From e971070b0f5b089547adedcb0517831195115fcc Mon Sep 17 00:00:00 2001 From: Antonio Ospite Date: Thu, 24 Dec 2015 10:29:29 +0100 Subject: [PATCH] CallDistanceTransceiver.py: use a min,max scheme instead of avg,uncertainty Specify parameters using a minimum and a maximum values, like call_setup_time_min,call_setup_time_max and ring_time_min,ring_time_max. This makes it more intuitive to measure the stability of the line, and makes the code more readable too. --- src/savemysugar/CallDistanceTransceiver.py | 251 +++++++++++++++++++---------- 1 file changed, 168 insertions(+), 83 deletions(-) diff --git a/src/savemysugar/CallDistanceTransceiver.py b/src/savemysugar/CallDistanceTransceiver.py index 7662b68..f9760bb 100755 --- a/src/savemysugar/CallDistanceTransceiver.py +++ b/src/savemysugar/CallDistanceTransceiver.py @@ -29,6 +29,41 @@ import logging import time +class SymbolTime(object): + """ + In theory the symbol distance (the distance to discriminate symbols) can + be arbitrary, and it's only bounded below by the stability of the pulse + time, but in practice it can be necessary to wait a predefined minimum + amount of time between pulses because of technological limits of the + transmitting devices, we call this time the "minimum inter-symbol + distance". + """ + + # pylint: disable=too-few-public-methods + def __init__(self, pulse_min, pulse_max, multiplier, + min_inter_symbol_distance=0.0): + assert multiplier >= 0 + if (pulse_min == pulse_max) and (min_inter_symbol_distance == 0): + raise ValueError("If (pulse_min == pulse_max) a non-zero", + "inter-symbol distance MUST be specified") + + symbol_distance = 2 * (pulse_max - pulse_min) + if symbol_distance == 0: + symbol_distance = min_inter_symbol_distance + + # The time the transmitter has to wait to disambiguate between this + # symbol and a different one. + self.dist = min_inter_symbol_distance + symbol_distance * multiplier + + # The minimum time which represents the symbol at the receiving end. + self.min = min_inter_symbol_distance + pulse_min + \ + symbol_distance * multiplier + + # The maximum time which represents the symbol at the receiving end + self.max = min_inter_symbol_distance + pulse_min + \ + symbol_distance * (multiplier + 1) + + class CallDistanceTransceiver(object): """Transmit Morse messages using the distance between calls. @@ -53,79 +88,113 @@ class CallDistanceTransceiver(object): """ def __init__(self, modem, - call_setup_average=8.5, call_setup_uncertainty=1.5, - ring_distance_average=5, ring_uncertainty=0.2): + call_setup_time_min=7, call_setup_time_max=15, + ring_time_min=4.8, ring_time_max=5.2, + add_inter_call_distance=True): """Encode the Morse symbols using the distance between calls. Args: - call_setup_average: the time between when the transmitter dials - the number and the receiver reports RING notifications. This is - needed in order to be sure than the receiver has received - _at_least_ one ring. The default chosen here should work fine - even with old analog modems, provided that there is some more - distance between two calls. - call_setup_uncertainty: uncertainty of call_setup_average, - a tolerance value - ring_distance_average: the time between two consecutive RINGs + + call_setup_time_min: the minimum time between when the transmitter + dials the number and the receiver reports RING notifications. + call_setup_time_max: the maximum time between when the transmitter + dials the number and the receiver reports RING notifications. + Waiting this time after dialing ensures that the receiver has + received _at_least_ one ring. The default chosen here have been + tested to work fine with old analog modems, provided that there + is some more distance between two calls, and with Android + receivers. + ring_time_min: the minimum time between two consecutive RINGs + in the same call. + ring_time_max: the maximum time between two consecutive RINGs in the same call, the standard interval is about 5 seconds, but - some tolerance is needed to account for line delays. - This is needed in order to ignore rings in the same call, and - differentiate two different calls. - ring_uncertainty: uncertainty of ring_distance_average, a tolerance - value - """ + line and/or software delays can make it vary. This is needed + in order to ignore multiple ring in the same call when multiple + RING in the same call are notified, and then be able to + discriminate between two different calls. + add_inter_call_distance: specify if