How to calculate ppm error relative error
Comparison of Oscillator Accuracy Type Accuracy (ppm/ppb) Accuracy Aging /ġ0 Year Aging / 10 Year Crystal 10ppm-100ppm 10 -5 - 10 -4 10-20ppm 10x10 -6 TCXO 1ppm 10 -6 3ppm 3x10 -6 OCXO 5-10Mhz 0.02ppm Many types designed for many different applications andĪ rubidium clock has an accuracy of about 1 x 10 -12 so the errorĪfter a day would be 86.4ns (84e-9 seconds 84 billionths of a second!) so theĮrror after a month would be 2.6us.
this OCXO has a ppm value of 0.001 ppm or 1ppb. They are not quoted in ppm as it becomes inconvenient to Sealed in a small chamber with a controlled heating element inside toĪ typical spec might be 1 x 10 -9 (1ppb) so the error after aĭay would be 86.4us and after a month 2.6ms (2.6e-3 seconds or 2.6 thousandths Watch crystal will be better because you keep it at a constantĪn OCXO is an Oven Controlled Crystal Oscillator. Oscillator - that generates heat and keeps a constant temperature). Temperature (This is why you can buy an OCXO or Oven Controlled Crystal Temperature coefficient graph meaning that another source of error is and the human body is at a constant temperature. One of the other factors in a wrist watch is that you wear it on your wrist Over a day of 86400 * 2e-5 = 1.73 seconds per day so in a month it loosesģ0x1.72 = 51 seconds or 1 minute a month (approx). How good is a watch crystal ?Ī watch crystal has an error of 20ppm (ish), but you have to design theīoard layout well, this translates as 20/1e6 (2e-5) which gives an error In a month you would loose 30x8.64 = 259 seconds or 4.32Įrror: 8.64 seconds per day. So the total error on a day is 86400 x 1e-4= 8.64 How good is a typical crystal ?Ī typical crystal has an error of 100ppm (ish) this translates So the maximum error after a day has passed is 1%Įrror: 14.4 minutes error per day. If you look at a day's worth of timekeeping then you have 24 x 60 x 60 =Ĩ6400 seconds in a day.
Note: A typical microcontroller crystal has a 100ppm specification
How to calculate ppm error relative error how to#
Arduino Toggle Switch - using a standard push button.Arduino Oversampling: How to Get More ADC Bits with No Extra Hardware!.However, I cannot find any reference actually using any of these or at least discussing these topics for my case.Īny answer substantiated with a peer-reviewed paper is greatly appreciated. This other question: How to calculate relative error? is somewhat related but I do not think it really applies.
I have seen: How to calculate relative error when the true value is zero?īut since I do not have access to a measurement and its true value I am not sure how to apply the discussion there to this case, and I could not find any reference in the literature. What would you recommend to use under such situations? However, when the value of the quantity to measure tends to zero, the relative error can become very large, although the measurement itself might be very reliable, because for example the quantity to measure is zero within the instrumentation error. The relative error has many useful application in error propagation and so on, and it is frequently used to determine the quality of a measurement. Let's consider the case of a measurement $x$ and its correspondent error $\Delta x$ (which are both always positive).