Abstract: An apparatus and a method for recovering clock and data from a multilevel pulse amplitude modulated signal received as input signal is suggested. The apparatus comprises a phase detector, a low-pass filter, a voltage-controlled oscillator, and a feedback loop forming a CDR loop. The voltage-controlled oscillator outputs a clock signal that is provided to the phase detector. The phase detector receives an MSB signal from a sampler. The apparatus also comprises an interleave circuit configured to receive the input signal and to generate two output signals having a smaller symbol rate than the input signal. The apparatus further comprises a logical gate configured to receive the output signals from the interleave circuit and to generate an enable signal for the phase detector indicating symmetrical transitions in the input signal. Lastly, the apparatus comprises a converter converting the output signals from the interleave circuit into an MSB and an LSB bit stream.

Abstract: A method of transmitting data and command through an RS232 serial port incorporated with a user-end device and a server-end device connected through the RS232 serial port is disclosed and includes following steps: accumulating a value of a first counter of the user-end device and a value of a second counter of the server-end device whenever a data is transmitted from the server-end device to the user-end device; controlling the server-end device to stop transmitting the data and to wait when both of the two values reach a triggering threshold; controlling the user-end device to transmit a control command to the server-end device through the RS232 serial port while the server-end device is waiting; and, resetting the first and the second counter and controlling the server-end device to restore to transmit the data to the user-end device after a waiting time is elapsed.

Abstract: A communications system for line-of-sight (LOS) and beyond-line-of-sight (BLOS) communications using a single aperture includes one or more operators positioned within an environment, wherein each operator includes a common aperture, one or more low-earth orbit satellites communicatively coupled to a plurality of communications sub-systems disposed on the operators. In one embodiment, the communications sub-systems may include a first antenna element to transmit and receive first radio frequency signals along a first directional link via the common aperture. In another embodiment, the communications sub-systems may include a second antenna element to transmit and receive second radio frequency signals along a second directional link via the common aperture.

Abstract: A bit interleaver, a bit-interleaved coded modulation (BICM) device and a bit interleaving method are disclosed herein. The bit interleaver includes a first memory, a processor, and a second memory. The first memory stores a low-density parity check (LDPC) codeword having a length of 64800 and a code rate of 2/15. The processor generates an interleaved codeword by interleaving the LDPC codeword on a bit group basis. The size of the bit group corresponds to a parallel factor of the LDPC codeword. The second memory provides the interleaved codeword to a modulator for 256-symbol mapping.

Abstract: A bit interleaver, a bit-interleaved coded modulation (BICM) device and a bit interleaving method are disclosed herein. The bit interleaver includes a first memory, a processor, and a second memory. The first memory stores a low-density parity check (LDPC) codeword having a length of 64800 and a code rate of 3/15. The processor generates an interleaved codeword by interleaving the LDPC codeword on a bit group basis. The size of the bit group corresponds to a parallel factor of the LDPC codeword. The second memory provides the interleaved codeword to a modulator for 16-symbol mapping.

Abstract: A bit interleaver, a bit-interleaved coded modulation (BICM) device and a bit interleaving method are disclosed herein. The bit interleaver includes a first memory, a processor, and a second memory. The first memory stores a low-density parity check (LDPC) codeword having a length of 16200 and a code rate of 4/15. The processor generates an interleaved codeword by interleaving the LDPC codeword on a bit group basis. The size of the bit group corresponds to a parallel factor of the LDPC codeword. The second memory provides the interleaved codeword to a modulator for 16-symbol mapping.

Abstract: A communication system for providing predictive adaptive coding and modulation (ACM) during transmission between terminals is provided. One or more receiving terminals are adapted for detecting changes in a transmission rate and automatically adapting its demodulation to the changes. A transmitting terminal is adapted for transmitting data to the one or more receiving terminals using predictive ACM by selecting channel parameters from a lookup table without receiving channel parameters over a return link from the one or more receiving terminals. The channel parameters may be at least one of a channel symbol rate, a code type, and a frequency.

Abstract: In described examples of a ramp circuit, a first terminal of a capacitor is coupled to a ramp terminal and a second capacitor terminal is coupled to a return terminal. A charge source has an input terminal coupled to a supply terminal and a charge output terminal. A resistor has a first terminal coupled to the return terminal. A first switch is coupled between the ramp terminal and a second terminal of the resistor. A second switch is coupled between the charge output terminal and the ramp terminal.

