Radio--Receivers and reception

In this research project the objective is to realize a software - hardware design implementation of a real time digital signal processing (DSP) radiometer - receiver for atmospheric noise temperature detection using the digital cross correlation technique. Atmospheric noise in the band of 20-30 GHz band is down-converted to 10.7
MHz IF and 3 MHz bandwidth in the form of statistical additive white gaussian noise
which is used as the received signal by a digital signal processing broadband microwave
radiometer based on the digital cross correlation technique.
Living in a technological era, which is characterized as the era of data
transmission and reception for RF-wireless communication systems, the theory of RF
digital signal processing detection has applied to radar, ultrasound, and digital
communications. Due to the need of high speed of data detection, much effort has gone into the
design and development of sophisticated equipment to obtain such DSP detectors.
Detection can also apply in seismic and big earthquake measurements by using
geophones, nuclear testing, sonar and acoustic localizations, and even for oil excavations.
Based on a statistical model and proposed design implementation, a basic DSP
atmospheric noise temperature radiometer system is introduced and developed. The
realization of the DSP Radiometer examines the noise characteristics (parameters) and
their corresponding parameter values at the received input at the Antenna. It is essential
to introduce the fundamental and statistical properties of the additive white gaussian
noise, as well as the key-parameters which are used for the development of this real time
design implementation. A design implementation of the proposed DSP atmospheric noise
radiometer is discussed and developed via a statistical analysis. The statistical analysis
utilizes the standard deviation, intermediate frequency, bandwidth, number of samples,
and the temperature of the noise received signal at the antenna. Measurements and real
time simulations in order to evaluate the noise temperature’s detectability in terms of
system’s accuracy and performance of the noise random variable are also presented in
this research work. The advantage of the digital cross correlation technique is examined
and investigated.

Time Division Multiple Access (TDMA) architecture is an established technology for digital cellular, personal and satellite communications, as it supports variable data rate transmission and simplified receiver design. Due to transmission bandwidth restrictions, increasing user demands and the necessity to operate at lower signal-to-noise ratio (SNR), the TDMA systems employ high order modulation schemes such as M-ary Quadrature Amplitude Modulation (M-QAM) and burst transmission. Use of such techniques in low SNR fading channels causes degradations of carrier frequency error, phase rotation error, and symbol timing jitter. To compensate for the severe degradation due to additive white Gaussian noise (AWGN) and channel impairments, precise and robust synchronization algorithms are required. This dissertation deals with the synchronization techniques for TDMA receivers using short burst mode transmission with emphasis on preamble-less feedforward synchronization schemes. The objective is to develop new algorithms for symbol timing, carrier frequency offset acquisition, and carrier phase tracking using preamble-less synchronization techniques. To this end, the currently existing synchronization algorithms are surveyed and analyzed. The performance evaluation of the developed algorithms is conducted through Monte-Carlo simulations and theoretical analyses. The statistical properties of the proposed algorithms in AWGN and fading channels are evaluated in terms of the mean and variance of the estimated synchronization errors and their Cramer-Rao lower bounds. Based on the investigation of currently employed feedforward symbol timing algorithms, two new symbol timing recovery schemes are proposed for 16-QAM land mobile signals operating in fading channels. Both schemes achieve better performance in fading channels compared to their existing counterparts without increasing the complexity of the receiver implementation. Further, based on the analysis of currently employed carrier offset and carrier phase recovery algorithms, two new algorithms are proposed for carrier acquisition and carrier tracking of mobile satellite systems utilizing short TDMA bursts with large frequency offsets. The proposed algorithms overcome some of the conventional problems associated with currently employed carrier recovery schemes in terms of capture range, speed of convergence, and stability.