CN108055090A - A kind of time-frequency power stability detection method of the AIS stations - Google Patents
A kind of time-frequency power stability detection method of the AIS stations Download PDFInfo
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- CN108055090A CN108055090A CN201710821598.4A CN201710821598A CN108055090A CN 108055090 A CN108055090 A CN 108055090A CN 201710821598 A CN201710821598 A CN 201710821598A CN 108055090 A CN108055090 A CN 108055090A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/10—Monitoring; Testing of transmitters
- H04B17/15—Performance testing
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/10—Monitoring; Testing of transmitters
- H04B17/101—Monitoring; Testing of transmitters for measurement of specific parameters of the transmitter or components thereof
- H04B17/102—Power radiated at antenna
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/10—Monitoring; Testing of transmitters
- H04B17/101—Monitoring; Testing of transmitters for measurement of specific parameters of the transmitter or components thereof
- H04B17/104—Monitoring; Testing of transmitters for measurement of specific parameters of the transmitter or components thereof of other parameters, e.g. DC offset, delay or propagation times
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/10—Monitoring; Testing of transmitters
- H04B17/15—Performance testing
- H04B17/17—Detection of non-compliance or faulty performance, e.g. response deviations
Abstract
The present invention devises a kind of time-frequency power stability detection method of AIS stations, and this method includes：The acquisition of ais signal based on VSA, the calculating of Testing index, data decoding are positioned with Bit, the index measurement based on Bit positions；The present invention using VSA Vector Signal Analysis carry out data acquisition, the data collected are decoded with the detection scheme carried out to it again than certain bits, reduces data volume, convenient for quickly decode with index calculating etc. subsequent arithmetics；Detection for the communication performance of the AIS stations, the particularly frequency of transmitter and power stability detection have great importance.
Description
(1) technical field：
The invention belongs to field of communication technology, more particularly to a kind of AIS (automatic recognition system --- Automatic
Identification System) station time-frequency power stability detection method.
(2) background technology：
Automatic recognition system (Automatic Identification System, AIS) is a kind of marine navigation equipment,
This ship information is sent by VHF (Very High Frequency, very high frequency(VHF)) and receives base station and letter that surrounding ship is sent
Breath, so as to reach collision prevention purpose, improves the navigation safety of ship.With AIS extensive uses, building berth is sent out by original single A classes
A classes and B classes are opened up, also has base station etc., inland river is developed in the waters of application by original sea.Demand on building berth also with
Day all increasings, the domestic and international manufacturer that can provide related building berth are numerous.Although international and national standard has AIS performances related want
It asks, but the production process of Related product and finished product do not have third party's monitoring and corresponding detection so that there is the part station not to be inconsistent
International standard requirement is closed, the station performance difference of different manufacturers is larger, and the communication between them is not necessarily unimpeded, to navigation safety
Hidden danger is brought with supervision.Wherein, the temporal frequency characteristic of transmitter and temporal power characteristic are detection building berth transmitter performances
Whether important indicator, the information that building berth is sent meet power and frequency requirement on different periods, are that influence other building berths correct
Receive the key of the ship information.General vector signal detecting instrument can only measure and show the when m- amplitude and frequency of signal
The information of rate-power, it is impossible to very easily detection time-frequency, when m- power stability.The present invention proposes a kind of detection
The signal of the station to be measured is received and decodes positioning by method, calculate corresponding T/F, when m- power function, analysis
Whether its performance indicator meets the requirements of the standard.This method can be used for detecting the performance of the AIS stations, safeguard that maritime system safety is high
The operation of effect is also used as AIS stations manufacturer and detects its corresponding performance in process of production, promote correlation technique into
Step.
For base station, A classes building berth, SOTDMA (Self-Organized Time Division Multiple
Access --- self-organizing time division multiple acess)-B building berths, CSTDMA (Carrier-Sense Time Division
MultipleAccess --- carrier sense time division multiple acess)-B class building berths time response detection in, it is specified that in transmitting signal
The requirement that power in time slot at different moments meets is as shown in table 1.
1 international standard of table is on power stability requirement
In the modulation accuracy Indexs measure of CSTDMA-B class building berths, it is desirable that the frequency in time slot at different moments is also being advised
In fixed scope, as shown in table 2.
2 international standard of table is on frequency stability requirement
In terms of signal demodulation, ais signal uses GMSK (Gaussian Filtered Minimum Shift
Keying --- gaussian minimum shift keying) modulation, there are many decoded modes of GMSK, main including coherent demodulation and incoherent
Demodulation.There are many decoded modes of GMSK, mainly includes coherent demodulation and non-coherent demodulation.Non-coherent demodulation mainly has Viterbi
Decoding and differential decoding.Due to being that signal capture is carried out in laboratory, so time delay and Doppler without the concern for ais signal
Frequency deviation problem, can efficient decoding using 2 conventional bit differential ference spirals.
