Abstract: To provide a digital modulator including: a signal adjuster (105) which is provided with a plurality of output lines, and which outputs, to the output line, which corresponds to a range to which a level of an input signal belongs, a signal of a level corresponding to the level of the input signal; a plurality of internal digital modulators (111-1 to 111-N), each of which is provided so as to correspond to each of the plurality of output lines and carries out delta-sigma modulation on the signal of the corresponding output line to output the modulated signal; and an encoder (113) which encodes the plurality of modulated signals respectively outputted by the plurality of internal digital modulators.

Abstract: The present disclosure relates to the field of pulse compression in signal processing, and more particularly, to systems and methods for the synthesis of waveforms for suppressing sidelobes and sidebands using a combination of time and spectral control. More specifically, the present disclosure relates to a set of waveform symbols which can be used to maximize use of disaggregated grey-space spectrum, adapt to changing spectral condition, and maintain or enhance data rates relative to standard binary phase-shift keying (BPSK) under normal conditions.

Abstract: A receiver for decoding a communication signal is disclosed. The receiver includes an input port and a filter. The input port receives the communication signal from a communication medium. The communication signal comprises a sequence of symbols. Each symbol of the symbol sequence is an analog pulse that has a leading edge of exponential shape. The exponential shape has an exponential growth parameter value that has been selected from values ?0 and ?1, which are distinct positive values. For each symbol of the symbol sequence, the exponential growth parameter value for the leading edge of the symbol has been selected based on a corresponding bit from a stream of information bits. The filter receives the communication signal from the input port and filters the communication signal to obtain an output signal. The transfer function of the filter has one or more zeros at ?0.

Abstract: In described embodiments, data streams with irregular patterns are processed by transformations defined by recursively changing processor state, or iteration level. The data transformations are applied to an arbitrary long portion of data, instead of small portions, that are defined directly by a current processor state. Embodiments combine small parts of, for example, puncturing/repetition patterns into a pattern of bigger parts and apply these patterns of bigger parts to relatively large portions of input data.

Abstract: Embodiments of this invention describe a method to reduce the effective inter carrier spacing between the sub-carriers of wireless, wired or optical transmissions and thereby increase the spectral efficiency of the communication system. Signal transmitted from multiple transmit chains are shifted in frequency at the transmitter. At the receiver a plurality of receive chains is used, the received signals are similarly shifted in frequency and used to reduce the inter carrier interference. Embodiments also describe a method for Full Duplex communication where the transmitters transmit using different frequency shifts. The receiver receives the transmitted signal and an echo of it's transmission. As the received transmission is shifted in frequency from it's transmission, it can cancel out the echo and receive the intended signal.

Abstract: Low latency and computationally efficient techniques may be employed to account for errors in data such as low bit-width, oversampled data. In some aspects these techniques may be employed to mitigate audio artifacts associated with sigma-delta modulated audio data. In some aspects an error may be detected in a set of encoded data based on an outcome of a channel decoding process. Upon determining that a set of data may contain at least one error, the set of data may be replaced with another set of data that is based on one or more neighboring data sets. For example, in some aspects a set of data including at least one bit in error may be replaced with data that is generated by applying a cross-fading operation to neighboring data sets. In some aspects a given data bit may be flipped as a result of a linear prediction operation that is applied to PCM equivalent data that is associated with the given data bit and its neighboring data bits.

Abstract: A method of estimating a level of severity of a network fault is provided. Performance parameters are monitored on upstream and downstream links to terminal network elements on a network to detect potential network faults. An alarm is raised with respect to a potential network fault automatically if at least one of the performance parameters as monitored crosses a preset threshold. After an alarm is raised, a level of severity is assigned to the alarm based on pre and post forward error correction (FEC) bit error rates (BER). In addition, the total number of terminal network elements that are impacted by the network fault is estimated and, when multiple alarms are raised of an equal level of severity, a higher priority is placed upon an alarm that affects service to a greatest number of terminal network elements.

Abstract: A first transmitter transmits symbols. The leading edge of each symbol has the form Djexp{?jt}, where Dj is real, where ?j is selected from N possible values based on a current group of bits. The receiver has N filters whose transfer functions correspond respectively to the N possible values. The filter outputs are used to recover the group of bits. A second transmitter transmits an exponential symbol or a zero symbol depending on a current bit to be transmitted. The zero symbol has zero amplitude over the symbol period. The corresponding receiver applies threshold detection to estimate the transmitted bits. A third transmitter transmits a sequence of analog pulses with known interpulse time separation(s). The pulse sequence reflects from a moving object. A receiver captures the reflected pulse sequence. The interpulse separation(s) of the reflect pulse sequence is used to determine the radial velocity of the object.

