2,769 research outputs found
VHF command system study
Solutions are provided to specific problems arising in the GSFC VHF-PSK and VHF-FSK Command Systems in support of establishment and maintenance of Data Systems Standards. Signal structures which incorporate transmission on the uplink of a clock along with the PSK or FSK data are considered. Strategies are developed for allocating power between the clock and data, and spectral analyses are performed. Bit error probability and other probabilities pertinent to correct transmission of command messages are calculated. Biphase PCM/PM and PCM/FM are considered as candidate modulation techniques on the telemetry downlink, with application to command verification. Comparative performance of PCM/PM and PSK systems is given special attention, including implementation considerations. Gain in bit error performance due to coding is also considered
Data driven optimal filtering for phase and frequency of noisy oscillations: application to vortex flowmetering
A new method for extracting the phase of oscillations from noisy time series
is proposed. To obtain the phase, the signal is filtered in such a way that the
filter output has minimal relative variation in the amplitude (MIRVA) over all
filters with complex-valued impulse response. The argument of the filter output
yields the phase. Implementation of the algorithm and interpretation of the
result are discussed. We argue that the phase obtained by the proposed method
has a low susceptibility to measurement noise and a low rate of artificial
phase slips. The method is applied for the detection and classification of mode
locking in vortex flowmeters. A novel measure for the strength of mode locking
is proposed.Comment: 12 pages, 10 figure
Optimum and suboptimum frequency demodulation
Optimum and suboptimum linear demodulators for telemetry communication syste
Command system study for the operation and control of unmanned scientific satellites, task III - Command system interference Third quarterly progress report, 1 Jan. - 31 Mar. 1965
Effects of CW and modulated interference on baseband of AM and FM demodulators used for control of unmanned scientific satellite
Time-Hopping Multicarrier Code-Division Multiple-Access
A time-hopping multicarrier code-division multiple-access (TH/MC-CDMA) scheme is proposed and investigated. In the proposed TH/MC-CDMA each information symbol is transmitted by a number of time-domain pulses with each time-domain pulse modulating a subcarrier. The transmitted information at the receiver is extracted from one of the, say , possible time-slot positions, i.e., assuming that -ary pulse position modulation is employed. Specifically, in this contribution we concentrate on the scenarios such as system design, power spectral density (PSD) and single-user based signal detection. The error performance of the TH/MC-CDMA system is investigated, when each subcarrier signal experiences flat Nakagami- fading in addition to additive white Gaussian noise (AWGN). According to our analysis and results, it can be shown that the TH/MC-CDMA signal is capable of providing a near ideal PSD, which is flat over the system bandwidth available, while decreases rapidly beyond that bandwidth. Explicitly, signals having this type of PSD is beneficial to both broadband and ultra-wide bandwidth (UWB) communications. Furthermore, our results show that, when optimum user address codes are employed, the single-user detector considered is near-far resistant, provided that the number of users supported by the system is lower than the number of subcarriers used for conveying an information symbol
Engineering evaluations and studies. Volume 3: Exhibit C
High rate multiplexes asymmetry and jitter, data-dependent amplitude variations, and transition density are discussed
Single Carrier Architecture for High Data Rate Wireless PAN Communications System
A 60 GHz wireless Gigabit Ethernet (G.E.) communication system is developed
at IETR. As the 60 GHz radio link operates only in a single-room configuration,
an additional Radio over Fibre (RoF) link is used to ensure the communications
in all the rooms of a residential environment. The realized system covers 2 GHz
bandwidth. Due to the hardware constraints, a symbol rate at 875 Mbps is
attained using simple single carrier architecture. In the baseband (BB)
processing block, an original byte/frame synchronization process is designed to
provide a smaller value of the preamble missing detection and false alarm
probabilities. Bit error rate (BER) measurements have been realized in a large
gym for line-of-sight (LOS) conditions. A Tx-Rx distance greater than 30 meters
was attained with low BER using high gain antennas and forward error correction
RS (255, 239) coding.Comment: Design, Experimentation, Measurement, Performance; IWCMC '10, Caen :
France (2010
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