#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on Wed Aug 21 10:44:38 2024
@author: pteysseyre
"""
import numpy as np
import vlf4ions.sunrise_sunset as srst
[docs]
def flags(amp_NS, amp_EW, previous_nb_points, today, path, this_receiver, phase):
"""Flags 1 if the antenna is down, 2 if the transmitter is down, 3 if it is nighttime
:param amp_NS: Amplitude in the N/S direction
:param amp_EW: Amplitude in the E/W direction
:param previous_nb_points: Number of points read last time
:param today: Datetime, instant of file reading
:param path: path to the precomputed sunrise/sunset times
:param this_receiver: receiver class instance
:param phase: Phase, before any filtering
:return: - flag: flag indicating the state of the transmitter/receiver
- length_data: number of points read this time
- data_last_min: median total amplitude over the last minute"""
flag = 0
data_last_min = 0
length_data = min(
len(amp_NS), len(amp_EW)
) # this is necessary as there may be one more point in amp_EW than amp_NS, as it is read later
# Check that we are in daytime
daytime = srst.check_if_daytime(today, path)
if daytime:
# Antenna down: the number of data points in the last written file stays the same
if length_data == previous_nb_points:
flag = 1
else:
previous_nb_points = length_data
if length_data > 60:
amp_NS = amp_NS[-60:]
amp_EW = amp_EW[-60:]
else:
amp_NS = amp_NS[-length_data:]
amp_EW = amp_EW[-length_data:]
amp = np.sqrt(np.square(amp_NS) + np.square(amp_EW))
data_last_min = np.median(amp)
if (data_last_min < this_receiver.threshold and flag != 1) or np.abs(
phase[-1] - phase[-2]
) > 20:
# If the amplitude is too low, the station is not transmitting
# If the phase is not well-decoded, the signal will be random and will vary greatly between two datapoints
flag = 2
else:
flag = 3
return flag, length_data, data_last_min