Abstract: A signal processing method for enhancing the dynamic range of a signal is disclosed. The method comprises: a) forming an attenuated signal from an input signal; b) filtering each of the input and the attenuated signals such that the sum of their bandwidths is less than or equal to the bandwidth of a transmission channel; c) modulating a first one of the filtered input signal and the filtered attenuated signal, whereby the filtered input signal and the filtered attenuated signal occupy respective non-overlapping frequency ranges within the bandwidth of the transmission channel; and d) combining the modulated signal with the second one of the filtered input signal and the filtered attenuated signal to form a composite output signal.

Abstract: Systems and methods of data transmission are disclosed. In an embodiment, at least two transmitters are selectively activated and at least one transmitter is deactivated at a serial interface to transmit data via at least two distinct lines.

Abstract: Some of the example embodiments presented herein are directed towards an eNodeB (401), and corresponding method therein, for providing data transmission in a multiple antenna system. The eNodeB (401) may be configured to receive a plurality of signal quality assessments and a CSI report from a user equipment. Based on the received data the eNodeB (401) may determine a received power difference between the received data. The eNodeB (401) may further determine a beamforming direction for subsequent data transmissions. Based on the power difference, the eNodeB (401) may account for the received power difference in the subsequent data transmissions, thus improving data communications towards the user equipment.

Abstract: A method and apparatus for processing feedback implemented in a wireless transmit/receive unit (WTRU) comprises estimating a channel matrix. The effective channel is calculated and a precoding matrix is selected. Feedback bits are generated and transmitted.

Abstract: A signal coding technique for switching amplifiers includes quantizing the amplitude A(t) of an input signal to produce a time series Â(t) having M levels; modulating a clock signal in response to Â(t), thereby to produce a control signal; switching among at least three different power supply output levels in response to the control signal, thereby to generate an output pulse stream; and filtering the output pulse stream to produce an output signal for transmission.

Abstract: A video transmission device 10 has: a packer 11 which receives a video signal, a sync signal, and a data-enable signal, and generates a plurality of packet signals by packetizing the video signal and the sync signal based on the data-enable signal and according to the number of bytes of a packet corresponding to the number of gradation bits of the video signal; an encode unit 15 which generates a plurality of encoded packet signals by encoding the plurality of packet signals; and a serializer 14 which generates a serial packet signal by parallel-serial converting the plurality of encoded packet signals. The packer 11 generates a control signal including a pulse with a pulse width corresponding to the number of bytes of the packet, and the encode unit 15 subjects a portion of the packet signals corresponding to the pulse in the control signal from the packer, to an encode process which is different from a process for the other portion.

Abstract: A transmitter (TX) for transmitting a pulse density modulated signal comprises means (SDM) for generating a pulse density modulated input signal (SI) and an encoder (ENC). The encoder (ENC) comprises a first input for receiving the pulse density modulated input signal (SI) and a second input for receiving additional information (AI) comprising at least one data bit. The encoder (ENC) is configured to generate a multi-bit telegram (TG) on the basis of the additional information (AI), the telegram (TG) comprising a predefined bit-sequence, and to replace an appropriate number of consecutive bits of the input signal (SI) with the telegram (TG) in order to generate an output signal (SO).

Abstract: A decoder pipeline may include a decoding (prior to deblocking) stage followed by a deblocking stage. A memory can be coupled to the decoder pipeline. A decoded first macroblock can be output from the decoding stage directly into the deblocking stage, bypassing the memory, if a decoded second macroblock depended on to deblock the first macroblock is already deblocked. Otherwise, the decoded first macroblock is stored in the memory until the second macroblock is deblocked and available to deblock the first macroblock.

Abstract: Techniques are provided for a demodulation and decoding method and apparatus for a given user equipment device to receive a one or more Orthogonal Frequency Division Multiplex (OFDM) symbols over a control channel, where the OFDM symbols comprise a plurality of resource element groups distributed in time and frequency that are combined to form control channel elements. Those resource element groups that form specific control channel elements for the user equipment device and those resource element groups that form common control channel elements for one or more user equipment devices including the given user equipment device are identified. The resource element groups that form the specific control channel elements and the resource element groups that form the common control channel elements are demodulated to generate encoded control messages comprising one or more control channel elements.