(3) content of the invention
It is an object of the invention to provide a kind of time-frequency power stability detection methods of AIS stations, it can solve existing
There is the deficiency of technology, a synchronous electric signal cannot be exported to outside when starting and emitting ais signal for due to the AIS stations,
The station is caused to be unable to reach with frequency spectrograph temporal synchronous, and cannot show absolute time information and cannot accurately determine
The problem of initial time when measuring signal exports, propose the time-frequency power stability detection side of automatic recognition system station a kind of
Method is a kind of easy to operate, method for being easy to implement.
Technical scheme：The time-frequency power stability detection method of a kind of AIS stations, it is characterised in that it includes
Following steps：
1. by the station to be measured and VSA (Vector Signal Analysis --- Vector SignalAnalyzer) software is installed
Frequency spectrograph connects, and the actual ais signal of station transmitting to be measured, receiving terminal received signal are obtained using VSA Vector Signal Analysis
Generally it is represented by：
Wherein：Time-varying amplitude when A (t) is；It is the phase information of signal；wcIt is carrier angular frequencies；
2. to step 1. in obtained ais signal preserve, and automatic frequency adjustment is carried out to signal, by radiofrequency signal
The baseband signal after carrier wave is transformed to,
R (t)=I (t)+jQ (t) (2)
Wherein,The respectively same phase and quadrature component of baseband signal,
Its numerical value is between ± 1.
Data volume can be so substantially reduced, convenient for subsequent arithmetics such as the quick decodings and index calculating of computer；
Due to,
So
Wherein, Vpk(t) it is voltage peak, unit is volt；Z is load impedance；
2. to step 1. in obtained ais signal be demodulated processing and obtain the binary decoded data of ais signal, and root
According to the structure and feature of known AIS infomational messages, to the location determination of binary data progress Bit after demodulation；And
To the Bit information between opening flag and end mark data are carried out again to judge, draw for ais signal when m- power, when
The relation of m- frequency；
3. after location determination, calculate Testing index；
(1) " when m- power " relation that the base band of signal exports is received by calculating, as shown in formula (4), quantitative analysis
Power stability calculates the power of different time according to formula (4), by time and the correspondence of decoded bits, Ke Yiji
Calculate the power on specific bit；
(2) " T/F " relation that the base band of signal exports, quantitative analysis frequency stability are received by calculating；
" T/F " relation can be obtained by phase time differential, and calculation formula is：
Wherein frequency, phase represent frequency and phase respectively；
Due to,
It differentiates, can be obtained respectively about the time to formula (5) formula (6) both sides：
So have：
I.e.：
Wherein, phase phase (t) is the function of time t；
For discretely-timed signal, differential calculation is replaced with difference, i.e.,：
Wherein, T is the sampling interval, also cries the sampling period；N is sampled point sequence number.
Specific temporal frequency is calculated according to formula (10), it, can be with by time and the correspondence of decoded bits
Obtain the frequency on specific bit；
4. to step 3. the result of middle gained " when m- power " and " T/F " with table 1, table 2 shown in index request
It is compared, and then weighs whether survey ais signal up to standard.
The method of the step 1. middle actual ais signal that the station to be measured transmitting is obtained using VSA Vector Signal Analysis method
It is made of following steps：
1.-A sets time span, points, the centre frequency of record data in the VSA softwares of frequency spectrograph, then wait
Station signal to be measured triggers VSA softwares；
1. for-B when station signal to be measured arrives, the VSA softwares of frequency spectrograph preserve actual ais signal, i.e. automatic record
Building berth signal, so as to fulfill effective capture of data；
1.-C carries out automatic frequency-conversion processing to the signal captured in step 1.-B, after radiofrequency signal is transformed to carrier wave
Baseband signal；Data volume is greatly reduced, convenient for subsequent arithmetics such as the quick decodings and index calculating of computer；
1.-D steps the data file that 1. VSA softwares preserve in-B can automatically be transferred to computer, to carry out
Subsequent decoding and data processing.
The 1. step sets record data in-A time span in VSA softwares is 26.67 milliseconds；The points are by 8
Times code check or 16 times of code checks are configured, and the centre frequency is 161.975MHz or 162.025MHz.
The step 2. in the structure and features of AIS infomational messages refer to the data formats of AIS messages, including starting to mark
Will and end mark.
