rtl sdr detect when signal is sent on frequency

#!/bin/bash
#sdr detect when signal is sent on frequency
sudo apt install rtl-sdr

r1=314M
r2=316M
bin=1M
g=300

let thres=11;

rtl_power -f $r1:$r2:$bin -g $g -i 1|\
  while read l;
  do
    let p="$(echo "$l"|cut -d\, -f7|cut -d\. -f1)";
    if [ "$p" -gt "$thres" ];
    then
      echo "click";
    fi;
  done