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Old 18-03-2009, 23:18   #16
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What is IMO? I don't agree with the CRT to LCD analogy. It somehow does not capture it for me. I was thinking more the switch from emulsion to CCD technology, that is, film to digital transformation. What BR is doing is imaging its surroundings, much like a digital camera. Least that is what it seems like to me. Hence, there is so much more that can be done with the raw image.

The youtube video was a little lacking in substance, but the photographs here: See for yourself | Simrad Yachting especially partially down the page that compares shots of Pile Moorings is amazing!

What causes the coloration around the images? Again, I am specifically referring to the pile mooring comparative shots. The broadband shows more color around different sized objects. Is this akin to a digital version of optical chromatic aberration such as you see in optics in poorer quality lenses?
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Old 18-03-2009, 23:33   #17
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This description, "Simrad Broadband Radar sends a continuous transmission wave with linear increasing frequency (hence the term Broadband). The wave retains its frequency as it travels out and reflects back from any objects. Meanwhile, the transmitter continues to output an increasing frequency." made me wonder if the manner in which BR works cause your boat to be "lit-up" on another boat's radar.

In other words, would the active manner in which broadband images its surroundings make your boat more visible to another boat using radar? I am thinking of active vs passive radar reflectors.

Michael
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Old 18-03-2009, 23:34   #18
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MV,

The reason I used that analogy is becasue CRT and LCD are worlds apart except for the fact that they display an imagine.

The shift from magnetron to solid state represents an huge shift in technology, much like that from CRT to LCD.

Magnetrons are fairly inefficient becasue of the fact that they emit a MUCH larger amount of energy to achieve the same effect.

If you look at the examples from Simrad, you notice that close in target detection is far superior to cavity mags. They accomplish this by emitting far less RF which, of course, makes it safer for the user to be around. But at the same time, the frequency is far more stable. This allows for higher accuracy.

The IMO is the International Maritime Organazation. They are a group of countries that have a large say in the equipment that must be used for larger vessels to operate in international waters.

Becasue JRC changed its business model to larger merchant vessels, the IMO became quite important to us. I am sure you have heard of SOLAS or Safet Of Life At Sea. This was a convention that spawned GMDSS (Global Maritime Distress and Safety Sysytem).

The IMO is constantly changing to support an ever cahnging merchant industry. However, the IMO is limited by the same political drawbacks as any multinational entity. Things happen slowly.

The reason why broadband radar will take off is becaue its development is not governed by the IMO.

Broadband radar is designed with you guys in mind. The personal craft owner who is interested in a better product for a higher level of safety and situational awareness.

Why broadband radar??

Lower emitted power
Higher target discrimination
longer equipment life

These are ground breaking claims that a cavity magnetron system could never make.

I would would love it if JRC made one for you guys, but as it is, all I can do it educate the public on why they should own one. I obviously can't support one manufacturer over another, but I can tell you that everyone on this forum should at least do thier due diligence and look into it.

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Old 18-03-2009, 23:37   #19
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This description, "Simrad Broadband Radar sends a continuous transmission wave with linear increasing frequency (hence the term Broadband). The wave retains its frequency as it travels out and reflects back from any objects. Meanwhile, the transmitter continues to output an increasing frequency." made me wonder if the manner in which BR works cause your boat to be "lit-up" on another boat's radar.

In other words, would the active manner in which broadband images its surroundings make your boat more visible to another boat using radar? I am thinking of active vs passive radar reflectors.

Michael
Even BBR units will employ some type of Pulse Rate Frequency modulation in order to avoid interferance that would show up as spoking or rabbit tracks. Even though the ouput power is low, the BBR is still an X-band transmitter and is therefore subject to interferance from other X-band transmitters.

