Calculate the ratio horizon for a 500-ft transmitting

Question

Telecommunications part 1 (Please show all work):

1. A signal level of 0.4μV is measured on the input to a satellite receiver.  Express this voltage in terms of dBμV. Assume a 50-Ω system.

2. A microwave transmitter typically requires a +8dBm audio level to fully drive the input.  If a +10dBm level is measured, what is the actual voltage level measured? Assume a 600-Ω system.

3. If an impedance matched amplifier has a power gain (Pout / Pin) of 15, what is the value of the voltage gain (Vout / Vin)?

4. Determine the deviation ratio for an FM system that has a maximum possible deviation of 5 kHz and the maximum input frequency is 3 kHz. Is this narrow- or wideband FM?

5. A receiver with a 10 MHz bandwidth has a S/N of 5dB and a sensitivity of -96dBm.  Calculate the NF.

6. What is the dynamic range (in dB) for a 12-bit PCM system?

7. Calculate the number of bits required to satisfy a dynamic range of 48dB.

8. The transmit power for a digital communications device is 1 W.  The data rate is 28.8kbps. Determine the energy per bit.

9. A 56kbps NRZ-L encoded data stream is used in a digital communication link.  Determine the minimum bandwidth required for the communications link.

Telecommunications part 2 (Please show all work):

1. A balanced transmission line picks up an undesired signal with a 5 mW level.  After conversion to an unbalanced signal using a center-tapped transformer, the undesired signal is 0.011μW. Calculate the common mode rejection ratio, CMRR.

2. A fast rise-time 10-V step voltage is applied to a 50-Ω line terminated with an 80-Ω resistive load. Determine the reflection coefficient Γ , E_F and E_R.

3. Calculate the ratio horizon for a 500-ft transmitting antenna and a receiving antenna of 20 ft. Calculate the required height increase for the receiving antenna if a 10% increase in the radio horizon were required.

4. An antenna has a maximum forward gain of 14dB at its 108-MHz center frequency. Its reverse gain is -8dB. Its bandwidth extends from 55 to 185 MHz, calculate  a) the bandwidth    and    b) the F/B ratio of the antenna.

5. Calculate the effective radiated power (ERP) of an antenna with a gain of 5 at a power of 0.5 kW.

6. The antenna in question 5 above has a forward gain of 18dB and a reverse gain of 5dB, calculate the F/B ratio of this antenna.

7. A ship radio-telephone transmitter operates at 2738 kHz.  At a distant point from the transmitter, the 2738 kHz signal has a measured field of 147mV/m. The second harmonic field at the same point is measured as 405  μV/m. How much has the harmonic emission been attenuated below the 2738 kHz fundamental?

8. Calculate the maximum usable range for a radar system with a PRT of 400 μs.

9. A green LED light source functions at a frequency of 5.7 x 10¹⁴ Hz, calculate its wavelength.

Answer 1

For the following numerical problem relating to electronics, solve each question by applying the laws of electrical engineering and provide the solution. 1) A signal level of 0.4µV is evaluated on the input to a satellite receiver. Deduce this voltage in terms of dBµV. Consider a 50-O system. 2) A microwave transmitter generally needs a +8dBm audio level to completely drive the input. If a +10dBm level is evaluated, determine the actual voltage level measured? Consider a 600-O system. 3) If an impedance matched amplifier consists of a power gain (Pout/Pin) of 15, determine the value of the voltage gain (Vout/Vin)? 4) Find out the deviation ratio for an FM system which consists of a maximum possible deviation of 5 kHz and the maximum input frequency is 3 kHz. Is this narrow or wide-band FM? 5) A receiver having a 10 MHz bandwidth consists of S/N of 5dB and a sensitivity of -96dBm. Compute the NF.