surface e p u00b7 u03b7 ch u00b7 1 u03c9 t u00b7 r 2 from the above equation it may be seen that the signal is inversely proportional to the code modulation frequency f m the noise n is given by the following equation noise s b id u00b7 1 q u00b7 1 f m q 1 6 u00b7 10 u2212 19 coulombs electron elementary charge and the snr per bit is snr n s b 2 1 s b 1 m speckle 1 2 to avoid oscillation due to measurement dynamics the snr per bit may be integrated over the chip length and the average snr may be calculated over the chip length this is the chip snr speckle in the above equation may be ignored for a 1 mhz modulation frequency and a 1024 bit chip length the integration time for computing one chip snr is 1 msec in an embodiment of the invention 1 mhz modulation frequency is the slowest code modulation frequency and 1024 bit chip length is the longest chip length these two values likely represent an extreme condition in which acquisition range may be at a maximum a predetermined number of consecutive chip snr measurements may be averaged for example 10 consecutive chip snr measurements and the result may be compared.