Abstract: A system and method for dynamically altering detection criterion value at a receiving device based on the portion of a call signal being received. A receiving device is configured to extract a first call signal portion from the call signal, and compare the first call signal portion to a plurality of call information portions, wherein each call information portion has a detection criterion value. If the first call signal portion matches one of the call information portions, the receiving device adjusts the detection criterion value for at least one of the plurality of call information portions, extracts a second call signal portion from the call signal, and compares the second call signal portion to the plurality of call information portions.

Abstract: The present invention relates to a method for measuring radio channel quality in a radio communication system. In the method a modulated signal is received over a communication channel. The modulated signal has been modulated by using modulation parameters. A decoder decodes (305) the modulated signal and forms decoded data. The decoder creates (306) a decoder performance indicator (PS) that depends on the decoded data. Then a radio channel quality indicator (RCQI) is created, the radio channel quality indicator being essentially independent of the modulation parameters.

Abstract: A MODEM device includes a detector configured to detect a synchronization signal transmitted from a source MODEM in a resynchronization process of a primary channel and a timer configured to count up starting from a beginning of a detection of the synchronization signal, and send information to forcibly move into a receiving mode for receiving image data when a time period from the beginning to a completion of the detection of the synchronization signal exceeds a predetermined time period.

Abstract: A method is provided for frequency acquisition, particularly for initial frequency acquisition, pursuant to a known synchronization sequence for synchronizing a mobile communications device having a local oscillator with previously known transmit frequencies of a base station that transmit in a known channel raster with defined frequency points within a band, wherein the method includes the steps of determining the inband power of the known synchronization sequence via a sensor by scanning a frequency band, performing coarse determination of the local power maximum of the inband power and, thus, of the received carrier frequency over the scanned frequency band, producing a presumed channel frequency at which the base station is transmitting on the basis of knowledge of the channel raster of the transmit frequencies of the base station, performing fine determination of the received carrier frequency by comparison with the known synchronization sequence, and correcting the frequency deviation of the local oscil

Abstract: Receivers (1) for receiving frequency signals are, to improve their time synchronization accuracy, provided with synchronization stages (20) for performing a coarse time synchronization through autocorrelating samples of a group of preamble symbols (t1,t2,t3) and a fine time synchronization through crosscorrelating samples of a further group of preamble symbols (t10,G1) with predefined samples. The synchronization stages (20) also perform a coarse and a fine frequency synchronization through detecting and accumulating phases of samples of a yet further group of preamble symbols (t8,t9) and of another group of preamble symbols (T1,T2). The synchronization stages (20) have buffering units (21) and controlling units (22) for controlling mixing units (11) and transformating units (12) in processing stages (10). The preamble symbols have ten short preamble symbols (t1-t10), a guard interval preamble symbol (G 1) and two training symbols (T 1,T2).

Abstract: A composite signal includes a high power beacon signal and low power corresponding wideband synchronization signal and is communicated over a time interval exceeding a single OFDM transmission time interval. A base station transmits one or more different such composite broadcast signals in a recurring timing structure. Each different potential beacon signal, e.g., a single tone signal, is paired with a unique wideband synchronization signal. A wideband synchronization signal includes at least some predetermined null tones and at least some predetermined non-null tones. For a given wideband synchronization signal, the predetermined null tones carry predetermined modulation symbol values, A wireless terminal receives a composite signal, identifies a beacon, determines a corresponding known wideband synchronization signal, compares received to known wideband synchronization signals, and determines at least one of a timing adjustment, frequency adjustment and channel estimation.

Abstract: Synchronization techniques for reducing the effects of time dispersive wireless communications channels are presented. A synchronization technique for communications over a time dispersive wireless channel includes receiving a signal having at least identical first and second symbols, and calculating a metric for each sampling time by correlating respective samples of the first symbol included in a first sampling window with respective samples of the second symbol included in a second sampling window. The technique further includes identifying one of the sampling times at which the metric attains a maximum value, and estimating an optimal time offset for synchronizing to the received signal based on the identified sampling time. Optionally, the technique further includes estimating a carrier frequency offset based on the difference of phase of the complex conjugate samples at the maximum absolute value of the metric.

Abstract: Methods and apparatuses for dynamically adjusting sync windows are described. A default sync window is set; a data signal is input; detecting if parts of the data signal within the sync window form a sync pattern; accumulating a count of the sync pattern within and without the sync window; and reducing the sync window when the count of sync pattern within the sync window achieves a first threshold value, and increasing the sync window when the count of the sync pattern outside the sync window achieves a second threshold value.

