[Unit]
Description=Wsprrypi
After=multi-user.target

[Service]
Type=forking
User=root
ExecStart=/usr/bin/screen -d -m -S wspr wspr -r YOURCALL YOURLOCATOR 10 20m
ExecStop=/usr/bin/killall -w -s 2 wspr
WorkingDirectory=/root

[Install]
WantedBy=multi-user.target