5,619 research outputs found
Optimum and suboptimum frequency demodulation
Optimum and suboptimum linear demodulators for telemetry communication syste
A Space Communications Study Final Report, Sep. 15, 1965 - Sep. 15, 1966
Reception of frequency modulated signals passed through deterministic and random time-varying channel
Digital test signal generation: An accurate SNR calibration approach for the DSN
A new method of generating analog test signals with accurate signal to noise ratios (SNRs) is described. High accuracy will be obtained by simultaneous generation of digital noise and signal spectra at a given baseband or bandpass limited bandwidth. The digital synthesis will provide a test signal embedded in noise with the statistical properties of a stationary random process. Accuracy will only be dependent on test integration time with a limit imposed by the system quantization noise (expected to be 0.02 dB). Setability will be approximately 0.1 dB. The first digital SNR generator to provide baseband test signals is being built and will be available in early 1991
A highly stable atomic vector magnetometer based on free spin precession
We present a magnetometer based on optically pumped Cs atoms that measures
the magnitude and direction of a 1 T magnetic field. Multiple circularly
polarized laser beams were used to probe the free spin precession of the Cs
atoms. The design was optimized for long-time stability and achieves a scalar
resolution better than 300 fT for integration times ranging from 80 ms to 1000
s. The best scalar resolution of less than 80 fT was reached with integration
times of 1.6 to 6 s. We were able to measure the magnetic field direction with
a resolution better than 10 rad for integration times from 10 s up to 2000
s
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