Abstract: A communications network and method thereof include a base station controller configured to provide a repetition period of a primary synchronization channel to be equal to a predetermined integer value times a scrambling code length of the scrambling code of a common pilot channel. A user equipment in the network is configured to search for a known sequence comprising the primary synchronization channel to select a cell and a corresponding sub-frame/symbol timing from the selected cell.

Abstract: An orthogonal frequency division multiplex signal and a digital modulation signal or an analog modulation signal can be identified by blind processing. The modulation mode identifying apparatus comprises: a correlation signal generating circuit which generates a duplicate signal for correlation processing based on an unknown communication signal; an autocorrelation circuit which performs autocorrelation processing through carrying out sliding processing on the duplicate signal with respect to the unknown communication signal; a detection unit which detects information regarding a pilot symbol and a guide interval symbol of the communication signal based on a correlation value output obtained by the autocorrelation processing; and an identifying circuit which identifies a modulation mode of the unknown communication signal based on the information regarding the pilot symbol and the guide interval symbol of the communication signal.

Abstract: A method for synchronizing on a pulsed waveform sequence including pulsed waveforms. An impulse radio receiver is provided including a radio frequency (RF) front end connected to a demodulator, and the demodulator is connected to a processing unit. Power is provided to at least a portion of an RF component such as the RF front end and/or the demodulator, during time windows sufficient for testing an hypothesis regarding timing of the pulsed waveforms. The powering is controlled by the processing unit. Preferably, testing the hypothesis includes accumulating a signal of the pulsed waveforms, correlating with the pulsed waveforms, or accumulating the correlation result of the pulsed waveforms. Preferably, others functions of the receiver are powered or enabled subsequent to the testing. Preferably, the impulse radio receiver is an ultra-wide band receiver.

Abstract: A synchronization extraction apparatus for a communication system and a method thereof are disclosed. A frame synchronization is obtained in a manner that the sum of an input signal and a delay signal is obtained without obtaining a simple correlation value between the input signal and the delay signal, and then a correlation value between a summed signal and the delay signal is obtained. The synchronization extraction apparatus and method can reduce the implementation complexity and power consumption in obtaining the frame synchronization, and thus increase the battery cycle of a terminal provided with the synchronization extraction apparatus or method.

Abstract: A method and system for transmitting signals between communication nodes is presented. The method includes generating a first waveform that includes a shaped portion; generating a second waveform that includes a shaped portion; and combining the first and second waveforms including overlapping the shaped portion of the first waveform with the shaped portion of the second waveform and adding the overlapped portions of the waveforms. The method includes generating a signal including the combined first and second waveforms. At least one of the first and second waveforms includes a characteristic signature configured for synchronizing with the signal.

Abstract: A synchronism pattern detecting timing recorder (20) records a synchronism pattern detecting timing at which a synchronism pattern is detected in reception data, a synchronism decider (12) collates the reception data with reference data to decide whether or not the reception data is consistent in phase with the reference data, and a timing generator (22) operates, when the synchronism decider (12) gives a decision for inconsistency in phase, for a match between the synchronism pattern detecting timing recorded in the synchronism pattern detecting timing recorder (20), as a subsequent one, and a timing of a synchronism pattern of the expectation data, and the subsequent synchronism pattern detecting timing in record is used to render the phases consistent, allowing for a rapid synchronization to be obtained, without the need of waiting a detection of synchronism pattern, even with an inconsistency in phase due to a false synchronism pattern.

Abstract: A communication system, clock generation circuit, and method are provided for receiving jitter upon data and to generate a clock reference that does not contain the received jitter. The clock reference can be used either by a digital subsystem of a communication system node, or can be transmitted as substantially jitter-free data from that node to a downstream node of the communication system. Instead of recovering the clock reference from the data having jitter, a pattern is regularly defined within the data stream preferably at periodic, timed intervals. The data pattern may be made up of a series of non-transitions which, regardless of any jitter in the data itself, does not impute any jitter onto a phase-locked loop triggered from an edge of the non-transitioning data pattern. Using the edge as a reference point, a jitter-free clocking signal can be derived at the same frequency as a clocking signal which would normally be produced from the jitter-induced data.

