Frequency translation and applications of same are described herein, including wireless local area network (WLAN) applications such as IEEE Standard 802.11 WLANs. Such applications include, but are not limited to, frequency down-conversion, frequency up-conversion, enhanced signal reception, unified down-conversion and filtering, and combinations and applications of same.

Wireless local area network (WLAN) technology and applications including techniques of universal frequency translation

Methods for down converting a modulated carrier signal to a demodulated baseband signal are described herein The method requires that a first portion of energy is transferred from the modulated carrier signal, and stored at a first storage device when a first switch is on At least some of the energy stored in the first storage device is discharged when the first switch is off The method further comprises transferring a second portion of energy from the modulated carrier signal, storing at a second storage device the second portion of transferred energy when a second switch is on, and discharging at least some of the energy stored in the second storage device when the second switch is off A down-converted in-phase baseband signal portion is generated from the energy accumulated in the first storage device while both the charging and the discharging occurs, and a down-converted inverted in-phase baseband signal portion is generated from the energy accumulated in the second storage device while both the charging and the discharging occurs, and the two portions are combined with a first differential amplifier circuit to form a down-converted differential in-phase baseband signal

Method and system for down-converting an electromagnetic signal

A signal under measurement is transformed into a complex analytic signal using a Hilbert transformer and an instantaneous phase of this analytic signal is estimated. A linear phase is subtracted from the instantaneous phase to obtain a phase noise waveform. The phase noise waveform is sampled in the proximity of a zero crossing point of a real part of the analytic signal. A differential waveform of the sample phase noise waveform is calculated to obtain a differential phase noise waveform. An RMS jitter is obtained from the phase noise waveform, and a peak-to-peak jitter is obtained from the phase noise waveform.

Jitter measuring device and method

Methods, systems, and apparatuses, and combinations and sub-combinations thereof, for down-converting and up-converting an electromagnetic (EM) signal are described herein. Briefly stated, in embodiments the invention operates by receiving an EM signal and recursively operating on approximate half cycles (½, 1½, 2½, etc.) of the carrier signal. The recursive operations can be performed at a sub-harmonic rate of the carrier signal. The invention accumulates the results of the recursive operations and uses the accumulated results to form a down-converted signal. In an embodiment, the EM signal is down-converted to an intermediate frequency (IF) signal. In another embodiment, the EM signal is down-converted to a baseband information signal. In another embodiment, the EM signal is a frequency modulated (FM) signal, which is down-converted to a non-FM signal, such as a phase modulated (PM) signal or an amplitude modulated (AM) signal. Up-conversion is accomplished by controlling a switch with an oscillating signal, the frequency of the oscillating signal being selected as a sub-harmonic of the desired output frequency.

Method and system for down-converting and up-converting an electromagnetic signal, and transforms for same

The present invention includes a system and method for ensuring reception of a communications signal. A modulating baseband signal with desired information is accepted, and a plurality of redundant spectrums is generated. Each redundant spectrum comprises the necessary amplitude, phase, and frequency information to substantially reconstruct the modulating baseband signal. It is expected but not required that the redundant spectrums will be generated at a first location and sent to a second location over a communications medium. At the second location, the redundant spectrums are independently processed to recover a demodulating baseband signal for each of the redundant spectrums. In one embodiment, an error detection process is employed at the second location to detect and eliminate those demodulated baseband signals that have been corrupted during transmission. An error-free demodulated baseband signal is selected from the remaining demodulated baseband signals. The error-free demodulated baseband signal is representative of the modulating baseband signal sent over the communications medium.

Method and system for ensuring reception of a communications signal

The authors review the technique of phase noise stability measurement using complex demodulation and the approach to an unlocked spread spectrum communications probe. This system has recently been developed to characterize a transhorizon communications channel at 11.6 GHz under both tropospheric scatter and anomalous propagation conditions. The receiver has a bandwidth of 31.25 MHz but has no carrier recovery and therefore no absolute phase reference. However, provided that the phase jitter and the frequency drift are small enough during the channel measurement period, it is possible to obtain an accurate channel transmittance estimate. The system has the capability of implementing time-domain signal averaging "on the fly", thus permitting high-speed channel identification under low SNR regimes. As the averaging period is increased (to improve the SNR), low phase jitter in the oscillators becomes imperative. The SNR improvement achieved is thus controlled by the maximum averaging period, which is a direct reflection of the stability of the oscillators. >

Measurement of the phase noise characteristics of an unlocked communications channel identifier

A high speed, wideband channel probe is briefly described. The use of the probe on an experimental 158 km link across the English Channel is reported. Preliminary results depicting the time-variant and frequency-selective characteristics of the link are presented.

Wideband sounding of 11.6 GHz trans-horizon channel

The authors give an overview of a wide band experiment at 11.6 GHz designed to analyze and model a transhorizon communications channel subject to both scattering and anomalous propagation conditions. The salient features of the measurement equipment and the associated signal processing techniques are described. The approach to remote sensing the propagation path is outlined and combines ray extraction and trajectory tracing. >

A wide band transhorizon experiment at 11.6 GHz

This paper presents a channel probing technique named spread spectrum time averaging and an experimental system which has been designed specially to measure the response of a channel subjected to various propagation mechanisms. In addition to the presentation of preliminary experimental results, a nonlinear spectral analysis approach for the modelling of the channel response is explained.

http://ieeexplore.ieee.org/iel3/1355/6937/00280201.pdf

W.K. Lam

Papers

Measurement of the phase noise characteristics of an unlocked communications channel identifier

Wideband sounding of 11.6 GHz trans-horizon channel

A wide band transhorizon experiment at 11.6 GHz

Wideband transhorizon channel sounder at 11 GHz