Abstract: A programmable digital radio is configured to perform navigation functions. A receiver in the programmable digital radio receives analog signals from a navigation unit and digitizes the analog signals to produce digital navigation signals. The digital navigation signals are processed digitally and valid navigation information is determined. Processing includes generation of baseband signals including in-phase signals and quadrature signals, AM demodulation, filtering, decimating, demultiplexing, discrete fourier transformation, and function processing according to a selected function. The selected functions may include Localizer, Marker Beacon and Glideslope.

Abstract: A common transmit module of a programmable digital radio has a digital submodule which receives a bit stream and produces a modulated IF signal, and an analog submodule which receives the modulated IF signal and converts the modulated IF signal to a frequency corresponding to a specific type of radio function. The digital submodule includes (a) a sequential/parallel instruction set processor for signal processing and control, (b) a reconfigurable format unit, and (c) a modulator which receives the output signals of the reconfigurable format unit and produces the modulated oscillation signal.

Abstract: A digital submodule is included in a software programmable common receive module for receiving IF signals and producing a serial bit stream. The digital submodule is programmable based on a selected application of a plurality of radio applications and, if present, a selected function of a plurality of functions of the selected radio application. The digital submodule may include an analog to digital converter for converting IF signals received from an analog submodule into digital signals. The digital signals are supplied to a programmable signal processing unit which is configured, according to the selected radio application and, if present, the selected function, to perform control functions, processing and analysis of the digital signals and generate output signals. The output signals are then formatted by a formatting unit producing formatted digital signals. The formatted digital signals are then supplied to a system bus.

Abstract: A wideband RF-to-IF frequency converter providing multiple use of frequency conversion components for many different types of RF input signals. In specific examples, many different types of signals for communication, navigation, and for interrogation are processed through at least partly common frequency-conversion channels. Such RF input signals in the range from approximately 2 MHz to 2,000 MHz are converted to output IF frequencies, such as 1 MHz and 30 MHz, for further processing in the common receiver. Some narrow band signals, after conversion to IF, are subjected to off-center filtering in relatively broadband IF filters. Input RF filters are not used. Among several frequency conversion stages, only one of the local oscillator signals is tunable; but it is made tunable in relatively small, precise steps by using a double phase-locked loop arrangement in the frequency synthesizer.

Abstract: A video amplifier having a reduced noise figure is realized by eliminating the need for a resistive matching termination at the input of the amplifier. A negative feedback loop reduces the effective input impedance of the amplifier by generating an active impedance at the input of the amplifier. Because the input impedance of the amplifier is actively matched to the output impedance of the video signal generator, a noise-generating resistive termination is unnecessary, and the noise figure of the overall impedance-matched amplifier is significantly reduced.

Abstract: Apparatus for decreasing effect of transition of more significant bits in D/A converter reference of A/D converter. A pair of D/A converters are connected in tandem to eliminate transition of more significant bits of half scale. Also, three D/A converters are connected in parallel with each being offset from one another so that the effect of bit transition is minimized and occurs at different steps in analog output.

Abstract: One aspect of the present invention provides for apparatus for dynamically calibrating the internal offsets of the various range conversion paths as well as the overall offset of a successive ranging A/D conversion system over time and temperature variations. More specifically, this apparatus includes at least two time-gated integrator circuits which are respectively coupled to each of the range conversion paths of the conversion system. Each integrator is operative at predetermined times to generate a corresponding compensating signal in response to the digital code of one of the path conversion results. The compensating signals are used to dynamically calibrate the internal and overall offsets of the A/D conversion system. Further included in the apparatus are switching devices disposed at the input and feedback paths of the system to provide for appropriate system conditions at the predetermined calibration times.