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ContinuousWave: Small Boat Electrical
360-degree SONAR Echogram
|Author||Topic: 360-degree SONAR Echogram|
posted 02-25-2012 10:59 AM ET (US)
The HUMMINBIRD company has announced a new innovation in recreational SONAR products, a 360-degree presentation of SONAR echogram on their HUMMINBIRD units which they have trademarked as "360 IMAGING."
The 360 IMAGING device is said to be able to look 150-feet in all directions, including in the forward direction, ahead of the boat. The presentation can also be altered to show the echogram in sectors of varying width, down to a sector as narrow as 10-degrees in width. The presentation can also be selected to be shown in any heading relative to the boat.
The 360 IMAGING requires use of a special transducer array assembly which is configured on a long pole. The pole is shown mounted on a boat transom and is lowered into the water by what appears to be an electric motor. It appears the transducer can only be deployed at very low boat speeds, as it would create considerable drag and bending moment on its mast. A local panel is used to operate the deployment device, or the device may be deployed by a control on the associated HUMMINBIRD display device. Judging from a graphic, the transducer array appears to be lowered to a depth of about three to four feet below the water surface when in the operating position. Correspondingly, when the device is not deployed it retracts into a housing that extends about three to four feet above the water, creating a rather significant presence on the boat transom.
The 360 IMAGING device is compatible with only certain HUMMINBIRD models, namely the 1198c SI Combo, the 998c SI Combo, the 898c SI Combo, and the 798ci HD SI Combo. These devices are side-imaging devices with Ethernet networking.
For more information visit the web page linked below:
Note that the web page is somewhat unusual in its presentation in that it can be scrolled horizontally in three or four vertically segmented panels by use of small arrowhead-shaped objects on the screen. Clicking those objects reveals more information in the individual panel being scrolled. There is also a very odd floating index panel with four segments that allows vertical scrolling. Apparently the web page design is as complicated as the SONAR imaging it explains.
A very short promotional audio-video presentation can be viewed at
posted 02-25-2012 11:06 AM ET (US)
In the promotional material, particularly in the video, the notion of rotation of the SONAR beam is introduced. In observing the hardware of the 360 IMAGING transducer array, the mast on which it is raised and lowered has a hydrofoil shape, so I do not believe that this mast actually rotates. The rotation of the SONAR beam is most likely accomplished by electrical means instead of mechanical means, perhaps using an array of individual transducer elements which are oriented in segments. An array of six transducers with a coverage of 60-degrees would provide 360-degree coverage, for example. Actual details of the construction of the 360 IMAGING transducer are not known at this writing.
posted 02-25-2012 11:37 AM ET (US)
In the HUMMINBIRD 360 IMAGING system there is good integration of the SONAR and navigation functions of the associated display device. For example, an echogram seen on the 360 IMAGING as being a certain distance away from the boat and at a certain heading can be marked on the SONAR display. This mark can then be immediately converted to a waypoint in the navigational system, providing a geographic coordinate for the source of the SONAR echo that was marked on the echogram display.
Such a computation is not particularly difficult if the GPS sensor and the SONAR sensor are co-located. I wonder if the 360 IMAGING system provides for entry of an offset for the GPS sensor if it is not co-located with the SONAR sensor. Also, the location of the echogram mark is relative to the boat heading. The boat heading can be derived from a GPS position fix, but for best accuracy a position heading sensor is often used, particularly when the boat is operating at low speeds as will be required for the deployment of the SONAR sensor. I also wonder if the 360 IMAGING system provides a boat heading sensor to enhance the accuracy of the marked echograms on the navigation system.
posted 02-25-2012 12:44 PM ET (US)
Interesting. If I was diving a lot I think this would be an interesting addition to the electronics.
I did not see on the web site if the transducer when retracted works like a standard transducer or do you need a second transducer for use at high speeds.
