Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00 Details of transmission systems not characterised by the medium used for transmission

HELECTRICITY H04Electric communication H04BTRANSMISSION

H04B1/00Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00 Details of transmission systems not characterised by the medium used for transmission

H04B1/0003Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware H04B1/0007wherein the AD/DA conversion occurs at radiofrequency or intermediate frequency stage H04B1/001Channel filtering H04B1/0014using DSP [Digital Signal Processor] quadrature modulation and demodulation H04B1/0017Digital filtering H04B1/0021Decimation H04B1/0025using a sampling rate lower than twice the highest frequency component of the sampled signal H04B1/0028wherein the AD/DA conversion occurs at baseband stage H04B1/0032with analogue quadrature frequency conversion to and from the baseband H04B1/0035Channel filtering H04B1/0039using DSP [Digital Signal Processor] quadrature modulation and demodulation H04B1/0042Digital filtering H04B1/0046Decimation H04B1/005adapting radio receivers, transmitters andtransceivers for operation on two or more bands H04B1/0053with common antenna for more than one band H04B1/0057using diplexing or multiplexing filters for selecting the desired band H04B1/006using switches for selecting the desired band H04B1/0064with separate antennas for the more than one band H04B1/0067with one or more circuit blocks in common for different bands H04B1/0071using a common intermediate frequency for more than one band H04B1/0075using different intermediate frequencied for the different bands H04B1/0078with a common intermediate frequency amplifier for the different intermediate frequencies H04B1/0082with a common local oscillator for more than one band H04B1/0085where one band is the image frequency band of the other and the band selection is done by image rejection H04B1/0089using a first intermediate frequency higher that the highest of any band received H04B1/0092using a wideband front end H04B1/0096where a full band is frequency converted into another full band H04B1/02Transmitters H04B1/03Constructional details H04B1/034Portable transmitters H04B1/0343to be carried on the body H04B1/0346Hand-held transmitters H04B1/036Cooling arrangements H04B1/04Circuits H04B1/0458Arrangements for matching and coupling between power amplifier and antenna or between amplifying stages H04B1/0466Fault detection or indication H04B1/0475with means for limiting noise, interference or distortion H04B1/0483Transmitters with multiple parallel paths H04B1/06Receivers H04B1/08Constructional details H04B1/082to be used in vehicles H04B1/086Portable receivers H04B1/088with parts of the receiver detachable or collapsible H04B1/10Means associated with receiver for limiting or suppressing noise or interference induced by transmission H04B1/1009Placing the antenna at a place where the noise level is low and using a noise-free transmission line between the antenna and the receivers H04B1/1018noise filters connected between the power supply and the receiver H04B1/1027assessing signal quality or detecting noise/interference for the received signal H04B1/1036with automatic suppression of narrow band noise or interference H04B1/1081Reduction of multipath noise H04B1/109by improving strong signal performance of the receiver when strong unwanted signals are present at the receiver input H04B1/12Neutralising, balancing, or compensation arrangements H04B1/123using adaptive balancing or compensation means H04B1/126having multiple inputs H04B1/14Automatic detuning arrangements H04B1/16Circuits H04B1/1607Supply circuits H04B1/1615Switching on; Switching off H04B1/1623using tubes H04B1/163Special arrangements for the reduction of the damping of resonant circuits of receivers H04B1/1638Special circuits to enhance selectivity of receivers not otherwise provided for H04B1/1646adapted for the reception of stereophonic signals H04B1/1653Detection of the presence of stereo signals and pilot signal regeneration H04B1/1661Reduction of noise by manipulation of the baseband composite stereophonic signal or the decoded left and right channels H04B1/1669of the demodulated composite stereo signal H04B1/1676of the sum or difference signal H04B1/1684of the decoded left or right stereo channel H04B1/1692using companding of the stereo difference signal H04B1/18Input circuits H04B1/20for coupling gramophone pick-up, recorder output, or microphone to receiver H04B1/202by remote control H04B1/205with control bus for exchanging commands between units H04B1/207with an audio or audio/video bus for signal distribution H04B1/22for receivers in which no local oscillation is generated H04B1/24the receiver comprising at least one semiconductor device having three or more electrodes H04B1/26for superheterodyne receivers H04B1/28the receiver comprising at least one semiconductor device having three or more electrodes H04B1/30for