- Mission Analysis.
Kepler’s laws. Circular and elliptical satellite orbits. Altitude regimes. Period of revolution. Geostationary Orbit. Orbital elements. Ground trace.
- Earth-Satellite Geometry.
Azimuth and elevation. Slant range. Coverage area.
- Signals and Spectra.
Properties of a sinusoidal wave. Synthesis and analysis of an arbitrary waveform. Fourier Principle. Harmonics. Fourier series and Fourier transform. Frequency spectrum.
- Methods of Modulation.
Overview of modulation. Carrier. Sidebands. Analog and digital modulation. Need for RF frequencies.
- Analog Modulation.
Amplitude Modulation (AM). Frequency Modulation (FM).
- Digital Modulation.
Analog to digital conversion. BPSK, QPSK, 8PSK FSK, QAM. Coherent detection and carrier recovery. NRZ and RZ pulse shapes. Power spectral density. ISI. Nyquist pulse shaping. Raised cosine filtering.
- Bit Error Rate.
Performance objectives. Eb/No. Relationship between BER and Eb/No. Constellation diagrams. Why do BPSK and QPSK require the same power?
- Coding.
Shannon’s theorem. Code rate. Coding gain. Methods of FEC coding. Hamming, BCH, and Reed-Solomon block codes. Convolutional codes. Viterbi and sequential decoding. Hard and soft decisions. Concatenated coding. Turbo coding. Trellis coding.
- Bandwidth.
Equivalent (noise) bandwidth. Occupied bandwidth. Allocated bandwidth. Relationship between bandwidth and data rate. Dependence of bandwidth on methods of modulation and coding. Tradeoff between bandwidth and power. Emerging trends for bandwidth efficient modulation.
- The Electromagnetic Spectrum.
Frequency bands used for satellite communication. ITU regulations. Fixed Satellite Service. Direct Broadcast Service. Digital Audio Radio Service. Mobile Satellite Service.
- Earth Stations.
Facility layout. RF components. Network Operations Center. Data displays.
- Antennas.
Antenna patterns. Gain. Half power beamwidth. Efficiency. Sidelobes.
- System Temperature.
Antenna temperature. LNA. Noise figure. Total system noise temperature.
- Satellite Transponders.
Satellite communications payload architecture. Frequency plan. Transponder gain. TWTA and SSPA. Amplifier characteristics. Nonlinearity. Intermodulation products. SFD. Backoff.
- Multiple Access Techniques.
Frequency division multiple access (FDMA). Time division multiple access (TDMA). Code division multiple access (CDMA) or spread spectrum. Capacity estimates.
- Polarization.
Linear and circular polarization. Misalignment angle.
- Rain Loss.
Rain attenuation. Crane rain model. Effect on G/T. Frequency dependence.
- The RF Link.
Decibel (dB) notation. Equivalent isotropic radiated power (EIRP). Figure of Merit (G/T). Free space loss. Why does the free space loss depend on wavelength? Satellite EIRP and G/T footprints. Power flux density. Carrier to noise ratio. The RF link equation.
- Link Budgets.
Communications link calculations. Uplink, downlink, and composite performance. Link budgets for single carrier and multiple carrier operation. Detailed worked examples.
- Performance Measurements.
Satellite modem. Use of a spectrum analyzer to measure bandwidth, C/N, and Eb/No. Comparison of actual measurements with theory using a mobile antenna and a geostationary satellite.
In addition to the course notes, each participant will receive a book
of collected tutorial articles written by the instructor, and soft
copies of the link budgets discussed in the course.
