TAILIEUCHUNG - DISCRETE-SIGNAL ANALYSIS AND DESIGN- P15

DISCRETE-SIGNAL ANALYSIS AND DESIGN- P15:Electronic circuit analysis and design projects often involve time-domain and frequency-domain characteristics that are difÞcult to work with using the traditional and laborious mathematical pencil-and-paper methods of former eras. This is especially true of certain nonlinear circuits and sys- tems that engineering students and experimenters may not yet be com- fortable with. | 56 DISCRETE-SIGNAL ANALYSIS AND DESIGN over the region 0 to 6000 Hz between adjacent channels. In a bandwidth P f 1Hz bw dBm -40 dBm - 20 f dB 6000 J 3-6 We convert dBm per Hz to watts per Hz integrate from 0 to 6000 Hz and adjust to the 300-Hz instrument bandwidth 300 r6000 6 Pout of band W P f df x 10-6Win300Hz 6000 0 3-7 The average Poutofband in dBm in a 300-Hz band is . The ratio of in-band to out-of-band power for a 300-Hz bandwidth is dBm dBm dB. Note the method of employing dBm and dB in an equation. If both sides of the filter are considered which they are not at this time the ratio becomes 3 dB smaller. We want the power in the alias zone shown in Fig. 3-6. To get this integrate the out-of-band spectrum P f from 3000 to 6000 Hz multiply by 2 to get both halves of the alias zone and adjust for the 300-Hz instrument bandwidth 300 6000 Pa AïôôïL P f df x 10-6 W dBm 3-8 The ratio of in-band power to alias band power between the two bands shown is dBm dBm dB. Subtract 3 dB for an additional alias band on the left side of the diagram. The instrument for this measurement can be a calibrated spectrum analyzer. Since the noise signal is the same kind at every frequency and amplitude of interest in this example we do not worry about the fact that the amplitude reading for noise on a spectrum analyzer is not quite the same as for a sine wave. The relative dB readings are correct. Also in Eqs. 3-7 and 3-8 we are finding the average power over the specified band and then normalizing that average power to a SPECTRAL LEAKAGE AND ALIASING 57 6 kHz 10 kHz 6 kHz 10 kHz a Figure 3-6 Power in the aliasing zone. 300 Hz bandwidth. It is important to not change any analyzer settings that might affect the internal adjustments or calibrations of the instrument. Finally if the spectrum analyzer contains a high-quality tracking generator it can be used as a sine-wave signal source instead of a noise generator. .

• Đồ họa - Thiết kế - Flash
• Cách sử dụng Corel
• thiết kế trực quan CorelDRAW
• Tạo đối tượng 3D
• công cụ Extrude
• nghệ thuật thiết kế
• phuơng pháp vẽ 3D
• hướng dẫn CrelDraw cơ bản
• Hướng dẫn sử dụng CrelDraw
• công cụ thiết kế đồ họa
• graphics design
• cách dùng Corel DRAW