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8.4.4 Alignment with phase measurement
Phase measurement with real time FFT analyzer can also provide reliable measurements, provided:
•
measurement microphone is set on the ground to avoid floor interference in the reading;
•
floor is perfectly rigid (concrete);
•
measurement microphone is set far from any walls / ceiling, or inside angles / corners;
•
coherence values are high (typically above 75%).
If one of above conditions is not respected, then distance measurement should be preferred.
8.5 Recommended installation tools and equipment
•
Tape measure – should be 30m/100ft in length and be of durable fibre material. Have one per
array available to speed up the installation process.
•
Laser Inclinometer – For measuring vertical and horizontal angles in the venue. An ideal product
is the Calpac ‘Laser projecting a dot’ version which costs approximately 60 €.
•
Spirit level – used to ascertain the trueness of the surface from which the angle measurements
originate.
•
Rangefinder measuring device – either a Disto type laser measure or an optical laser rangefinder
can be used. Devices such as the Bushnell ‘Yardage Pro’ sports rangefinders provide sufficiently
accuracy and are easy to use. They have the additional advantage of working very well in bright
sunlight.
•
Electronic calculator with trigonometric functions to calculate the height from ground level to
points in the room. The formula to calculate height of a point from measured angle and distance
is:
•
Height of point = Sin(vertical angle in degrees) x distance to point
•
NB: Take care when using spreadsheets as they calculate using radians by default. To convert
degrees to radians use the formula:
•
Angle (in radians)=3.142 x Angle (in degrees)/180
•
Computer – Laptop or Desktop PC running Windows 2000 or XP with the current version of
NEXO GeoSoft2 installed. It is not possible to configure a Geo tangent array properly without
using GeoSoft2. Note that, when GeoSoft2 designs are prepared prior to arrival at the venue, it is
often necessary to modify or update the design to accommodate special circumstances. A PC is
absolutely essential to make such changes.
•
Audio Analysis Software – recommended but not absolutely essential, programs such as Easera
Systune
TM
, Smaart
TM
or WinMLS
TM
enable rapid and detailed analysis of the installation.
Consider taking a training course in using one of these tools if you are not already competent
with them – it will pay dividends in increased performance of the system.
