[introduction] the utility that is engaged in the researcher of radio frequency application, engineer and technical personnel can understanding spectrum analyzer adequately normally and advantage, no matter be traditional sweep analyzer (TSA) or more contemporary vector signal analyzer (VSA) . They master the crucial standard of instruments of these important radio frequency and working principle adroitly. However, in be like,involve analyzer of real time spectrum (RSA or RTSA) when having different instrument this kind a bit, they are a little not close. Because be mixed to the function of RSA,measure ability to lack understanding, the user can fail to realize RSA regards his as the dominant position that radio frequency tool amasses place of a pivotal tool to have sometimes. Peaceful gram company is being designed, make and deploy RSA respect has old rich experience, we hope to make it clear that RSA uses a few misunderstanding that go up, it is gossip even.
The researcher that is engaged in radio frequency application, engineer and technical personnel can understand the utility of spectrum analyzer and good point adequately normally, no matter be traditional sweep analyzer (TSA) or more contemporary vector signal analyzer (VSA) . They master the crucial standard of instruments of these important radio frequency and working principle adroitly. However, in be like,involve analyzer of real time spectrum (RSA or RTSA) when having different instrument this kind a bit, they are a little not close. Because be mixed to the function of RSA,measure ability to lack understanding, the user can fail to realize RSA regards his as the dominant position that radio frequency tool amasses place of a pivotal tool to have sometimes. Peaceful gram company is being designed, make and deploy RSA respect has old rich experience, we hope to make it clear that RSA uses a few misunderstanding that go up, it is gossip even.
Misunderstanding 1: All contemporary is based on the analyzer of FFT is analyzer of real time spectrum.
Contemporary spectrum analyzer uses the spectrum that is based on FFT to analyse a method, the time domain signal of fast sampling changeover is frequency domain spectrum. These analyzers undertake sampling to signal with freeboard rate and obtain input signal through FFT logarithm according to having transition the amplitude of each heft and frequency. Although be based on the contemporary spectrum analyzer of FFT to have high frequency resolution, can measure the signal inside wide dynamic range, but they cannot detect possibly the event that produces between instrument sampling interval.
Accordingly, want modal analysis signal, mean analyzer of real time spectrum to must have the following characteristic:
? The sampling frequency that inputs signal must enough fast, in order to satisfy Nai Kui this special criterion. That is to say, sampling frequency must exceed double of signal bandwidth.
? All calculative are carried out must successive and enough fast, input the signal change inside short sampling interval in order to ensure analytic output catchs up with.
? Support is enough long analysis is removed, in order to satisfy the narrowest resolution bandwidth (the demand of RBW) .
? In addition, the speed that fast Fourier alternates must very fast, ensure do not omit any signal change.
Peaceful overcame a company to use a kind of distinctive framework in analyzer of spectrum of its real time, restrict in order to overcome the measurement of contemporary VSA, solved the problem related to transient state and signal of dynamic radio frequency effectively. Signal of real time number is used to handle before peaceful overcomes the RSA of the company to store in data (DSP) undertakes signal is analysed, resembling of and rather than is in in that way in VSA framework after data is collected, undertake handling again. This kind of real time handles means to be able to let the incident that the user discovers to other framework cannot be aware of. In the meantime, its support sparks when these incident happen, can capture these incident optionally in memory. Graph if why collect and the 1 RSA that revealed peaceful to restrain a company handles more FFT inside shorter interval, in order to catch up with very fast signal changes.
Graph 1: Depicted other sketch map is differred between the VSA that is based on FFT and RSA
Misunderstanding 2: The special place of RSA has spectrum graph or plan of radio frequency fall only
RSA special do sthon one’s own authority is immortal the visible a collection of illustrative plates that changes along with time into RF spectrum (namely spectrum pursues) . Use these 2 dimension figures, the user can observe easily specific the change that measures the spectrum inside interval. If pursue,2 medium blue spectrum graphs are shown, every tonal frequency changes along with time, and its amplitude apt keeps changeless.
Graph 2: The spectrum of polyphonic signal pursues with spectrum
But, the RSA of peaceful gram company can be in what more kind makes in time domain and frequency domain to measure result and visible a collection of illustrative plates, provide the additional information of the character that collects signal about place and feature for the user, it is VSA even what can miss normally is splitting signal of fast transient state.