it is needed to wait an extra + fixed time between calls. + """ self.modem = modem self.translator = MorseTranslator() self.destination_number = "" - self.call_setup_time = call_setup_average + call_setup_uncertainty - self.rings_distance = ring_distance_average + ring_uncertainty - - # In theory the symbol distance, the distance between calls which - # represent symbols, can be arbitrary, but in practice it's better to - # wait at least the duration of a ring between terminating one call and - # initiating the next call, as pick-up and hang-up can take some time - # with old analog modems. - symbol_distance = self.rings_distance - - def symbol_time(multiplier): - return self.call_setup_time + symbol_distance * multiplier - - self.dot_time = symbol_time(1) - self.dash_time = symbol_time(2) - self.signalspace_time = symbol_time(3) - self.wordspace_time = symbol_time(4) - self.eom_time = symbol_time(5) - - self.ring_uncertainty = ring_uncertainty - self.symbol_uncertainty = symbol_distance / 2. - - logging.debug("dot ---------> transmit time: %.2f " + self.call_setup_time_min = call_setup_time_min + self.call_setup_time_max = call_setup_time_max + + self.ring_time_min = ring_time_min + self.ring_time_max = ring_time_max + + if add_inter_call_distance: + # Analog modems don't like to dial a new call immediately after + # they hung up the previous one; an extra delay of about one + # ring time makes them happy. + inter_symbol_distance = ring_time_max + else: + inter_symbol_distance = 0 + + self.dot_time = SymbolTime(call_setup_time_min, + call_setup_time_max, 0, + inter_symbol_distance) + self.dash_time = SymbolTime(call_setup_time_min, + call_setup_time_max, 1, + inter_symbol_distance) + self.signalspace_time = SymbolTime(call_setup_time_min, + call_setup_time_max, 2, + inter_symbol_distance) + self.wordspace_time = SymbolTime(call_setup_time_min, + call_setup_time_max, 3, + inter_symbol_distance) + self.eom_time = SymbolTime(call_setup_time_min, + call_setup_time_max, 4, + inter_symbol_distance) + + logging.debug("call setup time between %.2f and %.2f " + "--------- dot transmit time: %.2f + %.2f " "receive time: between %.2f and %.2f", - self.dot_time, - (self.dot_time - self.symbol_uncertainty), - (self.dot_time + self.symbol_uncertainty)) - logging.debug("dash --------> transmit time: %.2f " + self.call_setup_time_min, + self.call_setup_time_max, + self.call_setup_time_max, + self.dot_time.dist, + self.dot_time.min, + self.dot_time.max) + logging.debug("call setup time between %.2f and %.2f " + "-------- dash transmit time: %.2f + %.2f " "receive time: between %.2f and %.2f", - self.dash_time, - (self.dash_time - self.symbol_uncertainty), - (self.dash_time + self.symbol_uncertainty)) - logging.debug("singalspace -> transmit time: %.2f " + self.call_setup_time_min, + self.call_setup_time_max, + self.call_setup_time_max, + self.dash_time.dist, + self.dash_time.min, + self.dash_time.max) + logging.debug("call setup time between %.2f and %.2f " + "- signalspace transmit time: %.2f + %.2f " "receive time: between %.2f and %.2f", - self.signalspace_time, - (self.signalspace_time - self.symbol_uncertainty), - (self.signalspace_time + self.symbol_uncertainty)) - logging.debug("wordspace ---> transmit time: %.2f " + self.call_setup_time_min, + self.call_setup_time_max, + self.call_setup_time_max, + self.signalspace_time.dist, + self.signalspace_time.min, + self.signalspace_time.max) + logging.debug("call setup time between %.2f and %.2f " + "--- wordspace transmit time: %.2f + %.2f " "receive time: between %.2f and %.2f", - self.wordspace_time, - (self.wordspace_time - self.symbol_uncertainty), - (self.wordspace_time + self.symbol_uncertainty)) - logging.debug("EOM ---------> transmit time: %.2f " + self.call_setup_time_min, + self.call_setup_time_max, + self.call_setup_time_max, + self.wordspace_time.dist, + self.wordspace_time.min, + self.wordspace_time.max) + logging.debug("call setup time between %.2f and %.2f " + "--------- EOM transmit time: %.2f + %.2f " "receive time: between %.2f and inf", - self.eom_time, - (self.eom_time - self.symbol_uncertainty)) + self.call_setup_time_min, + self.call_setup_time_max, + self.call_setup_time_max, + self.eom_time.dist, + self.eom_time.min) self.previous_ring_time = -1 self.previous_call_time = -1 @@ -153,7 +222,8 @@ class CallDistanceTransceiver(object): self.previous_ring_time = current_ring_time # Ignore multiple rings in the same call - if abs(ring_distance - self.rings_distance) < self.ring_uncertainty: + if ring_distance > self.ring_time_min and \ + ring_distance <= self.ring_time_max: logging.debug("multiple rings in the same call, distance: %.2f", ring_distance) return @@ -161,31 +231,35 @@ class CallDistanceTransceiver(object): call_distance = current_ring_time - self.previous_call_time self.previous_call_time = current_ring_time - if abs(call_distance - self.dot_time) < self.symbol_uncertainty: + if call_distance > self.dot_time.min and \ + call_distance <= self.dot_time.max: self.log_symbol(call_distance, '.') self.morse_message += "." return - if abs(call_distance - self.dash_time) < self.symbol_uncertainty: + if call_distance > self.dash_time.min and \ + call_distance <= self.dash_time.max: self.log_symbol(call_distance, '-') self.morse_message += "-" return - if abs(call_distance - self.signalspace_time) < self.symbol_uncertainty: + if call_distance > self.signalspace_time.min and \ + call_distance <= self.signalspace_time.max: signal = self.morse_message.strip().split(' ')[-1] character = self.translator.signal_to_character(signal) self.log_symbol(call_distance, ' ', "got \"%s\"" % character) self.morse_message += " " return - if abs(call_distance - self.wordspace_time) < self.symbol_uncertainty: + if call_distance > self.wordspace_time.min and \ + call_distance <= self.wordspace_time.max: signal = self.morse_message.strip().split(' ')[-1] character = self.translator.signal_to_character(signal) self.log_symbol(call_distance, '/', "got \"%s\"" % character) self.morse_message += " / " return - if call_distance >= self.eom_time - self.symbol_uncertainty: + if call_distance > self.eom_time.min: signal = self.morse_message.strip().split(' ')[-1] character = self.translator.signal_to_character(signal) self.log_symbol(call_distance, 'EOM', "got \"%s\"" % character) @@ -213,30 +287,35 @@ class CallDistanceTransceiver(object): def transmit_symbol(self, symbol): if symbol == ".": - sleep_time = self.dot_time + sleep_time = self.dot_time.dist elif symbol == "-": - sleep_time = self.dash_time + sleep_time = self.dash_time.dist elif symbol == " ": - sleep_time = self.signalspace_time + sleep_time = self.signalspace_time.dist elif symbol == "/": - sleep_time = self.wordspace_time + sleep_time = self.wordspace_time.dist elif symbol == "EOM": - sleep_time = self.eom_time + sleep_time = self.eom_time.dist elif symbol is None: # To terminate the transmission just call and hangup, with no extra # distance - sleep_time = self.call_setup_time - - logging.info("Dial and wait %.2f seconds (transmitting '%s')", - sleep_time, symbol) - - # Dial, then wait self.call_setup_time to make sure the receiver gets - # at least one RING, and then hangup and sleep the remaining time + sleep_time = 0 + + logging.info("Dial and wait %.2f = %.2f + %.2f seconds " + "(transmitting '%s')", + self.call_setup_time_max + sleep_time, + self.call_setup_time_max, + sleep_time, + symbol) + + # Dial, then wait self.call_setup_time_max to make sure the receiver + # gets at least one RING, and then hangup and sleep the time needed to + # transmit a symbol. self.modem.send_command("ATDT" + self.destination_number + ";") - time.sleep(self.call_setup_time) + time.sleep(self.call_setup_time_max) self.modem.send_command("ATH") self.modem.get_response() - time.sleep(sleep_time - self.call_setup_time) + time.sleep(sleep_time) def transmit_signal(self, signal): logging.debug("Transmitting signal: %s", signal) @@ -280,17 +359,23 @@ class CallDistanceTransceiver(object): logging.debug("signal: %s", signal) for symbol in signal: + transmitting_time += self.call_setup_time_max if symbol == ".": - transmitting_time += self.dot_time + transmitting_time += self.dot_time.dist elif symbol == "-": - transmitting_time += self.dash_time + transmitting_time += self.dash_time.dist elif symbol == "/": - transmitting_time += self.wordspace_time + transmitting_time += self.wordspace_time.dist if i != len(signals) - 1 and signals[i + 1] != "/" and symbol != "/": - transmitting_time += self.signalspace_time + transmitting_time += self.call_setup_time_max + transmitting_time += self.signalspace_time.dist + + transmitting_time += self.call_setup_time_max + transmitting_time += self.eom_time.dist - transmitting_time += self.eom_time + # The final call needed for the receiver to get the EOM + transmitting_time += self.call_setup_time_max logging.debug("Estimated transmitting time: %.2f seconds", transmitting_time) -- 2.1.4