Receive Bandwidth

Experimental Setup
In order to study and measure the receive bandwidth on the Sonix Systems, a series of experiments were performed. A signal generator was used for this purpose with the following settings: For each frequency, the signal was injected into the probe connector. The RF data corresponding to each signal was then recorded using RF mode for off-line processing. This process was repeated for all the frequencies.
 * Continuous wave sinusoidal signal,
 * The amplitude of the signal was set to be 20 mVpp (peak to peak),
 * The frequency of the signal was changed from 1MHz to 20MHz in steps of 1MHz.

The following Sonix systems we used for this study:
 * SonixRP (32 element receive aperture),
 * SonixTOUCH (64 element receive aperture),
 * SonixTOUCH version 4 hardware with adjustable anti-aliasing filter:
 * Anti-aliasing with 10MHz cutoff frequency
 * Anti-aliasing with 15MHz cutoff frequency
 * Anti-aliasing with 20MHz cutoff frequency
 * Anti-aliasing with 30MHz cutoff frequency

For all the systems decimation was set to be zero (i.e. 40MHz sampling frequency). To avoid signal saturation, the System gain was set to be low.

Signal Processing and Results
Recorded RF data were processed off-line. Fourier analysis was performed to estimate the transfer function for each system. A sample RF signal at 5MHz is shown in a figure below for both SonixRP and SonixTouch systems:



The estimated transfer function for all the systems are shown in the figure below. The results are displayed in dB. Separate normalization was used for each graph.



Remarks
SonixRP
 * -6dB drop from 3 to 5MHz,
 * -6dB drop from 5 to 7.5MHz,
 * -6dB drop from 7.5 to 10MHz.

SonixTOUCH
 * -6dB drop from 2 to 10MHz,
 * -12dB drop from 10 to 15MHz.

SonixTOUCH version 4 hardware
 * 10dB improvement compared to Old Touch @15MHz and 20dB improvement compared to the RF/OP/SP @15MHz,
 * -6dB to -12dB gain drop is still present at 15MHz to 20MHz.