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AFE5808A

Steven Colvin
Prodigy 20 points
Other Parts Discussed in Thread: AFE5808A, AFE5809, TMS320C6455, DAC0808, TL082

Hello,

I am a student trying to create a crude ultrasound system. Ultrasound typically emits 5 MHz pulses from an array of 128 transducer elements, and then stops to record the inbound signal at a sampling rate of 10 MHz. It has a 72 dB dynamic range that's digitized at 40 MHz into a 12 bit grayscale image.

For our purposes (we have time and budget concerns), we are planning on isolating 8 elements from a working transducer. We are thinking of connecting this to the AFE5808A board and processing it using an FPGA like the TSW1250EVM to create an ultrasound image. Would this work, with both the components and the processing power? We are very new at this, so any help would be appreciated.

  • 0
    TI__Expert 6320 points

    Steven,

    This sounds like it will work, but a couple of things:

    1. I use the TSW1250 with the AFE5808A, but it can only capture one channel at a time.  You might want to look at the TSW1400 board, its better and more stable. I recommend this.

    2. I am not sure why you mentioned 10MHz Fs and 40MHz.  Which one is the sampling frequency? Either would work though.  You can use the AFE5808A+TSW1400/1250 from Fs=5MSPS up to 65MSPS.  If you are sampling the 5MHz signal, then I recommend sampling faster than 10MHz, which is the Nyquist.

    3.Also, AFE5808A will support 14-bit as well as 12-bit. 

    4. If you are considering more advanced computation, take a look at the AFE5809.  It is very similar but has a Demodulator/Decimation Filter function.

    5. Can I ask what transducer you are using?

    Thanks,

    Chuck Smyth

  • 0 in reply to Chuck Smyth
    Prodigy 20 points

    Thank you for responding. I forgot to mention we are looking to real-time imaging. We are trying to get an actual image output (we know it will be a very thin slice with only 8 channels). Should we be looking at a DSP processor like the TMS320C6455 or TMS320DM6466 instead of the TSW family?

    1. How many channels can the TSW1400 board handle?

    2. 10 MHz is the sampling frequency. In your opinion, what is a good sampling frequency considering 10 is the Nyquist?

    3. Great, do you think we have the computational power to output a 14-bit image? We were thinking we would have to go lower.

    4. What is the benefit of this filter function? We don't know a lot about the extra features we could add to make a better image.

    5. We are scavenging a transducer from an old Philips ATL C9-5 ICT endocavity probe.  

  • 0 in reply to Steven Colvin
    Intellectual 710 points

    Hi Steven,

    Chuck is wright, I agree with his suggestions. Regarding your questions:

    1. TSW1400 can handle 4 channels. However, why you ask about it? It's useless for your application!! If you have a TGC on your mind, you can succesfully use just only one DAC0808 followed by TL082 OPAMP. For n-channel ultrasound system you need just ONLY ONE TGC analogue signal.

    2. Yes, Nyquist. I suggest to sample the signal with max. available frequency.

    3. 12-bit is OK for a good image quality.

    4. What kind of filter do you have on your mind? Antialiasing? If so, you don't have to worry too much about it. It's on chip, you can experiment the cut-off frequency. If you mean demodulation, use Hilbert transform filter. Matlab (FDATOOL).

    5. If the piezoelements are wired directly to the connector, it should be OK.

    Good Luck,

    Mariusz

  • 0
    Intellectual 710 points

    Hi Steven,

    1. Mapping into 12-bit greyscale is a nonsence. You need to perform a log compression into 8-bit greyscale.

    2. Generaly, your idea is OK. In order to make your design simple and flexible, I suggest to do it like this:

    Probe<=>TX/RX=>AFE5808A=>FPGA=>USB(FT2232H)=>PC+software

    Mariusz