Inside the callback for group1, get the value from the radio buttons of group2. Each radio button has a tag and a value, even though they all share a common callback routine.
value1 = get(handles.radioButton1, 'value');
value2 = get(handles.radioButton2, 'value');
value3 = get(handles.radioButton3, 'value');
% Set the noiseValue
if value1
noiseValue = 0.09; % or get the 'String' property and convert to double.
elseif value2
noiseValue = 0.02;
else
noiseValue = 0.05;
end