Dual-mixer time-difference multiplication (DMTDM) has already been investigated within the EUROMET Project #651 (completed by the end of 2004). The investigation was focused on short-term frequency (phase, time) stability measurement. In cooperation between IREE and BNM-SYRTE OP, an ultra-low-noise multiplier has been designed which currently has the Allan deviation of 7E-15 at 1s and the flicker-phase-floor time deviation of about 2 fs (5 MHz carrier, 15 Hz cutoff, 0.2s basic sampling interval). The excellent noise performance is stimulating our interest in further studying the DMTDM classical circuit structure and its possible applications in metrology. The proposed project will facilitate cooperation in solving the following problems :
Application in frequency (phase, time) short-term stability measurement: We will determine the practical limit of the noise floor by experimenting with a new version of the IEEE DMTDM whose construction will build on experience gained from previous research.
Application in time-delay measurement: We will investigate the performance of DMTDM in measurement of small delays in elements such as short cables, connectors and adaptors introduced into one of the DMTD input arms. A special version of the DMTD multiplier optimized for this application will be constructed.
Application in measurement of other physical quantities that can be transformed into time delay : The idea is to make use of the extreme sensitivity of DMTD multiplication for sensing variations in these quantities.