The most common cause of the "ERROR: Compass not responding. Re-initializing..." message in SonUtils is the connection between the ADV/ADP probe head and the 16 pin probe cable to the processing electronics. Check the female bulkhead connector with a flashlight for any dirt or debris that may have collected. It can be cleaned with a cotton swab, compressed air or water. Use some silicon grease or spray to lubricate the pins on the probe cable. Be sure to mate the connectors completely so that the faces are touching or within 1-2 mm before screwing down the locking sleeve. Do not use the locking sleeve to tighten the connection.

First, download the latest RiverSurveyor software here: http://www.sontek.com/sw/riversurveyor-live.php. Once the installation files are saved to the PC, you will need to transfer the .CAB file to your mobile device. There are two options for transferring files: an SD card reader or connect the mobile phone to your PC using ActiveSync (XP) or Windows Mobile Device Center (Vista or later). Once transferred, use the File Manager to open My Documents on the mobile device. Click on the RiverSurveyor Live.CAB file to run the installation

When increasing the amount of stirring does not result in an increase in the dissolved oxygen readings, enough stirring is being supplied.

The optical sensing elements are warranted for 1 year but may lastlonger. Be sure to keep the sensing element clean and stored in a moist
environment between uses to obtain the longest usable life possible.

As a rule, YSI recommends that a calibration be performed or verified daily, before sampling starts. But in general, calibration frequency is determined by the user and the importance of the data. The more critical the data, i.e. when used for compliance purposes, the more attention that should be paid to timely calibrations. The calibration of newer optical based dissolved oxygen meters is very stable but YSI still recommends that it be verified on a regular basis to ensure accurate data. Your data is as good as your calibration.

Beamcheck is the best diagnostic predictor of reliable ADV velocity data. Record Beamcheck data with the probe fully submerged in the water and the sampling volume clear of interference. Tap water is usually sufficient for this test, however depending on how "clear" your tap water is, you may need to add a handful of seeding material (e.g. dirt, chalk dust). In the beam check program, you can change the X-axis to samples/counts using the View menu. The rule of thumb for accurate velocity measurements is that all beams should be within 10 counts of each other for both the Peak Position and Peak Level. A nominal value of the peak level will depend on the amount of scattering material in the water. You should see an increase in the peak level if you add more seeding material. If you are uncertain of your results, please record at least 30 pings and send the .bmc file to support@sontek.com. We will be happy to provide feedback.

The Argonaut-SL has a pressure sensor that needs to be calibrated on site before deploying the instrument. In order to calibrate the pressure sensor, first connect to the SL using SonUtils. Send a BREAK to wake up the instrument. Type SENSOR CONT into the command line at the bottom and press Enter. Temperature, Pressure and Battery voltage will start to output. Press Enter again to stop data output. If your Argonaut is in air, it should read a pressure value of less than 0.1 dBar or if the unit is in the water it should read within 0.1 dBar of the depth (in meters). If the pressure sensor shows a significant offset, you will need to reset the pressure offset. To do this type RESETPRESSOFFSET into the command line, press Enter. If the system is in air, enter 0 when prompted. If the system is in water, measure the distance from the water surface to the top of the vertical beam and enter this value when prompted (the units will depend on your setup). Press Enter. Type SENSOR CONT into the command line, press Enter and verify the new pressure offset by comparing the output pressure to the deployment depth.

The ROX dissolved oxygen sensor has three key advantages over the YSI Rapid Pulse sensor:

1.The set-up and maintenance of the ROX sensor is much easier since there is no membrane or electrolyte to be changed by the user.
2.Testing indicates that the ROX sensor is significantly less susceptible to field drift. YSI Incorporated Environmental Monitoring Systems Operations Manual M-1 ROX Optical DO Sensor Appendix M
3.The ROX sensor is automatically wiped during field studies to eliminate effects of fouling. The Rapid Pulse sensor can be wiped, but only if a 6600EDS V2-2 sonde is used. In addition, the ROX DO sensor has NO flow dependence, giving it a large advantage over systems which utilize steady-state membrane covered polarographic oxygen sensors.

