CN103595676A - Continuous phase 8PSK modulation method - Google Patents
Continuous phase 8PSK modulation method Download PDFInfo
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Abstract
The invention discloses a continuous phase 8PSK modulation method. The method comprises the following steps of generating a carrier wave phase control word and an additional accumulation phase control word; detecting whether current sending data is changed; outputting different gating signals according to a phase difference value; outputting different numbers of additional phase control words according to the different gating signals; calculating step lengths of the phase control words; accumulating the step lengths of the phase control words; outputting a modulation waveform amplitude value; determining whether current data sending is completed; determining whether all the data is sent. By using the continuous phase 8PSK modulation method of the invention, a transition waveform whose phase is continuous with a previous data waveform phase is used so that a modulation waveform of the current data is smoothly transited and continuity of the modulation waveform is realized. Phase hopping existing in the modulation waveforms of data which is sent by adjacent clocks according to a time sequence is eliminated so that a pulse response generated because of the phase hopping is eliminated too. Symbol rate information contained in a waveform signal is concealed. Security and confidentiality of communication are increased.
Description
Technical field
The present invention relates to a kind of modulator approach, particularly a kind of eight phase phase shift keyings of continuous phase (8Phase Shift Keying is called for short 8PSK) modulator approach.
Background technology
Phase shift keying (Phase Shift Keying is called for short PSK) is a kind of modulation technique that represents transmission of signal information by carrier phase, utilizes phase place to change and carrys out transmitting digital information.In IS-95 and the two-phase PSK using in IMT-2000 (Binary Phase Shift Keying, abbreviation BPSK), quarternary phase-shift keying (QPSK) (Quadri Phase Shift Keying, abbreviation QPSK), the 8PSK using in transfer of data enhancement mode GSM evolution (Enhanced Data rate for GSM Evolution is called for short EDGE) and CDMA2000EV-DO system is typical phase shift keying modulation system.
While adopting phase shift keying technology to carry out signal modulation, phase place variation happens suddenly.In 8PSK modulation mode, adopt the carrier waveform with 8 different initial phase place values to characterize the transmission information of 3 bits, between different initial phase place values, there is equal phase interval, can be expressed as θ
0+ l π/4, l=0,1 ..., 7, θ wherein
0for basic initial phase place value, the phase intervals between each initial phase place value is π/4.Therefore,, when sending data generation saltus step, the phase difference between the carrier waveform of adjacent transmission data may be ± π/4, ± pi/2, ± 3 π/4, ± π, ± 5 π/4, ± 3 pi/2s and ± 7 π/4.Because changing, phase place happens suddenly, therefore at SPA sudden phase anomalies point, can inevitably introduce very large impulse response, these impulse responses are similar to impulse function (δ function), have very strong frequency spectrum observability, have greatly increased signal and have been intercepted and captured the probability with demodulation.Meanwhile, SPA sudden phase anomalies can cause system spectrum broadening, and when Bandwidth-Constrained, video stretching impels modulation signal envelope to change.In addition, PSK is higher to the linearity of amplifier, is to the having relatively high expectations of modulating equipment, and then has improved the cost of communication equipment.
The above-mentioned defect existing for PSK modulation system, this area researcher has proposed Continuous Phase Modulation (Continuous Phase Modulation is called for short CPM) modulation system.CPM modulation system is that information data is included in instantaneous carrier phase place or frequency, utilizes phase place memory effect to guarantee that carrier phase is all continuous at any time, thereby has avoided SPA sudden phase anomalies.The class modulation technique greatly that CPM modulation system has comprised that carrier phase changes with conitnuous forms, minimum shift keying (the Minimum Shift Keying for example using in current Generation Mobile Telecommunication System, abbreviation MSK), GMSK (Guassian Minimum Shift Keying) (Gaussian Minimum Shift Keying is called for short GMSK) is exactly common CPM modulation system.CPM modulation system has been avoided SPA sudden phase anomalies, compares with PSK modulation system, and CPM has better spectral characteristic, and power spectrum is more concentrated; The modulation signal envelope of CPM is constant simultaneously, and nonlinear amplifier easy to use, has reduced equipment cost.But, compare with linear modulation, the concrete form of CPM signal is not only relevant with moulding pulse, also relevant with the value of modulation index h, frequency response function pulse correlation length L, therefore CPM modulation system, than general linear modulation (as PSK) complexity, has increased the implementation complexity of modulating equipment.
Summary of the invention
The object of the invention is to overcome problem and the higher deficiency of CPM modulation system implementation complexity of the SPA sudden phase anomalies that in prior art, existing 8PSK modulation mode exists, a kind of continuous phase 8PSK modulator approach is provided, this modulator approach can overcome the shortcoming of the strong frequency spectrum observability of signal waveform that in existing 8PSK modulation mode, phase hit causes, and the apparatus structure of realizing this modulator approach is simple, and complexity is low.