We have lots of milfoil around here I wonder how much risk there is of damaging the transducer from dragging weeds.
posted 02-25-2012 12:47 PM ET (US)
On further reading of the literature available, it seems the depth of the sensor immersion can be controlled. You don't have to run it completely deployed. I suspect that if the sensor can be lowered several feet below the water there must be some advantage to using it at that depth, otherwise there would not be a mechanism to lower it that deep.
posted 02-25-2012 07:02 PM ET (US)
I suspect that what Humminbird is using is a pretty sophisticated phased array transducer. A big advantage with a phased array is it has no moving parts, the beam is steered mathematically. With a phased array the operator can not only scan with a wide beam but can narrow the beam, through the use of digital signal processing, to focus on a particular target. Since processing power now is so high and so cheap, an Aegis like capability can fit in a shoe box. The next evolution will probably be a tracking capability so you can know exactly where to cast your bait so it's right in front of the fish.
posted 02-25-2012 07:57 PM ET (US)
It occurs to me that with a presentation like the 360 IMAGING there is no longer any history being shown. You see only the present instant. In the usual SONAR echogram we have all become familiar with you see the past history of where your SONAR has been. I guess you can combine the 360 IMAGING view with other conventional views on screen at the same time. That might be helpful in learning how to use this new technology.
posted 02-25-2012 08:40 PM ET (US)
Any idea of the extra cost for this?
posted 02-25-2012 08:52 PM ET (US)
Word is [the cost for the 360 IMAGING device is] $2,000--[just that part, not the display]. Here are screen shots with the transducer on a 1198.
posted 02-25-2012 09:09 PM ET (US)
I don't think that non-colocation the sonar transducer and
the GPS antenna is an issue on a boat the size of a Whaler.
On my Montauk, that distance is about 10' (transom to console
rail). 10' is about the same as the accuracy of a WAAS-enabled
GPS, and less than the distance my Danforth will sail on the
posted 02-25-2012 10:56 PM ET (US)
Cabela's has the 360 IMAGING unit listed at $1,999--for delivery in AUGUST 2012.
Here is a segmented view:
Here is a split screen view, with a 360-degree presentation:
Note the very low boat speed shown in both the views above, less than 1-MPH.
posted 02-26-2012 10:24 AM ET (US)
So far Humminbird has only shown us still images of the display of their IMAGING 360. I notice that there is a white bar or white line in all of these views, which I suspect might be somewhat akin to the sweep line in a RADAR plan position indicator (PPI) display. That is to say, I don't think all the SONAR echoes in the image on the screen are drawn onto the screen instantaneously. The echoes have to be drawn onto the screen as the 360 IMAGING device electronically rotates its SONAR bean around the 360-degrees (or smaller sector) that is to be displayed. I also suspect that the white line or bar indicates where the display is being updated at any particular instant.
We are assuming that the SONAR beam is made to be directional by some electronic and mathematic method, perhaps akin to a RADAR steerable phased array. (Compare at http://en.wikipedia.org/wiki/Phased_array ) It probably takes some finite amount of time for the array to make a sweep over its steerable segment. I think we are also assuming that to cover 360-degrees one needs more than one array, as I don't think you can cover more than 180-degrees with one array, otherwise there would be ambiguity about the bearing of return signals.
Perhaps Humminbird will offer some motion picture images of their device in operation, and we can learn more about it. Let us look a resource like that on-line, next.
By the way, there seems to be some resistance to the price point of $2,000 for the technology, as a lot of the target customers are perhaps a bit technically unsophisticated and seem to think of this astonishing technology as being nothing more than a fancy "transducer"--a transducer they think should cost about $200, minus the electrical deployment system.
I would have thought that there must be some sort of black box electronics that goes along with the transducer and deployment mechanism to create the display image. If there is not, then the Humminbird devices that can host this system must have a lot of computational power in them. Or perhaps the system is much simpler than we have suspected.
posted 02-26-2012 10:36 PM ET (US)
This is normally called Searchlight sonar and has been available on larger vessels for a while, many commercial fishing vessels have it. There are also Omni sonar systems that instead of a spinning array they have many senors facing all direction at once with no need for a sweep.
I was hoping to see a consumer level version of a searchlight sonar at some point, and here it is, I am very interested. The next step will be a Omni version and perhaps a full 3d forward looking array.
