Fix repeated records in ANPP decoders

advanced_navigation/anpp_packets/an_packet_181.py

@@ -83,7 +83,7 @@ def decode(self, an_packet: ANPacket) -> int:
         )
         self.permanent = an_packet.data[0]
         self.clear_existing_packets = an_packet.data[1]
-        self.packet_periods = [PacketPeriod()] * packet_periods_count
+        self.packet_periods = [PacketPeriod() for _ in range(packet_periods_count)]
         for i in range(packet_periods_count):
             index = self.MINIMUM_LENGTH + i * PacketPeriod.LENGTH
             self.packet_periods[i].unpack(

advanced_navigation/anpp_packets/an_packet_202.py

@@ -70,7 +70,7 @@ class IPDataportConfigurationPacket:
     """Packet 202 - IP Dataport Configuration Packet"""
 
     ip_dataport_configuration: list[IPDataportConfiguration] = field(
-        default_factory=lambda: [IPDataportConfiguration()] * 4
+        default_factory=lambda: [IPDataportConfiguration() for _ in range(4)]
     )
 
     ID = PacketID.ip_dataports_configuration

advanced_navigation/anpp_packets/an_packet_31.py

@@ -123,7 +123,7 @@ def decode(self, an_packet: ANPacket) -> int:
             (len(an_packet.data) % DetailedSatellite.LENGTH) == 0
         ):
             number_of_satellites = int(len(an_packet.data) / DetailedSatellite.LENGTH)
-            self.satellites = [DetailedSatellite()] * number_of_satellites
+            self.satellites = [DetailedSatellite() for _ in range(number_of_satellites)]
             for i in range(number_of_satellites):
                 index = i * DetailedSatellite.LENGTH
                 self.satellites[i].unpack(

advanced_navigation/anpp_packets/an_packet_60.py

@@ -183,8 +183,8 @@ def unpack(self, data):
         self.satellite_system = SatelliteSystem(satellite_system_value)
 
         self.frequency_information = [
-            FrequencyInformation()
-        ] * self.number_of_frequencies
+            FrequencyInformation() for _ in range(self.number_of_frequencies)
+        ]
         for i in range(self.number_of_frequencies):
             index = 6 + i * FrequencyInformation.LENGTH
             self.frequency_information[i].unpack(
@@ -225,17 +225,19 @@ def decode(self, an_packet: ANPacket):
                 self.number_of_satellites,
             ) = self._structure.unpack_from(an_packet.data)
 
-            self.satellite_data = [SatelliteData()] * self.number_of_satellites
+            self.satellite_data = [
+                SatelliteData() for _ in range(self.number_of_satellites)
+            ]
 
-            number_of_previous_frequencies = 0
+            total_previous_frequencies = 0
             for i in range(self.number_of_satellites):
                 index = (
                     self.HEAD_LENGTH
                     + i * SatelliteData.MINIMUM_LENGTH
-                    + number_of_previous_frequencies * FrequencyInformation.LENGTH
+                    + total_previous_frequencies * FrequencyInformation.LENGTH
                 )
                 self.satellite_data[i].unpack(an_packet.data[index:])
-                number_of_previous_frequencies = self.satellite_data[
+                total_previous_frequencies += self.satellite_data[
                     i
                 ].number_of_frequencies
             return 0

advanced_navigation/anpp_packets/an_packet_84.py

@@ -106,7 +106,9 @@ def decode(self, an_packet: ANPacket) -> int:
             )
             self.total_number_of_packets = an_packet.data[0]
             self.packet_number = an_packet.data[1]
-            self.extended_satellites = [ExtendedSatellite()] * number_of_satellites
+            self.extended_satellites = [
+                ExtendedSatellite() for _ in range(number_of_satellites)
+            ]
             for i in range(number_of_satellites):
                 index = self.MINIMUM_LENGTH + i * ExtendedSatellite.LENGTH
                 self.extended_satellites[i].unpack(

