How to understand if the variance is constant reading GARCH model output?

Question

I'm using GARCH() function (tseries package) to fit garch model.

I tried it with random numbers: g <- garch(rnorm(750), order = c(1,1))

I know in this case the variance is constant BUT how to understand it reading the output of that function?

summary(g)
Call:
garch(x = rnorm(750), order = c(1, 1))

Model:
GARCH(1,1)

Residuals:
     Min       1Q   Median       3Q      Max 
-3.34115 -0.68029  0.07071  0.71918  3.31074 

Coefficient(s):
    Estimate  Std. Error  t value Pr(>|t|)
a0 9.454e-01   4.789e+00    0.197    0.843
a1 9.102e-03   4.535e-02    0.201    0.841
b1 2.448e-12   5.028e+00    0.000    1.000

Diagnostic Tests:
        Jarque Bera Test

data:  Residuals 
X-squared = 0.0373, df = 2, p-value = 0.9815


        Box-Ljung test

data:  Squared.Residuals 
X-squared = 2e-04, df = 1, p-value = 0.9879

Answer 1

A hint in the output is that neither a1 nor b1 are significantly different from zero. Another way to tell would be to do a Ljung-Box test on the squares of the original data.