Here is some information on existing large vessel systems: http:/ / www. maqsonar. com/ What%20is%20the%20difference%20between%20Se archlight%20Sonar%20and%20Omni%20sonar. pdf
posted 02-26-2012 11:04 PM ET (US)
That's a pretty significant investment. There have been times on reservoirs like Lake Powell when I would have welcomed the ability to look forward. Sometimes the depth changes from 90 ft to 2 ft in the length of the boat.
posted 02-27-2012 08:09 AM ET (US)
Do you know what frequency this uses? Lowrance's StructureScan uses 455 and 800 kHZ.
posted 02-27-2012 08:38 AM ET (US)
Re the integration of the SONAR and the navigation computer:
The SONAR gives a range and bearing to the location relative to the boat. To create a navigation mark or waypoint in the navigation computer, the heading of the boat must be known. In a standard GPS receiver, there is no way to know the boat heading. The GPS receiver only can know the boat position. The recent course can be deduced by comparing the present position to past positions. If the position fixes are all accurate, the recent course over ground can be deduced.
In the presence of any current in the water, the course over ground is often different from the boat heading. Imagine the boat is not under power and is drifting in the wind or current. The boat heading may be completely unrelated to its course over ground. Also, when the boat is moving at very low speeds, the change in position from the past fix to the present fix may only be a distance of a few feet. The error in the deduced position fix by GPS can be greater than the actual change in position. This leads to significant errors in the deduced course over ground based on those GPS position fixes.
The remedy for this is to include a heading sensor, which is usually based on magnetic force, just like a compass. Typically a magnetic heading sensor cost several hundred dollars, perhaps $500. If the 360 IMAGING system includes a magnetic heading sensor, that would explain some of its costs.
posted 02-27-2012 11:13 AM ET (US)
Heading sensors need not be very expensive. My iPhone has a GPS, magnetic compass, 3 axis accelerometer and 3 axis gyroscope. This allows software on the iPhone to precisely calculate the devices position, orientation, and acceleration relative to the earth. This allows for some amazing things like being able to apply virtual objects in 3d over the video image captured by the camera placing the virtual objects such that they appear to be in a specific physical location in the world, this is called Augmented Reality: http://en.wikipedia.org/wiki/Augmented_reality . I use an app on my iPhone when boating called Spyglass, it shows video from the camera while begin able to overlay a heads up display that includes compass, accelerometer and GPS data and overlay previously stored waypoints in the proper location in the field of view, very useful. All of that in a device that costs under $500.
I see no reason why a modern chartplotter does not have a built in magnetic compass and accelerometer just as many have a built in GPS for a reasonable price. The accelerometer could actually be used to correct the sonar readings for wave action and the compass for map display and sonar information such as this new device presents.
posted 02-27-2012 12:42 PM ET (US)
A heading sensor that can be interfaced to other marine electronic devices will generally require a NMEA-0183 output or a NMEA-2000 network connection. The ones that I have seen that provide those connections are all expensive.
I agree that the Apple iPhone as a generic device--not as a smart phone--offers a fantastic value in its included components, display, and operating system. If the Apple iPhone were built as a marine electronic device it would cost $10,000.
posted 02-27-2012 12:46 PM ET (US)
Also, it occurs to me--not being familiar with all of the HUMMIBIRD product line--that perhaps the host device has heading sensor already provided.
posted 02-27-2012 01:29 PM ET (US)
Another factor in cost is R&D and also overhead.
iPhone will sell millions, so there are a lot of sales to spread the R&D cost over as well as corporate overhead.
Hummingburd sales will be in the thousands - maybe more, but not near iPhone sales.
I would expect the price of the 360 to come down over the years, but then there will be "the next latest and greatest" technology to keep prices up.
posted 02-27-2012 01:38 PM ET (US)
No chart-plotters including the Humminbird currently integrate a magnetic compass sensor that I am aware of, and this has long been curious to me.
The iPhone uses an existing mass produced 3 axis magentic compass chip provided by AKM: http://www.asahi-kasei.co.jp/akm/en/product/ak8963/ak8963.html this device sells for about $6 in quantities of 25,000.
The iPhone sensors are not developed in-house nor would they be expensive for another company to use even in relatively small quantities.
posted 02-27-2012 08:36 PM ET (US)
Maretron's heading sensor is $740:
posted 02-27-2012 08:37 PM ET (US)
GARMIN's heading sensor is almost $800:
posted 03-21-2012 07:28 PM ET (US)
I am still seeking information on how the all-round 360-degree scanning is implemented. We are not clear if the scanning in done by mechanical methods or by electronic methods. Is there any clarifying information from the manufacturer about this?
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