In order to realize foregoing invention object, the invention provides following technical scheme:
A kind of continuous phase 8PSK modulator approach, the method is based on Direct Digital frequency synthesis (Direct Digital Synthesizer, be called for short DDS) technology, by extra cumulative phase control words, directly change the mode of control word, the continuous transition waveform of utilization and previous data waveform phase place is smoothly transitted into the modulation waveform of current data, realizes the continuity of modulation waveform, and its concrete steps comprise:
Step 1: calculate carrier phase control word and extra cumulative phase control words, wherein, described extra cumulative phase control words comprises the first extra cumulative phase control words, the second extra cumulative phase control words, the 3rd extra cumulative phase control words, the 4th extra cumulative phase control words, the 5th extra cumulative phase control words, the 6th extra cumulative phase control words and the 7th extra cumulative phase control words;
Step 2: read current data to be sent, and judge that whether current data to be sent are identical with adjacent last clock transmission data;
Step 3: if the same export the 8th gating signal, if different, calculate the phase difference value between adjacent transmission data waveform, and export corresponding gating signal according to out of phase difference;
Step 4: according to different gating signal continuous wave output M corresponding extra phase control words, described M represents: excessively the phase place of waveform reaches the phase difference value between described adjacent transmission data waveform after M clock cycle;
Step 5: calculate phase control words step-length, phase control words step-length=carrier phase control word+extra phase control words, described phase control words step-length is the ROM look-up table address increment between two adjacent sampled points, and described ROM look-up table is for storing the sinusoidal waveform range value of discretization;
Step 6: cumulative phase control words step-length, calculate total phase control words, described total phase control words is the ROM look-up table address of each clock;
Step 7: the look-up table address producing according to step 6, the modulation waveform signal amplitude value of searching present clock in ROM look-up table, and by this modulation waveform signal amplitude value output;
Step 8: judge whether current data transmission completes, if complete, enters step 9, if do not complete, returns to step 6, proceeds total phase control words and calculates;
Step 9: judge whether all data transmissions complete, if complete, finish, if do not complete, return to step 2, continue to read data to be sent.
According to embodiments of the invention, the computational methods of the control word of carrier phase described in step 1 are: the sinusoidal carrier signal of supposing to adopt N discrete sample signals value representation one-period, the phase difference between two adjacent discrete sampling points is Δ θ=2 π/N, and carrier phase control word is
wherein, the implication of K is: the degree of depth of ROM look-up table.
According to the embodiment of the present invention, described in step 1, the computational methods of extra cumulative phase control words are:
The first extra cumulative phase control words: the first extra cumulative phase place reaches π/4 after M clock cycle, the first extra cumulative phase step is
the first extra cumulative phase control words is
The second extra cumulative phase control words: establish the second extra cumulative phase place after M clock cycle and reach pi/2, the second extra cumulative phase step is
the second extra cumulative phase control words is
The 3rd extra cumulative phase control words: establish the 3rd extra cumulative phase place after M clock cycle and reach 3 π/4, the 3rd extra cumulative phase step is
the 3rd extra cumulative phase control words is
The 4th extra cumulative phase control words: establish the 4th extra cumulative phase place after M clock cycle and reach π, the 4th extra cumulative phase step is
the 4th extra cumulative phase control words is
The 5th extra cumulative phase control words: establish the 5th extra cumulative phase place after M clock cycle and reach 5 π/4, the 5th extra cumulative phase step is
the 5th extra cumulative phase control words is
The 6th extra cumulative phase control words: establish the 6th extra cumulative phase place after M clock cycle and reach 3 pi/2s, the 6th extra cumulative phase step is
the 6th extra cumulative phase control words is
The 7th extra cumulative phase control words: establish the 7th extra cumulative phase place after M clock cycle and reach 7 π/4, the 7th extra cumulative phase step is
the 7th extra cumulative phase control words is
According to the embodiment of the present invention, the method for exporting corresponding gating signal according to out of phase difference in described step 3 is:
If phase difference value is π/4 or-7 π/4, export the first gating signal; If phase difference is pi/2 or-3 pi/2s, export the second gating signal; If phase difference is 3 π/4 or-5 π/4, export the 3rd gating signal; If phase difference value is ± π to export the 4th gating signal; If phase difference is 5 π/4 or-3 π/4, export the 5th gating signal; If phase difference value be 3 pi/2s or-pi/2, export the 6th gating signal; If phase difference be 7 π/4 or-π/4, export the 7th gating signal.
According to the embodiment of the present invention, in described step 4, according to the method for different gating signal continuous wave output M corresponding extra phase control words, be:
When gating signal is the first gating signal, described extra phase control words is the first extra cumulative phase control words; When gating signal is the second gating signal, described extra phase control words is the second extra cumulative phase control words; When gating signal is the 3rd gating signal, described extra phase control words is the 3rd extra cumulative phase control words; When gating signal is the 4th gating signal, described extra phase control words is the 4th extra cumulative phase control words; When gating signal is the 5th gating signal, described extra phase control words is the 5th extra cumulative phase control words; When gating signal is the 6th gating signal, described extra phase control words is the 6th extra cumulative phase control words; When gating signal is the 7th gating signal, described extra phase control words is the 7th extra cumulative phase control words; When gating signal is the 8th gating signal, described extra phase control words is zero.
According to embodiments of the invention, described M value is
wherein, the implication of N is: adopt N
The sinusoidal carrier signal of discrete sample signals value representation one-period.