homodyne or synchrodyne receivers H04B1/302for single sideband receivers H04B1/38Transceivers H04B1/3805with built-in auxiliary receivers H04B1/3816Mechanical arrangements for accommodating identification devices H04B1/3818Arrangements for facilitating insertion or removal of identification devices H04B1/3822specially adapted for use in vehicles H04B1/3827Portable transceivers H04B1/3833Hand-held transceivers H04B1/3838Arrangements for reducing RF exposure to the user H04B1/385Transceivers carried on the body H04B1/3877Arrangements for enabling portable transceivers to be used in a fixed position H04B1/3883Arrangements for mounting batteries or battery chargers H04B1/3888Arrangements for carrying or protecting transceivers H04B1/40Circuits H04B1/401for selecting or indicating operating mode H04B1/403using the same oscillator for generating both the transmitter frequency and the receiver local oscillator frequency H04B1/405with multiple discrete channels H04B1/406with more than one transmission mode H04B1/408the transmitter oscillator frequency being identical to the receiver local oscillator frequency H04B1/44Transmit/receive switching H04B1/46by voice-frequency signals by pilot signals H04B1/48in circuits for connecting transmitter and receiver to a common transmission path H04B1/50using different frequencies for the two directions of communication H04B1/52Hybrid arrangements H04B1/525with means for reducing leakage of transmitter signal into the receiver H04B1/54using the same frequency for two directions of communication H04B1/56with provision for simultaneous communication in two directions H04B1/58Hybrid arrangements H04B1/581using a transformer H04B1/582with automatic balancing H04B1/583using a bridge network H04B1/585with automatic balancing H04B1/586using an electronic circuit H04B1/587using opto-couplers H04B1/588using sampling gates H04B1/59Responders Transponders H04B1/60Supervising unattended repeaters H04B1/62for providing a predistortion of the signal in the transmitter and corresponding correction in the receiver H04B1/64Volume compression or expansion arrangements H04B1/66for reducing bandwidth of signals for improving efficiency of transmission H04B1/662using a time/frequency relationship H04B1/665using psychoacoustic properties of the ear H04B1/667using a division in frequency subbands H04B1/68for wholly or partially suppressing the carrier or one side band or by using special modulation methods H04B1/69Spread spectrum techniques H04B1/692Hybrid techniques using combinations of two or more spread spectrum techniques H04B1/707using direct sequence modulation H04B1/70712with demodulation by means of convolvers H04B1/70718with asynchronous demodulation H04B1/7073Synchronisation aspects H04B1/70735Code identification H04B1/7075with code phase acquisition H04B1/70751using partial detection H04B1/70752Partial correlation H04B1/70753Partial phase search H04B1/70754Setting of search window H04B1/70755Setting of lock conditions H04B1/70756Jumping within the code H04B1/70757with increased resolution H04B1/70758Multimode search H04B1/7077Multi-step acquisition H04B1/70775Multi-dwell schemes H04B1/708Parallel implementation H04B1/7083Cell search H04B1/7085using a code tracking loop H04B1/7087Carrier synchronisation aspects H04B1/709Correlator structure H04B1/7093Matched filter type H04B1/7095Sliding correlator type H04B1/7097Interference-related aspects H04B1/71the interference being narrowband interference H04B1/7101with estimation filters H04B1/7102with transform to frequency domain H04B1/7103the interference being multiple access interference H04B1/7105Joint detection techniques H04B1/71052using decorrelation matrix H04B1/71055using minimum mean squared error [MMSE] detector H04B1/71057using maximum-likelihood sequence estimation [MLSE] H04B1/7107Subtractive interference cancellation H04B1/71072Successive interference cancellation H04B1/71075Parallel interference cancellation H04B1/711the interference being multi-path interference H04B1/7113Determination of path profile H04B1/7115Constructive combining of multi-path signals H04B1/7117Selection, re-selection, allocation or re-allocation of paths to fingers H04B1/712Weighting of fingers for combining H04B1/713using frequency hopping H04B1/7136Arrangements for generation of hop frequencies H04B1/7143Arrangements for generation of hop patterns H04B1/715Interference-related aspects H04B1/7156Arrangements for sequence synchronisation H04B1/7163using impulse radio H04B1/71632Signal aspects H04B1/71635Transmitter aspects H04B1/71637Receiver aspects H04B1/717Pulse-related aspects H04B1/7172Pulse shape H04B1/7174Pulse generation H04B1/7176Data mapping H04B1/7183Synchronisation H04B1/719Interference-related aspects H04B1/72Circuits or components for simulating aerials H04B1/74for increasing reliability H04B1/745using by-passing or self-healing methods H04B1/76Pilot transmitters or receivers for control of transmission or for equalising