Abstract: A transmitter comprises a frequency utilization status detector configured to detect the utilization status of an allocated frequency band based on a received signal, a symbol placement determination unit configured to determine placement of pilot symbols based on the detected status of frequency utilization, and a symbol placement unit configured to place the pilot symbols according to the determined symbol placement.

Abstract: In case of disposing a pilot symbol in data transmission which depends on a DWMC transmission system, in a plurality of transmission symbols on a time axis, a pilot symbol, which becomes a signal of a sine wave, is configured, by giving contiguous identical data in a plurality of predetermined symbols. By transmitting a transmission signal with the use of this pilot signal, between a transmitting device and a receiving device, it is possible to carry out channel equalization by complex information which is obtained from a pilot symbol.

Abstract: Various embodiments are described to provide for the transmission and reception of data in an improved manner. Data transmission is improved by including in a transmitter a null generator (110) to generate an output data symbol sequence that exhibits nulls in the frequency domain at particular frequencies that an input data symbol sequence does not. A pilot inserter (120) then adds a pilot symbol sequence to this output data symbol sequence to create a combined symbol sequence. Since the pilot symbol sequence exhibits pilot signals corresponding to the nulls of the output data symbol sequence in the frequency domain, the combined symbol sequence exhibits pilots that are orthogonal to the data in the frequency domain.

Abstract: Described is a system and method for providing a synchronization pattern in a communication system. The method includes generating a synchronization pattern with good randomness properties; packing a signal for transmission with m headers, each header consisting of the synchronization pattern 1/m symbol-time shifted from the previous header; and transmitting the signal. A further method provides for the sampling the transmitted signal with m headers of symbol-time shifted synchronization patterns; and determining symbol timing offset by computing and reordering correlation peaks from the synchronization patterns. A system includes a transmitting system, a receiving system, and a data channel. The transmitted signal includes m headers with 1/m symbol-time shifted synchronization patterns. The receiving system undersamples the transmitted signal with m synchronization patterns to simulate an oversampled synchronization pattern.

Abstract: When data bursts are transmitted between a base station and a mobile receiver, a changeover is made between a plurality of modulation methods during an existing radio link for modulation of the data. For resynchronization of the receiver in the event of the changeover, synchronization information items are determined from a first part (ET) of the data burst modulated by a first modulation method, and are used for synchronization with a second part (ZT) of the data burst modulated by the second modulation method.

Abstract: A DSRC communication technology that prevents unique word detection errors even when the frame changes in data reception and the timing of the unique word detection window and the timing of the received data do not match, and that adjusts the data transmission timing in a flexible fashion when the slot timing deviates from the frame timing. In this technology, bit counter 111 generates the frame timing from the frame synchronization signal, and bit counter 112 generates the sot timing in response to the slot synchronization signal. The unique word detection window is generated from the frame timing and the received data operation timing and the data reception timing are generated from the slot timing. In addition, the data transmission timing and the transmission data operation timing are generated based on one of the frame timing and the slot timing chosen in selector 123.

Abstract: A novel and useful acquisition and synchronization mechanism for spread spectrum communication systems whereby a synchronization sequence comprising a plurality of known symbols spaced apart by predefined time delay intervals is transmitted as the start of packet signal. At the transmitter, a synchronization sequence is transmitted at the beginning of each packet. A synchronization sequence is generated which includes a plurality of symbols with predefined time gaps between each of the symbols. Multiple synchronization sequences may be generated wherein each sequence comprises a unique set of time delays or gaps between each of the symbols. Each set of unique time delays or gaps between symbols of a sequence is stored as a synchronization sequence gap template in memory.

Abstract: A method provides for an improved compensation Fourier channel characteristics in a wireless communication embodiment. The method identifies one or more information carriers as pseudo pilot tones whose information may be realized to enhance the determination of the complex coefficient of the communication channel.

Abstract: In the synchronous compensator, a load generator loads a bit counter with data in dependence upon whether or not a detection signal from a UW detector falls within the range indicated by an enable signal from a synchronous compensator circuit, thereby excluding the detection signal appearing far from the normal position to establish an appropriate synchronous compensation. The synchronous compensation is thus accomplished on the basis of normally received signal waves without picking up abnormal waves supposed as reflected waves.

Abstract: A communications apparatus and method use tapped delay lines as multiplexers and demultiplexers. In one embodiment, a receiver (100) uses a tapped delay line (110) as a demultiplexer to acquire a burst communication at very high data rates in the range of 2.5 to 80 Gbps with low preamble overhead. A sliding window correlator (114) continually samples the delay line (110) to determine when a PN encoded word is contained therein. The transmission frequency is pre-acquired before any data is present through the use of a ring oscillator frequency calibration loop (130) that is imbedded within the tapped delay line (110).

