Developer's DescriptionBy ruklisThis app allows you to check remote control radio transmitters- car key fobs, garage door openers and others.This app allows you to check remote control radio transmitters- car key fobs, garage door openers and others. You can save time and money by checking it yourself prior to battery replacement or visiting the locksmith.please follow these 3 simple steps:install an app;install a rtl-sdr driver app (free):https://play.google.com/store/apps/details?id=marto.rtl_tcp_androconnect your rtl-sdr dongle to the phone and enable OTG-host mode in phone settings menuSome notes:rtl-sdr dongle is available at ebay for $8 to $30, please check if it comes with OTG cable.Cheapest "mini" dongles will not detect 868MHz band. If signal level is false high (urban area and good dongle), use it without antenna.