Design and Evaluation of Digital Baseband Converter Sub-channel Delay Compensation Method on Bandwidth Synthesis

The effect of sub-channel delay on bandwidth synthesis is investigated to eliminate the “phase step” phenomenon in bandwidth synthesis during the test of CDBE (Chinese Digital Backend). Through formula derivation, we realize that sub-channel delay may cause phase discontinuity between different sub-channels. Theoretical analysis shows that sub-channel delay can induce bandwidth synthesis error in group delay measurement of the linear system. Furthermore, in the differential delay measurement between two stations, bandwidth synthesis error may occur when the LO (Local Oscillator) frequency differences of corresponding sub-channels are not identical. Error-free conditions are discussed under different applications. The phase errors among different sub-channels can be removed manually. However, the most effective way is the compensation of sub-channel delay. A sub-channel delay calculation method based on Modelsim is proposed. The compensation method is detailed. Simulation and field experiments are presented to verify our approach

Investigation of Subjectively Assessed Health Symptoms and Human Thermal Perceptions in Transient Thermal Environments

AbstractPeople are often likely to expose themselves to sudden temperature change in daily life and they may suffer from not only thermal discomfort but also even some health symptoms. In this study, the influence of different air temperature steps (S5:32°C-37°C-32°C, S11:26°C-37°C-26°C, and S15:22°C-37°C-22°C) on subjective health symptoms and thermal perceptions was studied with 24 volunteered participants in the laboratory experiment. Several subjective rating scales were used to assess participant's subjective feelings imposed by temperature steps. Our results show that perspiration, eyestrain, dizziness, accelerated respiration and heart rate are found to be sensitive self-reported symptoms in response to temperature step changes. Thermal sensation and comfort just before temperature step are significantly distinguished from that immediately after step change except for thermal comfort under up step situation of S15 (22oC-37oC). Moreover, temperature step amplitude and direction have significant impact on subjective perceptions