Compared with prior art, beneficial effect of the present invention:
1, continuous phase 8PSK modulator approach of the present invention, based on direct digital frequency synthesis technology, by extra cumulative phase control words, directly change the mode of control word, produce the discontinuous waveform that transition waveform replaces phase hit in traditional 8PSK modulation, realized the continuity of modulation waveform, before and after having eliminated adjacent clock, send the phase hit existing in the modulation waveform of data, thereby eliminated the impulse response producing because of SPA sudden phase anomalies, the hidden symbol rate information containing in waveform signal, has increased fail safe and the confidentiality of communication.
2, continuous phase 8PSK modulator approach of the present invention is compared with CPM modulator approach, the value of the concrete form of the modulation signal of employing the inventive method and moulding pulse, modulation index h, frequency response function pulse correlation length L is irrelevant, so it is low to realize the complexity of modulator approach of the present invention, more easily realize, modulating equipment is simple in structure, and cost is low.
Accompanying drawing explanation:
Fig. 1 is the modulating device structured flowchart of realizing continuous phase 8PSK modulator approach of the present invention.
Fig. 2 is the FB(flow block) of continuous phase 8PSK modulator approach of the present invention.
Fig. 3 (a) is in embodiment, to adopt the modulation waveform figure of continuous phase 8PSK modulator approach of the present invention to Fig. 3 (g).
Fig. 4 is that the phase difference that in embodiment, data jump causes is π/4 o'clock, and the phase place of traditional 8PSK modulation and continuous phase 8PSK of the present invention modulation changes comparison diagram.
Fig. 5 is phase difference that in embodiment, data jump causes while being pi/2, the phase place variation comparison diagram of traditional 8PSK modulation and continuous phase 8PSK of the present invention modulation.
Embodiment
Below in conjunction with test example and embodiment, the present invention is described in further detail.But this should be interpreted as to the scope of the above-mentioned theme of the present invention only limits to following embodiment, all technology realizing based on content of the present invention all belong to scope of the present invention.
Continuous phase 8PSK modulator approach of the present invention realizes based on Direct Digital frequency synthesis (DDS) method, first the concise and to the point basic principle that adopts DDS to produce discrete digital modulation signal of setting forth.DDS generally includes 3 basic modules: phase control word modules, phase accumulator module and sinusoidal ROM look-up table means.Phase control words is by the determined ROM look-up table of two adjacent sampled point phase differences address increment; Phase accumulator is responsible for phase control words to carry out accumulating operation, and the total phase control words calculating is final ROM look-up table address; ROM look-up table, by carrier signal range value output corresponding to Input Address, obtains intermediate frequency digital modulation signals.
Suppose to adopt the pure oscillation signal of K discrete sample signals value representation one-period, so the phase difference between two adjacent discrete sampling points is Δ θ=2 π/K, the value of i sinusoidal sampled signal is sin (2 π (i-1)/K), i=1,2, L, K.Δ θ is the minimum phase precision that DDS can reach.The pure oscillation signal value of this group sampling is pre-deposited in ROM, and its address is followed successively by 0,1,2, L, K-1, and K value is the degree of depth of sine lookup table.Phase control words C
dDSby corresponding carrier wave physical frequencies f
c, the systematic sampling frequency f while realizing
sand sine lookup table degree of depth K determines jointly, its computational methods are:
Carrier wave physical frequencies f
cwith sample frequency f
sbetween ratio be phase intervals between two neighbouring sample points of carrier wave (with 2 πWei units meterings), the phase accuracy Δ θ that phase intervals can reach with DDS again compares (being that phase intervals is divided by phase accuracy), can calculate the ROM look-up table address increment between two neighbouring sample points of carrier wave, this value is phase control words.For example, sample frequency f
scarrier wave physical frequencies f
c4 times time, C
dDS=K/4, so the sinusoidal carrier signal of a complete cycle of every 4 somes output of DDS.
Before describing continuous phase 8PSK modulator approach of the present invention, first simple introduction realized the required modulating device of the inventive method.
As shown in Figure 1, the device of realizing continuous phase 8PSK modulator approach of the present invention comprises data variation detector 101, frequency selector 104, carrier phase control word generator 105, the phase control word generator 103 that additionally adds up, gate 102, phase control words calculator 106, phase control word accumulator 107 and ROM look-up table 108, wherein
Whether described data variation detector 101 sends data for detection of present clock identical with adjacent last clock transmission data, if it is identical with adjacent last clock transmission data that data variation detector detects present clock transmission data, output signal " 000 ", if it is different to send data, according to the phase difference output unlike signal between adjacent transmission data waveform: if phase difference value is π/4 or-7 π/4, output signal " 001 "; If phase difference value is pi/2 or-3 pi/2s, output signal " 010 "; If phase difference value is 3 π/4 or-5 π/4, output signal " 011 "; If phase difference value is ± π, output signal " 100 "; If phase difference value is 5 π/4 or-3 π/4, output signal " 101 "; If phase difference value be 3 pi/2s or-pi/2, output signal " 110 "; If phase difference value be 7 π/4 or-π/4, output signal " 111 ".
