Author: richard

Remote sensing and the Internet of Things

Wires. That’s the problem with remote sensing, at least it has been until recently. You needed wire to get the signal back to where you wanted to view it, and often to power your sensor too. That’s a grand PITA. The last time I looked at this, about a decade ago, you could get little RF modules running at around 433MHz but these presented the raw demodulated FM signal. Great for voice but you then needed a modem to wrap around the project. And some sort of protocol stack, possibly.

That exchanged the signal wiring problem for a sensor powering issue, and these radio modules were send or receive so everything would end up fire and forget.

I was chuffed to find there’s been a lot of movement in this field. A lot of it seems Arduino based and I selected PICs when getting into micros, so it is a new learning curve. In researching this I came across JeeLabs and Ciseco. The latter had some £12 bidirectional RF to serial cards, the XRF, which I expected to attach a PIC. However, they seeme ot also have used the microcontroller on the RF board to do some signal conditioning for a few sensors, including temperature via the Dallas 18B20 or a thermistor. Since temperature and battery voltage/contact status are some of the things I want to remote sense that saves me a load of programming grunt-work.

They have also documented a simple serial sensor protocol, LLAP, which fitted my needs. The Internet of Things is all very well but if you need a TCP/IP stack for each battery powered node you need a lot of processing power and electrical power, which is back to wiring again.

So I ordered four XRF boards, a couple of thermistor boards and a XBBO carrier board to interface to an FTDI cable to USB. Assembling the thermistor boards and the XBBO were easy enough, now it was time to test it all out and getting some readings. To do that you have to set your LLAP sensor device to some particular address. and this is where is started getting hard. You have to program them over the air, and you have 100ms to respond to the started command.

Ciseco XBBO board for LLAP devices

That’s great for security, but I don’t type that fast 🙂 Which is why I use this script to do that job.

 

Fairground roundabout and another sound recordist at Ipswich Maritime Festival

I was making a binaural recording of this fairground roundabout when another sound recordist arrived to get a clip from the ride itself – he asked the proprietor if it was okay at the beginning of the clip.

The actual fairground organ is a recording played out of speakers either side of the organ facade. The giveaway, apart from no moving parts, was when the operator fiddled with the volume control 😉

fellow sound recordist on fairground ride

OK kids, knock it off before you end up in Casualty

An exasperated mother has to take a big kid and a little kid to task after Dad pushes his child’s scooter too fast. Overheard on the way to the Ipswich Beer festival by the docks.

Borough Market, London

Borough Market is under the arches leading in to London Bridge Station, and this trader was hawking snacks and decent fast food, like wild boar sausages and hare. I couldn’t work out what the heck he was calling out when I was there and I still can’t work out what his exhortation is.

At  the beginning of the track there is the shrill call of starlings. I was chuffed, because something really bad has happened to London’s birdlife over the last thirty years, as many once common birds are common no more. There used to be thousands of starlings in London, there was an enormous roost at Charing Cross station decades ago.

Most tragically, the humble house sparrow seems to have surrendered the fight. As a child growing up in London they were everywhere, in the parks you could sometimes see some old boy feeding hundreds, in the ways tourists feed the sparrows outside Notre Dame in Paris.You’d walk past the hedges in suburban London and be chided with the peremptory chirp of a house sparrow. No more – in the last three decades the chirp has fallen silent as the cockney sparrows have abandoned the city. Central London is now pretty much a bird-free zone apart for the ubiquitous pigeon.

Starlings have also abandoned the city, so it was a treat to hear their call. Perhaps these have worked their way up the river, for Borough market is near the river at London Bridge.

 

Going beyond field recording

Nikita from soundtrip has a great mini-series of articles on the philosophy of sound recording different cities and locations. He goes beyond field recording, putting together his recording shot with a 10 minute mini-programme in mind. I’ve listed his four articles here as some of the links end up in Russian

  1. soundtrips – reasons, aims, ways
  2. practice of silence
  3. Sounds around
  4. creating a soundtrip

I’ve never done any combined recordings. I’ve attempted to be an observer, nether adding or taking away, with only editing and volume control, the equivalent of foundview in photography. That’s largely because I don’t feel I currently have any talent for that side of things. Nikita’s posts gave me some pointers. Like the point about not using an ipod but listening to the word around you.

I have a short commute so I don’t do that, indeed I don’t have an iPod, or listen to music on the move after getting off a plane and firing up my MD player with some music on. It was horrifying to hear how loud it was set to overcome the sound of the engines.

You have to be more careful as you get older to minimise loud sounds, because the middle ear loses the ability to tighten the eardrum using the tensor muscle and to separate the stirrup from the oval window via the stapedial muscle, so a valuable automatic gain control mechanism becomes less effective at reducing the transmission of loud sounds to the inner ear.

So I’ve managed to avoid the isolation due to music, perhaps more by luck than judgement.

I may get the opportunity to do more recording in a few months, and perhaps I need to move beyond the limitations of my thinking about the recording process.

Another landmark article was Des Coulam’s concept of the sound map when making recordings

  1. soundlandscapes’ street recording tips
  2. soundlandscapes on the concept of the sound map

These are my favourite articles about the art and vision of field recording. I’m generally okay on the technical stuff, but it’s the art of field recording that I haven’t yet got right, and these made me think. It’s easy for some people writing about sounds to go all luvvie and float off into fluffy clouds of art-school speak, it’s good to avoid that and get real ideas from real people out there doing it!

 

New Year 2012 Felixstowe Ship Horns

Even in Ipswich you get to hear the boat horns sounding on New Year’s day, so this time I went to Shotley Peninsula, between the large container port at Felixstowe and another port at Harwich to record the ship horns sounding the New Year in.

A nice touch was the Shotley residents have a sense of timing. Unlike in Ipswich, where people start releasing fireworks all the time as soon as it gets dark, in Shotley (and Felixstowe and Harwich by the looks of it) they wait for the New Year. In the foreground are the sounds of some Shotley residents celebrating at the pub, but it is the ship foghorns that make this for me.

Note the fireworks are quite loud after the horns 🙂

St Paul’s Cathedral Bells and massive reverb from glass-fronted financial district buildings

St Paul’s Cathedral is only a stone’s throw from the tall glass-faced buildings of London’s financial district. I was sitting in the gardens ot the cathedral, and the bells sounded really odd, as if there was an organist following on after then about 2 seconds late. This must be the echo coming from the glass-fronted buildings about 0,5km away, it does nothing for the tone

Spinney Birdlife

There’s a spinney nearby, so over the holidays I got myself into the tree and rigged a pair of omnis, and stood really still. The first thing I heard was the mournful repeated tone of the collared dove, a steady counterpoint to the recording, with its mournful ho-HOO-hoo, with the stress on the first syllable. Later on the woodpigeon appears, with its ho-hoo-HOO-HOO-ho-hoo, and there are various other birds flitting around in the undergrowth.

It was a very windy day, so there is a lot of wind noise in the trees, which adds atmosphere for me, reminding me of a special moment with the birds