A frequency modulation oscillator circuit is provided having three or more output frequencies corresponding to three or more possible input signals, the output frequency being a phase continuous frequency modulated signal with no discontinuities. For each desired output frequency, there is an input amplifier, responsive to an input binary signal, the output of that amplifier being summed with the outputs of the other amplifiers. For each input amplifier there is an active feedback network containing a delay element which will produce oscillation in the associated amplifier, the active feedback network from each amplifier being isolated from the other amplifiers and feedback networks. Input amplifiers comprising differential amplifiers emitter coupled to transistor switches are shown together with common base feedback amplifiers emitter coupled to the collectors of one of the transistors comprising the input differential amplifier.
An automatic deviation control circuit for an angle modulated data transmitter is disclosed wherein the deviation level of modulated data is controlled by a modulation cancelling deviation error detection feedback loop. After the modulation is cancelled from a sample of modulated carrier by a predetermined value of deviation, residual modulation is detected, sampled following a predetermined number of like-level data bits, and applied to the modulation path gain to increase or decrease the deviation such that the residual modulation is minimized.
In a multitrack motion analyzer in which video information representing a scene is recorded at a fast frame rate and played back at a slower frame rate, digital data timing and synchronization signals relating to each recorded frame is simultaneously recorded on a separate track as bipolar return to zero (BRZ) FM signals. A Non Return to Zero (NRZ) bit serial digital data signal and synchronous data clock signal are encoded as BRZ digital data signals and then frequency modulated so that the "1" bit, the "0" bit, and the "return to zero" signal levels of the BRZ data signal are converted to three frequencies. The three frequencies are integral multiples and synchronous to the data rate of the NRZ digital data signal so as to eliminate uncertainty between bit boundaries and allow packing more bits per unit time for a given carrier bandwidth. Additionally, accurate synchronization information is recorded and recovered by inserting a missing clock in the BRZ data stream. In a preferred embodiment in which the motion analyzer is operable at different frame rates, the FM frequencies representing the BRZ data signal are chosen to be a function of the ratio between the record frame rate and the playback frame rate which results in constant playback frequencies regardless of record rate.
