Digital RF-Mode provides data in digital (raw) format for further analysis

Vevo 2100 System

Digital RF-Mode allows users to acquire, digitize and view the raw RF data from the high-frequency ultrasound signal. MicroScan™ transducers convert electrical energy into a pressure wave which is transmitted into the tissue (transmitted pulse). Differences in density and speed of sound within tissue scatter the transmitted pulses such that a portion of the sound waves reflect back towards the transducer. When these reflected waves reach the transducer they are converted into an electrical signal which is amplified, digitized and processed to generate the image. Usually, the signal received by the transducer is composed of a number of reflections which combine together to form an interference pattern known as speckle. This receive signal is commonly referred to as an RF (radio frequency) signal. After amplification, the receive signal is sampled, (converted into a digital signal), and processed by the beamformer. Quadrature sampling is used, which converts the RF signal into two digital quadrature signals, the I (in-phase) and the Q (quadrature) signals, referred to collectively as the IQ signal. The beamformer processes data which is in the IQ data format. If required, a digital representation of the RF signal can be reconstructed from the IQ data. 

Raw Image Data

IQ data can be envelope detected and log compressed to then be exported as a raw data file (*.rfw). Envelope format is a useful way of storing raw data that correlates exactly to what is seen in the B-Mode image and is readily available for image processing applications.

Digital RF-Mode

Additionally, the RF data can be reconstructed from IQ data by a process which includes interpolation of the I and Q signals and multiplication by a complex exponential (e-jωt where ω=2πf; f= the quadrature sampling frequency and e-jωt= cos (2πf) + jsin (2πf)).

This option is available for Vevo 2100 and Vevo 770 Imaging System.

Graphical representation of VisualSonics data products
*Note that envelope data are log compressed prior to export as raw data (*.rfw)