Radar Question

C-Val · Posted: Fri May 07, 2021 12:29 am Post subject: Radar Question

Hi Everyone

I just installed a Lowrance Halo 20 on my boat. As I am trying to understand how it works, I read that it’s minimum range is 50m. (164’)

In comparison the Garmin minimum range is 25m and the Raymarine is only 6m

Does this mean on mine I will not see any boats or pilings closer to my boat than 50m? I tried it for the first time the other day and if I turn the gain up I get objects as close as 25’ showing up

What in layman’s terms does this “minimum range” thing mean?

Any other suggestions in learning this new toy?

Thanks

garyf · Posted: Fri May 07, 2021 1:59 am Post subject:

When a radar is transmitting, the receiver is blocked to prevent damage to the sensitive receiver. Once the transmitted pulse clears the antenna, the unit can switch back to receiving. The time it takes to switch between transmitting and receiving is what creates the nearby 'blind spot' or minimum range. Since the radar waves are moving at the speed of light, even a very quick transition will result in notable distance of blind spot.

Like many things with electronic design, the companies have to deal with tradeoffs in how the materials can perform within the constraint of physics. 50m minimum range doesn't necessarily make your unit inferior to the others (overall)... it probably has other specs that are better - higher power maybe or whatever.

If you turn up the gain and see "objects" less than 50m away, it could just be noise... were you able to correlate the returns with actual objects? Of course, there's often a slight difference between advertised specs and actual performance, so it is possible that you're seeing some closer objects... but I wouldn't count on it.

Enjoy your new toy Smile

thataway · Posted: Fri May 07, 2021 8:42 am Post subject:

From the Halo 20 manual the minimum range is 6 meters or 19.7 feet. I cannot speak for the Garmin, but it is correct that the Raymarine quantum radar is also 6 meters.

Where on the cabin top is the radar scanner mounted and how high off the cabin top is the radar scanner?

C-Val · Posted: Fri May 07, 2021 11:04 am Post subject:

Thanks for your input. I understand better now

The antenna on my 22 angler is mounted about 1/4 of the way forward of cabin roof which is about in middle of boat. (There were old mounting holes already there) Its only mounted on two pieces of starboard about 3/4' high

I have to tip my dinghy over it from cockpit as I put it on the roof so I had to keep it toward the back of roof and lower so it fits inside dinghy

thanks

David and Val