This paper presents new experimental results on a polymer light-emitting diode based visible light communications system. For the first time we demonstrate a 10 Mb/s link based on the on-off keying data format with real time equalization on a field programmable gate array. The 10 Mb/s transmission speed is available at a bit error rate less than 4.6 × 10(-3), which is the limit for forward error correction. At a BER of 10(-6) a transmission speed of 7 Mb/s is readily achievable.
We present recent progress on visible light communication systems using polymer light-emitting diodes as the transmitters and a commercial silicon photodetector as the receiver. In this work we use transmitters at red, green and blue wavelengths to investigate the maximum on-off keying link performance of each device type as the first steps towards a wavelength-division multiplexed link. We show that a total transmission speed of 13 Mb/s is achievable when considering the raw bandwidth of each of the RGB PLEDs. Such a rate represents a 30% gain over previously demonstrated systems. Further capacity improvement can be achieved using high performance artificial neural network equalizer offering a realistic prospect for transmission speeds up to 54.9 Mb/s.
We present a newly designed polymer light-emitting diode with a bandwidth of ~350 kHz for high-speed visible light communications. Using this new polymer light-emitting diode as a transmitter, we have achieved a record transmission speed of 10 Mb/s for a polymer light-emitting diode-based optical communication system with an orthogonal frequency division multiplexing technique, matching the performance of single carrier formats using multitap equalization. For achieving such a high data-rate, a power pre-emphasis technique was adopted.
We present a new instrument, "Boreas", a cryogen-free methane (CH 4 ) preconcentration system coupled to a dual-laser spectrometer for making simultaneous measurements of δ 13 C(CH 4 ) and δ 2 H(CH 4 ) in ambient air. Excluding isotope ratio scale uncertainty, we estimate a typical standard measurement uncertainty for an ambient air sample of 0.07‰ for δ 13 C(CH 4 ) and 0.9‰ for δ 2 H(CH 4 ), which are the lowest reported for a laser spectroscopy-based system and comparable to isotope ratio mass spectrometry. We trap CH 4 (∼1.9 μmol mol −1 ) from ∼5 L of air onto the front end of a packed column, subsequently separating CH 4 from interferences using a controlled temperature ramp with nitrogen (N 2 ) as the carrier gas, before eluting CH 4 at ∼550 μmol mol −1 . This processed sample is then delivered to an infrared laser spectrometer for measuring the amount fractions of 12 CH 4 , 13 CH 4 , and 12 CH 3 D isotopologues. We calibrate the instrument using a set of gravimetrically prepared amount fraction primary reference materials directly into the laser spectrometer that span a range of 500−626 μmol mol −1 (CH 4 in N 2 ) made from a single pure CH 4 source that has been isotopically characterized for δ 13 C(CH 4 ) by IRMS. Under the principle of identical treatment, a compressed ambient air sample is used as a working standard and measured between air samples, from which a final calibrated isotope ratio is calculated. Finally, we make automated measurements of both δ 13 C(CH 4 ) and δ 2 H(CH 4 ) in over 200 ambient air samples and demonstrate the application of Boreas for deployment to atmospheric monitoring sites.
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