Abstract: A group spacing device for keeping groups of people at least six feet apart or some other determined distance from other groups of people the group spacing device having four outer connection adapters joined by four corresponding exterior border strips, four inner connection adapters joined by at least four poles, at least four poles joining the outer connection adapters to corresponding inner connection adapters, a fence assembly that mounts to the outer connection adapters so as to stretch across and above the exterior border strips, a plurality of screw anchors that passes through apertures in the outer connection adapters and or inner connection adapters until stopped by an anchor stop to secure the group spacing device to a sand or ground surface and a tent mountable over the group spacing device.

Abstract: Orthogonal frequency division multiplexing (OFDM) receiver embodiments of the invention provide data demodulator synchronization by finding the end of the short preamble in an IEEE-802.11a burst transmission. This method exploits the fact that there are certain symmetries in the long-preamble that can be used to determine synchronization. The long-preamble sequence is composed of a guard interval (GI) and two long-preamble symbols; the GI is the last 32 samples of the long-preamble symbol. The 32nd sample of the long-preamble acts as a “pilot” or “anchor” sample in that the previous N and subsequent N samples are complex conjugates, or conjugate “mirror” vectors. Due to the periodicities of the long-preamble, this property repeats every 32 samples. No other samples in the long preamble exhibit this property. Coherent combining is used in one embodiment for robustness.

Abstract: An orthogonal frequency division multiplexing (OFDM) receiver which digitally estimates and corrects for frequency offset and demodulates quadrature amplitude modulated (QAM) signals transmitted in the 5 GHz frequency band embodies the current invention. Possible modulation types include binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), 16-QAM, 64-QAM, (and 256-QAM in future standard enhancements). During the so-called short-preamble, the first few basic constituents are deliberately skipped. Then every 2.4 &mgr;s, a 1.6 &mgr;s duration sequence is collected until three such sequences are collected. Because the same waveform can be safely assumed to being repeated during all three sequences, any differences amongst the sequences are directly related to the frequency-offset error. The solution is set-up as a simultaneous-equation mathematical problem with a single unknown variable, a pseudo-rank of one.

Abstract: Orthogonal frequency division multiplexing (OFDM) receiver embodiments of the invention provide data demodulator synchronization by finding the end of the short preamble in an IEEE-802.11a burst transmission. This method exploits the fact that there are certain symmetries in the long-preamble that can be used to determine synchronization. The long-preamble sequence is composed of a guard interval (GI) and two long-preamble symbols; the GI is the last 32 samples of the long-preamble symbol. The 32nd sample of the long-preamble acts as a “pilot” or “anchor” sample in that the previous N and subsequent N samples are complex conjugates, or conjugate “mirror” vectors. Due to the periodicities of the long-preamble, this property repeats every 32 samples. No other samples in the long preamble exhibit this property. Coherent combining is used in one embodiment for robustness.