Patent ID: 7668041

Claim:
A system for obtaining information about a formation, comprising: a controller having a first clock for time-stamping a record of a signal generated in the formation; and a receiver configured to be deployed in the wellbore and configured to detect the signal from the formation; a second clock comprising a first oven surrounding a crystal oscillator and a first temperature sensor configured to measure temperature of the crystal oscillator downhole; a second oven surrounding the first oven and a second sensor configured to measure temperature in the second oven; a downhole controller configured to maintain the crystal oscillator temperature substantially at a crystal oscillator turnover temperature in response to the temperature measurements of the first and second sensors; wherein, the second clock is synchronized with the first clock before deployment of the second clock in the wellbore, and wherein the receiver is configured to reference the second clock to time-stamp a record associated with the detected signal, and wherein the temperature measurements over time are used to correct the time of the second clock.