sudo apt-get install qt6-base-dev libfftw3-dev cmake pkg-config libliquid-dev
git clone https://github.com/miek/inspectrum.git
cd inspectrum
mkdir build
cd build
cmake ..
make -j4
sudo make install

sudo dnf install fftw-devel cmake liquid-dsp-devel qt6-qtbase-devel
git clone https://github.com/miek/inspectrum.git
cd inspectrum
mkdir build
cd build
cmake ..
make -j4
sudo make install

sudo apt-get update -y
sudo apt-get install qtbase6-dev libfftw3-dev cmake pkg-config libliquid-dev 
sudo apt-get install build-essential git
git clone https://github.com/miek/inspectrum.git
cd inspectrum/
mkdir build
cd build/
cmake ..
make -j4
sudo make install

sudo apt-get update -y
sudo apt-get install qt6-default libfftw3-dev cmake pkg-config libliquid-dev 
sudo apt-get install build-essential git
git clone https://github.com/miek/inspectrum.git
cd inspectrum/
mkdir build
cd build/
cmake ..
make -j4
sudo make install

Installing Inspectrum on Mint 18.03 is troublesome as `libliquid-dev` is not available for many variants. Hence the following is hack. You may try on Ubuntu as your own risk.

sudo apt-get update -y
echo "deb http://cz.archive.ubuntu.com/ubuntu artful main universe" | sudo tee -a /etc/apt/sources.list.d/temp.list
sudo apt-get update -y
sudo apt-get install libliquid-dev -y
sudo rm -f /etc/apt/sources.list.d/temp.list
sudo apt-get update -y #Top important! Otherwise system can break. We only take libliquid-dev from this repo.
sudo apt-get install qt6-default libfftw3-dev cmake pkg-config -y
git clone https://github.com/miek/inspectrum
cd inspectrum
mkdir build
cd build
cmake ..
make
sudo make install

#install the dependencies
sudo apt-get update
sudo apt-get install qt6-default libfftw3-dev cmake pkg-config
#Install libliquid1d and libliquid1d-dev from Artful manually by extracting them directly
cd ~/Downloads
wget http://mirrors.kernel.org/ubuntu/pool/universe/l/liquid-dsp/libliquid1d_1.3.1-1_amd64.deb
dpkg -x libliquid1d_1.3.1-1_amd64.deb .

wget http://mirrors.kernel.org/ubuntu/pool/universe/l/liquid-dsp/libliquid-dev_1.3.1-1_amd64.deb
dpkg -x libliquid-dev_1.3.1-1_amd64.deb .

sudo cp  usr/lib/x86_64-linux-gnu/libliquid.* /usr/lib/x86_64-linux-gnu/
sudo cp -ar usr/include/liquid /usr/include/

#Install necessary tools for compilation
sudo apt-get install build-essential git

#Clone repository and compile the program
cd ~/Downloads
git clone https://github.com/miek/inspectrum.git
cd inspectrum
mkdir build
cd build
cmake ..
make
sudo make install
#Note: For the last step (sudo make install) **checkinstall** can be used instead for more benefits. 

brew install qt6 fftw cmake pkg-config liquid-dsp
git clone https://github.com/miek/inspectrum.git
cd inspectrum
mkdir build
cd build
CMAKE_PREFIX_PATH=$(brew --prefix qt6)/lib/cmake cmake .. -DCMAKE_CXX_FLAGS:STRING=-I/usr/local/opt/qt6/include ..
make install

sudo port install qt6 fftw-3-single cmake pkgconfig liquid-dsp
git clone https://github.com/miek/inspectrum.git
cd inspectrum
mkdir build
cd build
cmake ..
make
sudo make install