Question

Please give brief descriptions and examples with diagrams on
TXCVR
TYPES OF COMMON FILTERS
BER VS POWER RELATIONSHIPS IN DB SCALE

Answer 1

TXCVR: transceiver is an antenna which can transmit and also receive Electromagnetic signals or waves. these transceivers are also impedence matching networks which deliver or can receive maximum power so that the noise or interference is less and quality of signal is more.

example. A basic transceiver using Bipolar junction transistor.

the common emitter configuration provides the amplification function to the transceiver. Please note that the Z_l in the figure is not actually a load. if you place an earphone at the position of load the transmitter wouldn't work. So to actually eliminate that problem, we add inductor in series with a resistor to not allow very high frequency signals such as noise.

Types of filters are Low pass, high pass, bandpass and a band stop(band reject or notch filter).

-->low pass will just allow low frequency signals. this is done by using a resistor in series with capacitor.

-->high pass filter will just allow high frequency signals .

-->bandpass or bandreject filters are the ones which allow or stop certain frequency components of a signal. these filters can be implemented by connecting high pass and low pass filters.

the circuits and their responses are shown below.

first of all BER(bit error rate) is the number of bit errors per unit timeperiod. which means it is a ratio of error bits to the number of bits transmitted. just like Signal to noise ratio.

But SNR ratio is related to the power levels of the signal where as BER is related to the information contained in the signal.

the relation between the BER and power is by decreasing number of error bits you increase the power efficiency of a system. the equation can be expressed as,

( )

this equation is for Bipolar NRZ.(non return to zero)

here Q is the Q function and N_o is the noise power. This equation can be converted as

where P is received power and R_b is bit transmission rate.

Hope this helps.

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