The specific implementation process of the step 2. is made of following steps：
2.-A to step 1. in obtained ais signal be decoded in a computer, due to being that letter is carried out in laboratory
Number capture and detection, so time delay and Doppler shift problem without the concern for ais signal, using 2 conventional bit differences
Demodulation method is divided to carry out efficient decoding to it, obtains a binary data；
2.-B is according to the data format of known AIS messages, including opening flag and end mark, to decoded two into
Data processed carry out determining for Bit positions, and carry out judging again for data to the Bit information between opening flag and end mark, obtain
Go out for ais signal when m- power, the calculation formula of T/F.
The present invention is advantageous in that：A kind of time-frequency power stability detection method of AIS stations is provided, is sweared using VSA
It measures signal analysis and carries out data acquisition, the data collected are decoded with the detection scheme carried out to it again than certain bits, with
It determines first Bit delivery time of AIS information, derives the temporal frequency for ais signal, temporal power calculation formula；
The acquisition of ais signal based on VSA softwares, and radiofrequency signal is transformed to baseband signal, data volume is reduced, convenient for quickly solving
The subsequent arithmetics such as code and index calculating；Building berth signal capture is carried out using VSA softwares, after obtaining signal data, so as to obtain pair
The frequency and power information of bit are answered, index request is compared and obtains testing result, more accurately complete to building berth index
Detection has certain reliability.
(4) illustrate：
Fig. 1 is the frame structure schematic diagram of ais signal.
Fig. 2 is based on the to be measured of VSA softwares in the time-frequency power stability detection method of a kind of AIS stations involved by the present invention
The ais signal of the station obtains structure diagram.
Fig. 3 is according to the data meter of acquisition in the time-frequency power stability detection method of a kind of AIS stations involved by the present invention
The waveform effect figure of evaluation time-power.
Fig. 4 is according to the data meter of acquisition in the time-frequency power stability detection method of a kind of AIS stations involved by the present invention
The waveform effect figure of evaluation time-frequency.
Fig. 5 is to be surveyed in the time-frequency power stability detection method of a kind of AIS stations involved by the present invention based on the power of Bit
Measure schematic diagram.
Fig. 6 is to be surveyed in the time-frequency power stability detection method of a kind of AIS stations involved by the present invention based on the frequency of Bit
Measure design sketch.
Fig. 7 is from the opening flag of message in the time-frequency power stability detection method of a kind of AIS stations involved by the present invention
To the time-frequency characteristics design sketch between end mark.
(5) specific embodiment：
Embodiment 1：The time-frequency power stability detection method of a kind of AIS stations, it is characterised in that it comprises the following steps：
1. the station to be measured is connected with being equipped with the frequency spectrograph of VSA softwares, scaffold tower is treated using the acquisition of VSA Vector Signal Analysis
It stands the actual ais signal of transmitting, with reference to Fig. 2, receiving terminal received signal is generally represented by：
Wherein：Time-varying amplitude when A (t) is；It is the phase information of signal；wcIt is carrier angular frequencies；
1.-A sets 26.67 milliseconds of the time span of record data in the VSA softwares of frequency spectrograph；Points are by 8 times of code checks
It is configured；Centre frequency is 161.975MHz, then waits station signal triggering VSA softwares to be measured；
1. for-B when station signal to be measured arrives, the VSA softwares of frequency spectrograph preserve actual ais signal, i.e. automatic record
Building berth signal, so as to fulfill effective capture of data, with reference to Fig. 2；
1.-C carries out automatic frequency-conversion processing to the signal captured in step 1.-B, after radiofrequency signal is transformed to carrier wave
Baseband signal；Data volume is greatly reduced, convenient for subsequent arithmetics such as the quick decodings and index calculating of computer；
1.-D steps the data file that 1. VSA softwares preserve in-B can automatically be transferred to computer, to carry out
Subsequent decoding and data processing；
2. to step 1. in obtained ais signal preserve, and automatic frequency adjustment is carried out to signal, by radiofrequency signal
The baseband signal after carrier wave is transformed to,
R (t)=I (t)+jQ (t) (2)
Wherein,The respectively same phase and quadrature component of baseband signal,
Its numerical value is between ± 1；
Data volume can be so substantially reduced, convenient for subsequent arithmetics such as the quick decodings and index calculating of computer；
Due to,
So
Wherein, Vpk(t) it is voltage peak, unit is volt；Z is load impedance；
3. to step 1. in obtained ais signal be demodulated processing and obtain the binary decoded data of ais signal, and root
According to the data format of the structure and feature, i.e. AIS messages of known AIS infomational messages, with reference to Fig. 1, including opening flag and knot
Bundle flag carries out the binary data after demodulation the location determination of Bit；And between opening flag and end mark
Bit information carries out data and judges again, draw for ais signal when m- power, T/F relation；
3.-A to step 1. in obtained ais signal be decoded in a computer, due to being that letter is carried out in laboratory
Number capture and detection, so time delay and Doppler shift problem without the concern for ais signal, using 2 conventional bit differences
Demodulation method is divided to carry out efficient decoding to it, obtains a binary data；