Abstract: Aspects of the present disclosure describe scrambling of information for wireless communications to prevent deciphering or altering by unintended recipients. An example method may include generating, by a first device, a scrambling key based on at least one of a freshness parameter or a private key. The private key is known by the first device and a second device. The method also includes scrambling a payload based on the scrambling key at a physical layer. A packet includes the payload for wireless transmission from the first device to the second device via a shared channel.

Abstract: Methods, computing devices, and systems that dynamically determine whether a service request is authorized or fraudulent are described herein. A computing device may receive a request from a user device, and a geographical location of the user device may be determined based on a signal received from the user device. A determination as to whether to activate the service or not may be made based on the determined geographical location of the user device.

Abstract: A method for processing data by an electronic data-acquisition device, requesting to obtain data from an electronic data-providing device. The electronic data-acquisition device and the electronic data-providing device communicate with each other by using a short-range wireless (NFC) communications technology defining a transmission/reception reference frequency. The method includes the following acts performed by the electronic data-acquisition device: determining a frequency of transmission/reception of an interrogation signal that is different from the transmission/reception reference frequency, as a function of a frequency-determining parameter, delivering an interrogation frequency; and after determining the interrogation frequency, transmitting the interrogation signal to the data-providing device at the interrogation frequency.

Abstract: A method for determining a position of a receiver via use of encrypted signals of a public regulated service. The method comprises transmitting PRN code chips to the receiver by an assistance server. The method further comprises storing the transmitted PRN code chips to be used before a designated time interval by the receiver. The method further comprises receiving the encrypted signals during the designated time interval by the receiver from satellites in line-of-sight to the receiver. The method further comprises determining the position of the receiver via use of the encrypted signals and the stored PRN code chips by the receiver.

Abstract: A method and apparatus for providing information about an encrypted signal transmitted by a satellite in a satellite navigation system are disclosed. A data sequence of the encrypted signal as transmitted is obtained, a signal sample is extracted from the data sequence, the signal sample including a part of the data sequence having a length less than a total length of the data sequence, and the signal sample and information about when the data included in the signal sample was transmitted by the satellite are transmitted, as the encrypted signal information, to a receiver for use in the satellite navigation system. A method and apparatus for authenticating an unencrypted signal based on the encrypted signal information are also disclosed.

Abstract: A system architecture for managing resources in a communication network comprises in combination at least the following elements: a plurality of radio equipments working in a given frequency band and with identical frequency hopping rules; the radio equipments are managed by a master device; and a radio equipment comprises at least: a radiocommunication module that carries the radiocommunications; a module suitable for tapping, monitoring and intercepting radio signals in the environment and for recording them locally in a database; a module suitable for disrupting non-authorized communications; and a local “3 in 1” management module receiving the orders emitted by the master device, the management module being suitable for controlling the various modules of the radio equipment; a radio-router module; and a tapping and monitoring module.

Abstract: The present invention provides a method. The method includes: performing coupling to acquire a first reference signal and a second reference signal from a transmit signal transmitted on a same transmit link at a transmit end; performing signal recombination according to the first reference signal and the second reference signal, to obtain a first interference cancellation signal and a second interference cancellation signal; enabling the first interference cancellation signal to pass through a simulated interference channel, and enabling the second interference cancellation signal to pass through the simulated interference channel; and coupling and output, to a same receive link at the local receive end, the first interference cancellation signal and the second interference cancellation signal that have passed through the simulated interference channel, and combining the first interference cancellation signal and the second interference cancellation signal with a signal received by the local receive end.

Abstract: Provided are techniques for distributing data in a trackable manner while suppressing an increase in the size of data to be distributed as much as possible and minimizing interruption of usage of the data. A method for distributing data to multiple clients from a server includes the steps of: generating a common noise by using noises unique to the multiple clients, respectively; embedding the common noise in the data to be distributed to make the data unusable; and distributing the data containing the embedded common noise, so that the data containing the embedded common noise is made usable by each of the multiple clients using a unique noise generated in the client.

