  This paper enables connectivity on everyday objects by transforming them into
FM radio stations. To do this, we show for the first time that ambient FM radio
signals can be used as a signal source for backscatter communication. Our
design creates backscatter transmissions that can be decoded on any FM receiver
including those in cars and smartphones. This enables us to achieve a
previously infeasible capability: backscattering information to cars and
smartphones in outdoor environments.
  Our key innovation is a modulation technique that transforms backscatter,
which is a multiplication operation on RF signals, into an addition operation
on the audio signals output by FM receivers. This enables us to embed both
digital data as well as arbitrary audio into ambient analog FM radio signals.
We build prototype hardware of our design and successfully embed audio
transmissions over ambient FM signals. Further, we achieve data rates of up to
3.2 kbps and ranges of 5-60 feet, while consuming as little as 11.07{\mu}W of
power. To demonstrate the potential of our design, we also fabricate our
prototype on a cotton t-shirt by machine sewing patterns of a conductive thread
to create a smart fabric that can transmit data to a smartphone. We also embed
FM antennas into posters and billboards and show that they can communicate with
FM receivers in cars and smartphones.