3.-B is according to the data format of known AIS messages, including opening flag and end mark, with reference to Fig. 1, to decoding
Binary data afterwards carries out determining for Bit positions, and carries out data again to the Bit information between opening flag and end mark
Judge, draw for ais signal when m- power, T/F calculation formula；
4. after location determination, calculate Testing index；
(1) " when m- power " relation that the base band of signal exports is received by calculating, as shown in formula (4), quantitative analysis
Power stability calculates the power of different time according to formula (4), by time and the correspondence of decoded bits, Ke Yiji
Calculate the power on specific bit；
(2) " T/F " relation that the base band of signal exports, quantitative analysis frequency stability are received by calculating；
" T/F " relation can be obtained by phase time differential, and calculation formula is：
Wherein frequency, phase represent frequency and phase respectively；
Due to,
It differentiates, can be obtained respectively about the time to formula (5) formula (6) both sides：
So have：
I.e.：
Wherein, phase phase (t) is the function of time t；
For discretely-timed signal, differential calculation is replaced with difference, i.e.,：
Wherein, T is the sampling interval, also cries the sampling period；N is sampled point sequence number；
Specific temporal frequency is calculated according to formula (10), it, can be with by time and the correspondence of decoded bits
Obtain the frequency on specific bit；
5. to step 4. the result of middle gained " when m- power " and " T/F " with table 1, table 2 shown in index request
It is compared, and then weighs whether survey ais signal up to standard.
Embodiment 2：The time-frequency power stability detection method of a kind of AIS stations, it is characterised in that it comprises the following steps：
1. the station to be measured is connected with being equipped with the frequency spectrograph of VSA softwares, scaffold tower is treated using the acquisition of VSA Vector Signal Analysis
It stands the actual ais signal of transmitting, with reference to Fig. 2, receiving terminal received signal is generally represented by：
Wherein：Time-varying amplitude when A (t) is；It is the phase information of signal；wcIt is carrier angular frequencies；
1.-A sets 26.67 milliseconds of the time span of record data in the VSA softwares of frequency spectrograph；Points are by 16 times of code checks
It is configured；Centre frequency is 162.025MHz, then waits station signal triggering VSA softwares to be measured；
1. for-B when station signal to be measured arrives, the VSA softwares of frequency spectrograph preserve actual ais signal, i.e. automatic record
Building berth signal, so as to fulfill effective capture of data, with reference to Fig. 2；
1.-C carries out automatic frequency-conversion processing to the signal captured in step 1.-B, after radiofrequency signal is transformed to carrier wave
Baseband signal；Data volume is greatly reduced, convenient for subsequent arithmetics such as the quick decodings and index calculating of computer；
1.-D steps the data file that 1. VSA softwares preserve in-B can automatically be transferred to computer, to carry out
Subsequent decoding and data processing；
2. to step 1. in obtained ais signal preserve, and automatic frequency adjustment is carried out to signal, by radiofrequency signal
The baseband signal after carrier wave is transformed to,
R (t)=I (t)+jQ (t) (2)
Wherein,The respectively same phase and quadrature component of baseband signal,
Its numerical value is between ± 1.
Data volume can be so substantially reduced, convenient for subsequent arithmetics such as the quick decodings and index calculating of computer；
Due to,
So
Wherein, Vpk(t) it is voltage peak, unit is volt；Z is load impedance；
3. to step 1. in obtained ais signal be demodulated processing and obtain the binary decoded data of ais signal, and root
According to the data format of the structure and feature, i.e. AIS messages of known AIS infomational messages, with reference to Fig. 1, including opening flag and knot
Bundle flag carries out the binary data after demodulation the location determination of Bit；And between opening flag and end mark
Bit information carries out data and judges again, draw for ais signal when m- power, T/F relation；
3.-A to step 1. in obtained ais signal be decoded in a computer, due to being that letter is carried out in laboratory
Number capture and detection, so time delay and Doppler shift problem without the concern for ais signal, using 2 conventional bit differences
Demodulation method is divided to carry out efficient decoding to it, obtains a binary data；
3.-B is according to the data format of known AIS messages, including opening flag and end mark, with reference to Fig. 1, to decoding
Binary data afterwards carries out determining for Bit positions, and carries out data again to the Bit information between opening flag and end mark
Judge, draw for ais signal when m- power, T/F calculation formula；
4. after location determination, calculate Testing index；
(1) " when m- power " relation that the base band of signal exports is received by calculating, as shown in formula (4), quantitative analysis
Power stability calculates the power of different time according to formula (4), by time and the correspondence of decoded bits, Ke Yiji
Calculate the power on specific bit；
(2) " T/F " relation that the base band of signal exports, quantitative analysis frequency stability are received by calculating；
" T/F " relation can be obtained by phase time differential, and calculation formula is：
Wherein frequency, phase represent frequency and phase respectively；
Due to,
It differentiates, can be obtained respectively about the time to formula (5) formula (6) both sides：
So have：
I.e.：
Wherein, phase phase (t) is the function of time t；
For discretely-timed signal, differential calculation is replaced with difference, i.e.,：
Wherein, T is the sampling interval, also cries the sampling period；N is sampled point sequence number.