Would you show up as a higher target? Probably.
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Old 18-03-2009, 23:39   #20
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This site, although it requires registration, is the cat's meow: http://www.kelvinhughes.com/equipment/radar/sharpeye

This is wonderful stuff!
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Old 18-03-2009, 23:41   #21
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So... what is the source of the coloration around some of the smaller images? Is there information in the coloration, or is it noise?
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Old 18-03-2009, 23:42   #22
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There ya go

This is new technology. It will be exspensive at first, but I firmly believe that it will bring a new level of reliability and safety to this market.
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Old 18-03-2009, 23:46   #23
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It would appear that BR uses the same doppler shift processing as used by the GOES satellites to pinpoint an EPIRB transmission. At least if I am reading this Dr. Norris' work correctly.
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Old 18-03-2009, 23:47   #24
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So... what is the source of the coloration around some of the smaller images? Is there information in the coloration, or is it noise?
Scan cooralation is a function of all radar. We all scan between 3 and 7 times to ensure a target is real.

BBR is no different. The difference is that BBR used far less energy to do so.

We are still talking about a radar here. Emitted RF bounces off a metal target and the return time is measures by a digital signal processor.

I would urge you guys to go check out some version of this radar.
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Old 18-03-2009, 23:48   #25
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It would appear that BR uses the same doppler shift processing as used by the GOES satellites to pinpoint an EPIRB transmission. At least if I am reading this Dr. Norris' work correctly.
HAHA!! Too right. This thread is getting really heavy into theory

Are you an engineer?
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Old 18-03-2009, 23:56   #26
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Scan cooralation is a function of all radar. We all scan between 3 and 7 times to ensure a target is real.

BBR is no different. The difference is that BBR used far less energy to do so.

We are still talking about a radar here. Emitted RF bounces off a metal target and the return time is measures by a digital signal processor.

I would urge you guys to go check out some version of this radar.
No, I think you are missing my question still. I think the coloration is a function of the shape of the object interacting with the shifting frequency, in other words, the color is likely due to noise from processing the doppler shift. Shifting frequencies are hitting different surfaces at different times -- sometimes I wish I was LaForge on Star Trek so that I could see the EM spectrum. This is just amazing stuff.

But that is really reaching for the stars as I am soooo out of my league here.

Wow. I have been accused of being a lot of things, but NEVER an engineer!!
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Old 19-03-2009, 00:02   #27
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Ahhh....

I see what you are saying.

You are sortof right and sortof wrong.

Even cavity mags can distinguise target intesity. We have radars that paint different colors for different density of tartgets. This is old hat...as it were.

Radar is not doppler. Doppler shift is a measurment of frequency shift due to attenuation of signal. We are not looking at that.

Radar is simply a measurement of time over distance by strength.

Target return is most certainly affected by mass.....we are counting on that. As such, larger mass return get higher visibility on the PPI.
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Old 19-03-2009, 00:05   #28
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But I thought that BR uses the shift and digitally processes the signal for greater target discrimination?

And you were right about wood boats. Professor Norris reported that a container ship captain wrote to him and said: ""Our problem is (and always will be) detection of small wooden vessels in restricted visibility, especially in Asia"."
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Old 19-03-2009, 00:11   #29
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^^

It does.

Let's bear in mind that I am not a BBR engineer. My area of knowledge if mainly confined to conventional methods of RF wave propogation. BBR is a new type of technology.

I may have to concede a bit to the possibility of learning more.

You have definetly challenged me to broaden my knowledge of BBR even though we don't make one for this market.

Thanks!

And with that, I will bid you all a good eve.
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Old 19-03-2009, 00:17   #30
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Thanks for the information. This pulse compression technology seems very different than regular rf stuff -- but I don't know squat about this. I do know that sampling the received signal at specified intervals and measuring the voltage therein and then comparing those measurements with the original standing wave must require a bazzilion something or other computational power -- and this is why I think this shift is more like the shift from film to digital imaging. There is simply a ton of information in the signal that is coming back to the unit -- I mean a butt-load of information.

Thanks again!

Michael
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