Old Forum Thread
Author Thread: HummingBird Matrix 37
francisco.xavier@csanet.pt HummingBird Matrix 37
Posted: Monday, June 14, 2004 1:25 PM (CST)
Hi subscribers,
Last Friday I aquired an Matrix 37 unit (display, QuadraBeam and Widebem ducers and transducer extension cable) to see what this unit is capable as sss.
I assemble the WideBeam ducer on a proper towing fish with stable balance.
On Saturday and Sunday I spent all time watching the bottom profile on M37 (flat sea and slow speed) and trying adjustments on "wide sensibility" and "sensibility" of main menu.
Even the high frequency, the WideBeam 455KHz ducer is to short length to discriminate anything less than a rocky bottom. Like Hummingbird inform, the fanshape pattern beam is 45 degrees wide vertical and 18 degrees horizontal! This exaggerate horizontal angle is unable to separate small objects.
Would be interesting implement Dan ideia on M37 asembling a 455KHz transducer with 2 x four paralel/serial wired elements.
Anybody can point me where can I find 455KHz transducer elements to try to build a sss transducer, for this purpose?
Other interested, having M37, would be grateful to share information.
Thank you,
Francisco Xavier
Author Thread:
JimKennard HummingBird Matrix 37
Posted: Monday, June 14, 2004 10:09 PM (CST)
Francisco,
I think that your range will be very limited with the 455 KHz “Dan” array of transducers. The effective impedance of multiple transducers will be mismatched to the proper impedance requirement of the Matrix 37 unit, which will cause additional limitations to the range of the array. The multiple transducers must be properly spaced to cause a narrower beam width otherwise the effective beamwidth could be very much different than what you might expect. My recommendation is that you save your money and time putting this transducer arrangement together. I think that you will be very disappointed with the very marginal results. Regards, Jim
francisco.xavier@csanet.pt HummingBird Matrix 37
Posted: Thursday, June 17, 2004 6:20 AM (CST)
Thank you Jim,
The impedance of the 4 element array will be kept wiring in serial way each 2 ducers and paralel beetewn the 2 serial groups (each ceramics will be feed by an half nominal voltage KV emiting, and double uV receiving). This will be necessary if the M37 control box would be able to detect any impedance shift and refuse startup.
Otherwise the ducers will be kept wired in paralel (the total impedance is divided by 4), once the piezo ceramics impedance is about some megaOhm (no total voltage loss on emiting and receiving).
The narrower beam problem can be solved if the emiting surface of the piezos will be very well aligned, once the narrow property is promoted by means of outside wave interference emited by piezos side by side, and can be computed knowing the wave lenght (3.18mm) and angle of cone beam pattern (40º).
The teorycal concept is ok. In pratical I would have very good alignement, sound isolation beetewn piezos and avoiding ringing.
After assembed, the fan beam gain patern will be gauge with an hydrofone.
Regards,
Francisco Xavier
JimKennard HummingBird Matrix 37
Posted: Saturday, June 19, 2004 2:11 PM (CST)
Francisco,
I would be interested to learn of the actual beamwidth and the amount of suppression of the array side lodes that you can achieve with the arrangement of these transducers and view the results of the sonar images. Several individuals have talked about building the “Dan” side scan transducer, but I have not seen any good sonar images (sonographs) of their results. I hope that when you get your system working that you could share the results on this forum. Best of luck with your project and Regards, Jim