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Author Topic:   RAYMARINE: A65; Patent on Digital SONAR Technology
wswillis posted 03-28-2006 11:02 PM ET (US)   Profile for wswillis   Send Email to wswillis  
I have recently rebuilt my 1979 Montauk. I plan to install a GPS Receiver + Chartplotter + SONAR for saltwater fishing.

I like the Raymarine A65, but at $1,700 I am not sure it's that much better than analog.

Give me reports about use of the A65.

I understand that RAYMARINE has had the patent on [some aspect of using digital technology with] fishfinders. The patent has expired, and other companies will be using digital. Is the price of the RAYMARINE A65 likely to be reduced from $1,700 when other companies go digital? Thanks wswillis.

jimh posted 03-28-2006 11:43 PM ET (US)     Profile for jimh  Send Email to jimh     
I was not aware that Raymarine held the exclusive rights to a patented digital technology associated with SONAR and fishfinders. It would be interesting to have a citation for the patent and its number.

Generally a patent for a useful invention is granted for 20 years. If the patent just expired recently, say in 2005, this would imply the invention was granted a patent in c.1985. It would be very interesting to know what the patented digital technique was that Raymarine was using for the last 20 years that is now available to others.

The relatively high cost of some of these color display equipped electronic devices is due to the high cost of a large color display which can be easily seen in direct sunlight.

jimh posted 03-29-2006 09:24 AM ET (US)     Profile for jimh  Send Email to jimh     
For more information from the manufacturer's website on the RAYMARINE A65 Chartplotter with GPS Receiver and optional SONAR, see: PAGE=1227&product_id=3364&ResourceID=1021

The MSRP on this device is$2,059.

They assert that the device uses patented technology which they refer to with the trademark name "HD Digital". They claim that this technology provides the following:

--an adaptive receiver: benefit claimed is a precision in targeting of fish and bottom structure

--elimination of surface clutter caused by turbulence and the SONAR signal itself; benefit claimed is ability to show fish targets in this region

--an adaptive system in which the receiver sensitivity, the transmitter ping rate, and the transmitter power are adjusted automatically; benefit claimed is hands-free operation.

Using the United States Patent and Trademark Office website, I searched for a registration of any trademarks owned by RAYMARINE, but I did not find "HD Digital" to be owned by them. Cf.:

From that I conclude that the phrase "HD Digital" is not a registered trademark. By indicating that "HD Digital" is a trademark, they may be asserting that it is being used as a trademark, but I could not find evidence they have registered it.

Using those same resources, I searched for a patent assigned to RAYMARINE containing the word "digital" in the abstract.

The search yielded US Patent 6,950,372. The inventor is Sten Sogaard of Boynton Beach, Florida. The invention is described thusly:

"The invention is a digital sounder module and its method for detection. The digital sounder module includes a sonar carrier wave producing means, a band-pass filter, a pre-amplifier for providing a high sensitivity and extending a wide dynamic range, and an analog-to-digital converter for providing a digital implementation of a superheterodyne detector and producing an intermediate frequency. The digital sounder module also includes a programmable logic device for controlling a gain of the pre-amplifier and for digitally filtering the intermediate frequency and a microprocessor. The method implemented by the controlled per-amplifier gain processes the return echo signal by controlled ramp up of the gain over time to compensate for the change in signal strength in proportion to the length of the return path."

The patent was granted on September 27, 2005. This would permit RAYMARINE (the assignee) to have exclusive use of this invention and to vigorously protect against infringement of it until at least 2025.

Link to full text of patent 6,950.372

The full text of the patent can be retrieved from the URI mentioned above.

jimh posted 03-29-2006 09:36 AM ET (US)     Profile for jimh  Send Email to jimh     
The portion of the invention which describes how the gain of the receiver is increased over time was interesting to me. In c.1973 I was employed by an electronics manufacturer in the business of making ultrasonic flaw detectors, devices very similar to a fishfinder, really. Our devices all employed automatic gain control which increased the sensitivity of the receiver over time. This idea is a fundamental concept, and I don't think you could patent it. Perhaps a particular method of accomplishing this is patented and assigned to Raymarine.
Chuck Tribolet posted 03-29-2006 02:04 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
Trademarks can be registered (indicated by an R in a circle)
or unregistered (indicated by TM superscriped). My employer
does both. The really important ones get regestered.

This MIGHT display as a registered trademark symbol: ®


Peter posted 03-30-2006 08:43 AM ET (US)     Profile for Peter  Send Email to Peter     
That patent will expire in November of 2023 (20 years from the filing date) if all maintenance fees are paid.

The claim to fame seems to lie in the use of a programmable logic device that provides:

(i) a variable gain control signal to said amplifier for normalization of the amplitude of reflected echos within said second signal by increasing gain in proportion to the distance of said echo reflection source from said sonar transducer, and

(ii) a harmonic sub-sampling rate, cosĪ†, to said analog to digital converter such that said reflected transmitted acoustic sonar wave is above the Nyquist frequency.

jimh posted 03-30-2006 09:37 AM ET (US)     Profile for jimh  Send Email to jimh     
I printed out the patent and intend to give it a careful reading.

Acoustic waves travel though a medium and are reflected back when they encounter something with a different acoustic impedance. The greater the difference in acoustic impedance the stronger the reflection. I recall that the target reflecting the acoustic wave can affect the phase of the wave, too. My memory is getting foggy, but I think the phase of the reflection varies depending on the acoustic impedance of the target. If higher than the transmission medium (water) you get one phase, and if lower, you get the opposite phase.

In a grayscale rasterized display of the return echoes, the amplitude of the echo is usually indicated by the luminance of the display representation. It is my understanding on a grayscale rasterized display of the echoes that very strong echo signals are indicated by black representations, and signals of less strength are indicated by lighter, gray representations.

In a SONAR display which uses color, what does the color scheme indicate? Is it just used to make differentiation between amplitude in echoes easier to interpret visually?

Is there any detection of the phase consistency of the return echoes?

bluewaterpirate posted 03-30-2006 09:04 PM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
A picture is worth a 1000 words. Figure it out. HD technology at work.

jimh posted 03-31-2006 05:50 AM ET (US)     Profile for jimh  Send Email to jimh     
I viewed the pictures of your RAYMARINE fishfinder in operation, but I cannot deduce what the color shading is intended to represent.

Is there a RED fish below your boat?

bluewaterpirate posted 03-31-2006 07:27 AM ET (US)     Profile for bluewaterpirate  Send Email to bluewaterpirate     
Fish and bottom .... if you'll look at the Chartplotter to the left you'll see I just coming off a ledge.
John from Madison CT posted 03-31-2006 08:10 AM ET (US)     Profile for John from Madison CT  Send Email to John from Madison CT     
I own a Raymarine Digital fishfinder, in the form of the DSC300 running on a C120 head unit.

All I can say is "WOW". For the avid fisherman, this is a must have technology. For just boaters who want to know their depth, then you can save money by going to a more typical analog system.

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