Abstract: The replacement of secret keys is a central problem in key management. Typical solutions exchange handshaking messages, involve complex computations, or require the cooperation of trusted third parties. Disclosed herein is a key replacement method that exploits the randomness of Markov models to efficiently provide fresh keys to users. Unlike other methods, the proposed method removes the need for extra communications, intensive computation, or third parties. It is demonstrated that the proposed method has perfect forward secrecy as well as resistance to known-key attacks.

Abstract: A method is described for negotiating the use of multi-link ciphering and for the generation of unique keys for each of the links using a single 4-way handshake protocol exchange.

Abstract: A wheel suspension system for a three-wheeled motorcycle or “trike” includes parallel wheels mounted on vertically pivoting suspension arms governed by hydraulic pistons. The pistons have upper liquid reservoirs that are interconnected through a valve system, which interconnects the upper reservoirs when the trike is in motion, allowing opposing vertical wheel movements when banking through turns, and prevents liquid exchange when the trike is stopped, thereby holding the motorcycle upright, Embodiments include a manual and/or automatic valve control. A threshold switching speed for an automatic controller can be factory set and/or user adjustable. The pistons can include directly interconnected lower fluid reservoirs. A shock-absorbing reservoir can allow transient vertical movement of both wheels to absorb shocks. A cover system can emulate the appearance of saddle bags and can appear to be covering only a single wheel.

Abstract: Tampering monitoring system can detect whether protection control module is tampered with even if some of detection modules are tampered with. Tampering monitoring system includes protection control module detection modules, and management device. Protection control module includes: generation unit generating d pieces of distribution data from computer program, n and d being positive integers, d smaller than n; selection unit selecting d detection modules; and distribution unit distributing d pieces of distribution data to d detection modules. Each detection module judges whether received piece of distribution data is authentic to detect whether protection control module is tampered with, and transmits judgment result indicating whether protection control module is tampered with. Management device receives judgment results from d detection modules and manages protection control module with regard to tampering by using received judgment results.

Abstract: A method determines an elliptical curve, suitable for a cryptographic method. An elliptical curve to be tested is prepared. The order of a twisted elliptical curve associated with the elliptical curve to be tested is determined. It is automatically checked whether the order of the twisted elliptical curve is a strong prime number. If the order of the twisted elliptical curve is a strong prime number, the elliptical curve to be tested is selected as an elliptical curve suitable for cryptographical methods.

Abstract: Embodiments are directed to switching of stations STA, access points APs and PCPs that are communicating through a wireless link from one frequency band to another. One embodiment is directed to switching of stations STA that are communicating through a tunneled direct link setup (TDLS) link from one frequency band to another. A multiband element may be added to a TDLS discovery request and TDLS discovery response frames to allow each of the stations communications through a TDLS to determine if the other station has multiband capability. In one embodiment, a pairwise transient key (PTK) is created for both a current band in which the stations STA are communicating and a new band over which the stations may communicate in the future. In this way there is no need to calculate a new pairwise transient key PTK for the new frequency band.

Abstract: A method is described that allows a first mobile device to persistently lock onto a second mobile device, thereby allowing the first mobile device to not only constantly monitor the dynamic location of the second mobile device but also to adaptively navigate in real-time to the dynamic location associated with the second mobile device. The dynamic location may include a current location of the second mobile device or a final destination for travel of the second mobile device.

Abstract: A wireless communication method for transmitting information to the designated region with the boundary defined by the sharp cutoff is provided. Receivers outside the designated region are excluded from retrieving the encoded information. The boundary of designated region is adjustable. The wireless communication method can be applied to clearly defining the accepted region and rejection region in satellite communications. The wireless communication method includes steps of providing an information; encoding the information into an encoded data regarding a designated bit-energy-to-noise-ratio; transmitting the encoded data to form a virtual antenna radiation pattern covering a designated region with boundary defined by the sharp cutoff based on the designated bit-energy-to-noise-ratio; receiving the encoded data; and decoding the encoded data into the original information only when receivers within the designated region with bit-energy-to-noise-ratio no less than the designated bit-energy-to-noise-ratio.

Abstract: Multiple applications sharing common resources are arbitrated such that failures resulting from unavailable resources can be avoided. Whenever an application (e.g., a data application) desires to perform an operation (e.g., PPP resynchronization) that requires the use of a shared resource (e.g., an RF receiver), a determination is made as to whether that resource is available. The operation may be delayed while the resource is unavailable. The application may be assigned the resource if it is available or becomes available and may then start the operation. The resource is locked while the operation is pending to avoid assignment to another application. The resource arbitration allows applications to complete their operations without encountering failures due to other applications taking over the resources.

