Sound Bomb
I was at the finish line of the “Hood to Coast” running relay race a few weeks ago. As each team’s last runner approached the finishing area, the rest of the relay team was called up to run with them, across the finish line, together. As each team finished, an announcer called out the team’s name.
Some of the team’s names bordered on the obscene, others were named after songs. One team was named after the Beastie Boys song, “Brass Monkey”. My mind drifted to other Beastie Boys songs and locked on to “Sabotage”. For those not familiar with the song, it starts with some extremely loud and in-charge guitar and drums. It seemed to me to be the ultimate, dramatic “finishing” song. If only the organizers would be willing to play team songs over the PA… Of course, there are many reasons why they wouldn’t. It’d be a logistical nightmare to get CD tracks or MP3s from the teams in advance, and the organizers would no doubt need to pay ASCAP or BMI for the rights to “perform” the music. But what if the team or their support crew could play the song, guerilla-style?
I turned that thought over in my head for a bit. You couldn’t bring in your own PA. It’d be unwieldy and would attract attention. It would require set-up and power. You’d need a portable, self-contained PA. I’d seen that before… A guy came to my DorkBot “chapter” recently with a battery-powered amplifier/speaker cabinet. It was a wood box with a battery (probably lead-acid), a fairly hefty solid-state amplifier, and a speaker. Take that idea and build it into a smallish box (backpack-sized) with some sort of audio source — maybe an inexpensive FM receiver?
But a single system loud enough to have the desired effect would be too large for a backpack — without causing severe skeletal trauma, that is. Parallel-ize the solution — make six or so smaller cabinets. How do you make sure they all play the same sound at the same time? Put FM radio receivers into each? That would work, but seemed inelegant. How would you make sure the cabinets stayed tuned-in but quiet and innocuous until blast-off? And where would you find a decent, semi-powerful FM transmitter and how would you power it? And what about the FCC?
Perhaps the solution is to put the audio source inside each box. Have a digital audio playback device (something like a simple MP3 player), capable of playing just a minute worth of audio. Maybe it could reuse all these useless CompactFlash micro-SD cards that come with mobile phones and cameras. Trigger the playback in each box using a low-power, low-bandwidth, long-range wireless technology. I don’t think a BlueTooth UART link would work — can you pair one transmitter with multiple receivers (broadcast)? Maybe ZigBee? Or a super-simple, proprietary (Nordic) or IEEE 802.15.4 transceiver? Make each system hold up a two-way link. The master box would transmit a periodic beacon and receive responses from the slave boxes. The slave boxes would have an indicator showing if they were in range. And the master trigger would not fire unless all the slaves transmitted an acknowledgement and received a secondary go-ahead from the master (after all the slave acks are received).
So what could you do with this? I must confess I haven’t thought too much about it — the technical design challenge is enough to keep me distracted for a while. But you and your five closest friends could take these boxes on a walk to a public square or parade and drop a short political speech or social commentary sound bomb. And because the audio would eminate from many directions, it would be immersive and perhaps difficult to identify the exact source. That could be fun…