fastest growing service network
Fastest growing service network
Indeed, it is rarely possible to be in line of sight with a transmitter, it can be obscured by a building. In this case, it is sufficient to receive an echo or mobile recharge api a sum of echoes, sufficiently reflected by another building. Frequency distortion, Doppler effect. A mobile having a velocity v in the of a sinusoidal wave, receives a sinusoidal signal whose frequency is offset from the emitted frequency.
If the direction is arbitrary, the frequency shift depends on the mobile recharge api vector component projected speed on the mobile axis- transmitter. The relationship is as follows. Networks Academic year 2010-2011 More mobile goes fast, and the offset is important. The latter remains between example is that of a car on the highway, passing next to a transmitter.
Almost brutally, Shift changes from negative to positive, the image sound of a motorcycle, passing abruptly from low to high when it exceeds us. It follows, having regard to the receiver, that the carrier frequency does not mobile recharge api appear stable. In general, the use of a PLL during demodulation, makes it possible to follow these frequency variations. The phenomenon is even more complicated in reality.
The reception is made of many of reflected signals, the frequency shift depends on the relative speed of the mobile mobile recharge api with respect in each direction reflections. The frequency shift is different for all reflections. This virtually amounts to the same thing to consider a shift single frequency of a carrier with poor spectral purity. The width of the spectrum of 2.f.v/ c.
The frequency shift is relatively low in general, but in the case of narrow band transmission, it can be annoying making out the band used the allocated channel. In the context of frequency modulation, it will choose a tour sufficiently high frequency mobile recharge api compared to the Doppler shift as possible. Propagation loss As with any radio link, the greater the distance, the more power is low. The received power is proportional to the transmitted power, and conversely proportional to the square of the distance (Formula Fritz Networks Academic year 2010-2011 PR received power PE power emissions recharge retailer network GE Gain from issue GR Gain on receipt Wavelength d distance transmitter-receiver To have a good transmission quality, it is necessary recharge retailer network that the received power is sufficient.