H03CMODULATION masers or lasers H01S; coding, decoding or code conversion H03MThis subclass covers only modulation, keying, or interruption of sinusoidal oscillations or electromagnetic waves, the modulating signal having any desired waveform.In this subclass, circuits usable both as modulator and demodulator are classified in the group dealing with the type of modulator involved.The following IPC groups are not in the CPC scheme. The subject matter for these IPC groups is classified in the following CPC groups: H03C1/38 - H03C1/44 covered by H03C1/36 H03C1/00 H03C1/00Amplitude modulation H03C5/00, H03C7/00 take precedence H03C1/02Details H03C1/04Means in or combined with modulating stage for reducing angle modulation H03C1/06Modifications of modulator to reduce distortion, e.g. by feedback, and clearly applicable to more than one type of modulator H03C1/08by means of variable impedance element H03C1/28 - H03C1/34, H03C1/46 - H03C1/52, H03C1/62 take precedence H03C1/10the element being a current-dependent inductor H03C1/12the element being a voltage-dependent capacitor H03C1/14the element being a diode H03C1/16by means of discharge device having at least three electrodes H03C1/28 - H03C1/34, H03C1/50, H03C1/52, H03C1/62 take precedence H03C1/18carrier applied to control grid H03C1/20modulating signal applied to anode H03C1/22modulating signal applied to same grid H03C1/24modulating signal applied to different grid H03C1/26modulating signal applied to cathode H03C1/28by means of transit-time tube H03C1/30by means of a magnetron H03C1/32by deflection of electron beam in discharge tube H03C1/34by means of light-sensitive element H03C1/36by means of semiconductor device having at least three electrodes H03C1/34, H03C1/50, H03C1/52, H03C1/62 take precedence H03C1/46Modulators with mechanically-driven or acoustically-driven parts H03C1/48by means of Hall-effect devices H03C1/50by converting angle modulation to amplitude modulation H03C1/28 - H03C1/34, H03C1/46, H03C1/48 take precedence H03C1/52Modulators in which carrier or one sideband is wholly or partially suppressed H03C1/28 - H03C1/34, H03C1/46, H03C1/48 take precedence H03C1/54Balanced modulators, e.g. bridge type, ring type or double balanced type H03C1/542comprising semiconductor devices with at least three electrodes H03C1/545using bipolar transistors H03C1/547using field-effect transistors H03C1/56comprising variable two-pole elements only H03C1/58comprising diodes H03C1/60with one sideband wholly or partially suppressed H03C1/62Modulators in which amplitude of carrier component in output is dependent upon strength of modulating signal, e.g. no carrier output when no modulating signal is present H03C1/28 - H03C1/34, H03C1/46, H03C1/48 take precedence H03C3/00Angle modulation H03C5/00, H03C7/00 take precedence H03C3/005Circuits for asymmetric modulation H03C3/02Details H03C3/04Means in or combined with modulating stage for reducing amplitude modulation H03C3/06Means for changing frequency deviation H03C3/08Modifications of modulator to linearise modulation, e.g. by feedback, and clearly applicable to more than one type of modulator H03C3/09Modifications of modulator for regulating the mean frequency H03C3/0908using a phase locked loop H03C3/0916with frequency divider or counter in the loop H03C3/0925applying frequency modulation at the divider in the feedback loop H03C3/0933using fractional frequency division in the feedback loop of the phase locked loop H03C3/0941applying frequency modulation at more than one point in the loop H03C3/095applying frequency modulation to the loop in front of the voltage controlled oscillator H03C3/0958applying frequency modulation by varying the characteristics of the voltage controlled oscillator H03C3/0966modulating the reference clock H03C3/0975applying frequency modulation in the phase locked loop at components other than the divider, the voltage controlled oscillator or the reference clock H03C3/0983containing in the loop a mixer other than for phase detection H03C3/0991including calibration means or calibration methods H03C3/10by means of variable impedance H03C3/30 - H03C3/38 take precedence H03C3/12by means of a variable reactive element H03C3/14simulated by circuit comprising active element with at least three electrodes, e.g. reactance-tube circuit H03C3/145by using semiconductor elements H03C3/16in which the active element simultaneously serves as the active element of an oscillator H03C3/18the element being a current-dependent inductor H03C3/20the element being a voltage-dependent capacitor H03C3/22the element being a semiconductor diode, e.g. varicap diode H03C3/222using bipolar transistors H03C3/227 takes precedence H03C3/225using field effect transistors H03C3/227 takes precedence H03C3/227using a combination of bipolar transistors and field effect transistors H03C3/24by means of a variable resistive element, e.g. tube H03C3/245by using semiconductor elements H03C3/26comprising two elements controlled in push-pull by modulating signal H03C3/28using variable impedance driven mechanically or acoustically H03C3/30by means of transit-time tube H03C3/32the tube being a magnetron H03C3/34by deflection of electron beam in discharge tube H03C3/36by means of light-sensitive element H03C3/38by converting amplitude modulation to angle modulation H03C3/40using two signal paths the outputs of which have a predetermined phase difference and at least one output being amplitude-modulated H03C3/403using two quadrature frequency conversion stages in cascade H03C3/406using a feedback loop containing mixers or demodulators H03C3/42by means of electromechanical devices H03C3/28 takes precedence H03C5/00Amplitude modulation and angle modulation produced simultaneously or at will by the same modulating signal H03C7/00 takes precedence H03C5/02by means of transit-time tube H03C5/04the tube being a magnetron H03C5/06by deflection of electron beam in discharge tube H03C7/00Modulating electromagnetic waves devices or arrangements for the modulation of light G02F1/00 H03C7/02in transmission lines, waveguides, cavity resonators or radiation fields of antennas H03C7/022using ferromagnetic devices, e.g. ferrites H03C7/025using semiconductor devices H03C7/027using diodes H03C7/04Polarisation of transmitted wave being modulated H03C7/022 takes precedence H03C99/00Subject matter not provided for in other groups of this subclass H03C2200/00 H03C2200/00Indexing scheme relating to details of modulators or modulation methods covered by H03C H03C2200/0004Circuit elements of modulators H03C2200/0008Variable capacitors, e.g. a varicap, a varactor or a variable capacitance of a diode or transistor H03C2200/0012Emitter or source coupled transistor pairs or long tail pairs H03C2200/0016Pre-emphasis or de-emphasis circuits H03C2200/002Filters with particular characteristics H03C2200/0025Gilbert multipliers H03C2200/0029Memory circuits, e.g. ROMs, RAMs, EPROMs, latches, shift registers H03C2200/0033Transmission lines, e.g. striplines, microstrips or coplanar lines H03C2200/0037Functional aspects of modulators H03C2200/0041Calibration of modulators H03C2200/0045Pulse width, duty cycle or on/off ratio H03C2200/005Modulation sensitivity H03C2200/0054Filtering of the input modulating signal for obtaining a constant sensitivity of frequency modulation H03C2200/0058Quadrature arrangements H03C2200/0062Lowering the supply voltage and saving power H03C2200/0066Reduction of carrier leakage or the suppression of the carrier H03C2200/007with one sideband wholly or partially suppressed H03C2200/0075FM modulation down to DC H03C2200/0079Measures to linearise modulation or reduce distortion of modulation characteristics H03C2200/0083Predistortion of input modulating signal to obtain a linear modulation characteristic H03C2200/0087Measures to address temperature induced variations of modulation H03C2200/0091by stabilising the temperature H03C2200/0095by compensating temperature induced variations