Specific temporal frequency is calculated according to formula (10), it, can be with by time and the correspondence of decoded bits
Obtain the frequency on specific bit；
5. to step 4. the result of middle gained " when m- power " and " T/F " with table 1, table 2 shown in index request
It is compared, and then weighs whether survey ais signal up to standard.
According to the VSA data amount checks captured and sampling interval, it is known that sampling time Tp (about 32.5ms), with Tp ×
9600 can estimate the data collected about how many symbol.Assuming that there are 312 symbols, start near the 70th symbol
The appearance AIS starts of message (SOM) indicate " 01111110 ", nearby AIS the message ends marks occur in the 257th (168+16+3) a symbol
“01111110”。
According to AIS message structures, for the CSTDMA-B stations, the starting buffering area that is made of before message 23Bit,
The training sequence of 24Bit compositions, followed by opening flag.Therefore the sequence number of first BIT of CSTDMA-B station messages should be
44 (80-47+1) are calculated successively.
" when m- power " relation, " T/F " relation that the base band of signal exports, quantitative point are received by calculating
Analyse power and frequency stability.
Fig. 3 is the when m- power waveform design sketch that formula (4) calculating is pressed according to the data of acquisition, can simply find out it
The time-continuing process of raising and lowering and power stationarity.Based on the figure, according to the correspondence of decoded symbol and time with
Determine the power on each bit, and compared with power bracket bit-by-bit corresponding with table 1, the temporal power characteristic of the building berth
Substantially conform to index request.
Fig. 4 is to press the T/F waveform effect figure that formula (10) calculates according to the data of acquisition, and intermediate change is gentle
Part is corresponding to useful signal.Based on the figure, according to the correspondence of decoded symbol and time with definite each bit
On frequency, and compared with frequency range bit-by-bit corresponding with table 2, have component frequency in the experiment under normal condition
Frequency requirement, but the limited and amplitude that goes beyond the scope is smaller, substantially conforms to index request.
Fig. 5 m- power waveform design sketch when being pair, according to decoded symbol and the correspondence of time, by corresponding in table 1
Power bracket marked, it can be seen that the temporal power characteristic of the building berth substantially conforms to index request.
Fig. 6 is to T/F waveform effect figure, according to decoded symbol and the correspondence of time, by corresponding in table 2
Frequency range marked as a result, due to the presence of interference signal, its amplitude is made to be not easy comparative analysis.
Fig. 7 is to removing the interference signal outside slot range in Fig. 6, and mark part is corresponding routine and pole in table 2
Frequency range under the conditions of end, it can be seen that have frequency requirement of the component frequency under normal condition, but going beyond the scope has
It limits and amplitude is smaller, substantially conform to index request.
Claims (5)
1. the time-frequency power stability detection method of a kind of AIS stations, it is characterised in that it comprises the following steps：
1. the station to be measured is connected with being equipped with the frequency spectrograph of VSA softwares, obtaining the station to be measured using VSA Vector Signal Analysis sends out
The actual ais signal penetrated, receiving terminal received signal are generally represented by：
Wherein：Time-varying amplitude when A (t) is；It is the phase information of signal；wcIt is carrier angular frequencies；
2. to step 1. in obtained ais signal preserve, and automatic frequency adjustment is carried out to signal, radiofrequency signal is converted
To go the baseband signal after carrier wave,
R (t)=I (t)+jQ (t) (2)
Wherein,The respectively same phase and quadrature component of baseband signal, number
Value is between ± 1.