Described frequency selector 104 is for selecting the required carrier frequency of output modulation.
Described carrier phase control word generator 105 is connected with frequency selector 104, for producing carrier phase control word according to the selected carrier frequency of frequency selector 104.
Described extra cumulative phase control word generator 103 is connected with frequency selector 104, and additionally cumulative phase control word generator 103 is for generation of extra cumulative phase control words.
Described gate 102 is connected with extra cumulative phase control word generator 103 with data variation detector 101 respectively, and gate is for gating the outer phase control words of amount of exports.
Described phase control words calculator 106 respectively be connected gate 102 and be connected with carrier phase control word generator 105, phase control words calculator 106, for carrier phase control word and extra phase control words are carried out to addition calculation, obtains phase control words step-length.
Described phase control word accumulator 107 is connected with phase control words calculator 106, and phase control word accumulator 107 is cumulative for phase control words step-length, obtains total phase control words, and this total phase control words is the address of ROM look-up table 108;
Described ROM look-up table 108 is connected with phase control word accumulator 107, and ROM look-up table 108 is for storing the sinusoidal waveform range value of discretization.
It should be noted that, K represents the degree of depth of ROM look-up table, i.e. the higher limit of ROM look-up table address, and in the present embodiment, K value is 128.
It should be noted that, in the present embodiment, M represents the length of excessive waveform, the i.e. modulation waveform smooth connection of excessive waveform realization and current data after M clock cycle, that is the phase place that represents excessive waveform after M clock cycle reaches the phase difference value between adjacent transmission Data Modulation waveform, concrete:
When phase difference be π/4 or-during 7 π/4, after M clock cycle, the first extra cumulative phase place reaches π/4, the excessively modulation waveform smooth connection of waveform and current data;
When phase difference be pi/2 or-during 3 pi/2, after M clock cycle, the second extra cumulative phase place reaches pi/2, the excessively modulation waveform smooth connection of waveform and current data;
When phase difference be 3 π/4 or-during 5 π/4, after M clock cycle, the 3rd extra cumulative phase place reaches 3 π/4, the excessively modulation waveform smooth connection of waveform and current data;
When phase difference be ± during π, after M clock cycle, the 4th extra cumulative phase place reaches π, the excessively modulation waveform smooth connection of waveform and current data;
When phase difference be 5 π/4 or-during 3 π/4, after M clock cycle, the 5th extra cumulative phase place reaches 5 π/4, the excessively modulation waveform smooth connection of waveform and current data;
When phase difference be 3 pi/2s or-during pi/2, after M clock cycle, the 6th extra cumulative phase place reaches 3 pi/2s, the excessively modulation waveform smooth connection of waveform and current data;
When phase difference be 7 π/4 or-during π/4, after M clock cycle, the 7th extra cumulative phase place reaches 7 π/4, the excessively modulation waveform smooth connection of waveform and current data.
M can get arbitrary value, in the present embodiment, gets
n represents: adopt the sinusoidal carrier signal of N discrete sample signals value representation one-period, in the present embodiment, get N=32, M=16.
With reference to figure 2, when traditional 8PSK modulation, if two adjacent data differences, the phase hit point of can produce ± π/4 of modulation waveform, ± pi/2, ± 3 π/4, ± π, ± 5 π/4, ± 3 pi/2s and ± 7 π/4.Continuous phase 8PSK modulator approach of the present invention is by extra cumulative phase control words, directly change the mode of phase control words, utilize the transition waveform continuous with previous data waveform phase place to be smoothly transitted into the modulation waveform of current data, utilize this transition waveform to replace the discontinuous waveform of phase hit in traditional 8PSK modulation, realize the continuity of modulation waveform, its concrete steps comprise:
Step 201: carrier phase control word generator, according to the selected carrier frequency of frequency selector, produces carrier phase control word; Extra cumulative phase control word generator produces extra cumulative phase control words, and wherein, the computational methods of described extra cumulative phase control words are:
The first extra cumulative phase control words: the first extra cumulative phase place reaches π/4 after M clock cycle, the first extra cumulative phase step is
the first extra cumulative phase control words is
The second extra cumulative phase control words: establish the second extra cumulative phase place after M clock cycle and reach pi/2, the second extra cumulative phase step is
the second extra cumulative phase control words is
The 3rd extra cumulative phase control words: establish the 3rd extra cumulative phase place after M clock cycle and reach 3 π/4, the 3rd extra cumulative phase step is
the 3rd extra cumulative phase control words is
The 4th extra cumulative phase control words: establish the 4th extra cumulative phase place after M clock cycle and reach π, the 4th extra cumulative phase step is
the 4th extra cumulative phase control words is
The 5th extra cumulative phase control words: establish the 5th extra cumulative phase place after M clock cycle and reach 5 π/4, the 5th extra cumulative phase step is
the 5th extra cumulative phase control words is
The 6th extra cumulative phase control words: establish the 6th extra cumulative phase place after M clock cycle and reach 3 pi/2s, the 6th extra cumulative phase step is
the 6th extra cumulative phase control words is
The 7th extra cumulative phase control words: establish the 7th extra cumulative phase place after M clock cycle and reach 7 π/4, the 7th extra cumulative phase step is
the 7th extra cumulative phase control words is
Suppose to adopt N(N=32) sinusoidal carrier signal of individual discrete sample signals value representation one-period, the phase difference between two adjacent discrete carrier sampled points is π/N=π/16, Δ θ=2, be that carrier phase step-length is π/N=π/16, Δ θ=2, carrier phase control word is
Step 202: read current data to be sent, and judge that whether current data to be sent are identical with adjacent last clock transmission data.
