Dispersed low-frequency radio astronomical pulses may result from exploding primordial black holes, gamma ray bursts, supernovae, or mergers of exotic objects, but have not yet been detected. Detection would be of great scientific significance because such events must involve extreme physics. The transient nature of these events makes detection unlikely with traditional instruments due to lack of sensitivity to single pulses and narrow field of view. For this thesis, a low-frequency wide-bandwidth astronomical search instrument has been developed as an alternative approach. This instrument consists of a single dipole which yields all-sky field of view, albeit at reduced sensitivity. The spectrum from 37 - 55 MHz is coherently digitized at 200 million samples per second, recorded, and analyzed off-line for the presence of dispersed pulses. A preliminary survey has been made at a remote site in western North Carolina. In a 20 minute observation, 9 detections greater than 6.5σ occurred, corresponding to pulses of ≤ 20 ms duration and dispersion measures (DMs) ranging from 15 to 70 pc cm⁻³. In addition, groups of pulses were detected ( 5) at DMs of 43.1, 52.1, and 52.2 pc cm⁻³. The possibility of association with known pulsars is considered; however, it is also possible these are due simply to radio frequency interference. Improvements to this instrument and survey technique are suggested. / Master of Science

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / It can be challenging to select the best architecture for DSP filters for a given application. Design constraints often include both objective and subjective information. This paper discusses the initial results of an investigation into using expert system techniques to address this problem. The goal is a system that allows users to specify traditional constraints such as impulse response, frequency response, stability, SNR, etc., but they may also constrain the filter’s cost, complexity, or any parameter which can be clearly identified for the specific application.

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / In many spacecraft receiver applications, the Fast Fourier Transform (FFT) provides a powerful tool for measuring the amplitude and frequency of an unmodulated RF signal. By increasing the FFT acquisition time, tiny signals can be coaxed from the noise and their frequency measured by determining which frequency bin the signal energy appears. The greater the acquisition time, the narrower the bin bandwidth and the more accurate the frequency measurement. In modern satellite operations it is often desirable for the receiver to measure the frequency of a carrier which is modulated with BPSK data. The presence of the BPSK data limits the FFT acquisition time since the signal may switch polarities a number of times while the FFT samples are being acquired. This polarity switching spreads the signal energy into multiple frequency bins making frequency measurement difficult or impossible. The Bit Templating Technique, used for the first time in the CMC Electronics Cincinnati TDRSS / BPSK Spacecraft Receiver, collects the modulated waveform energy back into a signal bin so that accurate amplitude and frequency information can be calculated.

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The drive towards higher accuracy and sampling rates has raised the bar for modern FTI signal conditioning. This paper focuses on the issue of anti-alias filtering. Today's 16-bit (and greater resolution) ADC’s, coupled with the drive for optimum sampling rates, means that filters have to be more accurate and yet more flexible than ever before. However, in order to take full advantage of these advances, it is important to understand the trade-offs involved and to correctly specify the system filtering requirements. Trade-offs focus on: • Analog vs. Digital signal conditioning • FIR vs. IIR Digital Filters • Signal bandwidth vs. Sampling rate • Coherency issues such as filter phase distortion vs. delay This paper will discuss each of these aspects. In particular, it will focus on some of the advantages of digital filtering various analog filter techniques. This paper will also look at some ideas for specifying filter cut-off and characteristics.

International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, Nevada / With the advancement in speed and complexity of Application Specific Integrated Circuits (ASICs), Digital Signal Processing (DSP) algorithms can now be used to achieve fully programmable, multiple channel demodulation of Frequency Modulation (FM) multiplexes. This paper describes the DSP algorithms and ASIC implementation used in the design of a digital FM demodulator system. Each digital demodulator has programmable subcarrier frequency demodulation to 4 MHz, programmable digital output filtering, and tape speed compensation (TSC). The demodulator output is available in both digital form for direct computer interface and in analog form for conventional analysis.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / During the cold war, undersea warfare (USW) was perceived as a large-area, deep-water operation. The need for USW has recently shifted to the shallow water, littoral environment. Consequently, US naval forces must train to operate in these littoral environments where regional conflicts are most likely to occur. In light of these requirements the Shallow Water Training Range (SWTR) has been initiated. Telemetry is used in the following areas of SWTR: fiber optic, microwave, RF and underwater. Only phase 1 of 8 phases of the program is executing therefore SWTR is a good opportunity for telemetry industry involvement.

