OpenCPN SIMRAD/LOWRANCE Radar Overlay PlugIn

[Douwe Fokkema]

The software of a beta version following up the release 1.0 of the br24_radar_pi is now at https://github.com/douwefokkema/BR24...ree/master/src
Feel free to test and report any issues there.

[NahanniV]

Originally Posted by Douwe Fokkema

The software of a beta version following up the release 1.0 of the br24_radar_pi is now at https://github.com/douwefokkema/BR24...ree/master/src
Feel free to test and report any issues there.

Great !

Can someone make the .dll available, I don't have a windows build environment.

Cheers,
JM.

[BMD21]

Hakan

Thanks for the description. In order to make sure I understand what you're saying, let me give you my understanding. I'm not trying to teach you anything, just trying to make sure I have the correct understanding.

So, the radar works in radial coordinates. For 2000 sectors by 500 segments, that's the equivalent of 2000*500 = 1,000,000 pixels or radar elements. I assume that each (radar) pixel contains the necessary data to indicate what level of return is in that element as well as its position in radial space.

Then, the _pi uses the radar settings it transmitted at startup and converts the radial pixels into orthogonal (x,y) pixels for display in the overlay.

Is the above near the truth? Whatever it is, I think it's wonderful.

BTW, the 3/4G frequency is the same as most small boat radars, X-band, just low power and different modulation.

Boris

[Hakan]

Boris..
Your summary looks good to me. As you've noticed my English is not the best.
But one thing can be mentioned; Not all sectors and segments are covered in every transmit. But I don't remember all details for the moment. I think we've discussed the foundation for the plugin before but a link to the "paper" is here: OpenBR24 | SourceForge.net

Håkan

[Hakan]

JM... at all..

A Win binary of Douwe's master compiled against OCPN 4.0 is attached. Please discard the .pdf extension.


Håkan

[rgleason]

Thanks Hakan. Bcn, Nahanni Very helpful.
What is experience seeing bad weather storms? Understand it is less capanle than regular radar. However guick start up. Low power use, low standby use amd great close detail are its assets. Can ypu confirm?

Sent from my SCH-I545 using Cruisers Sailing Forum mobile app

[RobbieW]

Originally Posted by rgleason

...What is experience seeing bad weather storms?...

I used my 3G set to track rain cells on our last trip of last season. Typical northern hemisphere (Mediterranean) low with a frontal system that crossed us. We could pick up and track the cells from about 5 miles out, it was all a bit unstable though so difficult to reliably identify stuff much farther away. I dont remember in detail but I would have tweaked the settings to highlight the cells rather than try to see through them. However this was using a Simrad MFD, I dont think I used the radar with OCPN on that trip.

[NahanniV]

Originally Posted by rgleason

Thanks Hakan. Bcn, Nahanni Very helpful.
What is experience seeing bad weather storms? Understand it is less capanle than regular radar. However guick start up. Low power use, low standby use amd great close detail are its assets. Can ypu confirm?

Sent from my SCH-I545 using Cruisers Sailing Forum mobile app

These RADARs do have low power emission at RADAR frequencies making them very safe. But, they use almost the same amount of DC power as an equivalent range pulse RADAR when transmitting.

The big power saving is in standby mode they only draw a few watts.

Now thanks to Hakan we can use timed transmit mode and keep a RADAR watch with very low power consumption.

e.g. Assuming: 20W TX, 3W Idlle, 2min. Tx time, Batt=12.5V

Constantly on the RADAR would use (20/12.5)*24=38.4Ah/day

At 5min. timed transmit interval, the power usage would average:
((2*20)+(5*3))/(2+5)=8W for a daily power saving of 23Ah

At a 10min. interval:
((2*20)+(10*3))/(2+10)=6W for a daily power saving 27Ah

At a 15min. interval:
((2*20)+(15*3))/(2+15)=5W for a daily power saving 29Ah

At a 20min. interval:
((2*20)+(20*3))/(2+20)=5W for a daily power saving 29Ah

Higher off intervals only make a very small difference and are really too long for a safe watch when freighters can travel at 23 Knots or more.

A 1min. on time option might be a consideration.

Cheers,
JM.

[Hakan]

Originally Posted by NahanniV

............
A 1min. on time option might be a consideration.
JM.

