Regarding rf data spectrum

[Alighieri1231]

Hello,
I am doing a comparison of a CIRS phantom in clarius using H-scan

While in verasonics for the same phantom the map is like this

In clarius C3 (3.5Mhz)

In clarius L15 (10Mhz) is like this:

I realized while in verasonics the spectrum of the RF data is centered like this

In clarius C3 spectrum

In clarius the L15 spectrum (after passing a high pass filter at 0.5Mhz - Because I realized there is a DC component) is like this:

So the fitting of the RF data for L15 is a bit weird. I wanted to know if are you using harmonics or why do I have signal after 11 Mhz (raw spectrum). what would be a recommended bandpass filter then?

As an extra question, I am using RF data to reconstruct my Bmode. I wanted to know if I use IQ data this IQ data has better resolution and if I can modulate this IQ into a RF data to have an improved spectra.

Thanks in advance.

[HamidClarius]

Thank you for your comment.

The L15 RF spectrum looks broad because the probe is excited with short pulses rather than a pure continuous 10 MHz sine wave. Short pulses naturally contain a wide range of frequencies, and the transducer responds according to its own bandwidth and resonant modes. Based on the measured response, the dominant resonance appears around 7–8 MHz, with additional energy extending beyond 11 MHz due to the broadband nature of the probe and possible higher-order mechanical modes. Therefore, the signal observed above 11 MHz is most likely part of the normal broadband response of the probe rather than harmonic imaging.

For B-mode reconstruction, a bandpass filter around the main energy region should work well, for example 5–13 MHz, or slightly narrower (6–12 MHz) if lower noise is preferred.

Using IQ data does not inherently improve image resolution. IQ mainly simplifies signal processing because it stores the signal in baseband form while preserving both amplitude and phase information. IQ data can be remodulated back into RF, but this will not create additional frequency content or improve the spectrum beyond what was originally captured by the transducer.

You may also tune the transmit frequency and pulse parameters depending on whether you want stronger high-frequency content or a smoother, more Gaussian-shaped spectral response.

[Alighieri1231]

So using a bandpass from 2 to 12mhz

I can see the scatters now, but because of the spectral shape there is too much lower frequency component

But yes, it seems I would like a more gaussian shaped spectral response as in C3. How would be possible to have this behaviour? Is there a script for this?

And regarding IQ, so RF.raw data and IQ.raw would be the same then, is there no more than demodulation? The B-mode quality then is defined by just plain postprocessing but not anything about compounding right?

Psdta: I realized there is a P-wave mode in the app; is this gonna affect the rf data? What does this button do?
Thanks in advance

[HamidClarius]

As mentioned, you can tune the transmit frequency to have different responses, although I am not sure whether you have access to make such changes. Your C3 B-mode image does not look as good as I would expect, so make sure your reconstruction produces an image comparable to what is displayed by the Clarius app. The P-wave is related to Doppler.

Good luck with your research endeavor!