Abstract: Methods and systems for detecting a preamble of a data packet in wireless communication systems is provided. To determine a preamble from a received signal, which may include a noise-altered preamble bit sequence, linear feedback shift registers (LFSRs) can be used to generate a count of the received preamble, and the count is compared to pre-generated scores to identify a match. Example methods include for each of a number of different preamble orientations of a preamble, generating a count value based on a comparison of bits of the preamble with a random bit sequence to produce a sequence of count values, and comparing the sequence of count values with m sequences of count values. A sequence of count values is identified that includes a maximum number of matching elements, and the received preamble is determined to be one of the m preambles corresponding to the identified sequence.

Abstract: A system, medium, and method compressing and/or restoring images. Such a data compression method may include selecting a mode from among a plurality of modes for compressing current data, according to predetermined criteria, and calculating a difference between the current data and reference data, according to the selected mode, and compressing the current data, or truncating a part of the current data and compressing the current data. Accordingly, it is possible to significantly lower the complexity of an image encoder/decoder system and exactly meet a picture-based CBR required by LCD DCC devices/systems.

Abstract: A video transmission method is provided, which includes receiving state information from at least one mobile terminal that intends to perform a video stream service through a wireless network, determining a size of an image by selecting a specified spatial layer bit stream on the basis of the state information of the mobile terminal from a plurality of spatial layer bit streams generated at different bit rates during encoding of the bit stream, selecting a specified time and an SNR layer bit stream by increasing or decreasing time of the image and a layer position of the SNR layer bit stream on the basis of network parameters included in the state information of the mobile terminal, and transmitting the bit stream generated by extracting the specified layer bit stream of the selected layer to the mobile terminal.

Abstract: Wireless communication is ubiquitous today and deployments are growing rapidly leading to increased interference, increasing conflicts, etc. As a result monitoring the wireless environment is increasingly important for regulators, service providers, Government agencies, enterprises etc. Such monitoring should be flexible in terms of the networks being monitored within the wireless environment but should also provide real-time monitoring to detect unauthorized transmitters, provide dynamic network management, etc. Accordingly, based upon embodiments of the invention, a broadband, real-time signal analyzer (RTSA) circuit that allows for the deployment of RTSA devices in a distributed environment wherein determination of policy breaches, network performance, regulatory compliance, etc. are locally determined and exploited directly in network management or communicated to the central server and network administrators for subsequent action.

Abstract: Method and arrangement for use in a receiving node, for determining whether received data is encoded with a certain channel code candidate. The method involves obtaining baseband data encoded with an unknown channel code and calculating the respective posterior probabilities that a set of syndrome checks are satisfied, given the obtained data, which syndrome checks are associated with the channel code candidate. The method further involves combining the posterior probabilities and determining whether the channel code candidate was used for encoding the obtained data, based on the combined posterior probabilities.

Abstract: A method for quantizing prediction memory during fast recovery coding is disclosed. A best shape vector that describes prediction memory for a current frame is quantized. It is determined whether to send the quantized best shape vector. The quantized best shape vector is sent based on the determination. An encoded current frame is sent.

Abstract: A pulse signal receiving apparatus may include a reception unit that receives a pulse signal modulated by a double-edge modulation scheme, a measurement unit that measures an edge interval of the pulse signal, which has been received by the reception unit, a detection unit that detects a deviation of the edge interval, which has been measured by the measurement unit, for a pulse-width reference value indicating a reference value of a width of the pulse signal, a correction unit that corrects the edge interval, which is to be measured next by the measurement unit, by using the deviation, which has been detected by the detection unit, and a decoding unit that decodes the pulse signal, of which the edge interval has been corrected by the correction unit, so as to output a digital signal.

Abstract: Disclosed are a filter and a method to improve the objective and subjective video coding performance The filter comprises: a parameter estimation unit configured to determine means and variances from a pilot frame; a filter unit configured to receive quantized residual coefficients in video coding process and restore coefficients from the quantized residual coefficients and the determined means and variances; an inverse ICT unit configured to apply an inverse ICT to the restored coefficients to obtain a filtered frame; a rate-distortion optimization unit configured to determine a quadtree block partition index; and an adaptive block selection unit configured to select final blocks according to quadtree block partition index, the final blocks being utilized to form the filtered frame.

