fcd_nfm_rx: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/fcd_nfm_rx - from package: gnuradio

You may install the required package with command apt-get install {package}

Error in other languages:
fcd_nfm_rx: bevel nie gevind nie
fcd_nfm_rx: comandă negăsită
fcd_nfm_rx: comando não encontrado
fcd_nfm_rx: commande introuvable
fcd_nfm_rx: command not found
fcd_nfm_rx: käsku ei ole
fcd_nfm_rx: không tìm thấy lệnh
fcd_nfm_rx: komanda nerasta
fcd_nfm_rx: Kommando nicht gefunden.
fcd_nfm_rx: kommandot finns inte
fcd_nfm_rx: komut yok
fcd_nfm_rx: nie znaleziono polecenia
fcd_nfm_rx: níor aimsíodh an t-ordú
fcd_nfm_rx: no se encontró la orden
fcd_nfm_rx: no s'ha trobat l'ordre
fcd_nfm_rx: opdracht niet gevonden
fcd_nfm_rx: parancs nem található
fcd_nfm_rx: perintah tidak ditemukan
fcd_nfm_rx: príkaz nenájdený
fcd_nfm_rx: příkaz nenalezen
fcd_nfm_rx: команда не найдена
fcd_nfm_rx: командата не е открита
fcd_nfm_rx: 命令找不到
fcd_nfm_rx: コマンドが見つかりません