Judge in the test of electromagnetic radiation sensitivity degree that power amplifier gets into the method for the base area of making an uproar
Technical field
The invention belongs to the electromagnetic compatibility sensitivity field tests, specifically, be meant in a kind of electromagnetic radiation sensitivity degree test and judge that power amplifier gets into the method for the base area of making an uproar.
Background technology
According to GJB-151A " military equipment and subsystem Electromagnetic Launching and susceptibility require " regulation, electromagnetic compatibility test comprises electromagnetic interference (EMI) test and electromagnetic susceptibility (EMS) test two large divisions.Wherein electromagnetic susceptibility test be test specimen in normal operation; According to relevant limit value; Utilize testing apparatuss such as antenna or current probe to accomplish to the electromagnetic radiation of test specimen or connection cable or applying of conducted signal; Any fault should not appear in test specimen, performance reduces or depart from the set quota value, or exceeds the index tolerance that provides in individual equipment and the subsystem standard.Typical pilot project such as CS114 and RS103 test etc., this type of pilot project all need be used power amplifier, with the external emitted power of lifting test system.
The ultimate principle of susceptibility test is to disturb generation equipment to produce the electromagnetic interference (EMI) of certain magnitude; Lose time very much and manually signal source is regulated, so use automated EMC test system respectively each frequency of test specimen to be carried out the automatic adjusting of signal source amplitude.As shown in Figure 1, electromagnetism conducted susceptibility Auto-Test System generally is made up of signal source, power amplifier, directional coupler, injection probe, current monitoring probe, receiver, PC.Signal source output signal transfers to the input end of power amplifier through radio-frequency cable; Power amplifier output terminal output high-power signal to injection probe excitation end; Injection probe produces the undesired signal of certain intensity under the high-power signal excitation; Current monitoring probe receives electromagnetic interference (EMI) that the test specimen cable obtains and shows the intensity that adds undesired signal through measuring receiver A; PC is control survey receiver A and signal source respectively, compares between undesired signal that on the one hand the current monitoring probe is obtained and the ultimate value; The also instrument parameter setting in control signal source according to the regulation of GJB151A-97 standard for the field intensity ultimate value, is adjusted the output amplitude of signal source on the other hand, makes it reach the desired ultimate value of GJB151A-97 standard.
In electromagnetism conducted susceptibility test, need be in wider frequency add interference to investigate the electromagnetic susceptibility characteristic of test specimen to what test specimen applied certain intensity.The test specimen cable adds the ultimate value requirement that electromagnetism Interference must meet certain testing standard; So when each frequency applies interference, need an initial amplitude be set, adjust the signal source output amplitude with this as the starting point to signal source; The strength of current that makes the current monitoring probe obtain reaches the intensity (ultimate value) of testing standard regulation; And resident certain hour, observe test specimen and whether have responsive phenomenon, just can step to next test frequency point then and continue test.If initial value occurs condition with higher is set; The interference current that records is higher than ultimate value; Need reduce signal source output, in the electromagnetism conducted susceptibility is tested automatically, need judge when the signal source output amplitude is regulated whether power amplifier gets into the non-linear base area of making an uproar; As shown in Figure 2; When the ingoing power amplifier nonlinearity was not made an uproar the base area, the family curve of power amplifier had amplification characteristic preferably, can continue to reduce input signal strength and satisfy the requirement of standard limit value until output at input signal; The base area if input signal entering amplifier nonlinearity is made an uproar is then continued to reduce input signal strength and will can not changed power amplifier output signal intensity, can not reach the desired ultimate value of standard.The build-in attribute that the gain compression phenomenon is a power amplifier appears in the non-linearity of power amplifier base area of making an uproar, and inevitable, but the position of the non-linear base area of making an uproar can not accurately be located.Therefore, whether when reducing power amplifier input signal amplitude (being the signal source output amplitude), need differentiate the ingoing power amplifier nonlinearity base area of making an uproar.
Existing judgement power amplifier gets into the method for the non-linear base area of making an uproar and all differentiates with experience Control Circulation number of times.As shown in Figure 3, work as standard limit value A in the process of the test
0The difference DELTA that monitors current value A with current monitoring probe does not satisfy the threshold values requirement, but a small range Z (in the Z>X) time, promptly | Δ |<Z; The beginning cycle count when cycle index reaches an empirical value, is generally 6 times; Also signal source output has arrived minimum limit value before this, can't meet the requirements of ultimate value, thinks that power amplifier gets into the non-linear base area of making an uproar; The output of judgement power amplifier can not be satisfied the requirement of standard limit value, quits a program.