Abstract: A base station generates a unicast channel, a MBMS channel, and a pilot channel, that are multiplied by a scrambling code specific to a particular cell. The pilot channel is replicated as necessary. The unicast channel and the MBMS channel are time-multiplexed. For data in a unit transmission frame, a same frequency component is multiplied by a same scrambling code.

Abstract: A request to receive multicast data, associated with a multicast group, may be transmitted. The request may be transmitted via a tunnel. Group keys may be received in response to the request. The group keys may be based on the multicast group. An encapsulated packet may be received via another tunnel. The encapsulated packet may be processed, using the group keys, to obtain a multicast packet associated with the multicast data. The multicast packet may be forwarded to at least one multicast recipient.

Abstract: A method is provided for tamper detection of a transmitted signal. The method is comprised of generating a first digital data signal having a first data rate. The method is also comprised of generating a second digital data signal having a second data rate. The method is further comprised of concurrently transmitting the first digital data signal at a first carrier frequency using a first modulation format and the second digital data signal at a second carrier frequency using a second modulation format. The method includes selecting the second carrier frequency and a bandwidth of the second digital data signal so that the second digital data signal is contained within a frequency spectrum defined by a bandwidth of the first digital data signal. The method also includes verifying an integrity of the first digital data signal at a remote receiver based on defection at the remote receiver of the second digital data signal. A system (100) is also provided for generating a tamper-protected transmitted signal.

Abstract: A disclosed base station randomizes downlink physical channels in OFDM radio access by scrambling codes suitable for the respective physical channels. The base station includes a base-station-specific scrambling code generating unit configured to generate a base-station-specific scrambling code for randomizing downlink physical channels; a sector-specific orthogonal sequence generating unit configured to generate a sector-specific orthogonal sequence; and a multiplication control unit configured to determine, for each of the physical channels, whether to multiply the base-station-specific scrambling code by the sector-specific orthogonal sequence based on whether each of the physical channels requires soft combining.

Abstract: A method is described that allows a first mobile device to persistently lock onto a second mobile device, thereby allowing the first mobile device to not only constantly monitor the dynamic location of the second mobile device but also to adaptively navigate in real-time to the dynamic location associated with the second mobile device. The dynamic location may include a current location of the second mobile device or a final destination for travel of the second mobile device.

Abstract: Methods and apparatus, including computer program products, are provided for channel estimation. In one aspect, there is provided a receiver including a demodulator for decoding a signal including at least one of a transmission parameter signaling (TPS) carrier and a data carrier. The receiver further includes a channel estimator, coupled to the demodulator, for determining a channel estimate for the TPS carrier. Moreover, the receiver includes an interpolator, coupled to the channel estimator, for determining, based on the determined channel estimate for the TPS carrier, another channel estimate for the data carrier. Related systems, methods, and articles of manufacture are also disclosed.

Abstract: A method and system enables the selective addressing of groups of broadcast receivers within part of a satellite footprint. It uses two satellites having a common transmission band to transmit respective signals, and at receivers in the footprint the phases of the signals received from the two satellites are compared. This phase difference is dependent upon receiver location, but by measuring phase difference no absolute timing or phase measurement is required. A common key is generated at the receivers in a certain area. The output of selected receivers is fed back to the broadcast control centre and is used to encode the location-based services for that area. Preferably the operation is conducted on multiple frequencies and in multiple rounds of such frequencies. A multibit keyword can be directly generated at the receivers by use of a discrete Fourier transform (DFT) and combining its outputs for different rounds.

Abstract: Secure tunneled multicast transmission and reception through a network is provided. A join request may be received from a second tunnel endpoint, the join request indicating a multicast group to be joined. Group keys may be transmitted to the second tunnel endpoint, where the group keys are based at least on the multicast group. A packet received at the first tunnel endpoint may be cryptographically processed to generate an encapsulated payload. A header may be appended to the encapsulated payload to form an encapsulated packet, wherein the header includes information associated with the second tunnel endpoint. A tunnel may be established between the first tunnel endpoint and the second tunnel endpoint based on the appended header. The encapsulated packet may be transmitted through the tunnel to the second tunnel endpoint. The second tunnel endpoint may receive the encapsulated packet. Cryptographic processing of the encapsulated packet may reveal the packet having a second header.

