sounds, sensors, stones
The east coast has to be defended from the sea by placing massive rocks on the beach. Hopton is almost about as far east as you can get. The rocks make little inlets which make for an interesting soundscape, with the rattle of the pebbles against the long swoosh of the incoming waves, with some very low-frequency rumble from the rocks.
Binaural recording
As long as you recognise that the stock antenna is truly dire. And you’re prepared to fiddle a lot to get the AP510 and software going. This is not something that works out of the box. As supplied from Ebay in April 2016 the firmware of this didn’t match the software, in fact the firmware was too old. Cue much frustration and turning off and on to try and get it to talk. No dice.
Do what this guy says he has a treasure trove of the files in the links to the youtube post. It worked for me. I had to flash the firmware before my box would talk to the Sainsonic config software, and without doing that this device is no use at all.
Now if you can get an integrated GPS, APRS tracker, 2m rig for £78 it’s a great deal, if you can’t configure it it’s a rotten deal. But it worked for me in the end. There’s much to like, it’s small, it has its own battery, the price is right etc. There are things not to like – the male SMA on the board. SMAs are fragile, that pin is gonna break after about 500 cycles, which is why it’s nice to have the plug on the cable or the rubber duck aerial so you get to change that rather than the rig. Oh and the USB connector is a 3.3V RS232 connector, not a USB connector, though it can use a mini USB connector to a normal USB outlet to charge.
So I configured it and fired it up and it sort of works, well, out to about 200m for a J-pole vertical in my loft. Now I admit a J-pole with its somewhat live coax even after a CM coax choke doesn’t belong in the cluttered environment of the loft and I’ll change it for a Diamond X-30 or the like outside at some point, but I have a receive igate on it and it serves other mobile APRS stations okay enough, and serves me up to about 500m in the town with a Kenwood THD7. Continue reading “The Sainsonic AP510 APRS tracker can work well”
I was in Glastonbury, Somerset, and the house sparrows have started calling at nest sites there, They haven’t started in Ipswich. So I tried the audio recorder/GPS track surveying method. Each of the flags is where there was a male calling, or a male was sighted, along the lines of the BTO survey protcol [ref]Protocol for censusing urban sparrows, DeLaet, Peach and Summers-Smith, British Birds, 104, May 2011, p255 ff[/ref]
I covered a decent area, but not as thoroughly as I thought I had done. The sparrows seem in good heart, however, a more continuous coverage than I feel they are in Ipswich, where the colonies strike me as more fragmented. We will see.
My general impression was that sparrows are doing better in Glastonbury than many parts of Ipswich. The route I took left residential areas for the high Street, I know there are sparrows in Northload street so the two clusters might join.
The Ipswich RSPB Local Group is looking at surveying Ipswich’s house sparrows, ten years on after I took part in the first Ipswich Sparrow Survey. Most bird surveys cover a wide, fairly homogeneous area and avian subjects that are mobile over several hundred metres, or specific colonies. Surveying sparrows in the heterogeneous urban environment, with subjects that stay within 70m of the nest site when feeding young are a different kind of challenge.
We didn’t have the benefit of this BTO House Sparrow Survey protocol [ref]Protocol for censusing urban sparrows, DeLaet, Peach and Summers-Smith, British Birds, 104, May 2011, p255 ff[/ref]. As such the results show sample bias from the observer locations, survey effort and the difficulty to getting negative reports. However, it did answer the question ‘where are there sparrows in Ipswich?’, although not the question ‘where are all the sparrows in Ipswich’. It also answered the question ‘where are there no sparrows’ although the sparrowless areas were not exhaustively surveyed. Proving a negative is hard, though the BTO paper shows the way.
In the intervening time I solved the need to create waypoints on a handheld GPS and announce them to tie the audio to the location. Modern audio recorders contain clocks and timestamp the recording, this can be synchronised with the GPX tracks created by the GPS handheld. Smartphone applications like viewranger can also create GPX tracks. However, although a smartphone does many things it doesn’t do any of them very well.
I set the Samsung to give the most precise location. The issue doesn’t seem to be as simple as the Viewranger Samsung app updating slower than the Garmin, there are enough points, but they aren’t in the right place, particularly when the border trees by the road and railway line
The aim of all this was to write a web app to record sparrows in the field. However, it turns out that the Location API is very hit and miss. Sometimes I got 20m accuracy. Sometimes I get 3km accuracy, and I can’t easily see how to fix that, having already selected high geolocation accuracy. If I can’t do that for myself, I certainly can’t support other people using it on two different operating systems and on some mobiles that may not actually have a GPS receiver.
I love the sound of curlews, and it was surprising to find these so close to the town, with that wonderful bubbling call. They reach their peak numbers this time of year.
The problem is still the same as it was this time last year – the birds get up before I do in the Spring and I can only be one place at a time. Automatic recording devices let me scout locations in parallel.
A timed field recorder needs to be cheap, because somebody might nick it, it needs to be weather-resistant because it’ll be stuck outside, and it needs to be low-power, because 13A mains sockets are rare outside. Oh and it needs to be standalone, and not part of some cloud, because mobile Internet is ratty and expensive.
You can make this work but it isn’t fun at all. If you can use something like a USB stereo audio in board then do that rather than use this Cirrus Logic Audio Card, particularly if you have mains power available. I like the Behringer UCA202 and it works with the Pi.