In this way whether power amplifier is got into the non-linear base area of making an uproar and judges that following shortcoming is arranged:
1, the method adopts the experience cycle index, possibly in the non-linear base area of making an uproar of power amplifier, carry out repeatedly circulation, the cost plenty of time, has reduced the efficient of testing.
2, in non-linearity of power amplifier is made an uproar the base area, constantly carry out small-signal input meeting power amplifier is caused energy dissipation.
Summary of the invention
The present invention judges in order the gain compression situation whether to occur through the observation power amplifier whether it gets into the non-linear base area of making an uproar; Confirm that can power amplifier output satisfy the requirement of standard limit value; Protect power amplifier simultaneously, adopted a kind of quick judgement power amplifier to get into the method for the non-linear base area of making an uproar (abbreviation make an uproar base area).Through comparing the relation of current monitoring probe signal changes in amplitude amount and signal source amplitude output signal variable quantity, judge whether power amplifier gets into the non-linear base area of making an uproar.
Judge that power amplifier gets into the method for the base area of making an uproar, and comprises the steps: in a kind of electromagnetic radiation sensitivity degree test
Step 1, the initial cycle count value is made as i=1; The initial output amplitude S in setting signal source.
Initial output amplitude S in difference test frequency signal source sets according to the coefficient of used injection probe.
Step 2, signal source output amplitude S read the current value A of the undesired signal that current monitoring probe records
0, current value A
0Applying unit is dB μ A.
The current value A of step 3, basis of calculation ultimate value A and the actual undesired signal that records
0Between difference DELTA, Δ=A-A
0, the same applying unit of standard limit value A this moment is dB μ A, the unit that obtains difference DELTA is dB.
Step 4, judgement cycle index i, carry out different operation according to cycle index i:
A. if i=1, then order execution in step five;
B. as if i>1, the current change quantity and the signal source output amplitude variable quantity that then earlier test are obtained compare, and judge whether power amplifier gets into the non-linear base area of making an uproar; Described current change quantity is (A
0-A
1), signal source output amplitude variable quantity is the current value A of standard limit value A and the actual undesired signal that records
0Difference DELTA; Wherein, A
1The current value that records for current monitoring probe in the last circulation.
If 0.8<(A
0-A
1)/Δ, then power amplifier does not get into the non-linear base area of making an uproar, and then execution in step five, otherwise power amplifier gets into the non-linear base area of making an uproar, and then can not satisfy the requirement of standard limit value in this test frequency power amplifier output signal intensity, directly jumps off a frequency.
Step 5, judge whether difference DELTA satisfies the requirement of threshold values X, promptly | Δ |<X, if difference DELTA satisfies the requirement of threshold values X, tracer signal source output amplitude and carry out next frequency adjustment then; If difference DELTA does not satisfy the requirement of threshold values X, then execution in step six.The unit of described threshold values X is dB, and its concrete numerical value is set according to needed measuring accuracy in the electromagnetic radiation sensitivity degree testing experiment, and general value is 0.1~0.5dB.
Step 6, adjustment signal source output amplitude S=S-Δ, cycle index adds 1 simultaneously, i.e. i=i+1, and make A
1=A
0
Step 7, adjusted signal source output amplitude S is exported, repeating step two~step 6 satisfies the requirement of threshold values X up to difference DELTA, promptly | Δ |<X, then the signal source adjustment finishes, and proceeds the amplitude adjustment of next frequency.
The invention has the advantages that:
1, reduces the time of experimental test, improve the efficient of test.
2, the mode with stepping makes the interference signal amplitude of current monitoring probe acquisition draw close to the standard limit value, has both protected testing apparatus, has guaranteed the accuracy of test again.
3, judge through quick whether power amplifier gets into the non-linear base area of making an uproar, reduce the number of times that in the non-linear base area of making an uproar, increases the signal input, the protection power amplifier prolongs the power amplifier life-span.
Description of drawings
Fig. 1 is a conducted susceptibility test block diagram during electromagnetic compatibility is tested automatically;
Fig. 2 is the power amplifier family curve;
Fig. 3 is the method flow diagram that existing definite judgement power amplifier gets into the base area of making an uproar;
Fig. 4 is the process flow diagram of the inventive method.
Embodiment
Below in conjunction with accompanying drawing and embodiment method provided by the invention is elaborated.
The present invention provides in a kind of electromagnetic radiation sensitivity degree test and judges that power amplifier gets into the method for the base area of making an uproar, and flow process is as shown in Figure 4, specifically comprises the steps:
Step 1, the initial cycle count value is made as i=1.The initial output amplitude S in setting signal source, at different test frequencies, the coefficient of the injection probe that set basis adopts of the initial output amplitude S of signal source is set.