This advantage is minimal relative to the YSI Rapid Pulse technology which is effectively flow-independent in monitoring studies and shows
only minimal flow dependence (ca. 3%) in continuous-on sampling studies

In general, optical dissolved oxygen sensors from a variety of manufacturers are based on the well-documented principle that dissolved oxygen quenches both the intensity and the lifetime of the luminescence associated withcarefully-chosen chemical dyes. The
6150 sensor operates by shining a blue light of the proper wavelength on this luminescent dye which is immobilized in a matrix and formed into a disk about 0.5 inches in diameter. This dye-containing disk will be evident on inspection of the sensorface. The blue light causes the immobilized dye to luminesce and the lifetime of this dye luminescence is measured via a photodiode in the probe. To increase the accuracy and stability of the technique, the dye is　also irradiated with red light during　part of the measurement cycle to act as a reference in the determination　of the luminescence lifetime.　When there is no oxygen present,　the lifetime of the signal is maximal; as oxygen is introduced to the　membrane surface of the sensor, the lifetime becomes shorter. Thus, the lifetime of the luminescence is　inversely proportional　to the amount of oxygen present and the relationship between the oxygen pressure　outside the sensor and the lifetime can be quantified by the Stern-Volmer equation. For most lifetime-based optical DO sensors (including the YSI 6150), this Stern-Volmer relationship (((Tzero/T) – 1)) versus　O2　pressure) is not strictly linear (particularly at higher oxygen pressures) and the data must be processed　using analysis by polynomial non-linear regression rather than the simple linear regression used for most　polarographic oxygen sensors. Fortunately, the non-linearity does not change significantly with time so
that, as long as each sensor is characterized with regard to its response to changing oxygen pressure, the curvature in the relationship does not affect the ability of the sensor to accurately measure oxygen for an extended period of time. Each YSI sensor module (the assembly which is attached to the face of the probe by three screws) is factory-calibrated over a range of 0-100 percent oxygen to quantify the relationship of its luminescence lifetime as a function of oxygen pressure. The Stern-Volmer parameters from this data are then fit to a third order regression equation (ax3+ bx2+ cx) and values of a, b, and c determined. These coefficients,
along with the luminescence lifetime at zero oxygen pressure (Tzero), are provided to the user in coded form with each sensor membrane module or probe/sensor module combination. If you install a replacement sensor membrane assembly (YSI 6155) on
your existing probe, you will be required to enter these coded constants into the sonde as described in the instructions which come with the 6155 prior to the use of the sensor. If you have purchased a probe/membrane combination, i.e. a new 6150 Optical DO
sensor, the constants are already stored in your probe and will automatically be transferred to your sondewhen the sensor is installed.

If you are using a native serial port, it is usually COM 1. If you are using a USB to Serial adapter, navigate to the Device Manager to verify the COM port number. The Device Manager can be found by searching from the Start menu or Control panel depending on the Windows version installed on the PC. Open the Device Manager, expand the 'Ports (COM & LPT)' section and look for USB Serial Port. The COM port number appears in parentheses.

Note: If you are trying to connect to your instrument using SonUtils, ViewArgonaut, FlowTracker, or HorizonADV and the COM port number is greater than 8, you will need to reassign the COM port number. To do this, right click on the USB Serial Port and choose Properties. Under the Port Settings tab, choose Advanced and change the COM Port Number from the drop down menu.

Accessory for the pH instrument simply provides a pH 4, 7, and 10 reading to the instrument. This ensures the instrument is reading properly but does not calibrate the instrument or probe. It is used just to verify the accuracy of the pH handheld.

There are several possibilities, but the most common reason is the COM port connection. Native serial ports (particularly on laptops) can be intermittent at the higher baud rates used by SonTek software to communicate and download data. For this reason, SonTek supplies a USB to serial adapter with new instruments (http://www.easysync-ltd.com/product.php?ProductID=526).

The first thing to do with the USB adapter is to install the latest driver. It can be downloaded as a Setup Executable from the Comments section of the table here: http://www.ftdichip.com/Drivers/D2XX.htm

Note: It may be required to reboot the PC after installing the device driver.