Simple Diode Circuit Research Articles

3-Level LED 변조를 이용한 동기식 가시광통신 시스템

In this paper, we introduce a new synchronous visible light communication system in which the synchronizing pulse and the data bits are simultaneously transmitted using a 3-level light signal. In the transmitter, the synchronizing pulse and the data bits modulate independently two identical visible LEDs, whose output lights add in free space, make 3-level optical signal. In the receiver, a photodiode detects the light and generates a 3-level output voltage, whose positive and negative part correspond to the synchronizing pulse and the data bits, respectively. The two signals are easily separated and recovered by a simple diode circuit. This configuration provides two independent VLC channels without any multiplexing technique, simplifies the circuit design and construction of synchronous VLC systems.

A 256 x 256 2-D array transducer with row-column addressing for 3-D rectilinear imaging.

We present simulation and experimental results from a 5-MHz, 256 x 256 2-D (65,536 elements, 38.4 x 38.4 mm) 2-D array transducer with row-column addressing. The main benefits of this design are a reduced number of interconnects, a modified transmit/receive switching scheme with a simple diode circuit, and an ability to perform volumetric imaging of targets near the transducer with transmit beamforming in azimuth and receive beamforming in elevation. The final dimensions of the transducer were 38.4 mm x 38.4 mm x 300 microm. After a row-column transducer was prototyped, the series resonance impedance was 104 Omega at 5.4 MHz. The measured -6 dB fractional bandwidth was 53% with a center frequency of 5.3 MHz. The SNR at the transmit focus was measured to be 30 dB. At 5 MHz, the average nearest neighbor crosstalk was -25 dB. In this paper, we present 3-D images of both 5 pairs of nylon wires embedded in a clear gelatin phantom and an 8 mm diameter cylindrical anechoic cyst phantom acquired from a 256 x 256 2-D array transducer made from a 1-3 composite. We display the azimuth and elevation B-scans as well as the C-scan for each image. The cross-section of the wires is visible in the azimuth B-scan, and the long axes can be seen in the elevation B-scan and C-scans. The pair of wires with 1-mm axial separation is discernible in the elevational B-scan. When a single wire from the wire target phantom was used, the measured lateral beamwidth was 0.68 mm and 0.70 mm at 30 mm depth in transmit beamforming and receive beamforming, respectively, compared with the simulated beamwidth of 0.55 mm. The cross-section of the cyst is visible in the azimuth B-scan whereas the long axes can be seen as a rectangle in the elevation B-scan and C-scans.

A New Simple Phase-Dependent Detector

A new and simple diode circuit for phase-dependent detection is presented. It is phase dependent in the sense that a phase reversal of the input ac signal alters the sign of the dc output. The circuit therefore requires a reference input as well.