International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / The monitoring of multi phase 400 Hz aircraft power includes monitoring the phase voltages, currents, real powers, and frequency. This paper describes the design of a multi channel card that uses digital signal processing (DSP) to measure these parameters on a cycle by cycle basis. The card measures the average, peak, minimum cycle, and maximum cycle values of these parameters.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / There are two misty understandings about PCM telemetry system in conventional concept: Waveform can not be restored accurately; to be restored accurately, a measured signal must be sampled at a higher sample rate. This paper discusses that by making use of multi-sample rate DSP technology, the sample rate of a measured signal can be reduced in transmission equipment, or system precision can be retained even if the performance of low pass filter declined.

Directly modulated lasers (DMLs) are a low cost solution for moderate reach systems due to their small footprint, low power dissipation and high output optical power. However, commercial 10-Gb/s on-off keying DMLs have been limited by an inherent modulation of the optical phase that accompanies the desired modulation of the optical intensity, which reduces their transmission distance to below 20 km. Furthermore, the ability to generate bit rates beyond 10-Gb/s with advanced modulation formats has been limited by the strict requirements on the laser drive current. The primary objective of this research is to dramatically enhance the capability of DML based systems through precise control over the drive current. This is achieved by digital signal processing (DSP) combined with a single digital-to-analog converter (DAC). In this research, a novel method to pre-compensate dispersion for metro and regional networks is demonstrated at 10.709-Gb/s. A look-up table (LUT) for the driving current is optimized for dispersion mitigation. Experimental results show a 25 fold increase in the transmission reach of a DML from 10 km to 252 km. A similar approach applied to a directly modulated chirp managed laser reveals a remarkable increase in the achievable transmission reach from 200 km to 608 km. In the context of access networks the DSP and DAC configuration is utilized for directly modulating a passive feedback laser (PFL) to generate differential phase shift keying (DPSK) signals at bit rates of 10.709-Gb/s, 14-Gb/s and 16-Gb/s. The quality of the DPSK signals is assessed using both noncoherent detection for a bit rate of 10.709-Gb/s and coherent detection with DSP involving a LUT pattern-dependent distortion compensator. For very short reach optical links, a 16-ary quadrature amplitude modulation signal is generated using subcarrier modulation with a subcarrier frequency of half the symbol rate, Nyquist pulse shaping, and a directly modulated PFL at bit rates up to 56-Gb/s. Using polarization multiplexing emulation, a pre-amplified direct detection receiver and DSP, loss margins of 12.6 dB and 8 dB are achieved for a 112-Gb/s dual polarization signal within a 33 GHz optical bandwidth at back-to-back and after 4 km transmission, respectively. / Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2013-01-31 13:58:56.327

International Telemetering Conference Proceedings / October 26-29, 1992 / Town and Country Hotel and Convention Center, San Diego, California / This paper addresses a method to provide both secure and non-secure voice communications to a DS-1 network from a common keyset. In order to comply with both the electrical isolation requirements and the operational security issues regarding voice communications, an all-digital approach to the keyset was developed based upon the AD2101 DSP. Protocols that are handled by the keyset include: Multiple PTT modes, hot mike, telephone access, priority override, direct access, indirect access, paging, and monitor only. Special features that are addressed include: independent channel by channel assignment of access protocols, headset assignment, speaker assignment, and PTT assignment. Multiple microprocessors are used to implement the foregoing as well as down-loadable configurations, remote keyset control and monitoring, and composite audio outputs. Partitioning of the digital design provides RED to BLACK channel isolation and RED channel to AC power isolation of greater than 107 dB.