Abstract: A packet stream multiplexer may include one or more control loops (e.g., digital phase locked loops) for tracking the source clock frequency associated with a packet stream. A first control loop may slowly drive an error between a received timestamp and an estimated timestamp to zero. A second control loop may more quickly drive a first derivative of the error to zero. The second control loop may include a set of digital filters ordered according to tracking speed. The output of the slowest filter is initially selected for updating the source clock frequency estimate. As time progresses, the faster filters are selected in succession. The estimated source clock frequency is used to restamp packets of the packet stream as they are sent out onto an output channel.

Abstract: Synchronization and impairment estimations can be performed jointly, thereby saving valuable time for decoding of the received packet. An initial synchronization in a TDMA system can be performed. Using this synchronization, the frequency offset choices and timing offset choices can be advantageously bounded within predetermined ranges. At this point, an algorithm can find the minimum error that gives the best frequency offset choice and timing offset choice combination over their respective ranges, together with the estimates of the signal magnitude and phase and at least one of a DC offset magnitude and phase, and a spur magnitude and phase.

Abstract: In a DSRC communications controller equipped with a plurality of reception means for DSRC communications according to the invention, a reception reservation storage section 104 comprises means for detecting a communications frame start signal (unique word 1) of DSRC communications by using reception means not engaged in communications among the plurality of reception means and means for storing the control information of DSRC communications where the communications frame start signal is detected. On completion of DSRC communications by way of reception means, a controller uses the control information stored in the reception reservation storage section to establish next communications. This allows continuous reception of information from a plurality of roadside machines to be made efficiently even in case a plurality of communications areas overlap one another.

Abstract: A master unit sends a start signal to a slave unit. When receiving the start signal from the master unit, the slave unit sends, to the master unit, a synchronization field that is a data train (pulse signal) indicative of a transfer clock with which the slave unit is able to perform transferring and receiving operations. The master unit sends, to the slave unit, command data in accordance with the transfer clock indicated by the synchronization field sent from the slave unit. In response to the command data sent from the master unit, the slave unit sends, to the master unit, response data in accordance with the transfer clock indicated by the synchronization field. Thus, in a communication system employing a serial data transferring apparatus of the present invention, the master unit establishes the synchronization for the data transfer, while the slave unit is free from a burden of establishing the synchronization for the data transfer.

Abstract: A method is for decoding a bit stream from a waveform representing the bit stream, having a first synchronization mark, data, and a second synchronization mark. Digitized samples are decoded to form a reconstructed bit stream. The reconstructed bit stream is then stored. At least one of the first synchronization mark and the second synchronization mark are then extracted from the reconstructed bit stream. Finally, the data are extracted from the reconstructed bit stream using an iterative decoding process, in accordance with at least one of the first synchronization mark and the second synchronization mark. As such, loss of the data between the first synchronization mark and the second synchronization mark, if there is a problem with the first synchronization mark, is avoided.

Abstract: A system receives input data frames that are configured according to a SONET or an SDH standard. The input data is converted to parallel data. The system provides groups of bits along parallel signal lines. In each group of bits, N contiguous bits in the group form a complete word of input data. The system identifies the boundary between complete words in the input data by comparing subsets of the bits to predefined framing patterns. The system then aligns the input data based on the location of each word using the boundary information. The output data of the system includes data that is word aligned. The system can also detect boundaries between the frames.

Abstract: A transmission control section 101 temporarily stores a transmission signal, outputs the stored transmission signal to a coding section 102 and outputs transmission timing information to a counter section 107. A preamble insertion section 104 inserts AGC preambles corresponding to the number set by a preamble number control section 110 into the transmission signal. The preamble number control section 110 compares a transmission time interval input from a subtraction section 109 with a threshold, decides to insert ten AGC preambles into the transmission signal when the transmission time interval is equal to or greater than the threshold and decides to insert five AGC preambles into the transmission signal when the transmission time interval is smaller than the threshold. By so doing, it is possible to make the transmission efficiency compatible with the error rate characteristic.

