As high-accuracy frequency and time test instrument, it is tested that the precision is higher than ordinary spectrum analyzer and ondoscope in the frequency counter, so test the calculation of the precision is paid close attention to. Influence and test the precision, the factor of producing the error in other words is numerous, and the most master factor is stability of time base, definition within the instrument, touch off precision and internal noise etc. among them.

Frequency and periodic test precision

Frequency and cycle are both as reciprocally, so in the test of the frequency counter, frequency and periodic error algorithmic method are uniform. From testing the production of the error to say that mainly there are two kinds, one is random error, one kind is a fixed error. The random error, mainly because such as the noise or error that some random factors produce, it is very difficult to dispel. The fixed error is mainly the error that because test method, instrument are set up or the instrument characteristic causes. Different apparatus manufacturers all have one’s own algorithmic method about the error, very much the same, this text expounds the fact FCA3000 series frequency counter of Tyke tests the algorithmic method of the error.

Combined error: U tot

Among them MR = Meas. Result Freq or Period ,MR test result, it can be frequency or time

MT = Mear. Time testing time

TBE = Time Base Error time base error

As high-accuracy frequency and time test instrument, it is tested that the precision is higher than ordinary spectrum analyzer and ondoscope in the frequency counter, so test the calculation of the precision is paid close attention to. Influence and test the precision, the factor of producing the error in other words is numerous, and the most master factor is stability of time base, definition within the instrument, touch off precision and internal noise etc. among them.

Frequency and periodic test precision

Frequency and cycle are both as reciprocally, so in the test of the frequency counter, frequency and periodic error algorithmic method are uniform. From testing the production of the error to say that mainly there are two kinds, one is random error, one kind is a fixed error. The random error, mainly because such as the noise or error that some random factors produce, it is very difficult to dispel. The fixed error is mainly the error that because test method, instrument are set up or the instrument characteristic causes. Different apparatus manufacturers all have one’s own algorithmic method about the error, very much the same, this text expounds the fact FCA3000 series frequency counter of Tyke tests the algorithmic method of the error.

Combined error: U tot

Among them MR = Meas. Result Freq or Period ,MR test result, it can be frequency or time

MT = Mear. Time testing time

TBE = Time Base Error time base error

Calculate and give an example

We can calculate the error tested by a concrete example. We suppose the following parameters:

l Use Tyke FCA3000 Frequency counter

95% of the confidence intervals of l

L 100MHz measured signal reading, tests time for one second

l Signal level 5 V

l The time base is after normalizing 1.7 ppm

l The signal is purer, the noise Vnoise-signal =0And shake Ejitter =0

Calculate the random error at first

1,Pass the formula 5 Calculate Enoise=Vnoise/inp.sign.slew rate v/s at trig point

Inp.sign.slew rate v/s when the measured signal is CW at trig point =2 100MHz *5V =3.14*10 9

Enoise =Vnoise / inp.sign.slew rate v/s at trig point=500uv/3. 14*10 9 =0.159 ps

2,Start Trigger Error = Ess = Enoise, inserts formulae 3

Urnd = [2.5* 100ps2 0.159ps2 1/2 /1*8001/2 ]*100MHz =8*10-4Hz

Calculate the fixed error, pass formulae 6

Usys ={1/3*[ 1.7*10-6*100MHz 2 [ 200ps / 1s *100MHz ] 2]} 1/2 =93Hz

Calculate the combined error, pass formulae 1

Utot =2* [ Urnd 2 Usys2 ]1/2 =186Hz

Conclusion

Can find out from we in assumed result, the source of the error is mainly fixed error, and the promotion of time base stability can improve and test the precision greatly.