Long-distance comparison of measures and measuring apparatus

Conclusions

• 1. The long-distance comparison of measures and measuring instruments is in principle perfectly possible, but at the moment there are a number of limiting factors which prevent us from selecting an optimum version for the solution of the problem. These primarily include: a) the fact that at the moment there is only one physical quantity (a time interval) capable of being transmitted to great distances with adequate metrological accuracy; b) the necessity of furnishing the receiving points in the system of long-distance comparison with converters previously certified at the transmitting end by reference to the original converter, these being capable of retaining their certified metrological characteristics for a long time.

• 2. The process of long-distance comparison differs fundamentally from long-distance transmission in telemetric systems, since in the latter case the channel links two ends with a single system of reckoning and is designed for the transmission of coded information, while in the former case we are concerned with the long-distance matching of two reckoning systems, in which the value of a real physical quantity must necessarily be transmitted along the channel.

• 3. Despite the necessity of providing the receiving points with calibrated and certified converters, the introduction of a system of long-distance comparison will offer substantial advantages in comparison with existing methods of transmitting the values of measuring units from higher to lower links in the chain. One of the main advantages (not counting that of eliminating the necessity of transporting various measuring instruments) is the possibility of developing and mass-manufacturing unified converters for converting various physical quantities into the form of a capacity for subsequent transmission of their values and comparison at the receiving point. Subject to an acceptable accuracy of the converters, this will greatly reduce the number and range of classification of the standard instruments used for many forms of measurements.