Steven H. Goode

A comparison of a limiter-discriminator, delay and coherent detection for pi /4 QPSK

A brief description is given of limiter-discriminator, delay, and coherent detection of pi /4 quadrature phase shift keying (QPSK). Simulated bit error rate (BER) performance of these detectors in static and Rayleigh faded fields is presented. Performance in delay spread faded fields is also given. Results of the use of an equalizer with the coherent detector in delay spread faded fields is evaluated. Three methods of detecting pi /4 QPSK are evaluated. A brief description of the operation and an estimate of implementation complexity is given for each detector. Simulated results of BER performance for each detector in static, Rayleigh, and delays spread faded fields are then presented. The use of an adaptive decision feedback equalizer with a coherent detector is then evaluated for use in delay spread faded fields.<<ETX>>

A comparison of Gaussian minimum shift keying to frequency shift keying for land mobile radio

Data is presented comparing Gaussian Minimum Shift Keying (GMSK) to Frequency Shift Keying (FSK) for use in the UHF land mobile radio band at 800 MHz. The FSK system uses a Gaussian premodulation filter set at one half the bit Pate. Deviation is set at 0.41 times the bit rate. The FSK receiver has an IF bandwidth of 1.0 times the bit rate and uses discriminator detection. The GMSK system uses coherent detection. Data is presented on the effect of premodulation cutoff frequency and receiver bandwidth on system sensitivity and spectral efficiency. From this data a relationship between channel spacing, frequency stability, IF bandwidth, and transmitter spectrum is derived. Additional data on the performance of the FSK and GMSK systems in Rayleigh fading is presented.

An evaluation of the tone calibrated technique for data transmission over land mobile radio channels

The performance in land mobile radio channels of the Tone Calibrated Technique for data transmission originally proposed by the Jet Propulsion Laboratory is experimentally evaluated. A transmitter implementation allowing spectral shaping at baseband is presented. A phase coherent receiver structure is also presented which uses a hard limiter to remove the fading envelope. Data on the performance of this tone calibrated system and of a frequency shift keyed system are compared. A simple method of evaluating a modulation system for fading protection is advanced. By observing the response of the system to a double sideband modulated tone interferer a rough idea of the performance of the system in fading can be obtained.

An open-loop technique for the detection of minimum shift keyed signals

An open-loop technique for the coherent detection of Minimum Shift Keyed (MSK) signals is presented. This technique allows direct observation of a recovered carrier. Observations of the recovered carrier when this detector is used to demodulate Gaussian Minimum Shift Keyed (GMSK) signals are presented. Data is also presented comparing this open-loop detector to a conventional closed-loop detector in static and Rayleigh fading fields.