120716 UT calibrations from BS4331-1 1978

[MA45 probe and compression probe]

5. linearity of distance

Compression probe:
10 echoes over 20 mm thickness of solid test block - no error obvious

6. timebase -> distance

Yes - compression probe got 69 mm for 69 mm
after calibration on Sonatest block for 50 mm then shift one echo along.

7. linearity of gain

24 - 100%
22 - 80% set
16 - 40%
4 - ~6% to 7%
[ie. all as should be]

8. and 9. - index and beam angle of shear probes - already familiar

10. sensitivity and S-N

"8" gives 18% of screen for 1.5 mm hole of "30 mm depth" but seen from
end face approximately 102 mm away
"40" gives approximately same " grass " height of 18% of screen

11. squint - encountered it but no measurement(s) noted

12. beam width

Using Sonatest block with "30 mm deep" hole
Index at 32.25mm   beam dist. = 42mm
[is MA45 probe - gives beam angle 47.07deg]
12db gives 82% of screen height
12db + 20dB => 32db
82% of screen height at 40.25mm
82% of screen height at 24.25mm
40.25 - 24.25 = 16mm index displacement at beam distance of 42mm
With 47.07deg beam angle, 16mm index displacement => 10.9mm beam-width

Small hole @ "15mm deep"
90% @ 8dB
Maximum echo at 42mm from datum corner
28dB gave 90% of screen at 35mm and 47mm probe-index from datum
47-35 = 12mm index displacement at beam distance of 21mm
=> 8.2mm beam width

13. pulse duration
peak width = 2.5mm at 10% height