Data volume can be so substantially reduced, convenient for subsequent arithmetics such as the quick decodings and index calculating of computer；
Due to,
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2. to step 1. in obtained ais signal be demodulated processing and obtain the binary decoded data of ais signal, and according to
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The mark that begins carries out data the Bit information between end mark and judges again, draw for ais signal when m- power, when it is m-
The relation of frequency；
3. after location determination, calculate Testing index；
(1) " when m- power " relation that the base band of signal exports is received by calculating, as shown in formula (4), quantitative analysis power
Stability calculates the power of different time according to formula (4), by time and the correspondence of decoded bits, can calculate
Power on specific bit；
(2) " T/F " relation that the base band of signal exports, quantitative analysis frequency stability are received by calculating；" when
M- frequency " relation can be obtained by phase time differential, and calculation formula is：
<mrow>
<mi>f</mi>
<mi>r</mi>
<mi>e</mi>
<mi>q</mi>
<mi>u</mi>
<mi>e</mi>
<mi>n</mi>
<mi>c</mi>
<mi>y</mi>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
<mo>=</mo>
<mfrac>
<mn>1</mn>
<mrow>
<mn>2</mn>
<mi>&pi;</mi>
</mrow>
</mfrac>
<mfrac>
<mrow>
<mi>d</mi>
<mrow>
<mo>(</mo>
<mi>p</mi>
<mi>h</mi>
<mi>a</mi>
<mi>s</mi>
<mi>e</mi>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
<mo>)</mo>
</mrow>
</mrow>
<mrow>
<mi>d</mi>
<mi>t</mi>
</mrow>
</mfrac>
<mo>-</mo>
<mo>-</mo>
<mo>-</mo>
<mrow>
<mo>(</mo>
<mn>5</mn>
<mo>)</mo>
</mrow>
</mrow>
Wherein frequency, phase represent frequency and phase respectively；
Due to,
<mrow>
<mi>t</mi>
<mi>a</mi>
<mi>n</mi>
<mrow>
<mo>(</mo>
<mi>p</mi>
<mi>h</mi>
<mi>a</mi>
<mi>s</mi>
<mi>e</mi>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
<mo>)</mo>
</mrow>
<mo>=</mo>
<mfrac>
<mrow>
<mi>Q</mi>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
</mrow>
<mrow>
<mi>I</mi>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
</mrow>
</mfrac>
<mo>-</mo>
<mo>-</mo>
<mo>-</mo>
<mrow>
<mo>(</mo>
<mn>6</mn>
<mo>)</mo>
</mrow>
</mrow>
It differentiates, can be obtained respectively about the time to formula (5) formula (6) both sides：
<mrow>
<mfrac>
<mrow>
<msup>
<mi>phase</mi>
<mo>&prime;</mo>
</msup>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
</mrow>
<mrow>
<msup>
<mi>cos</mi>
<mn>2</mn>
</msup>
<mrow>
<mo>(</mo>
<mi>p</mi>
<mi>h</mi>
<mi>a</mi>
<mi>s</mi>
<mi>e</mi>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
<mo>)</mo>
</mrow>
</mrow>
</mfrac>
<mo>=</mo>
<mfrac>
<mrow>
<msup>
<mi>Q</mi>
<mo>&prime;</mo>
</msup>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
<mi>I</mi>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
<mo>-</mo>
<msup>
<mi>I</mi>
<mo>&prime;</mo>
</msup>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
<mi>Q</mi>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
</mrow>
<mrow>
<msup>
<mi>I</mi>
<mn>2</mn>
</msup>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
</mrow>
</mfrac>
<mo>-</mo>
<mo>-</mo>
<mo>-</mo>
<mrow>
<mo>(</mo>
<mn>7</mn>
<mo>)</mo>
</mrow>
</mrow>
So have：
<mrow>
<msup>
<mi>phase</mi>
<mo>&prime;</mo>
</msup>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
<mo>=</mo>
<msup>
<mi>cos</mi>
<mn>2</mn>
</msup>
<mrow>
<mo>(</mo>
<mi>p</mi>
<mi>h</mi>
<mi>a</mi>
<mi>s</mi>
<mi>e</mi>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
<mo>)</mo>
</mrow>
<mfrac>
<mrow>
<msup>
<mi>Q</mi>
<mo>&prime;</mo>
</msup>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
<mi>I</mi>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
<mo>-</mo>
<msup>
<mi>I</mi>
<mo>&prime;</mo>
</msup>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
<mi>Q</mi>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
</mrow>
<mrow>
<msup>
<mi>I</mi>
<mn>2</mn>