Step 203: if the same output signal " 000 ", if it is different to send data, calculate the phase difference value between adjacent transmission data waveform, it is the phase value that the phase value of current data deducts last data, again according to phase difference value output unlike signal: if phase difference value is π/4 or-7 π/4, output signal " 001 "; If phase difference value is pi/2 or-3 pi/2s, output signal " 010 "; If phase difference value is 3 π/4 or-5 π/4, output signal " 011 "; If phase difference value is ± π, output signal " 100 "; If phase difference value is 5 π/4 or-3 π/4, output signal " 101 "; If phase difference value be 3 pi/2s or-pi/2, output signal " 110 "; If phase difference value be 7 π/4 or-π/4, output signal " 111 ".
Step 204: gate is according to the output signal gating of data variation detector the outer phase control words of amount of exports, if the output signal of data variation detector is " 000 ", the outer phase control words of gate amount of exports is zero; If data variation detector output signal is " 001 ", gate continuous wave output M(M=16) individual extra phase control words is the first extra cumulative phase control words, i.e. the extra cumulative phase control words of continuous 16 clocks output first; If output signal is " 010 ", 16 extra phase control words of gate continuous wave output are the second extra cumulative phase control words; If output signal is " 011 ", 16 extra phase control words of gate continuous wave output are the 3rd extra cumulative phase control words; If output signal is " 100 ", 16 extra phase control words of continuous wave output are the 4th extra cumulative phase control words; If output signal is " 101 ", 16 extra phase control words of continuous wave output are the 5th extra cumulative phase control words; If output signal is " 110 ", 16 extra phase control words of continuous wave output are the 6th extra cumulative phase control words; If output signal is " 111 ", 16 extra phase control words of continuous wave output are the 7th extra cumulative phase control words.
Step 205: phase control words calculator is added carrier phase control word and extra phase control words, obtains phase control words step-length.In the present embodiment, when the output signal of data variation detector is " 000 ", phase control words step-length is carrier phase control word
corresponding phase step is carrier phase step-length
when data variation detector output signal is " 001 " or " 010 " or " 011 " or " 100 " or " 101 " or " 110 " or " 111 ", phase control words step-length is carrier phase control word C
dDSwith extra phase control words C
asum, corresponding phase step is carrier phase step-length and extra cumulative phase step sum, concrete:
When output signal is " 001 ", phase control words step-length is C
dDS+ C
a1=4+1=5, corresponding phase step is
When output signal is " 010 ", phase control words step-length is C
dDS+ C
a2=4+2=6, corresponding phase step is
When output signal is " 011 ", phase control words step-length is C
dDS+ C
a1=4+3=7, corresponding phase step is
When output signal is " 100 ", phase control words step-length is C
dDS+ C
a1=4+4=8, corresponding phase step is
When output signal is " 101 ", phase control words step-length is C
dDS+ C
a1=4+5=9, corresponding phase step is
When output signal is " 110 ", phase control words step-length is C
dDS+ C
a1=4+6=10, corresponding phase step is
When output signal is " 111 ", phase control words step-length is C
dDS+ C
a1=4+7=11, corresponding phase step is
Step 206: phase control word accumulator carries out phase control words step-length accumulating operation, obtain total phase control words, it is the ROM look-up table address of each clock, its accumulation calculating method is: phase control word accumulator will feed back to the input of self in total phase control words of a upper clock, at present clock, continue to be added with phase control words step-length, obtain total phase control words of present clock, the ROM look-up table address that this total phase control words is current time, input ROM is as the address of tabling look-up of modulation waveform.
Step 207: the look-up table address producing according to step 206, the modulation waveform signal amplitude value of searching present clock in ROM, and by this modulation waveform signal amplitude value output.
Step 208: judge whether current data transmission completes, if complete, enters step 209, if do not complete, returns to step 206, proceeds total phase control words and calculates;
Step 209: judge whether all data transmissions to be sent complete, and send if complete end data, if do not complete, return to step 202.
