Since the poor performance of orthogonal binary Pulse Position Modulation (PPM) compared with binary Pulse Amplitude Modulation (PAM), this paper presents a new modulation scheme named Pulse Width Modulation (PWM) for...Since the poor performance of orthogonal binary Pulse Position Modulation (PPM) compared with binary Pulse Amplitude Modulation (PAM), this paper presents a new modulation scheme named Pulse Width Modulation (PWM) for Impulse Radio Ultra-WideBand (IR-UWB) communication systems. This modulation scheme uses pulses with equal amplitude and different widths to carry different information. The receiver employs differences between similarity coefficients among these pulses to distinguish different information. Both theoretical analysis and simulation results verify that this novel scheme has a Signal to Noise Ratio (SNR) gain of about 1.75 dB compared with or- thogonal binary PPM, and has an SNR loss of about 1.4 dB compared with binary PAM. Although both the theoretical analysis and simulations are based on time-hopping multiple access, this modulation scheme can also be applied to other accessing techniques of UWB communication systems.展开更多
From the view of practical application, this paper designs an infrared information collection nodes, the coordinator node, wireless transmission system using CC2430 microcontroller, and in detail design the infrared s...From the view of practical application, this paper designs an infrared information collection nodes, the coordinator node, wireless transmission system using CC2430 microcontroller, and in detail design the infrared sensor （temperature, heart rate, ECG / pulse） circuit diagram. This paper set up a wireless network （ZigBee protocol）, sensor signal acquisition, wireless transmitting and receiving, serial communication software design of coordinator node and PC machine. Finally, we on-line debug each module of the system hardware and software. Experiments show that the network node data transmission accurate, reliable work, has basically met the design requirements.展开更多
A mid-infrared carbon dioxide(CO_2) sensor is presented for the application in greenhouse environment. An integrated multi-pass gas chamber and a dual-channel differential detection method are adopted to decrease resp...A mid-infrared carbon dioxide(CO_2) sensor is presented for the application in greenhouse environment. An integrated multi-pass gas chamber and a dual-channel differential detection method are adopted to decrease response time and suppress environmental influence, respectively. An optical module is developed using a cost-effective wideband mid-infrared light source, a dual-channel pyre electrical detector and a spherical mirror, and the moisture-proof function is specially designed for enabling the application of this sensor in greenhouse with high humidity. Experiments are carried out to evaluate the sensing performance on CO_2 concentration. According to the experimental results, the limit of detection(Lo D) is about 3×10^(-5) with an absorption length of 30 cm. The relative detection error is less than 5% within the measurement range of 3×10^(-5)—5×10^(-3). Based on 10 h long-term stability measurement on 5×10^(-4) and 2×10^(-3) standard CO_2 samples, the maximum fluctuations are 1.08% and 3.6%, respectively. By using a 2.4 GHz wireless network communication system for remote monitoring and data recording, a field measurement of this sensor in a greenhouse is conducted, and good performance is proven in such circumstance.展开更多
文摘Since the poor performance of orthogonal binary Pulse Position Modulation (PPM) compared with binary Pulse Amplitude Modulation (PAM), this paper presents a new modulation scheme named Pulse Width Modulation (PWM) for Impulse Radio Ultra-WideBand (IR-UWB) communication systems. This modulation scheme uses pulses with equal amplitude and different widths to carry different information. The receiver employs differences between similarity coefficients among these pulses to distinguish different information. Both theoretical analysis and simulation results verify that this novel scheme has a Signal to Noise Ratio (SNR) gain of about 1.75 dB compared with or- thogonal binary PPM, and has an SNR loss of about 1.4 dB compared with binary PAM. Although both the theoretical analysis and simulations are based on time-hopping multiple access, this modulation scheme can also be applied to other accessing techniques of UWB communication systems.
文摘From the view of practical application, this paper designs an infrared information collection nodes, the coordinator node, wireless transmission system using CC2430 microcontroller, and in detail design the infrared sensor （temperature, heart rate, ECG / pulse） circuit diagram. This paper set up a wireless network （ZigBee protocol）, sensor signal acquisition, wireless transmitting and receiving, serial communication software design of coordinator node and PC machine. Finally, we on-line debug each module of the system hardware and software. Experiments show that the network node data transmission accurate, reliable work, has basically met the design requirements.
基金supported by the National Key Technology R&D Program of China(Nos.2014BAD08B03 and 2013BAK06B04)the National Natural Science Foundation of China(Nos.61307124 and 11404129)+2 种基金the Science and Technology Department of Jilin Province of China(Nos.20120707 and 20140307014SF)the Changchun Municipal Science and Technology Bureau(Nos.11GH01 and 14KG022)the State Key Laboratory of Integrated Optoelectronics,Jilin University(No.IOSKL2012ZZ12)
文摘A mid-infrared carbon dioxide(CO_2) sensor is presented for the application in greenhouse environment. An integrated multi-pass gas chamber and a dual-channel differential detection method are adopted to decrease response time and suppress environmental influence, respectively. An optical module is developed using a cost-effective wideband mid-infrared light source, a dual-channel pyre electrical detector and a spherical mirror, and the moisture-proof function is specially designed for enabling the application of this sensor in greenhouse with high humidity. Experiments are carried out to evaluate the sensing performance on CO_2 concentration. According to the experimental results, the limit of detection(Lo D) is about 3×10^(-5) with an absorption length of 30 cm. The relative detection error is less than 5% within the measurement range of 3×10^(-5)—5×10^(-3). Based on 10 h long-term stability measurement on 5×10^(-4) and 2×10^(-3) standard CO_2 samples, the maximum fluctuations are 1.08% and 3.6%, respectively. By using a 2.4 GHz wireless network communication system for remote monitoring and data recording, a field measurement of this sensor in a greenhouse is conducted, and good performance is proven in such circumstance.
