A range-determining-module for a transceiver, for determining a range between the transceiver and a remote transceiver, and configured to: transmit a signal comprising a transmission-data-packet having a plurality of known-sequence-sections, in which each known-sequence-section contains a known-data-sequence and is associated with a respective transmission-time; receive a signal comprising a received-data-packet, wherein the received-data-packet comprises a repetition of the transmission-data-packet from the remote transceiver; identify first and second known-sequence-sections of the received-data-packet, in which the first known-sequence-section is a different section from the second known-sequence-section, each known-sequence-section containing the known-data-sequence that is known to the range-determining-module; determine a respective reception-time-stamp associated with each of the first and second known-sequence-sections; determine a first packet-round-trip using the reception-time-stamp associated with the first known-sequence-section; determine a second packet-round-trip using the reception-time-stamp associated with the second known-sequence-section; verify the integrity of the received-data-packet using the respective reception-time-stamp associated with the first and second known-sequence-sections of the received-data-packet, wherein verifying the received-data-packet comprises comparing the first packet-round-trip with the second packet-round-trip, wherein the received-data-packet is verified if the first packet-round-trip time matches the second packet-round-trip time; and provide a verified range estimate between the transceiver and the remote transceiver in accordance with one or more of the reception-time stamps of the verified received-data-packet. transmit a signal comprising a transmission-data-packet having a plurality of known-sequence-sections, in which each known-sequence-section contains a known-data-sequence and is associated with a respective transmission-time; receive a signal comprising a received-data-packet, wherein the received-data-packet comprises a repetition of the transmission-data-packet from the remote transceiver; identify first and second known-sequence-sections of the received-data-packet, in which the first known-sequence-section is a different section from the second known-sequence-section, each known-sequence-section containing the known-data-sequence that is known to the range-determining-module; determine a respective reception-time-stamp associated with each of the first and second known-sequence-sections; determine a first packet-round-trip using the reception-time-stamp associated with the first known-sequence-section; determine a second packet-round-trip using the reception-time-stamp associated with the second known-sequence-section; verify the integrity of the received-data-packet using the respective reception-time-stamp associated with the first and second known-sequence-sections of the received-data-packet, wherein verifying the received-data-packet comprises comparing the first packet-round-trip with the second packet-round-trip, wherein the received-data-packet is verified if the first packet-round-trip time matches the second packet-round-trip time; and provide a verified range estimate between the transceiver and the remote transceiver in accordance with one or more of the reception-time stamps of the verified received-data-packet.