typical TCXO may have a frequency accuracy of 5 ppm to 1 ppm with stabilities on the order of 300 ppb. This may still be too ambiguous for Cellular or RF Engineering applications... solution. A well-designed OCXO will guard against temperature, voltage and load variations. But there is still the fundamental problem of frequency accuracy. By comparing the frequency.... For the above GSM example, this would translate to 0.88 Hz frequency error. So now we have the means to correct environmental and inherent errors in a well-designed OCXO oscillator...