JM..
The transmit time is not a option in the normal settings menu but can so far be changed in the config file, e.g. opencpn.ini in Windows.
Change the [PlugIns/BR24Radar] setting: RunTimeOnIdle=2
2 is the transmit time in minutes.(No decimals! and not zero)

More descriptions are found here: http://www.cruisersforum.com/forums/...ml#post1792007

Håkan

[NahanniV]

Originally Posted by Hakan

JM..
The transmit time is not a option in the normal settings menu but can so far be changed in the config file, e.g. opencpn.ini in Windows.
Change the [PlugIns/BR24Radar] setting: RunTimeOnIdle=2
2 is the transmit time in minutes.(No decimals! and not zero)

More descriptions are found here: http://www.cruisersforum.com/forums/...ml#post1792007

Håkan

Thanks, I missed (or forgot) that setting.

Cheers,
JM.

[BMD21]

NahanniV/JM


A minor point, but one of the reasons I got the 3G radar.


I was curious when you said that the 3G used about the same input power transmitting as the magnetron based radars. Based on the transmitted power, that didn't make sense, unless the 3G was really inefficient. And the wasted power would go into heat, right? 3G specs 18 watts transmit, 2 watts standby. 4G is 20 w and 3 w, respectively.



So, I checked. Raymarine RD418D/RD424D radars are specified at 40 watts transmitting, 20 watts standby . Garmin gives 35 watts typical, which I assume is an average.


Chirp modulation does offer a lot of advantages and low input power is one of them. The installation manual specifically states that there is no danger from standing in the transmit beam. Also, note the big difference between 3G in standby with the Raymarine. That's a surprise, since they're both digital processor driven.



Certainly a timed transmit mode is a desirable option when you're sailing and every watt counts. Just pointing out a difference between 3G/4G chirp and the others (magnetron.)


Boris

[oldmonk]

Originally Posted by BMD21

Also, note the big difference between 3G in standby with the Raymarine. That's a surprise, since they're both digital processor driven.

Magnetron heating takes power even in standby.

[NahanniV]

Originally Posted by BMD21

NahanniV/JM


A minor point, but one of the reasons I got the 3G radar.


I was curious when you said that the 3G used about the same input power transmitting as the magnetron based radars. Based on the transmitted power, that didn't make sense, unless the 3G was really inefficient. And the wasted power would go into heat, right? 3G specs 18 watts transmit, 2 watts standby. 4G is 20 w and 3 w, respectively.



So, I checked. Raymarine RD418D/RD424D radars are specified at 40 watts transmitting, 20 watts standby . Garmin gives 35 watts typical, which I assume is an average.


Chirp modulation does offer a lot of advantages and low input power is one of them. The installation manual specifically states that there is no danger from standing in the transmit beam. Also, note the big difference between 3G in standby with the Raymarine. That's a surprise, since they're both digital processor driven.



Certainly a timed transmit mode is a desirable option when you're sailing and every watt counts. Just pointing out a difference between 3G/4G chirp and the others (magnetron.)


Boris

What I said was " they use almost the same amount of DC power as an equivalent range pulse RADAR when transmitting."

What I should have emphasized was "equivalent range".

The RADARs you are quoting are 48NM range. The 4G states 36NM maximum, but the reports I have read say the useful range is much less:Panbo: The Marine Electronics Hub: Simrad Broadband Radar 4G, hand's-on #1

So for instance, the Furuno DRS2D uses 19.2W and is rated 24NM:
http://www.furunousa.com/ProductDocu...Manual%20F.pdf

The broadband RADARS certainly have advantages (I bought one), but I think the low power usage is overstated. Especially when you consider that none of the Navico MFDs implement a timed transmit function.

Cheers,
JM.

[Hakan]

Originally Posted by oldmonk

Magnetron heating takes power even in standby.

The Navico, BR24/3G/4G, has neither a magnetron nor a heater. That's why the idle power is negligible and start up is instantaneous.
Håkan

[NahanniV]

Just to add to my analysis of power usage, here is a graph from Navico comparing their RADARs:



It seems to show the 3G/4G effective range as just over 11NM ?.
Again, similar range as a 2KW RADAR that uses a similar amount of power.

JM.