Research note / Cycle 019
Before the first reading
An ideal RC simulation shows how a half-second uncertainty in the start of a test alters its early values.
The step that starts a clock
The Noema Institute's Aletheia program is examining conventional signal acquisition before attributing meaning to a source. How much circuit does the meter add? retained manually timed RC observations and a conditional meter-loading calculation. Those displayed times do not reveal the precise instant of electrical switching relative to the observer's stopwatch.
On January 30 Okafor and Ibarra execute a separate normalized model: an ideal unit step, nominal five-second RC time constant and readings at 2, 5 and 10 seconds. They run it twice, shifting the assumed step origin by exactly half a second in the second case. These are software outputs, not additional meter readings.
A small offset can matter early
At nominal 2 s, the ideal 0.330 response becomes 0.259 when the model's step begins half a second later. At 5 s the model changes from 0.632 to 0.593, and at 10 s from 0.865 to 0.850. The model specifies the offset, so it can calculate its consequences. The real apparatus has no comparably verified offset.
Analog Devices' RC teaching material supplies the conventional charging relation. The official JCGM 100:2008 publication record provides a general basis for uncertainty evaluation, not a numeric uncertainty for this meter. Neither reference fills in a missing timestamp or instrument specification.
An acquisition plan, not a fitted signal
The next check needs a verified switching timestamp, actual component values, wiring/loading limits and recorded sampling behavior. It must separate uncertain start time from the response itself. The earlier 0.91/0.50 V divider displays remain nominal, not instrument calibration. NIST's stopwatch calibration guide also identifies the need to characterize the timing device and its uncertainties; only its official publication abstract was consulted, and neither guide calibrates this apparatus.
The case does not change the program's ET/ED stance, find a biological signal or test an amplifier. A simulation that is perfectly timed by construction cannot prove that a real instrument was timed.
Results at a glance
| Model sample time (s) | No offset (normalized V) | Injected +0.5 s step delay (normalized V) |
|---|---|---|
| 2 | 0.330 | 0.259 |
| 5 | 0.632 | 0.593 |
| 10 | 0.865 | 0.850 |
External research and methods
- Activity: Transient Response of RC Circuit, For ADALM1000 · Analog Devices University Program · Wiki approved revision, 3 November 2021 19:14 (2021-11-03 approved wiki revision). Background, RC time constant and charging-voltage equation (3)..
- Evaluation of measurement data — Guide to the expression of uncertainty in measurement · Joint Committee for Guides in Metrology · JCGM 100:2008 (2008). Previously cited JCGM 100:2008; BIPM official publication listing and abstract (current check).
- Stopwatch and Timer Calibrations (2009 edition) · Jeff C. Gust, Robert M. Graham and Michael A. Lombardi · NIST Special Publication 960-12 (2009 edition) (2009-01-28). NIST publication record and abstract on stopwatch calibration and timing-device uncertainty.