Abstract: Systems and methods for the pulse edge modulation of digital carrier signals for communications systems. A digital carrier signal is generated and the carrier is pulse edge modulated with digital data. A pulse edge modulated signal is generated by either retarding or advancing each pulse edge of a carrier to be modulated relative to its original position in time, depending on the state of the digital bit to be modulated on that edge.

Abstract: A soft decision threshold control system and method may be used with a forward error correction (FEC) scheme to adjust or tune one or more soft decision thresholds in response to one or more bit value averages for the threshold(s) and in response to a bit error rate (BER). The bit value average for a soft decision threshold generally refers to an average number of binary values (e.g., logic ones and/or zeros) occurring in a bit stream detected using the soft decision threshold. For different BER levels in a particular system, for example, one or more of the soft decision thresholds may have a predetermined bit value average, which has been determined to provide a certain level of performance (e.g., an optimum performance). Thus, one or more of the soft decision thresholds may be adjusted such that the bit value averages for the soft decision thresholds are adjusted as a function of the BER.

Abstract: A data modulation circuit has an adder adding an input signal, and an output signal of a memory device; and an output circuit part discriminating and quantizing the output signal of the adder by a predetermined threshold value. The memory device receives and holds the output signal of the adder and a predetermined signal, and supplies the held signals to the adder as an output signal of the memory device.

Abstract: A method and an apparatus for playout scheduling in a Voice over Internet Protocol (VoIP) system are provided. The method includes acquiring Pulse Code Modulation (PCM) samples by decoding a received packet; setting a first scale ratio according to a length of PCM samples stored in a playout buffer based on a preset scale ratio table; setting a second scale ratio by predicting a packet delay; setting a final scale ratio using the first scale ratio and the second scale ratio; and adjusting the length of the acquired PCM samples at the final scale ratio.

Abstract: Systems and methods for processing and decoding TCM/BCM-coded signal vectors. A multi-dimensional signal vector is received by, for example, a TCM or BCM decoder. The TCM/BCM decoder identifies the closest signal points in the signal constellation set, or “nearest neighbors,” for each dimension of the received signal vector. The TCM/BCM decoder then forms a test set that includes a plurality of multi-dimensional test vectors, where each dimension of each test vector is based on an identified nearest neighbor. In particular, each test point in the test set is based on a different combination of the nearest neighbors. The TCM/BCM decoder can compute branch metrics based on only the test points in the test set, and can make detection decisions using the computed branch metrics.

Abstract: A device includes a zero symbol rate (ZSR) coding/modulation module and a second type coding/modulation module. Both modules generate modulation symbols to be conveyed using the same air link resources but with the non-zero ZSR symbols having a higher power level. The ZSR module generates a mixture of zero and non-zero modulation symbols. A ZSR modulation scheme communicates information using both the position of the non-zero modulation symbols and the phase and/or amplitude of the non-zero modulation symbols. Different ZSR schemes, implementing different ratios relating the number of zero symbols to the total number of symbols, can be associated with different low data rates while second module modulation schemes can be associated with different high data rates. Modulation symbols from two modules are in some embodiments, superimposed. In some embodiments, non-zero ZSR modulation symbols punch out second module modulation symbols which occupy the same air link resource.

Abstract: A frame formed of a plurality of code words encoded with an encoding mode in which two different types of code words are assigned one-to-one to two smallest quantization intervals is checked to determine whether it contains just the two types of code words assigned to the two smallest quantization intervals, and lossless encoding is applied to the frame containing just the two types of code words. A code obtained by this lossless encoding is decoded with a decoding method corresponding to the lossless encoding.

Abstract: The invention concerns an ultra-wideband information transmission method comprising a first encoding step on the part of the transmitter, in which a pulse group which is formed from a predetermined number of individual pulses is encoded in dependence on values of a random number sequence, and a correlation step on the part of the receiver in which correlation of a reception signal with a signal pattern is effected, wherein the signal pattern corresponds to the whole pulse group to be expected when using the same values of the random number sequence.

Abstract: A system and method adds and manages entries on a list of entries of routing information to allow the top entry to be used for routing to a destination corresponding to the list. Costs of a wireless link may be a function of the success rate experienced on that wireless link.