Abstract: A method for detecting a communication relay attack involves the steps of counting a number of clock cycles occurring in a clock signal between transmission of two predetermined elements of data with a data transmission device, counting a number of clock cycles occurring in the clock signal between receipt of the two predefined elements of data and comparing the number of clock cycles counted by the data transmission device with the number of clock cycles counted by the data receiving device.

Abstract: A method for securing human to human communication over a network includes receiving, by a first computer, an incoming authenticated data stream from a second computer over a first communication channel, the incoming authenticated data stream having been computed using an incoming digital experiential data stream and a first imprint, and extracting the first imprint from the incoming authenticated data stream. The incoming authenticated data stream is then presented for sensory experience by a human. An outgoing digital experiential data stream is then input and the method computes a second imprint associated with the first computer and computes an outgoing authenticated data stream using the outgoing digital experiential data stream and the second imprint. A second communication channel is then secured from the first computer to the second computer using the first imprint, the second communication channel suitable for sending the outgoing authenticated data stream to the second computer.

Abstract: Entertainment content is stored in a memory. The content can be audio or video or both. According to an aspect, encryption is keyed to the disc contents to produce a cryptographically created value. That cryptographically created value is based on the content on the memory along with the cryptographic operation. The cryptographic value can be used to determine if data on the memory is valid. One aspect of the memory can be an optical disc. Another aspect carries this out only for recorded discs and does not do this for prerecorded discs.

Abstract: A system and method for providing an encrypted media stream to clients includes a plurality of remote multiple media stream manager and provider (RMP) units to receive a plurality of source media streams. The RMP units modulate the source media streams to provide a plurality of modulated media streams; encrypt the modulated media streams to provide a plurality of encrypted and modulated media streams; de-modulate the encrypted and modulated media streams to provide a plurality of encrypted and demodulated media streams; and transmit the encrypted and demodulated media streams over a high speed network.

Abstract: Multiple logical partitions are provided in a data processing system. A unique context is generated for each one of the logical partitions. When one of the logical partitions requires access to the hardware TPM, that partition's context is required to be stored in the hardware TPM. The hardware TPM includes a finite number of storage locations, called context slots, for storing contexts. Each context slot can store one partition's context. Each one of the partitions is associated with one of the limited number of context storage slots in the hardware TPM. At least one of the context slots is simultaneously associated with more than one of the logical partitions. Contexts are swapped into and out of the hardware TPM during runtime of the data processing system so that when ones of the partitions require access to the hardware TPM, their required contexts are currently stored in the hardware TPM.

Abstract: A method is described for negotiating the use of multi-link ciphering and for the generation of unique keys for each of the links using a single 4-way handshake protocol exchange.

Abstract: A system and method in a wireless network for discovering which resources (e.g., other wireless computing devices) are proximate a user's wireless computing device. Wireless signal strengths with respect to various base stations are compared with the signal strengths of other network devices or resources, to determine which devices are experiencing similar signal strengths. Devices with similar signal strengths are deemed proximate. Each participating computing device may send its signal strength reports to a proximity server, which distributes proximity data to network clients. Each client may receive and process the signal strength data for determining which other clients/resources are proximate, or the server can perform proximity computations and return a list of proximate clients. Once computed, the identities of the proximate clients can be used to query for additional data about the clients, such as the names and other details of their owners, or information about the resource.

Abstract: A method, apparatus and computer program product for transmitting data secures the data by adaptively transforming it and spreading the transformed data piecewise over plural transmission channels. The method, apparatus and computer program product may select low-cost channels preferentially to transmit greater amounts of the data; may disorder the data and transmit ordering information separately over a preferred channel of higher security; may conceal data in a lower-security channel by steganographic methods; and may conceal the sequence of the data by placing segments of it statically, for example, in a WWW website, while providing sequencing data on the preferred channel of higher security. A receiving method, apparatus and computer program product may also be provided for recovering information content from signals on the plural channels.