tests/anpp_packets_tests/test_repeated_record_decoding.py

@@ -0,0 +1,140 @@
+################################################################################
+##                                                                            ##
+##                   Advanced Navigation Python Language SDK                  ##
+##                    test_repeated_record_decoding.py                        ##
+##                     Copyright 2026, Advanced Navigation                    ##
+##                                                                            ##
+################################################################################
+#                                                                              #
+# Copyright (C) 2026 Advanced Navigation                                       #
+#                                                                              #
+# Permission is hereby granted, free of charge, to any person obtaining        #
+# a copy of this software and associated documentation files (the "Software"), #
+# to deal in the Software without restriction, including without limitation    #
+# the rights to use, copy, modify, merge, publish, distribute, sublicense,     #
+# and/or sell copies of the Software, and to permit persons to whom the        #
+# Software is furnished to do so, subject to the following conditions:         #
+#                                                                              #
+# The above copyright notice and this permission notice shall be included      #
+# in all copies or substantial portions of the Software.                       #
+#                                                                              #
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS      #
+# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,  #
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE  #
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER       #
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING      #
+# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER          #
+# DEALINGS IN THE SOFTWARE.                                                    #
+################################################################################
+
+import struct
+
+import pytest
+
+from advanced_navigation.anpp_packets.an_packet_31 import DetailedSatellitesPacket
+from advanced_navigation.anpp_packets.an_packet_60 import RawSatelliteDataPacket
+from advanced_navigation.anpp_packets.an_packet_84 import ExtendedSatellitesPacket
+from advanced_navigation.anpp_packets.an_packet_181 import PacketsPeriodPacket
+from advanced_navigation.anpp_packets.an_packet_202 import (
+    IPDataportConfigurationPacket,
+)
+from advanced_navigation.anpp_packets.an_packet_protocol import ANPacket
+
+DETAILED_SATELLITE = struct.Struct("<BBBBHB")
+FREQUENCY_INFORMATION = struct.Struct("<BBddff")
+SATELLITE_DATA = struct.Struct("<BBBHB")
+RAW_SATELLITE_DATA_HEADER = struct.Struct("<IIiBBBB")
+EXTENDED_SATELLITE = struct.Struct("<BBbBHBBB")
+PACKET_PERIOD = struct.Struct("<BI")
+IP_DATAPORT_CONFIGURATION = struct.Struct("<IHB")
+
+
+def make_packet(packet_id, data):
+    return ANPacket(id=packet_id, length=len(data), data=data)
+
+
+@pytest.mark.parametrize(
+    ("packet_type", "data", "records_attribute", "value_attribute", "expected"),
+    [
+        (
+            DetailedSatellitesPacket,
+            DETAILED_SATELLITE.pack(1, 11, 1, 10, 100, 31)
+            + DETAILED_SATELLITE.pack(4, 22, 2, 20, 200, 42),
+            "satellites",
+            "number",
+            [11, 22],
+        ),
+        (
+            ExtendedSatellitesPacket,
+            bytes([1, 0])
+            + EXTENDED_SATELLITE.pack(1, 11, 1, 10, 100, 31, 32, 1)
+            + EXTENDED_SATELLITE.pack(4, 22, 2, 20, 200, 41, 42, 2),
+            "extended_satellites",
+            "number",
+            [11, 22],
+        ),
+        (
+            PacketsPeriodPacket,
+            bytes([1, 0]) + PACKET_PERIOD.pack(31, 100) + PACKET_PERIOD.pack(84, 200),
+            "packet_periods",
+            "packet_id",
+            [31, 84],
+        ),
+        (
+            IPDataportConfigurationPacket,
+            bytes(2)
+            + b"".join(
+                IP_DATAPORT_CONFIGURATION.pack(0, port, 2)
+                for port in [16718, 16719, 16720, 16721]
+            ),
+            "ip_dataport_configuration",
+            "port",
+            [16718, 16719, 16720, 16721],
+        ),
+    ],
+    ids=["packet-31", "packet-84", "packet-181", "packet-202"],
+)
+def test_decodes_distinct_repeated_records(
+    packet_type, data, records_attribute, value_attribute, expected
+):
+    packet = packet_type()
+
+    assert packet.decode(make_packet(packet.ID, data)) == 0
+
+    records = getattr(packet, records_attribute)
+    assert [getattr(record, value_attribute) for record in records] == expected
+
+
+def pack_frequency(frequency):
+    return FREQUENCY_INFORMATION.pack(frequency, 0, float(frequency), 0, 0, 0)
+
+
+def pack_satellite(system, number, frequencies):
+    return SATELLITE_DATA.pack(system, number, 0, 0, len(frequencies)) + b"".join(
+        pack_frequency(frequency) for frequency in frequencies
+    )
+
+
+def test_packet_60_uses_cumulative_frequency_offsets():
+    frequencies = [[1, 5], [3], [8, 9]]
+    data = RAW_SATELLITE_DATA_HEADER.pack(0, 0, 0, 1, 1, 1, 3) + b"".join(
+        pack_satellite(system, number, satellite_frequencies)
+        for system, number, satellite_frequencies in [
+            (1, 11, frequencies[0]),
+            (2, 22, frequencies[1]),
+            (4, 33, frequencies[2]),
+        ]
+    )
+    packet = RawSatelliteDataPacket()
+
+    assert packet.decode(make_packet(packet.ID, data)) == 0
+
+    assert [satellite.prn_satellite_number for satellite in packet.satellite_data] == [
+        11,
+        22,
+        33,
+    ]
+    assert [
+        [record.satellite_frequency for record in satellite.frequency_information]
+        for satellite in packet.satellite_data
+    ] == frequencies