of carrier signals within a symbol period, dividing the collected carrier signals into subcarrier signals for sending DCSK information signals and subcarrier signals for sending polarity modulation signals, a chaotic signal generator generating a discrete chaotic signal sequence based on the carrier signals collected within the symbol period, and the discrete chaotic signal sequence undergoes pulse shaping filtering by a pulse shaper to obtain a DCSK information signal; Step B: The unipolar modulation bit is used to generate a bipolar modulation bit through a polarity converter, and the bipolar modulation bit is multiplied with the DCSK information signal through a carrier multiplier to obtain a DCSK polarity modulation signal; Step C, the carrier selector selects a subcarrier signal N1 for transmitting a DCSK information signal from the subcarrier signals used to send information signals, and selects a subcarrier signal N2 for transmitting a DCSK polarity modulated signal from the subcarrier signals used to send polarity modulated signals. The carrier multiplier sequentially multiplies the DCSK information signal with the subcarrier signal N1, and multiplies the DCSK polarity modulated signal with the subcarrier signal N2. The multiplication results of the carrier multiplier are added by the carrier adder and sent to the receiver.

3. The de-referenced modulation and demodulation method based on CI-DCSK according to claim 2, characterized in that: The receiving end is used to receive the modulated signal sent by the transmitting end and demodulate the modulated signal through a demodulator, which specifically includes the following steps: Step D, the demodulator receives the signal sent by the modulator, and multiplies the received signal with the corresponding synchronization signal through the carrier multiplier to obtain a product signal, and further obtains the matched filtered product signal through the matched filter; Step E: time-domain sampling is performed on the product signal after matched filtering to recover the discrete sequence with DCSK information signal and the signal sequence with DCSK polarity modulation signal. The discrete sequence with DCSK information signal and the discrete sequence with DCSK polarity modulation signal are used to obtain correlation values ​​through the DSP chip to further obtain polarity modulation bits, and then enter step F; Step F: The correlation value and polarity modulation bit obtained by the DSP chip are demodulated in turn by a sign bit converter and a polarity converter to obtain an index bit and a bipolar modulation bit.

4. The de-referenced modulation and demodulation method based on CI-DCSK according to claim 3, characterized in that: In step E, the DSP chip correlates the two sets of discrete chaotic signal sequences obtained respectively to obtain correlation values ​​consistent with the number of subcarrier signals, and calculates the absolute value, finds the position of the maximum absolute value, compares the correlation value corresponding to the position with the threshold value, and determines the output bipolar modulation bit according to the threshold value.

5. The de-referenced modulation and demodulation method based on CI-DCSK according to claim 4, characterized in that: In step F, the sign bit converter converts the row and column values ​​of the found position into binary signals and outputs the corresponding index bits; based on the index bits, the polarity converter converts the bipolar modulation bits into unipolar modulation bits.

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