Abstract: In a digital protection relay with a time sync function, the sampling timing of which is specified based on a reference timing transmitted from a time signal generator to a time sync unit, with a determination value. The time sync unit includes a reception circuit that receives a discrimination code and time data transmitted from the time signal generator, a code discrimination circuit that discriminates the reference timing on condition that the received discrimination code coincides with a desired code, a time calculation circuit that calculates the sampling timing on the basis of the discriminated reference timing and the time data, and a sampling sync circuit that specifies the sampling timing of a digital quantity of electricity on the basis of the calculated sampling timing.

Abstract: A receiver device for a packet communication system receives a packet signal appended at its head with a known number (N) of repetition signals. A correlation value of a received signal is outputted from a normalizing correlator and compared with a threshold value in a comparator. The output of the comparator is inputted to a synchronization signal generating circuit, which includes M (?N?1) delay elements connected in series and an AND circuit for taking the logical product of the outputs of the delay elements. When the output of the comparator is high-level and the outputs of the M delay elements 431 are also all high-level, a synchronization signal at symbol timing is outputted from the AND circuit.

Abstract: A correlation between a received signal and a sync word signal is calculated. A window signal having a time span which is equal to an equalization range for an adaptive equalizer is defined. A power sum of the correlation output signal in each of window signals #1, #2, #3, . . . are calculated by sequentially shifting the window signal in the time domain, and a rising edge of the particular window signal whose power sum maximum defines a symbol sync timing.

Abstract: A system for accessing broadcast SMS messages over a wireless communication system. A base station transmits SMS messages periodically and aperiodically over a broadcast channel. The base station allocates periodic slots in the broadcast channel for each of the subscriber services providing the SMS messages and transmits slot parameters to mobile units. Using the slot parameter information, the mobile units periodically wake up to scan the broadcast channel. The period for each category of broadcast SMS messages may be different and the period may apply to a single broadcast channel. Messages arriving aperiodically can be queued and transmitted in pre-scheduled broadcast channel frames. Messages with inter-arrival interval greater than the specified transmission period are simply repeated.

Abstract: Systems and methods can provide, in one aspect, a method for modulating the pulse width of control signals generated on a plurality of separate channels. In one practice, the methods described herein are suitable for execution on a microprocessor or micro controller platform that includes a timer interrupt mechanism which will generate an interrupt in response to a timer counting down a selected time interval or time period. In one practice, the timer is set to count down a period of time that is representative of a portion, or sub period, of the PWM cycle. Upon expiration of that time period, the timer executes an interrupt that causes the micro controller to enter an interrupt service routine (ISR) that can further modulate the PWM cycle of one or more signals.

Abstract: A mobile wireless communications device and methods therefore, including receiving a signal (710), storing a portion of the received signal (730), identifying all possible pilot signals by determining slot boundary information for the stored signal portion (720), determining frame boundary information and/or scrambling code information (760) of the stored signal portion by correlating the stored signal portion with the scrambling codes based on the slot boundary information. In other embodiments, the search is performed in real-time without storing the signal.

Abstract: A sync mark detector identifies a sync mark in an incoming bitstream of a communications channel. A bit comparing circuit compares the sync mark bit-by-bit to the incoming bitstream if channel irregularities do not exist. A symbol comparing circuit compares the sync mark symbol-by-symbol to the incoming bitstream if channel irregularities do exist. The bit comparing circuit implements a bit level matching rule. The symbol comparing circuit implements a symbol level matching rule. The bit comparing circuit generates a sync mark found state when the bit level matching rule is satisfied. The symbol comparing circuit generates a sync mark found state when the symbol level matching rule is satisfied. Post coding such as NRZ, INRZI, or NRZI can be used.

Abstract: A method (and system) of finding byte synchronization over random data, which includes selecting a synchronization symbol maximizing the Hamming distance when slid over itself, and appending the synchronization symbol to random data.

Abstract: An apparatus and method for OFDM demodulation establish symbol synchronization to minimize between-symbol interference even under an environment where multipath occurs. An incoming signal is an OFDM signal including a transmission symbol structured by a valid symbol period and a guard interval, and a predetermined synchronization symbol is included in the OFDM signal for every transmission frame. A correlator calculates how a signal generated by a synchronization symbol generator and the OFDM signal are correlated. A correlation calculator then calculates a correlation therefrom. An integrator integrates the calculated correlation by the guard interval. A timing determination device determines symbol timing from the integrated correlation. An FFT window generator outputs operation timing for Fourier transform from the determined symbol timing.