Abstract: An apparatus and method for transmitting and recovering encoded data streams across Physical Medium Attachments (PMA) are provided. The data stream includes a plurality of data blocks. The method of transmitting includes tagging at least some of the plurality of data blocks in the data stream. The method also includes splitting the data stream into first and second lanes of data blocks. The method further includes transmitting the first lane of data blocks to a first PMA and the second lane of data blocks to a second PMA.

Abstract: The present invention relates to network coding and discloses a method, an apparatus, and a system for random linear network coding to prevent the complicated and time-consuming process of network coding. The coding method for random linear network includes: splitting original data into at least two data blocks sequentially; determining at least two coefficient groups, wherein a length of each coefficient group is the same as the number of the data blocks, and the coefficient group comprises two elements; performing a bitwise-AND operation on the data blocks and coefficients corresponding to the data blocks to obtain code blocks; and performing a bitwise-XOR operation between the code blocks to obtain a code packet. The present invention is applicable to the network coding which requires a high efficiency of coding.

Abstract: Speech frames of a first speech coding scheme are utilized as speech frames of a second speech coding scheme, where the speech coding schemes use similar core compression schemes for the speech frames, preferably bit stream compatible. An occurrence of a state mismatch in an energy parameter between the first speech coding scheme and the second speech coding scheme is identified, preferably either by determining an occurrence of a predetermined speech evolution, such as a speech type transition, e.g. an onset of speech following a period of speech inactivity, or by tentative decoding of the energy parameter in the two encoding schemes followed by a comparison. Subsequently, the energy parameter in at least one frame of the second speech coding scheme following the occurrence of the state mismatch is adjusted. The present invention also presents transcoders and communications systems providing such transcoding functionality.

Abstract: Techniques for sending signaling information using hierarchical coding are described. With hierarchical coding, individual messages for users are encoded using multiple interconnected encoders such that (1) the message for each user is sent at a data rate suitable for that user and (2) a single multicast message is generated for the messages for all users. A base station determines data rates supported by the users and the code rates to achieve these data rates. Each data rate is determined by one or more code rates. Signaling information for the users is mapped to data blocks to be sent at different data rates. Each data block is then encoded in accordance with the code rate(s) associated with the data rate for that data block. A final coded block is generated for all users and transmitted. Each user performs the complementary decoding to recover the message sent to that user.

Abstract: A method and apparatus to encode and decode an audio/speech signal is provided. An inputted audio signal or speech signal may be transformed into at least one of a high frequency resolution signal and a high temporal resolution signal. The signal may be encoded by determining an appropriate resolution, the encoded signal may be decoded, and thus the audio signal, the speech signal, and a mixed signal of the audio signal and the speech signal may be processed.

Abstract: Systems and methods for detecting device failures in a network having nodes coupled to a central controller, in which a first of the nodes communicates with the central controller via a second of the nodes. When the second node determines that the first node has not transmitted a predetermined number of messages over a predefined number of time periods, the second node provides a failure alert to the central controller. The central controller records a failure alert received from the second node in a log. Based on a set of failure alerts received from a number of nodes recorded in the log, the central controller determines whether the first node has failed.

Abstract: A communication apparatus may include a demodulation unit, a waveform memory unit, a decoding unit, an encoding unit, a modulation unit, and a transmission unit. The demodulation unit demodulates a received signal to create a demodulated signal. The waveform memory unit stores the demodulated signal and a waveform of the demodulated signal. The decoding unit decodes the demodulated signal to create a decoded signal. The encoding unit encodes the decoded signal to create an encoded signal. The modulation unit modulates one of the encoded signal to create a modulated encoded signal and the demodulated signal to create a modulated demodulated signal. The transmission unit transmit one of the modulated encoded signal and the modulated demodulated signal according to a reception state of the received signal.

Abstract: A system and method are provided for calibrating the IQ-imbalance in a low-IF receiver. A Test Signal can be generated in a mirror frequency and conveyed to the receiver. The power of the signal produced in the receiver from the conveyed Test Signal can be measured. In the absence of an IQ-imbalance, the Test Signal can be completely eliminated in the receiver and the corresponding measured power of the produced signal can be minimized. Accordingly, a two dimensional algorithm is described for calibrating a receiver and correcting the IQ-imbalance by adjusting the phase and gain difference between the I and Q channels in the receiver based on the measured power of the signal produced in the receiver.

