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Session_3.md

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Session 3 - 15 March 2016

## Other sessions

  • Session 1 : Powering the board, power use, first (bad) trigging and echoes (06 March 2016)
  • Session 2 : Non-controlled pulsing, inverters, better echoes (11 March 2016)
  • Session 3 : Getting controlled pulsing, but width not controlled (15 March 2016)
  • Session 4 : Width of the pulses is getting controlled =) (19 March 2016)
  • Session 4b : Simple data visualisation with BitScope (19 March 2016)
  • Session 5 : moving the transducer to get the first image (20 March 2016)
  • Session 6 : Getting a clinically usable image (28 March 2016)
  • Session 7 : Getting cleaner images - code improvements (3 April 2016)
  • Session 8 : Comparing acquisition speeds (3 May 2016)

## Today

^^

_ Getting nicer pulses._

TL;DR

  • Managed to switch on and off the HV with USPP and USPN.
  • With a 7.5us wide pulse, we see two echoes separated by 7.5us, hence the double echoes for switching on and off the transducer.

Technical points

Setup

Overall setup

DSC_0215

Transducer for a reflection

DSC_0214

Pulser: the HV7360

  • Same setup as Session 1 and Session 2.

  • The issue is that the two pulses were not controlled.. so we'll need to find something to synchronise these two, with a 150ns delay..

Discussion and issues

Discussion

  • High pulses: from a small pulse, echoes are amplified to a 1.54V , on an average of ~0V.

TEK_14

  • Need to get a better pulser!

Issues

  • Tests were done without having put the DAC inputs to GND. That may lead to some issues in reproductibility.
  • Need to document the role of Jumper 1 more precisely.
  • Let's try to get images from only 2/3, trigging from an external source? -- Without SPI control of the DAC -- With SPI
  • We can't get anything at the TP 5/6 signal..

TEK_13

Images

Moving along the chain of capture

Before the MD0100

TEK_06

After the MD0100

TEK_05

After the LC after the MD0100

TEK_08

After the TGV (points 2/3) with Jumper on gain low

TEK_12

After the TGV (points 2/3) with Jumper on gain high

TEK_14

Before the transformer (TP 5/6)

TEK_13

Controlling the pulse width

Trigging without USPN

TEK_00

Triggin with USPN

TEK_01

Details of the controls

Trigging on with USPP

TEK_02

Trigging off with USPN

TEK_03

Plugging the transducer

Trigging without transducer

TEK_01

Trigging with the transducer

TEK_04