With reference to figure 3 (a) to Fig. 3 (g), suppose once to transmit data variation when modulating signal phase is 4 π, for example, shown in Fig. 3 (a), the phase place of traditional 8PSK modulation waveform (dotted line waveform in Fig. 3 (a)) has the saltus step that a size is π/4; Again for example, shown in Fig. 3 (b), the phase place of traditional 8PSK modulation waveform (dotted line waveform in Fig. 3 (b)) has the saltus step that a size is pi/2; Again for example, shown in Fig. 3 (c), it is the saltus step of 3 π/4 that the phase place of traditional 8PSK modulation waveform (dotted line waveform in Fig. 3 (c)) has a size; Again for example, shown in Fig. 3 (d), the phase place of traditional 8PSK modulation waveform (dotted line waveform in Fig. 3 (d)) has the saltus step that a size is π; Again for example, shown in Fig. 3 (e), it is the saltus step of 5 π/4 that the phase place of traditional 8PSK modulation waveform (dotted line waveform in Fig. 3 (e)) has a size; Again for example, shown in Fig. 3 (f), it is the saltus step of 3 pi/2s that the phase place of traditional 8PSK modulation waveform (dotted line waveform in Fig. 3 (f)) has a size; Again for example, shown in Fig. 3 (g), it is the saltus step of 7 π/4 that the phase place of traditional 8PSK modulation waveform (dotted line waveform in Fig. 3 (g)) has a size.Adopt continuous phase 8PSK modulator approach of the present invention, the continuous fast transition waveform (solid line waveform in the solid line waveform in the solid line waveform in the solid line waveform in the solid line waveform in the solid line waveform in the solid line waveform in Fig. 3 (a) between two vertical dotted lines or Fig. 3 (b) between two vertical dotted lines or Fig. 3 (c) between two vertical dotted lines or Fig. 3 (d) between two vertical dotted lines or Fig. 3 (e) between two vertical dotted lines or Fig. 3 (f) between two vertical dotted lines or Fig. 3 (g) between two vertical dotted lines) of utilization and previous data waveform phase place is smoothly transitted into the modulation waveform of current data, thereby hide symbol trip point information, reduce the high fdrequency component of SPA sudden phase anomalies point.According to 2 π periodic characteristics of pure oscillation signal phase, can learn, Fig. 3 (a), Fig. 3 (b), Fig. 3 (c), Fig. 3 (d), Fig. 3 (e), Fig. 3 (f), Fig. 3 (g) is also respectively that phase difference size is-7 π/4,-3 pi/2s,-5 π/4,-π,-3 π/4,-pi/2 and-situation of π/4 o'clock, be that phase difference is that π/4 are consistent with the waveform of-7 π/4, phase difference is that pi/2 is consistent with the waveform of-3 pi/2s, phase difference is that 3 π/4 are consistent with the waveform of-5 π/4, it is consistent with the waveform of-π that phase difference is π, phase difference is that 5 π/4 are consistent with the waveform of-3 π/4, it is consistent with the waveform of-pi/2 that phase difference is 3 pi/2s, it is consistent with the waveform of-π/4 that phase difference is 7 π/4.
With reference to figure 4, suppose k
1total phase control words in+1 moment is 120, and signal phase is
at k
1+ 3 and k
1between+4 clocks, once transmit the variation of data, this changes corresponding phase difference value is π/4.Carrier phase in Fig. 4 shown in secondary series is continuous.At k
1+ 1 to k
1+ 3 clock periods, it is that extra phase control words of this period is zero that the total phase control words under the inventive method be take step-length 4() increase, corresponding modulating waveform phase is with step-length
change, modulation waveform phase place is consistent with the phase preserving of traditional 8PSK modulation waveform.At k
1+ 3 clocks, in phase control word accumulator, master control word has reached higher limit 128(phase value and has reached 2 π), so total phase control words zero clearing in phase control word accumulator.K
1+ 4 clocks are to k
1between+7 clocks, in Fig. 4 the 4th row, total phase control words of traditional 8PSK modulation waveform is because of k
1the data variation of+4 clocks, and at k
1+ 4 clock generating saltus step, become 20 from 8, extra address increment is K/8=16, corresponding modulating waveform phase has produced the saltus step of π/4, from
jump to
after saltus step, total phase control words still increases by step-length 4, and modulation waveform phase place is by step-length
increase.And there is not obvious phase hit in modulation waveform under modulator approach of the present invention, but with 5 phase control words step-length,
phase step " catch up with " waveform phase in traditional 8PSK modulation.At k
1+ 4 clocks, in phase control word accumulator, total phase control words is 5, corresponding modulation waveform phase place is
at k
1+ 5 clocks, in phase control word accumulator, total phase control words is 10, corresponding modulation waveform phase place is
to k
1+ 19 clocks, total phase control words under modulator approach of the present invention and modulation waveform phase place be identical with under traditional 8PSK modulation, so extra phase control words vanishing of gate output, phase control words step-length revert to carrier phase control word 4, completes the modulation waveform smooth connection with current data.K
1+ 19 clocks and k
1between+20 clocks, transmit data and do not change, the control word of modulation waveform is with step-length 4, and phase place is with step-length
continue to change.
