b'TECHNICAL TIPSBEAM SEPARATIONin ADPs and ADCPsVarious examples of beam separation including one example of good beam SNR. (For illustration only.)Good SNR Profile Single Beam SplitTwo Beam Split Multiple SeparationBrittany Jenner, Application Engineer at SonTek, a Xylem brandWhat is Beam Separation?What can you do to To test for beam separation,identify, test, and resolvefollow these steps: Monostatic acoustic transducers usedBeam separation? on acoustic Doppler current profilersStop or complete the measurement (ADPs or ADCPs) are used in pairs andBeam separation will directly impactby finishing atransect or the groups to resolve multi-directionalthe accuracy of an ADPs calculatedaveraging period for that station: water velocity and sometimes trackvelocity and position data. No position. It is critical that the acousticpost-processing steps will correct If one or more beams weresignal from these groups of beamsbeam separation. For this reason,intermittently displayingshow the same acoustic decay at theit is crucial that operators canseparation, lower the ADP further same decibel (dB) level. identify and work to correct beaminto the water. separation in the field duringIf the separation persists or is Beam separation is defined by thedata collection. consistently seen on one (ordifference in dB among the beams, ifmore) beams, rotate the ADPany one beam differs by more thanIdentifying beam separation is easy90180 degrees.10 dB, this beam is considered to beand has been made even easier by separated from the others.the addition of real-time QC alertsProceed with the next measurement in recent software updates. Beamstep while watching the SNR profile. OK, Whats the Big deal? separation can be seen in the SNRIf a different beam separates, try(Signal to Noise Ratio) profile. Somethe following: If multiple transducers are being used,site conditions that cause beam wont the others resolve velocity andseparation are: Place the ADP further below thetrack position? This is a valid questionsurface or wipe the beams withand in certain circumstances, this may High flows in shallow, mountain your hand or cloth. be true.streams where turbulent water causes excessive tilt Check the tilt values if workingHowever, for moving boat or dischargefrom a bridge, cableway, etc., aapplications, where water velocity Boat mounted applications counter-weight on the towline canin 3D must be computed along withwhere the wake may cause help lower the bow. position, it is essential that all beamscavitation around the ADP are functioning properly and profilingIf the same beam is separated, then under similar conditions. Each beam Measuring from a bridge,your instrument will require service. of an ADP is used to compute onecableway, etc. that causes anPlease contact SonTek Technical component of 3D velocity. angle on the line, pulling the bow Support for instructions. up and exposing transducer(s)Make sure to document any new When one beam is malfunctioning orposition or rotate the ADP back to its separating, this will directly impact the Debris or surface plumes moving original configuration, if proceeding velocity and possibly position data, and downstream that block the with the measurement.thus discharge.acoustic beams Contact the SonTek technical team: email@example.com For customer support services: SonTek.com/Total-Care50 MISSION: WATER'