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CONTACT DETAILS
Tel UK: 01275
847787
Tel Intl: + 44 1275 847787
Fax UK: 01275 847303
Fax Intl: + 44 1275 847303 |
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Email
Biral
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Notes on Maximum Measuring Height
The definition of a "maximum measuring height" is often used
as a key specification to compare the typical performance of a SODAR system, but the users
must be aware of the inherit principal difficulties with this definition. From the basic
SODAR equation which prescribes the signal intensity of the back scattered sound signal it
can be seen that the SODAR signal quality depends (inter alia) on:
Atmospheric Parameters
- intensity of turbulent temperature fluctuations
- atmospheric absorption
- natural background noise (generated by wind, rain drops, hail stones, etc.)
Measuring Parameters
- signal frequency and signal intensity
- height resolution (nominal and effective resolution)
- averaging time
Site Parameters
- back ground noise (machines, fans, traffic, etc.)
- reflections from solid structures
- annoyance of neighbourhood (limits signal intensity)
System Parameters
- emitted acoustic power
- antenna area
- antenna gain
- internal electronic noise level
The user can adjust the measuring parameters and the system parameter
can be optimised by the electronic design of the SODAR electronic. However, the
atmospheric parameter can not be influenced. Unfortunately, these atmospheric parameter
can vary in much wider ranges. Therefore, the specification of a "typical"
measuring height needs special care and some information about the assumed weather
conditions. At least a clear distinction should be drawn to the "nominal"
maximum height, which is simply determined by the product of the maximum number of
available height steps and the spacing of the height steps. |
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