With reference to figure 5, suppose k
2total phase control words in+1 moment is 120, and signal phase is
at k
2+ 3 and k
2between+4 clocks, once transmit the variation of data, this changes corresponding phase difference value is pi/2.Carrier phase in Fig. 5 shown in secondary series is continuous.At k
2+ 1 to k
2+ 3 clock periods, the total phase control words under the inventive method increases with step-length 4, and corresponding modulating waveform phase is with step-length
change, modulation waveform phase place is consistent with the phase preserving of traditional 8PSK modulation waveform.At k
2+ 3 clocks, in phase control word accumulator, master control word has reached higher limit 128(phase value and has reached 2 π), so total phase control words zero clearing in phase control word accumulator.K
2+ 4 clocks are to k
2between+11 clocks, in Fig. 5 the 4th row, total phase control words of traditional 8PSK modulation waveform is because of k
2the data polarity reversion of+4 clocks and saltus step occurs, becomes 36 from 4, and extra address increment is K/4=32, corresponding modulating waveform phase from
jump to
after saltus step, total phase control words still increases by step-length 4, and modulation waveform phase place is by step-length
increase.And there is not phase hit in modulation waveform under modulator approach of the present invention, but with 6 phase control words step-length,
phase step " catch up with " waveform phase in traditional 8PSK modulation.At k
2+ 4 clocks, in phase control word accumulator, total phase control words is 6, corresponding modulation waveform phase place is
at k
2+ 5 clocks, in phase control word accumulator, total phase control words is 12, corresponding modulation waveform phase place is
to k
2+ 19 clocks, total phase control words under modulator approach of the present invention and modulation waveform phase place be identical with under traditional 8PSK modulation, so extra cumulative phase control words vanishing of gate output, phase control words step-length revert to carrier phase control word 4, completes the modulation waveform smooth connection with current data.
When phase difference is 3 π/4, the modulation waveform under modulator approach of the present invention is with 7 phase control words step-length,
phase step " catch up with " waveform phase in traditional 8PSK modulation, complete the modulation waveform smooth connection with current data.When phase difference is π, the modulation waveform under modulator approach of the present invention is with 8 phase control words step-length,
phase step " catch up with " waveform phase in traditional 8PSK modulation, complete the modulation waveform smooth connection with current data.When phase difference is 5 π/4, the modulation waveform under modulator approach of the present invention is with 9 phase control words step-length,
phase step " catch up with " waveform phase in traditional 8PSK modulation, complete the modulation waveform smooth connection with current data.When phase difference is 3 pi/2, the modulation waveform under modulator approach of the present invention is with 10 phase control words step-length,
phase step " catch up with " waveform phase in traditional 8PSK modulation, complete the modulation waveform smooth connection with current data.When phase difference is 7 π/4, the modulation waveform under modulator approach of the present invention is with 11 phase control words step-length,
phase step " catch up with " waveform phase in traditional 8PSK modulation, complete the modulation waveform smooth connection with current data.
The phase difference that data variation causes is that π/4 change consistent with-7 π/4 o'clock modulation waveform phase place, phase difference be pi/2 during with-3 pi/2 modulation waveform phase place change consistent, phase difference is that 3 π/4 change consistent with-5 π/4 o'clock modulation waveform phase place, when phase difference is π with-π, modulation waveform phase place changes consistent, phase difference is that 5 π/4 change consistent with-3 π/4 o'clock modulation waveform phase place, when phase difference is 3 pi/2s with-pi/2, modulation waveform phase place changes consistent, to be 7 π/4 change unanimously with-π/4 o'clock modulation waveform phase place phase difference, do not repeating herein.
In the present embodiment, the first extra cumulative phase control words, the second extra cumulative phase control words, the 3rd extra cumulative phase control words, the 4th extra cumulative phase control words, the 5th extra cumulative phase control words, the 6th extra cumulative phase control words and the 7th extra cumulative phase control words are precalculated, and be stored in extra cumulative phase control word generator, gate is again according to the corresponding extra cumulative phase control words of the output signal gating of data variation detector.In real work, also can realize the inventive method by another kind of mode, be that data variation detector transfers to gate and extra cumulative phase control word generator by output signal simultaneously, additionally cumulative phase control word generator produces corresponding extra cumulative phase control words in real time according to output signal.
Continuous phase 8PSK modulator approach of the present invention, based on direct digital frequency synthesis technology, by extra cumulative phase control words, directly change the mode of control word, produce the discontinuous waveform that transition waveform replaces phase hit in traditional 8PSK modulation, realized the continuity of modulation waveform, before and after having eliminated adjacent clock, send the phase hit existing in the modulation waveform of data, thereby eliminated the impulse response producing because of SPA sudden phase anomalies, the hidden symbol rate information containing in waveform signal, fail safe and the confidentiality of communication have been increased, this modulator approach and application of installation are in the military wireless communication system of anti-intercepting and capturing, or civilian narrowband wireless communication is.
Continuous phase 8PSK modulator approach of the present invention is compared with CPM modulator approach, the value of the concrete form of the modulation signal of employing the inventive method and moulding pulse, modulation index h, frequency response function pulse correlation length L is irrelevant, so it is low to realize the complexity of modulator approach of the present invention, more easily realize, modulating equipment is simple in structure, and cost is low.
