40 C.F.R. § 1065.202
Your test system must be able to update data, record data and control systems related to operator demand, the dynamometer, sampling equipment, and measurement instruments. Set up the measurement and recording equipment to avoid aliasing by ensuring that the sampling frequency is at least double that of the signal you are measuring, consistent with good engineering judgment; this may require increasing the sampling rate or filtering the signal. Use data acquisition and control systems that can record at the specified minimum frequencies, as follows:
Table 1 of § 1065.202 -Data Recording and Control Minimum Frequencies
| Applicable test protocol section | Measured values | Minimum command and control frequencya | Minimum recording frequencybc |
| § 1065.510 | Speed and torque during an engine step-map | 1 Hz | 1 mean value per step. |
| § 1065.510 | Speed and torque during an engine sweep-map | 5 Hz | 1 Hz means. |
| § 1065.514 ; § 1065.530 | Transient duty cycle reference and feedback speeds and torques | 5 Hz | 1 Hz means. |
| § 1065.514 ; § 1065.530 | Steady-state and ramped-modal duty cycle reference and feedback speeds and torques | 1 Hz | 1 Hz. |
| § 1065.520 ; § 1065.530 ; § 1065.550 | Continuous concentrations of raw or dilute analyzers | 1 Hz. | |
| § 1065.520 ; § 1065.530 § 1065.550 | Batch concentrations of raw or dilute analyzers | 1 mean value per test interval. | |
| § 1065.530 ; § 1065.545 | Diluted exhaust flow rate from a CVS with a heat exchanger upstream of the flow measurement | 1 Hz. | |
| § 1065.530 ; § 1065.545 | Diluted exhaust flow rate from a CVS without a heat exchanger upstream of the flow measurement | 5 Hz | 1 Hz means. |
| § 1065.530 ; § 1065.545 | Intake-air or raw-exhaust flow rate | 1 Hz means. | |
| § 1065.530 ; § 1065.545 | Dilution air flow if actively controlled (for example, a partial-flow PM sampling system)d | 5 Hz | 1 Hz means. |
| § 1065.530 ; § 1065.545 | Sample flow from a CVS that has a heat exchanger | 1 Hz | 1 Hz. |
| § 1065.530 ; § 1065.545 | Sample flow from a CVS that does not have a heat exchanger | 5 Hz | 1 Hz means. |
a The specifications for minimum command and control frequency do not apply for CFVs that are not using active control.
b 1 Hz means are data reported from the instrument at a higher frequency, but recorded as a series of 1 s mean values at a rate of 1 Hz.
c For CFVs in a CVS, the minimum recording frequency is 1 Hz. The minimum recording frequency does not apply for CFVs used to control sampling from a CVS utilizing CFVs.
d Dilution air flow specifications do not apply for CVS dilution air.
40 C.F.R. §1065.202