Abstract: In an AM system directed to commercial broadcasting, a pure unmodulated (CW) carrier signal and two sideband signals are generated and processed separately as three independent signals that are summed as output of a final linear mixer. The sideband signals are derived independently utilizing audio spectrum-sharing based on complementary comb filtering, quadrature phase-shifting at both audio and carrier sideband frequencies, and exclusive alternate toggling at a designated switching rate between the two sidebands so that at any instant in time only one of the two sidebands is present along with the continuous carrier. The overall performance provides the capability of advantageous modulation beyond the conventional 100% modulation limit.

Abstract: In this micro-controller-based line voltage meter/monitor instrument, an AC signal-under-test is sensed from the line voltage via a broadband isolation transformer, and processed to provide RMS and fast peak signals. These are A/D converted in the micro-controller in a sampling process synchronized from a zero-cross signal detected from the AC voltage-under-test. An LED (light-emitting diode) display with 40 LED segments provides resolution of one volt RMS per LED step/segment, and is color-coded to overlay the CBEMA nominal limits. RMS values ranging from 95 to 135 volts are indicated on a bar graph, and fast peak values ranging from 120 to 500 volts at the waveform crest are indicated by the selected LED cell flashing at a 1 Hz rate, with selectable peak hold time. An internal real time calendar/clock enables accumulation of time-related data regarding the ongoing quality of the power line voltage levels.

Abstract: For professional audio operations such as recording and broadcasting, an LED bar-graph display instrument monitors average and peak loudness levels of stereophonic audio signals that have been encoded in serial digital format such as AES/EBU digital audio format. Internal audio processing circuitry, that can be implemented digitally with a custom chip gate array set, receives as input a serial stream of digital stereo audio data and converts this to ballistically conditioned logarithmic average and peak levels which are simultaneous displayed, generally simulating the ballistics of contemporary standard electronically displayed loudness meters such as the Dorrough analog model. The peak hold can be switched manually or internally between three hold durations: indefinite, 3 seconds or zero.

Abstract: A two channel audio switcher includes two analog switches, which may be implemented as a CMOS integrated circuit, receiving at their control input ports a complementary pair of drive signals, typically square wave, so as to toggle their outputs at a supersonic rate, which may be made variable. The switcher may receive as input two channels of a stereophonic source, two independent audio sources or a common monophonic source. The outputs typically drive an audio output unit such as the transmitter of a radio broadcasting system, an audio recording system, or amplifiers, controls and loudspeakers of a sound reinforcement system in an auditorium or studio. The system may be monophonic or stereophonic. In a stereophonic a.m. broadcasting system such as the Kahn independent sideband system, alternate switching allows each sideband to be modulated to full available power, thus allowing an increase in the apparent radiated power.

Abstract: For monitoring, metering and dynamically displaying key static and dynamic parameters of composite video signals and visually indicating compliance status relative to important system specifications, this electronic meter is particularly useful in connection with video cameras. In studio environments, the compliance indications supplement existing capabilities, and in remote locations where large, complex and costly CRT type waveform monitors are not feasible, the compactness of this video meter provides an unusual degree of picture quality assurance. A bar/graph type LED display provides two independent scale regions: a sync region dynamically displaying sync amplitude, and a picture region dynamically displaying average picture levels in a bar mode and peak levels in a dot mode. The response times of the sync, average and peak level are selectable. Peak indications are lengthened to a display time which is optimal for human response to short term events.

Abstract: A dual loudness meter and method for simultaneously indicating the apparent loudness of composite audio program material representing peak material or of persistent material employing a first detector means responsive to peak signals for instantaneously indicating the same as a singly actuated LED indicator in an array thereof displayed in accordance with the peak strength of the signal, a second detector for detecting the persistence of the signal and displaying the same as a bar graph on said LED display, the materials being colinearlly displayed and having dual upper extreme warning/operating indicator means separated by about 12 to 14 dB so that the meter is read as requiring adjustment of the associated recording or broadcast facilities to avoid having either of said programming indicator displays reading consistently in either warning/operating zone. Specific circuits and time constants of response and decay are given as appropriate to the simultaneous reading, dual meter system disclosed.