On counters used for node synchronization
A suboptimal quick look decoding algorithm for the deep space network convolutional code is discussed. Particular emphasis is given to the encoding and decoding schemes.
Greenhall, C. A.↗
Engineering topics
Greenhall, C. A.
Publications and source records attributed to Greenhall, C. A..
A quick-look decoder with isolated error correction and node synchronization
It is noted that in a low-noise environment, a simple inversion circuit can be used for quick-look decoding of a convolutional code. An improvement in the bit error performance of the raw inversion circuit is effected by a simple pattern-recognition technique operating on the syndrome stream, which is also used to acquire node sync.
Greenhall, C. A.↗
Open-loop radio science with a suppressed-carrier signal
When a suppressed-carrier signal is squared, the carrier reappears in doubled form. An open-loop receiver can be used to deliver a recording of a band-limited waveform containing this carrier, whose amplitude and phase can be tracked by the radio science experimenter.
Greenhall, C. A.↗
Internal noise of a phase-locked receiver with a loop-controlled synthesizer
A local oscillator design that uses a digitally programmed frequency synthesizer instead of an analog VCO was proposed. The integral of the synthesizer input, the digital phase, is a convenient measure of integrated Doppler. The internal noise of such a receiver was examined. At high carrier margin, the local oscillator phase noise equals that of the Block IV receiver, about 2 deg rms at S-band, whereas the digital phase noise is about 0.5 deg rms.
Greenhall, C. A.↗
Some effects of quantization on a noiseless phase-locked loop
If the VCO of a phase-locked receiver is to be replaced by a digitally programmed synthesizer, the phase error signal must be sampled and quantized. Effects of quantizing after the loop filter (frequency quantization) or before (phase error quantization) are investigated. Constant Doppler or Doppler rate noiseless inputs are assumed. The main result gives the phase jitter due to frequency quantization for a Doppler-rate input. By itself, however, frequency quantization is impractical because it makes the loop dynamic range too small.
Greenhall, C. A.↗
Quick-look decoding schemes for DSN convolutional codes
Decoding schemes are proposed for the tracking systems of the galileo project. Quick look decoding schemes requiring only shift registers are given for the DSN (7, 1/2) and (7, 1/3) convolutional codes. These schemes are used when the communication channel is error free. The schemes decode the data, symbol errors, and the lack of node syncronization.
Greenhall, C. A.↗
S-band maser phase delay stability tests
The results of the S-band traveling wave maser phase delay stability measurements performed at DSS 62 are presented. These tests were required for the Pioneer-Venus wind experiment.
Urech, J. M.↗
Simulation of time series by distorted Gaussian processes
Distorted stationary Gaussian process can be used to provide computer-generated imitations of experimental time series. A method of analyzing a source time series and synthesizing an imitation is shown, and an example using X-band radiometer data is given.
Greenhall, C. A.↗
DSN telemetry system performance with convolutionally coded data: Sequential decoding update
DSN telemetry system performance in decoding convolutionally coded data by both sequential and maximum likelihood techniques is being determined by testing at various deep space stations. This article describes corrections and refinements to the sequential decoding tests.
Greenhall, C. A.↗
DSN performance tests of a maximum likelihood decoder
Viterbi decoding tests were carried out at DSS 62, Madrid, Spain. Results of bit error rate, burst statistics, and estimation of signal-to-noise ratio are presented.
Urech, J. M.↗
DSN telemetry system performance with convolutionally code data
The results obtained to date and the plans for future experiments for the DSN telemetry system were presented. The performance of the DSN telemetry system in decoding convolutionally coded data by both sequential and maximum likelihood techniques is being determined by testing at various deep space stations. The evaluation of performance models is also an objective of this activity.
Mulhall, B. D. L.↗