Direct digital recording of air pollution measurements
John S. Nader, William L. Coffey · Proc., Annu. Meet., Air Pollut. Control Assoc.; (United States) · 1961
A modification of a commercially available punch tape recorder is presented, in which analog information is converted directly into digital data (binary-decimal code) on punched paper tape. The prototype was designed to give 3 digit full scale output (000 to 999) for full scale signals as low as 10 mv and as high as 100 mv. It is provided with span and zero adjustments and electrical overtravel at both ends of the range. Accuracy is +/- 0.1% or +/- 50 microvolts, whichever is greater. Response is linear and full range (000 to 999) response is approximately 3.5 seconds. Reproducibility is within +/- 0.05% of full scale. Additional results of a performance evaluation are given and application of the instrument to air pollution is discussed. 4 figures.