Abstract: A system and method have been provided for programming synchronization features of a multidimensional digital frame structure. Such a frame structure acts as a digital wrapper, and includes overhead, payload, and forward error correction (FEC) sections. Words in the overhead section are used to synchronize the frame structure. The described invention permits the location of the frame synchronization bytes (FSBs) to be made programmable, so that the system and method are flexible for changes in communication protocols. This flexibility also impacts the number, the value, bandwidth, and the allowable bit error rate (BER) of the located FSBs.

Abstract: A method is disclosed for synchronizing a OFDM signal. The method includes receiving an OFDM signal including a plurality of long and short synchronization symbols, each comprising a plurality of points. The method includes correlating a predetermined number of points in a long symbol of the received OFDM signal against corresponding points in a reference symbol. A correlation peak is obtained between the received long symbol and the reference symbol, wherein the peak occurs at the time when the receiver has clock synchronization.

Abstract: A method and apparatus for time-shift extraction in a wideband transmitted signal containing strong narrowband interference or noise. The time-shift extraction is based on the time domain and frequency domain relation of symbol misalignment. The invention uses the sign of the product of a recieved signal sample and a reference symbol in the frequency domain to determine the time-shift. It does not rely on the signal magnitude and is therefore less dependent on the signal gain. It also does not rely on the soft phase values, which have ambiguity for values more than three hundred sixty (360) degrees.

Abstract: A method of optimizing the search for cells in a mobile telecommunication network comprising a plurality of cells, each cell accommodating one base station exchanging synchronization data with a mobile device UE via a channel SCH, so as to allow subscribers' mobile devices to perform measurements on at least one cell adjacent to the current cell for retrieving a scrambling code specific to the adjacent cell. The method has a step of applying a digital filtering to measurement samples collected in a plurality of time windows so as to give a major weight to measurements performed in the most recent time windows.

Abstract: Data transactions are partitioned to transfer data across a communication connection requiring naturally aligned data transfers of quad-words. It is determining from byte enable signals whether the bytes of the data to be transferred start in the high order dword or end in the low order dword of a quad-word. The transaction is separated into two transactions if the bytes of the data to be transferred start in the high order dword or end in the low order dword of a quad word. A second transaction is created by pre-appending if the bytes of the data to be transferred start in the high order dword. A second transaction is created by post-appending if the bytes of the data to be transferred end in the low order dword of a quad word.

Abstract: A signal processing circuit having a data sync signal detector and a disk device. Input data read from a magnetic disk is input to a data discriminator. A data discrimination output constituting a code bit output discriminated by the data discriminator is input to a post-coder the output of which is input to a decoder and a (1+D) processing unit. The processed output of the processing unit is input to an error detection/correction unit and separated into bit strings of odd numbered bits and even numbered bits, divided into groups. An error detection/correction output is input to a data sync signal detector, and matched against a sync pattern. When the number of coincident groups is greater than a threshold value, a sync signal is output and upon detection causes the decoder to demodulate the data.

Abstract: A network device configured to detect a framing pattern includes a data scanner and a frame detector. The data scanner examines parallel bytes of data and detects portions of a framing pattern in the parallel bytes of data, identifies the phase of the framing pattern and outputs alignment information and phase information when a framing pattern has been detected. The frame detector receives the alignment information and phase information and determines whether framing patterns having the same phase relationship have been detected within a predetermined number of frames.

Abstract: A method is provided for transmission of packets (102) as a sequence of data packets (104). A redundancy or check word (106) is composed for each packet of the sequence of data packets. A transmission packet is composed of a packet, a check word of a prior packet in the sequence of packets, and a check word of a subsequent packet in the sequence of packets. The transmission packets are transmitted in a sequence and received in a sequence. After reception, the transmission packets are separated so that the packets are compared with the corresponding check words transmitted with adjacent packets in the sequence.

Abstract: A digital signal detection system, method and computer program product, including (a) partitioning a digital signal into a plurality of frames; (b) calculating a number of zero crossings of the digital signal within each frame; (c) determining whether or not an absolute value of a difference of the number of zero crossings in between frames is less than a first predetermined value; (d) determining whether or not a sum of the zero crossings of the frames is greater than or equal to a second predetermined value and less than or equal to a third predetermined value; (e) calculating a maximum amplitude of the digital signal for each of the frames; (f) calculating an average amplitude of the digital signal for all of the frames; (g) determining whether or not an absolute value of a difference between the maximum amplitude of a frame and the average amplitude is less than a fourth predetermined value times the average amplitude for each of the frames; and (h) determining that a frame contains a narrowband digital s