Step 2, signal source output amplitude S read the current value A of the undesired signal that current monitoring probe records
0, current value A
0Applying unit is dB μ A;
Step 3, according to the GJB151A-97 standard, the current value A of basis of calculation ultimate value A and the actual undesired signal that records
0Between difference DELTA, i.e. Δ=A-A
0, this moment, standard limit value A applying unit was dB μ A, the unit that obtains difference DELTA is dB.In electromagnetic radiation sensitivity degree testing experiment, the variable quantity numerically equal that described difference DELTA and signal source need be adjusted.
Step 4, judgement cycle index i, carry out different operation according to cycle index i:
(a) as if i=1, then execution in step five;
(b) as if i>1, the current change quantity (A that then earlier test is obtained
0-A
1) compare with signal source output amplitude variable quantity, judge whether power amplifier gets into the non-linear base area of making an uproar.If 0.8<(A
0-A
1)/Δ, then power amplifier does not get into the non-linear base area of making an uproar, and then execution in step five;
Wherein, A
1The current value that records for current monitoring probe in the last circulation.Described current change quantity is meant the difference of the current value that the current value and the current monitoring probe in the last circulation when Pretesting of current monitoring probe are tested, and finishes at each round-robin, all gives the current value in the last circulation with current current value assignment.
Otherwise power amplifier gets into the non-linear base area of making an uproar, and then can not satisfy the requirement of standard limit value in this test frequency power amplifier output signal intensity, jumps off a frequency.
Step 5, judge whether difference DELTA satisfies the requirement of threshold values X, promptly | Δ |<X, if difference DELTA satisfies the requirement of threshold values X, tracer signal source output amplitude and carry out next frequency adjustment then; If difference DELTA does not satisfy the requirement of threshold values X, then execution in step six.The unit of described threshold values X is dB, and its concrete numerical value is set according to needed measuring accuracy in the electromagnetic radiation sensitivity degree testing experiment, and general value is 0.1~0.5dB.
Step 6, adjustment signal source output amplitude S=S-Δ, cycle index adds 1 simultaneously, i.e. i=i+1, and make A
1=A
0
Step 7, adjusted signal source output amplitude S is exported, repeating step two~step 6 satisfies the requirement of threshold values X up to difference DELTA, promptly | Δ |<X, then the signal source adjustment finishes, and proceeds the amplitude adjustment of next frequency.
Embodiment
Choose pilot project CS114 among the GJB151A-97, and according to curve 1 as the standard limit value.On the 10MHz frequency, when adopting existing method to judge,,, make the current value A of current monitoring probe monitoring gradually through reducing signal source output amplitude S if the situation that measured value is higher than ultimate value occurs
0Approach the process of standard limit value A, greater than once circulation,, explain that power amplifier does not get into the non-linear base area of making an uproar usually,, non-linear base area and the end loop of making an uproar of entering is described, off-test if reach 6 circulations if this frequency still can be adjusted to ultimate value.
Adopt method of the present invention; At first initial value S in signalization source is-80dBm; Conducted interference signal is injected on the cable of test specimen through injection probe, the current value of current monitoring probe acquisition reads with receiver simultaneously, and this moment, the receiver data were current value A
0=81dB μ A.Should be A=77dB μ A according to the standard limit value; Reduce the signal source output amplitude this moment gradually; When not reaching the restriction that the signal source minimum levels is exported (generally elect as-130dBm); Should reduce 4dB according to measuring the difference DELTA that obtains, this moment, signal source was output as-84dBm, and it is A that receiver records data
1=80.5dB μ A.Calculate 0.8<(A
0-A
1Whether)/Δ is set up, and judges whether the ingoing power amplifier nonlinearity base area of making an uproar.
Can find out that the test specimen cable induced electricity flow valuve that the current monitoring probe obtains does not have according to the output of power amplifier linearity rule, the amplitude that reduces is not obvious, judges that like this power amplifier has got into the base area of making an uproar.
Can know through above-mentioned instance comparison, under equal conditions, measure the round-robin number of times and reduce to 1 time by 6 times at most, can judge that whether power amplifier gets into the non-linear base area of making an uproar, and has saved the test period of single frequency point, thereby has improved efficient.For the higher test of accuracy requirement, judging actual measurement variable quantity A
0-A
1And calculate ratio between the variation delta whether in a certain scope (being 0.8) time here, change the precision that this scope can change test.According to this method, reduce unnecessary signal input, thereby prolong the serviceable life of power amplifier.