</msup>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
</mrow>
</mfrac>
<mo>=</mo>
<msup>
<mi>I</mi>
<mn>2</mn>
</msup>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
<mfrac>
<mrow>
<msup>
<mi>Q</mi>
<mo>&prime;</mo>
</msup>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
<mi>I</mi>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
<mo>-</mo>
<msup>
<mi>I</mi>
<mo>&prime;</mo>
</msup>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
<mi>Q</mi>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
</mrow>
<mrow>
<msup>
<mi>I</mi>
<mn>2</mn>
</msup>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
</mrow>
</mfrac>
<mo>-</mo>
<mo>-</mo>
<mo>-</mo>
<mrow>
<mo>(</mo>
<mn>8</mn>
<mo>)</mo>
</mrow>
</mrow>
I.e.：
<mrow>
<mi>f</mi>
<mi>r</mi>
<mi>e</mi>
<mi>q</mi>
<mi>u</mi>
<mi>e</mi>
<mi>n</mi>
<mi>c</mi>
<mi>y</mi>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
<mo>=</mo>
<mfrac>
<mn>1</mn>
<mrow>
<mn>2</mn>
<mi>&pi;</mi>
</mrow>
</mfrac>
<msup>
<mi>phase</mi>
<mo>&prime;</mo>
</msup>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
<mo>=</mo>
<mfrac>
<mn>1</mn>
<mrow>
<mn>2</mn>
<mi>&pi;</mi>
</mrow>
</mfrac>
<mo>&lsqb;</mo>
<msup>
<mi>Q</mi>
<mo>&prime;</mo>
</msup>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
<mi>I</mi>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
<mo>-</mo>
<msup>
<mi>I</mi>
<mo>&prime;</mo>
</msup>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
<mi>Q</mi>
<mrow>
<mo>(</mo>
<mi>t</mi>
<mo>)</mo>
</mrow>
<mo>&rsqb;</mo>
<mo>-</mo>
<mo>-</mo>
<mo>-</mo>
<mrow>
<mo>(</mo>
<mn>9</mn>
<mo>)</mo>
</mrow>
</mrow>
Wherein, phase phase (t) is the function of time t；
For discretely-timed signal, differential calculation is replaced with difference, i.e.,：
<mfenced open = "" close = "">
<mtable>
<mtr>
<mtd>
<mrow>
<mi>f</mi>
<mi>r</mi>
<mi>e</mi>
<mi>q</mi>
<mi>u</mi>
<mi>e</mi>
<mi>n</mi>
<mi>c</mi>
<mi>y</mi>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mo>)</mo>
</mrow>
<mo>=</mo>
<mfrac>
<mn>1</mn>
<mrow>
<mn>2</mn>
<mi>&pi;</mi>
</mrow>
</mfrac>
<mo>&lsqb;</mo>
<msup>
<mi>Q</mi>
<mo>&prime;</mo>
</msup>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mo>)</mo>
</mrow>
<mi>I</mi>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mo>)</mo>
</mrow>
<mo>-</mo>
<msup>
<mi>I</mi>
<mo>&prime;</mo>
</msup>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mo>)</mo>
</mrow>
<mi>Q</mi>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mo>)</mo>
</mrow>
<mo>&rsqb;</mo>
</mrow>
</mtd>
</mtr>
<mtr>
<mtd>
<mrow>
<mo>=</mo>
<mfrac>
<mn>1</mn>
<mrow>
<mn>2</mn>
<mi>&pi;</mi>
<mi>T</mi>
</mrow>
</mfrac>
<mo>{</mo>
<mi>I</mi>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mo>)</mo>
</mrow>
<mo>&lsqb;</mo>
<mi>Q</mi>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mo>)</mo>
</mrow>
<mo>-</mo>
<mi>Q</mi>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mo>-</mo>
<mn>1</mn>
<mo>)</mo>
</mrow>
<mo>&rsqb;</mo>
<mo>-</mo>
<mi>Q</mi>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mo>)</mo>
</mrow>
<mo>&lsqb;</mo>
<mi>I</mi>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mo>)</mo>
</mrow>
<mo>-</mo>
<mi>I</mi>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mo>-</mo>
<mn>1</mn>
<mo>)</mo>
</mrow>
<mo>&rsqb;</mo>
<mo>}</mo>
</mrow>
</mtd>
</mtr>
</mtable>
</mfenced>
<mrow>
<mo>=</mo>
<mfrac>
<mn>1</mn>
<mrow>
<mn>2</mn>
<mi>&pi;</mi>
<mi>T</mi>
</mrow>
</mfrac>
<mo>&lsqb;</mo>
<mi>Q</mi>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mo>)</mo>
</mrow>
<mi>I</mi>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mo>-</mo>
<mn>1</mn>
<mo>)</mo>
</mrow>
<mo>-</mo>
<mi>I</mi>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mo>)</mo>
</mrow>
<mi>Q</mi>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mo>-</mo>
<mn>1</mn>
<mo>)</mo>
</mrow>
<mo>&rsqb;</mo>
<mo>-</mo>
<mo>-</mo>
<mo>-</mo>
<mrow>
<mo>(</mo>
<mn>10</mn>
<mo>)</mo>
</mrow>
</mrow>
Wherein, T is the sampling interval, also cries the sampling period；N is sampled point sequence number.
