Rockwell International Corporation

Rockwell International Coproration

Roger K Loper

Richard A Freeman

Thomas R Hope

Ernest J Moes

Charles S Farlow

A system connecting and controlling gain and phase errors in a direct conversion receiver having a pair of signal channels carrying I and Q baseband signal components in a quadrature relationship. The system operates by treating all phase and gain errors as resident in the Q channel and thus describes an iterative process generating a plurality of intermediary signals that in turn incorporate a trigonometric product of the IF signal and the I and Q signal component to produce a pair of correction factors that ideally maintains a matched quadrature relationship between the two signal channels.

System for correcting quadrature gain and phase errors in a direct

An amplitude modulated (AM) radio receiver uses a digital signal processor, responsive to in-phase (I) and quadrature-phase (Q) component signals, to compensate for carrier energy removed by a capacitive coupling circuit. A quadrature mixer converts the received AM signal to the I and Q component signals representative of the AM signal, and a signal filter passes a desired frequency segment of the I and Q component signals. A capacitive coupling circuit couples the I and Q component signals to provide representative I and Q signals with no DC bias to the input of an analog-to-digital converter. The analog-to-digital converter converts the representative unbiased I and Q signals to digital I and Q signals for processing by the digital signal processor. The digital signal processor then: (a) determines the absolute values of the I and Q digital signals; (b) compares the absolute value of the I digital signal to the absolute value of the Q digital signal and determines which value is greater; and in response to the outcome of the comparison, provides a digital output word as function of one of the following terms

AM demodulation receiver using digital signal processor

A system for controlling for gain and phase errors due to mismatches between signal channels in direct conversion receiver having a pair of signal channels carrying I and Q baseband component signals which are in quadrature. In accordance with the system new I' and Q' signals are generated which may be viewed as analogs of the I and Q baseband components but which are related to twice the phase angle defined by the original I and Q baseboard components signal components. Phase angles are determined based on the original I and Q baseband components signals and the new I' and Q' signals. An error signal is then formed from these signals which can be analyzed to determine the gain and phase errors affecting the I and Q baseband components. These components can then be adjusted to correct for gain and phase errors in order to compensate for hardware mismatches between the signal channels in the receiver.

Phase and gain error control system for use in an I/Q direct conversion

A system for detecting and controlling gain and phase errors in a direct conversion receiver having a pair of signal channels carrying I and Q baseband signal components which are in quadrature and are a function of a phase angle .theta.. The system operates by generating I' and Q' signals which correspond to sin(2.theta.) and cos(2.theta.). These I' and Q' signals are then normalized with respect to signal amplitude and filtered to produce signals DC.sub.I and DC.sub.Q corresponding to their DC components. The resulting signals DC.sub.I and DC.sub.Q have been discovered to be separately correlated with the gain and phase errors, respectively, and are used in adjusting the original I and Q baseband signal components to correct for any such errors existing between them.

System for controlling phase and gain errors in an I/Q direct conversion

A direct conversion receiver having a tri-phase architecture including three separate baseband signal channels. RF communications signals which are being tuned by the receiver are split into three equal and in-phase components which are mixed with three equal but substantially out-of-phase injection signals on frequency with the communications signal. The resulting baseband component signals are independently filtered and amplified on the three signal channels. The baseband components are then directed to a signal processing unit which corrects the baseband components for gain or phase mismatch errors between the signal channels based on the information carried by the three components and thereafter demodulates the signals in order to acquire the information carried by the RF communications signal. An automatic gain control system and a signal filtering system adapted for use with direct conversion receivers are also disclosed.

Selectivity system for a direct conversion receiver

A direct conversion receiver having a tri-phase architecture including three separate baseband signal channels. RF communications signals which are being tuned by the receiver are split into three equal and in-phase components which are mixed with three equal but substantially out-of phase injection signals on frequency with the communications signal. The resulting baseband component signals are independently filtered and amplified on the three signal channels. The baseband components are then directed to a signal processing unit which corrects the baseband components for gain or phase mismatch errors between the signal channels based on the information carried by the three components and thereafter demodulates the signals in order to acquire the information carried by the RF communications signal. An automatic gain control system and a signal filtering system adapted for use with direct conversion receivers are also disclosed.

Automatic gain control system for a direct conversion receiver

Direct conversion receiver with tri-phase architecture

The bandwidth of frequency modulated signals is limited in a digital data transmission system by shaping the square digital waveform to form a trapezoidal shaped waveform having a positively-sloped ramp on the leading edge of the waveform and negatively-sloped ramp on the following edge of the waveform. Provisions are made to selectively determine the slope of the ramps and the amplitude of the waveform so that the system can be used with a wide range of data transmission speeds without resort to bandpass filter or component changes as were required in the prior art. Provision is also made for transmission of analog data in the same system by providing a feedback loop which causes the ramping to follow, and thus approximate, the analog waveform. The shaped data signal is fed to a frequency synthesizer which produces a frequency modulated sine wave whose frequency deviation is related to the magnitude of the digital or analog data signal.

Digital voice and data frequency modulation circuit

A battery monitoring system for monitoring the status of a battery provides for including within the battery package a nonvolatile memory for storing digital data symbols representative of the power that has been supplied by the battery. The equipment in which the battery is utilized has associated with it a power monitor system that senses the power delivered by the battery and converts the sense power into digital data symbols which are applied to the nonvolatile memory for accumulation and thereby maintains a permanent record of the power that has been supplied by the battery.

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Marion, IA, United States of America

Roger K Loper