Abstract: The present invention relates to data processing techniques in multi-channel data transmission systems. In this invention, a method to efficiently deal with FEXT is proposed and a circuit architecture to implement the proposed MIMO-THP equalizer is developed for the application of high/ultra-high speed Ethernet systems. The proposed method relies on the fact that FEXT inherently contains information about the symbols transmitted from the far end transmitters and it can be viewed as a signal rather than noise. Compared with the traditional FEXT cancellation approaches, the proposed design inherits both advantages of MIMO equalization technique and TH precoding technique, thus having better performance. Unlike the existing MIMO-THP technology, the proposed design completely removes the feedback loops in the existing MIMO-THP architecture. Therefore, pipelining techniques can be easily applied to obtain a high-speed design of a multi-channel DSP transceiver.

Abstract: Techniques, apparatuses and systems for providing communications based on time reversal of a channel impulse response of a pulse in a transmission channel between a transmitter and a receiver to enhance reception and detection of a pulse at the receiver against various effects that can adversely affect and complicate the reception and detection of the pulse at the receiver.

Abstract: Systems and methods of securely updating BIOS are disclosed. One such system comprises a reprogrammable memory, a first and a second register, and comparison logic. The reprogrammable memory comprises a first portion and a protect input. The protect input is configured to disallow writes to at least the first portion when the memory protect input is at a first level, and to allow writes to at least the first portion when the protect input is at a second level; The comparison logic is configured to drive a comparison output to a third level responsive to the first and second registers having equal values, and to drive the comparison output to a fourth level responsive to the first and second registers having different values. The comparison output is electrically coupled to the memory protect input.

Abstract: A method for adjusting a system clock in terms of an operational status of at least one non-baseband module includes: getting first information corresponding to the system clock required by at least one baseband module, wherein the first information comprises a frequency characteristic of the system clock; getting second information corresponding to the at least one non-baseband module, wherein the second information comprises a frequency characteristic of a radio frequency (RF) signal to be received by the non-baseband module; and selectively adjusting a frequency of the system clock by referring to the first information and the second information.

Abstract: A serializer is equipped with a plurality of input terminals into which a plurality of binary signals are input in parallel, and converts the plurality of input binary signals into serial binary signals and transmits the serial binary signals to an optical transmission module. One input terminal out of the plurality of input terminals is assigned as an input terminal for preventing bit continuation by inserting “1” signals or “0” signals into the serial binary signals so that a predetermined number of bits of the same value may not be inserted continuously. Due to this structure, bit continuation can be prevented even for a signal generating source with no coding function by a simple configuration without increasing cost and size.

Abstract: The present invention relates to information processing technologies and discloses an encoding and decoding method and device to solve the poor decoding quality problem. The technical solution of the present invention includes: encoding each sample of an input signal to generate an encoded signal of a core layer; comparing residuals of all or a part of the samples of the input signal with encoding thresholds, where the residuals are generated by core layer encoding, and performing encoding according to comparison results to generate an encoded signal of an enhancement layer; and writing the encoded signal of the core layer and the encoded signal of the enhancement layer into a bitstream to generate an encoded signal of the input signal.

Abstract: A method for generating an UWB pulses based on LC oscillator topology. Fast turn on of the oscillator is achieved by creating large asymmetry in a normally symmetrical topology which is used in a typical differential type oscillator. One method for achieving large asymmetry is activating one branch of a differential pair of branches for a short duration before activating both branches in a normal operation. The bandwidth of the pulse is controlled by modifying the duration of the oscillator activation. Fast turn on and turn off is essential for high bandwidth generation. The method is adaptable for generating binary phase shift keying (BPSK) modulation. Selecting the activated branch of a fully symmetrical topology controls the output phase and creates two possibilities which differ exactly by 180 degrees. In a preferred embodiment, all the pulse generator components are on-clip leading to a low cost solution. The circuit can generate high power pulses directly on a load.

Abstract: A signal for use on a wired network interconnecting electronic devices, comprising: a base voltage for conveying power to the electronic devices; a pulsed voltage signal bearing coded information for transfer between the electronic devices; and a digital signal superimposed onto selected portions of the pulsed voltage signal, wherein the digital signal comprises a carrier signal modulated by a data signal for transfer between the electronic devices. This is used in fire alarm networks, for example, to convey multimedia or other data such as control signals, whilst maintaining compatibility with existing protocols using the pulsed voltage signal.