Specific temporal frequency is calculated according to formula (10), by time and the correspondence of decoded bits, can be obtained
Frequency on specific bit；
4. to step, 3. middle gained " when m- power " and the result of " T/F " are carried out with the index request shown in table 1, table 2
It compares, and then weighs whether survey ais signal up to standard.
A kind of 2. time-frequency power stability detection method of AIS stations according to claim 1, it is characterised in that the step
1. the method for the middle actual ais signal that station transmitting to be measured is obtained using VSA Vector Signal Analysis method is made of following steps：
1.-A sets time span, points, the centre frequency of record data in the VSA softwares of frequency spectrograph, then wait to be measured
Station signal triggers VSA softwares；
1. for-B when station signal to be measured arrives, the VSA softwares of frequency spectrograph preserve actual ais signal, i.e. record building berth automatically
Signal, so as to fulfill effective capture of data；
1.-C carries out automatic frequency-conversion processing, base radiofrequency signal being transformed to after carrier wave to the signal captured in step 1.-B
Band signal；Data volume is greatly reduced, convenient for subsequent arithmetics such as the quick decodings and index calculating of computer；
1.-D steps the data file that 1. VSA softwares preserve in-B can automatically be transferred to computer, follow-up to carry out
Decoding and data processing.
A kind of 3. time-frequency power stability detection method of AIS stations according to claim 2, it is characterised in that the step
1. the time span for setting record data in-A in VSA softwares is 26.67 milliseconds；The points are by 8 times of code checks or 16 times of code checks
It is configured, the centre frequency is 161.975MHz or 162.025MHz.
A kind of 4. time-frequency power stability detection method of AIS stations according to claim 1, it is characterised in that the step
2. the structure and feature of AIS infomational messages in refers to the data format of AIS messages, including opening flag and end mark.
A kind of 5. time-frequency power stability detection method of AIS stations according to claim 1, it is characterised in that the step
2. specific implementation process be made of following steps：
2.-A to step 1. in obtained ais signal be decoded in a computer, due to being the progress signal in laboratory
It captures and detects, so time delay and Doppler shift problem without the concern for ais signal, using 2 bit differential ference spiral methods pair
It carries out efficient decoding, obtains a binary data；
2.-B is according to the data format of known AIS messages, including opening flag and end mark, to decoded binary number
According to determining for progress Bit positions, and judging again for data is carried out to the Bit information between opening flag and end mark, draw pin
To ais signal when m- power, T/F calculation formula.
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| CN112152758A (en) * | 2020-10-10 | 2020-12-29 | 交通运输部规划研究院 | Navigation communication method and device |
| CN114553331A (en) * | 2022-02-25 | 2022-05-27 | 上海创远仪器技术股份有限公司 | Method, device, processor and computer readable storage medium for realizing system self-test for radio monitoring station |
| CN114553331B (en) * | 2022-02-25 | 2024-04-19 | 上海创远仪器技术股份有限公司 | Method, device and storage medium for realizing system self-checking for radio monitoring station |
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| CN103457682A (en) * | 2013-09-05 | 2013-12-18 | 天津理工大学 | Portable equipment for detecting physical layer performance of AIS receiver |
| CN103701542A (en) * | 2013-12-25 | 2014-04-02 | 武汉理工大学 | Measuring device and method for AIS (automatic identification system) signal field intensity |
| CN203691422U (en) * | 2013-12-05 | 2014-07-02 | 成都天奥信息科技有限公司 | Automatic identification system signal simulator |
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| EP2651046A2 (en) * | 2012-04-12 | 2013-10-16 | Com Dev International Limited | Methods and systems for consistency checking and anomaly detection in automatic identification system signal data |
| CN103457682A (en) * | 2013-09-05 | 2013-12-18 | 天津理工大学 | Portable equipment for detecting physical layer performance of AIS receiver |
| CN203691422U (en) * | 2013-12-05 | 2014-07-02 | 成都天奥信息科技有限公司 | Automatic identification system signal simulator |
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| CN112152758A (en) * | 2020-10-10 | 2020-12-29 | 交通运输部规划研究院 | Navigation communication method and device |
| CN112152758B (en) * | 2020-10-10 | 2023-05-26 | 交通运输部规划研究院 | Navigation communication method and device |
| CN114553331A (en) * | 2022-02-25 | 2022-05-27 | 上海创远仪器技术股份有限公司 | Method, device, processor and computer readable storage medium for realizing system self-test for radio monitoring station |
| CN114553331B (en) * | 2022-02-25 | 2024-04-19 | 上海创远仪器技术股份有限公司 | Method, device and storage medium for realizing system self-checking for radio monitoring station |
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