The site is a residential road on the edge of Todmorden, in the South Pennines, West Yorkshire. The road peters out into a track with a wooded valley to one side. Down below is the main road to Burnley.  Up above it's a short walk to roughly grazed moorland.  The bats can be spotted at dusk, flying in amongst the trees but also across the open spaces. 

The stream set up is as follows:  A mini headphone jack lead out from the bat detector's (a Bat Box Duet) 'rec' output, to a passive stereo DI box.  Two XLR cables out from the DI box to the inputs on a Zoom HN4 recorder.  A USB cable out from the Zoom HN4 to an iPhone 'Lightening to USB 3 Camera Adapter', which also has a battery pack plugged into it. The camera adapter then plugs into the lightening port on an iPhone7 with the Locus Cast app installed. The extra power provided by the battery pack is essential for the app to operate.  Ultrasound calls from bats can be captured and converted into human-audible outputs using different methods. The Batbox Duet sends a Frequency Division signal to its left channel and a heterodyne signal to its right channel.