DPX? Spectrum contrail is the radio frequency signal that is used at presenting rapid change, or one of the most useful tools of signal of transient state radio frequency. The DPX patent technology of peaceful gram company uses hardware DSP to handle and resemble example translate into element information, in order to found spectrum of radio frequency of completely dynamic real time. It has color to classification function, allow an user to examine frequency identical, but time or power discriminating are different signal.
Graph 3: The sweep after comparing 120 seconds collects MaxHold contrail, with the DPX MaxHold contrail after 20 seconds
Spectrum analyzer basically is frequency domain instrument, but in a lot of measurement, it can be used at observing the spectrum feature in time domain, or the opportunity that will undertake spectrum measure certainly according to the change of time.
The measurement that can undertake to radio frequency signal has a variety of, include what regard parameter as time to measure, for example:
? Frequency and phasic the relation with time
? The relation of amplitude or power and time
? The relation of I and Q and time
? The relation of modulation parameter and time (amplitude of vector of frequency deviation, phasic error, amplitude error, error)
? The relation of frequency and phasic stability
Measure the impact that changes along with time through checking frequency, the engineer can diagnose the crucial question of emitter quickly. Modulation is met normally change frequency, amplitude as the change of time or phasic wait for parameter, the time figure that watchs these parameter can understand systematic act.
Measure to pulse, existence is associated between time domain and frequency domain, make the user can undertake detailed analysis to individual pulse, obtain logarithm the statistic of 1 million follow-up pulse and trend analysis. Graph the 4 character that explained peaceful overcomes software to be able to measure individual pulse and many pulse.
Graph 4: SignalVu-PC software moves on Tek RSA, use at analysing the measurement between individual pulse, pulse and thousands of statistic result of pulse
Misunderstanding 3: Of RSA spark ability and VSA are equal
As similar as VSA, the RTSA of peaceful gram company is offerred a variety of interior and exterior spark method, include exterior voltage ascendant edge and in-house IQ power source to spark. However, what differ with traditional VSA is, signal changes to offer when DPX technology still can be analyse newly and spark method:
? Frequency pattern plate sparks: Appearance of RSA general spectrum and the pattern plate that the user defines undertake comparative, spark when designation spectrum appearance changes instrument (graph 5) . RSA can spark when frequency rises or dropping, be similar to the working way that time domain n sparks. This plants have the aid of powerful technology, although be put in n louder other signal, tek RSA also can detect reliably far the signal under instrument full span. Spark below this kind of case that is being put in strong signal the ability of weak signal, keep within limits of spectrum of the existence of child of intermittent to detecting signal, intermodulation, transient state violates compasses and other frequency effect crucial.
Graph 5: Pattern plate of frequency of breakthrough of transient state signal sparks attrib borderly incident
? DPX density trigger: Because DPX spectrum is the 2 dimension array of frequency and amplitude, the pane that because this user is OK,the definition has frequency to be restricted with amplitude up and down up and down (graph 6) . When the signal density in this pane assigns threshold value more than, the instrument can be sparked. For example, the frequency that this function makes the user appears in signal only exceeds the ability when anticipating to be able to be recorded, help them thereby stray of divisional transient state and more abiding system stray.
Graph 6: Setting DPX density sparks the frequency of pane and amplitude
? Time limit trigger: RSA examines the width of radio frequency pulse, undertake sparking according to its duration, this makes its make the good choice below environment of pulse of fast and dynamic radio frequency.
We made it clear that about vector signal analyzer is mixed between analyzer of real time spectrum 3 of difference main misunderstanding. We point out above all, the RSA of peaceful gram company is OK and successive and apace handles FFT to record, input the rapid change of signal in order to catch up with. We still can review peaceful to overcome the RSA of the company to be able to make spectrum plan not only, still can generate all sorts of measurement inside time domain and frequency result and visible image. Then, the new analysis that signal changes to offer when we introduced DPX technology to be and spark method. The function that overcomes company RSA in new knowledge peaceful and after measuring ability, you can bring into them concentration of your radio frequency tool now, make full use of its powerful time and frequency analysis ability.
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