[Acoustics] WM5 stops to work well

[Nick j Everard]

Paulo

Are you trying  to measure outside the capabilities of these modes?

The high resolution modes 5 and 11 are designed for low velocities and relatively shallow water. For the 1200s I operate the highest velocity it will typically measure is roughly 0.5m/sec. As the water gets deeper the maximum velocity it will measure decreases -  in 2 metres depth 0.5m/sec, in 4 metres 0.25m/sec. In theory it can go to 1m/sec in 1m depth, but in practise I haven't been able to achieve this! For the 600s you are using the limits will be higher - maybe a 600 user can advise on what they can measure?

5 and 11 give fantastic low noise data when they can work, but if velocities or turbulence are too high they will fail. Typically as you approach the limits you'll get good data where slower water is and it'll fail in faster sections. In very fast water you'll get no data at all. Sometimes excessive turbulence in even quite slow water can cause these modes to fail too.

Mode 1 is a much coarser measurement, but will cope with high velocities and turbulence.

Mode 12 makes a good compromise as it is robust (won't fail in tough conditions) but is less noisy than Mode 1.

To test if Modes 5/11 are working just go to a real slow river or take it to a backwater or lake, if it doesn't work there you have a problem!

I hope this helps (and I'm not just telling you stuff you already knew!!)

Regards, Nick Everard.

Nick Everard
FMD Officer 1 (Hydrometry)
Environment Agency - W Area
Thames Region
Windrush House
Howbery Park
Wallingford
Oxon, OX10 8BD
UK

Tel: +44 (0)1491 828400
Mobile: +44 (0)7831 559379
E-mail nick.everard at environment-agency.gov.uk
Internet www.environment-agency.gov.uk


>>> Paulo Everardo Muniz Gamaro <pemg at itaipu.gov.br> 16/06/06 14:10:51 >>>
Hi all

Does any of you have a problem of a high resolution modes 5 e 11, just
stops operating  ?

My 600 kHz WHRG just start to produce  bad ensembles and once and while a
good one, as the mode1 is OK,  I assume that is the HIgh resolution mode
problem, which I do not know is if is a firmware problem, or a hardware, I
imagine is a firmware because mode 1 is working, so any idea if I am right
?
And if I am, how do I fix it ??


Cheers

Paulo


______________________________________________
PAULO EVERARDO M. GAMARO
Divisão de Estudos Hidrologicos e Energeticos
ITAIPU BINACIONAL
Brazil
fone +55 045 5206824
fax +55 045 5202074

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