Abstract: The present invention provides a method and system for secure access to computer equipment. An embodiment includes a secure access controller connected to a link between a transceiver (such as a modem) and the computer equipment. Public and private keys are used by the secure access controller and a remote user. The keys are provided to the secure access controller by an authentication server. Once the transceiver establishes a communication link with the user, the access controller uses these keys to authenticate packets issued by the user to the computer equipment. If the packet is authenticated, the access controller passes the packet to the computer equipment. Otherwise, the packet is discarded. Another embodiment includes a secure access controller having a plurality of ports for connection to a plurality of different pieces of computer equipment. The secure access controller thus intermediates communications between the modem and the plurality of different pieces of computer equipment.

Abstract: An assembly of simultaneously transmitted electrically generated signals, which contains a subset of binary spreading-code sequences that are members of a larger set of binary spreading-code sequences available to a particular node of a multi-node communication network. All sequences in the set of spreading-code sequences available to the particular node of the network can be generated by the same configuration of two linear-feedback binary shift registers, where feedback taps of the two linear-feedback binary shift registers correspond to primative polynomials of the same degree over GF(2), the field of two elements.

Abstract: A spectral notch modulation technique for encoding information in a signal involves transforming the signal into the frequency domain via a fast Fourier transform (FFT) of length N, such that the signal is represented by N frequency bins, selectively nulling M of the N frequency bins, where nulled combinations of M frequency bins respectively correspond to encoded information bits, transforming the selectively nulled signal to the time domain via an inverse FFT, and transmitting the selectively nulled signal. At the receiving end, the signal is demodulated to recover the encoded information by transforming the signal into the frequency domain via a fast Fourier transform (FFT) of length N, identifying the set of M nulled frequency bins among the N frequency bins, and converting the set of M nulled frequency bins to corresponding information bits.

Abstract: A process for distributing digital audio sequences according to a nominal flux format including a succession of fields, each of which includes at least one digital block clusterizing a selected number of coefficients corresponding to single audio elements that are digitally coded inside the flux and utilized by audio decoders that are able to play it to be able to decode it correctly, including a preparatory step including modifying at least one of the coefficients, and a transmission step including a primary flux in compliance with a nominal format including blocks that were modified during the preparatory step and by a route separated from the primary flux by an additional piece of digital information which allows reconstruction of the original flux starting with a calculation, on recipient equipment, as a function of the primary flux and of the additional information.

Abstract: A computer implemented method for recovering a partition context in the event of a system or hardware device failure. Upon receiving a command from a partition to modify context data in a trusted platform module (TPM) hardware device, a trusted platform module input/output host partition (TMPIOP) provides an encrypted copy of the context data and the command to the TPM hardware device, which processes the command and updates the context data. If the TPM hardware device successfully processes the command, the TMPIOP receives the updated context data from the TPM hardware device and stores the updated context data received in encrypted form in a context data cache or a non-volatile storage off-board the TPM hardware device. If the TPM hardware device fails to successfully process the command, the TMPIOP uses a last valid copy of the context data to retry processing of the command on a different TPM hardware device.

Abstract: A process for distributing digital video sequences in accordance with a nominal stream format including a succession of frames, each frame including at least one digital block regrouping a plurality of coefficients corresponding to simple, digitally coded visual elements is disclosed.

Abstract: A time domain communications system wherein a broadband of time-spaced signals, essentially monocycle-like signals, are derived from applying stepped-in-amplitude signals to a broadband antenna, in this case, a reverse bicone antenna. When received, the thus transmitted signals are multiplied by a D.C. replica of each transmitted signal, and thereafter, they are, successively, short time and long time integrated to achieve detection.

Abstract: An apparatus and method for high speed transmission of data over a transmission line/medium/network telephone, wherein this high speed is achieved by simultaneously, or in a timed and marked relationship, transmitting multiple bits of data over parallel frequencies rather than serially transmitting one bit of data at a time over one frequency.

Abstract: A first endpoint generates an acoustic spread spectrum signal including a pilot sequence and a data sequence representing a token synchronized to the pilot sequence, transmits the acoustic spread spectrum signal, and records a transmit time at which the acoustic spread spectrum signal is transmitted. A receive time at which a second endpoint received the acoustic spread spectrum signal transmitted by the first endpoint is received from the second endpoint along with an indication of a second token as recovered from the received acoustic spread spectrum signal by the second endpoint. A separation distance between the first endpoint and the second endpoint is computed based on a time difference between the transmit time and the receive time. The first endpoint is paired with the second endpoint when the token matches the second token and the computed distance is less than a threshold distance.