A Raspberry Pi and A Wolfson audio card sort of fitted the bill, but the Wolfson Audio card is no more. I say sort of, because I’m still looking at about £70 for a Pi1, the audio card and enough odds and sods to power it. You can buy a Zoom H1 for about £80, although there’s still a bit more cost in powering it for long times, keeping the water out and making up some gizmo to pretend to be you pressing the big rec record button early in the morning.
But with the Pi I get to drive the recorder via cron and ssh, and transfer the files via the internet or mobile data in some places. Even if I don’t get a case, though they are to be had for the Pi/CL Audio card combination…
Continue reading “Timed Audio Field Recorder with a Raspberry Pi Cirrus Logic Audio Card”
You can buy a pukka Wattsup meter from RC Electronics for $60. That’s just too dear for me, I want to be able to apply a few of these in various places, so I go with the cheap fake Ebay version for £5.99 🙂 At the time I didn’t realise it was a cheap fake Wattsup, it was simply billed as Watt Meter
It duly arrived from some joint in Shenzhen and it wasn’t hard to see that quality control left something to be desired. But hey, whaddya expect for £6? I couldn’t source the LCD display and box for £6!
Chinese suppliers don’t actually have to deliver reliability at these low prices because the cost of sending the product back to China for a refund is higher than writing off the goods. Since I’m prepared to fix the odd part I’m happy to take the risk. It didn’t seem to be a good idea to apply a 12V car battery to this sucker as is, without some investigation. Plus having the display centred is a nice touch…
Hmm, nothing to centre the boards. Other than that, looks okay, except for the exposed positive solder joint in the main battery 12V line Insulated from the case by the blue anodising and now’t else. At least the LCD contacts are pushed away from the metal by some foam. The LCD groundplane ends just shy of the edge of the board so it may not short on the box, but it still seems a risky business to risk having the box at +12V potential when the anodising gets scraped through. Most 12V systems assume exposed metalwork is either isolated or connected to the negative terminal. I don’t feel that lucky as to go around with a +12V exposed metal box, so I got some of that pressed card (plastic can easily melt if it gets hot) and put it in inside the box, to at least give me an extra layer. I do see the wisdom of RC electronics using a plastic case, but then an 80% discount speaks a language of its own. How do I know it’s a fake Wattsup? Continue reading “Making a fake Chinese Wattsup 12V power meter less dangerous”
I made a couple of sound to light units at school and university many years ago.
Not much has changed about the technology, but on the display side LEDs are made for these – not only do we now have the chance of running the system at 12 or 24 V but we can avoid all the fun and games with mains triacs and pulse transformers – I got several mains shocks in those days, because while I optoisolated the main circuit from the triacs using MOC3020 opto-triacs the metal tabs on the triacs were live via the lamps, and on the same circuit board…
Now the Chinese make these things to drive LEDs by the millions on ebay and Amazon, and the sound to light is usually an add-on to a box designed to set moodlighting by colour with a remote control. And the sound to light function is crap on the two I’ve tested – I sent one back to Amazon because it was so dreadful it wasn’t worth the £12, although the cheaper Chinese device I have the light chase mode is acceptable.
There’s not much that has changed about the filtering from Don Lancaster’s 1970s article – sure we can use opamps or DSP but the essentials are still the same half a century later. I want to use proportional PWM control with the LEDs. Continue reading “12V LED Sound to Light or Color Organ”
This project is to make something that used to be common – a GPS receiver with serial data output. Modern APRS handhelds like the THD72 have GPS on board, but my Kenwood TH-D7 is from the turn of the century and doesn’t have onboard GPS. I used to pipe the output of a handheld GPS into the serial port. That worked fine, but in the field it’s a drag to use a handheld GPS tethered to a rig. Every time you want to put something down or set the rucksack down you end up with a knitting session on the cables. This is why they invented Bluetooth, and one option I considered was running a little Bluetooth receiver to a Copilot BT GPS. Trouble with the Copilot is how do you recharge it in the field, and I need to pick off power from somewhere to run the Bluetooth receiver. So I still get cables to the rig and another battery to manage 🙁
Most handheld GPS receivers like my Garmin Vista HCx have moved on to USB serial interfaces now, whereas the 1990s vintage Kenwood TH-D7e uses 4800-n-8-1 RS232, which is what GPS units chucked out in those days. Early THD7s had a problem reading the serial stream since NMEA 0183.3 superseded 0183.2 for the reasons described in the Potator article. I assumed my unit was one of these, so I constructed the Potator, but while the rig worked through it, it also worked without it, so I was lucky and dispensed with that 🙂
I have one of these Ravpower iSmart USB batteries, and it works a treat when used as the manufacturer intended – to power a mobile phone or an iPod (4th gen touch in my case). No complaints whatsoever.
I constructed a remote GPS module with MAX232 RS232 chip, and all this wants to run off 5V – the MAX232 is specced at 4.5V to 5.5V, the GPS is probably more tolerant. So the obvious thing to do is to cut off a USB cable, use the USB A plug and wire the power to my device from this. No need for a regulator, job done, and indeed the GPS fires up. Dandy. No need for 5V regulators, no need to mess about with undervolt cutoff, 5V power straight out of the box, what’s not to like?
The USB battery gives me a USB chargeable device and integrated power management, you can’t overcharge these or run them flat, and as someone who has just trashed a LiPo battery by leaving it connected overnight and flattening it, I appreciate that thought. Until I find out that
and decides my device isn’t drawing enough power and pulls the plug after a couple of minutes. Damn. My GPS draws a hefty 50-60mA, depending on whether the unbelievably bright LED the Chinese makers decided to fit is on or not.
Continue reading “A Ravpower USB iSmart battery doesn’t like low loads”
