Originally Posted by
rustypigeon
My understanding, and correct me if I am wrong, but a radar is callibrated to show level 1 as green, level 2 yellow, 3-4 red, 5-6 magenta.
With all this in mind why would you have to play with the gain knob to determine the level of the weather?
The variable gain is basically resetting the value at which the baseline threshold for the display to show anything starts at. In the example I spoke of the baseline was 20 DB's to get a return. By being able to turn the gain down to make the "magenta" areas go away, you get to actually count the total DB's being returned.
Not all radar's are four color, most of the newer ones are, but not all.
Also, not all radar's are set to match the national weather service scales for level 1-6. You are correct, on most models, level 3 & 4 will get shown as the same color; and level 5-6 will get their own color for both levels. It can be very beneficial to be able to diferentiate between the levels... even though they are being displayed as the same colors.
being able to find the "weaker" area in a line, or the lower tops (tilt), are all tools in the arsenal for doing battle with the beast.
I know you haven't had much time with the units in the RJ's, but trust me, being able to do this stuff can make a huge difference. Our units are running with such wide beam widths they they are pretty useless at long ranges. They are very good up close and out to around 25 miles.... but for picking off stuff at long range you need a much larger plate, with a much smaller beam width.
The typical mainline aircraft will have a 2 or 3 degree beamwidth, compared to an RJ's 8 to 12 degree beamwidth... it is much like going out in your backyard on a dark night with a spotlight, and a floodlight. One works great for long distance, and the other works great to light up the small patio. To use the floodlight effectively, you need to make full use of it's limited abilities.