Specifications

3.3.2 Magnetic compass

The inclination and orientation angles of the DWR-MkIII are presented after a status request.

Inclination is the angle the local earth magnetic field makes with the local earth surface. A

measured inclination angle which matches the true local inclination within 1.5º indicates that (1)

the compass is functioning well, and (2) the offset angle of the platform is not too large. Local

inclination may be found on the web, e.g. visit www.ngdc.noaa.gov/seg/potfld/geomag.html.

Orientation is the angle between the reference axis of the buoy and the magnetic north

direction. It does not depend on any buoy tilt. The serial number on the hull indicates the

reference axis. Orientation may be easily verified with help of a hand held magnetic compass or

the known local north.

Furthermore, a plot of the inclination as function of the orientation can be made. The

inclination should remain constant for different orientation angles. A dependency of inclination

on buoy orientation can be caused by a platform offset angle or by an offset of the fluxgate

compass.

3.3.3 Test box, batteries

For all Waveriders each battery section can be checked individually via the test box.

3.3.4 Test box, motion sensors (DWR-MkIII only)

In the test box of the DWR-MkIII the x-, y- and vertical axis accelerometer, pitch, roll and the

three fluxgate compass analog outputs can be monitored directly. With help of a voltmeter the

correct functioning of each of the eight sensors may be tested, subsection 5.9.9.

3.4 GPS motion sensor and GPS position

A GPS receiver is a complex though reliable system. As a consequence a GPS receiver either

works perfectly or does not work at all, which makes life simple. However, there are a few

things to check before boldly replacing a seemingly faulty GPS receiver.

If you don’t get a new GPS position or if your GPS wave signal is zero all the time, your

GPS antenna, coaxial cable or connectors may be broke or loose. Also verify that the GPS

antenna is clean.

When in doubt about the health of the GPS wave sensor, please conduct a stationary test.

Place the buoy on a spot with a clear view of the sky and observe the output in RXD-mode

(section 5.11). If your displacements remain within a few centimetres the GPS motion sensor

works just fine. Note that with GPS satellites moving at 4 Km/s, buoy motion becomes a

negligible factor and a stationary test is as good as a 20 m real wave test.

3.5 HF transmitter

Transmitter problems typically are indicated by multiple small fractions or occasional large

blocks of data missing while running W@ves21 software. Furthermore, the signal quality

indicator on your RX-D, RX-C receiver or Buoyfinder informs you about the transmitter’s well-

being. In case of malfunction you should consider both the transmitter and the transmission link

as probable causes.

Intermitting radio contact could indicate occasional buoy submersion. This can be

checked by a disappearing and reappearing 1500 Hz tone on the RX-D, RX-C or Buoyfinder. If

this is the case your transmitter is probably fine but your mooring could be inappropriate

(rubber cord resilience is not enough or current is too strong). In the extreme situation where the

antenna touches the water transmission will be very poor. Apart from little ability to overlook

the waves also polarization in the wrong direction plays a roll.

A well known cause of loss of radio contact is a slight misalignment between transmitter

and receiver. Usually slight readjustment of your receiving frequency will suffice to restore

radio contact. Please consult your manual.