def GetEHataStandardDeviation(freq_mhz, is_urban):
  """Gets the Log Normal standard deviation of E-Hata.

  Inputs:
    freq_mhz:  the frequency in MHz. Used to compute the eHata stdev.
    is_urban:  if False, an extra 2dB is added to the stdev

  Returns:
    the offset in dB to apply to the median
  """
  return 8.4 if is_urban else 10.4
  # Exact formula is:
  # std = (_ALPHA_U + _BETA_U * math.log10(freq_mhz)
  #       + _GAMMA_U * math.log10(freq_mhz)**2)
  # if not is_urban:
  #  std += 2
  # return std