Environmental effects on errors in two-way time transfer

We have investigated errors in two-way time transfer due to environmental fluctuations in temperature and power levels. The overall temperature coefficient of two Earth stations at the National Institute of Standards and Technology (NIST) have been found to be on the order of 100 pS/K Sub-component temperature coefficients are as high as 400 pS/K. The errors in two-way time transfer due to variations in power levels have been measured to be as large as 12 nS. These errors are due to distortion in the pn sequence due to gain compression in the earth-station.