Claims (6)
1. a continuous phase 8PSK modulator approach, it is characterized in that, the method is based on direct digital frequency synthesis technology, by extra cumulative phase control words, directly change the mode of control word, the continuous transition waveform of utilization and previous data waveform phase place is smoothly transitted into the modulation waveform of current data, realizes the continuity of modulation waveform, and its concrete steps comprise:
Step 1: calculate carrier phase control word and extra cumulative phase control words, wherein, described extra cumulative phase control words comprises the first extra cumulative phase control words, the second extra cumulative phase control words, the 3rd extra cumulative phase control words, the 4th extra cumulative phase control words, the 5th extra cumulative phase control words, the 6th extra cumulative phase control words and the 7th extra cumulative phase control words;
Step 2: read current data to be sent, and judge that whether current data to be sent are identical with adjacent last clock transmission data;
Step 3: if the same export the 8th gating signal, if different, calculate the phase difference value between adjacent transmission data waveform, and export corresponding gating signal according to out of phase difference;
Step 4: according to different gating signal continuous wave output M corresponding extra phase control words, described M represents: excessively the phase place of waveform reaches the phase difference value between described adjacent transmission data waveform after M clock cycle;
Step 5: calculate phase control words step-length, phase control words step-length=carrier phase control word+extra phase control words, described phase control words step-length is the ROM look-up table address increment between two adjacent sampled points, and described ROM look-up table is for storing the sinusoidal waveform range value of discretization;
Step 6: cumulative phase control words step-length, calculate total phase control words, described total phase control words is the ROM look-up table address of each clock;
Step 7: the look-up table address producing according to step 6, the modulation waveform signal amplitude value of searching present clock in ROM look-up table, and by this modulation waveform signal amplitude value output;
Step 8: judge whether current data transmission completes, if complete, enters step 9, if do not complete, returns to step 6, proceeds total phase control words and calculates;
Step 9: judge whether all data transmissions complete, if complete, finish, if do not complete, return to step 2, continue to read data to be sent.
2. continuous phase 8PSK modulator approach according to claim 1, it is characterized in that, the computational methods of the control word of carrier phase described in step 1 are: the degree of depth of supposing sinusoidal ROM look-up table is K, adopt the sinusoidal carrier signal of N discrete sample signals value representation one-period, the phase difference between two adjacent discrete sampling points is Δ θ=2 π/N, and carrier phase control word is C
dDS=K/N.
3. continuous phase 8PSK modulator approach according to claim 1, is characterized in that, described in step 1, the computational methods of extra cumulative phase control words are:
The first extra cumulative phase control words: the first extra cumulative phase place reaches π/4 after M clock cycle, the first extra cumulative phase step is
the first extra cumulative phase control words is
wherein, the implication of K is: the degree of depth of ROM look-up table;
The second extra cumulative phase control words: establish the second extra cumulative phase place after M clock cycle and reach pi/2, the second extra cumulative phase step is
the second extra cumulative phase control words is
The 3rd extra cumulative phase control words: establish the 3rd extra cumulative phase place after M clock cycle and reach 3 π/4, the 3rd extra cumulative phase step is
the 3rd extra cumulative phase control words is
The 4th extra cumulative phase control words: establish the 4th extra cumulative phase place after M clock cycle and reach π, the 4th extra cumulative phase step is
the 4th extra cumulative phase control words is
The 5th extra cumulative phase control words: establish the 5th extra cumulative phase place after M clock cycle and reach 5 π/4, the 5th extra cumulative phase step is
the 5th extra cumulative phase control words is
The 6th extra cumulative phase control words: establish the 6th extra cumulative phase place after M clock cycle and reach 3 pi/2s, the 6th extra cumulative phase step is
the 6th extra cumulative phase control words is
The 7th extra cumulative phase control words: establish the 7th extra cumulative phase place after M clock cycle and reach 7 π/4, the 7th extra cumulative phase step is
the 7th extra cumulative phase control words is
4. continuous phase 8PSK modulator approach according to claim 1, is characterized in that, the method for exporting corresponding gating signal according to out of phase difference in described step 3 is:
If phase difference value is π/4 or-7 π/4, export the first gating signal; If phase difference is pi/2 or-3 pi/2s, export the second gating signal; If phase difference is 3 π/4 or-5 π/4, export the 3rd gating signal; If phase difference value is ± π to export the 4th gating signal; If phase difference is 5 π/4 or-3 π/4, export the 5th gating signal; If phase difference value be 3 pi/2s or-pi/2, export the 6th gating signal; If phase difference be 7 π/4 or-π/4, export the 7th gating signal.
5. continuous phase 8PSK modulator approach according to claim 4, is characterized in that, in described step 4, according to the method for different gating signal continuous wave output M corresponding extra phase control words, is:
When gating signal is the first gating signal, described extra phase control words is the first extra cumulative phase control words; When gating signal is the second gating signal, described extra phase control words is the second extra cumulative phase control words; When gating signal is the 3rd gating signal, described extra phase control words is the 3rd extra cumulative phase control words; When gating signal is the 4th gating signal, described extra phase control words is the 4th extra cumulative phase control words; When gating signal is the 5th gating signal, described extra phase control words is the 5th extra cumulative phase control words; When gating signal is the 6th gating signal, described extra phase control words is the 6th extra cumulative phase control words; When gating signal is the 7th gating signal, described extra phase control words is the 7th extra cumulative phase control words; When gating signal is the 8th gating signal, described extra phase control words is zero.
6. according to the continuous phase 8PSK modulating device one of claim 1 to 5 Suo Shu, it is characterized in that, described M value is
wherein, the implication of N is: the sinusoidal carrier signal that adopts N discrete sample signals value representation one-period.
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