Andy's Postbag and random ebay links

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RogerClark
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Re: Andy's Postbag and random ebay links

Postby RogerClark » Fri May 12, 2017 9:23 pm

I think the key phrase may be

"passes at a fixed distance from it"

Which seems to imoly, that you need to know when the vehicle, is directly in front of the detector, as only at that point in time, do you know the distance from the vehicle.

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ahull
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Re: Andy's Postbag and random ebay links

Postby ahull » Fri May 12, 2017 9:25 pm

zoomx wrote:Maybe it's better a spectrogram app that can do this
Image

Nice.. what is the App?
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Re: Andy's Postbag and random ebay links

Postby ahull » Fri May 12, 2017 9:36 pm

RogerClark wrote:I think the key phrase may be

"passes at a fixed distance from it"

Which seems to imoly, that you need to know when the vehicle, is directly in front of the detector, as only at that point in time, do you know the distance from the vehicle.


Let me think about that... we know it must lie in one of two lanes, (when travelling left to right in the UK, it will be in the lane furthest away, call this vector one, and when travelling right to left it will be on the nearest lane, vector two) and we know (from the doppler shift) what its angular velocity is.

We also know that when the volume peaks, it is at its closest, so we should therefore be able to figure out that it is travelling at one of two speeds, depending on which distance it passed at, even if we don't actually know which lane it is in.

With two microphones at 45 degrees to each other, we should even be able to figure out the direction of travel.. but can we figure this out with only one microphone I wonder?
- Andy Hull -

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Re: Andy's Postbag and random ebay links

Postby ag123 » Fri May 12, 2017 10:20 pm

ahull wrote:
ag123 wrote:wow, @ahull, it seem that the screen suffer quite a bit of violence, the vocals cracked the glass? :lol:

There is a reason why this one only cost £1 on ebay (plus postage) :P

The smashed digitizer is actually pretty easy to fix. if you can wield a small screwdriver and a hot air gun, it comes away clean without damaging the LCD below. Replacements only cost a couple of quid. In the case of this phone, (a Galaxy Ace 2), the digitizer is £3.49 shipped from the usual suspects. So for <£10 plus a little time spent rooting it and installing Cyanogenmod, you have a small wifi enabled Android/linux box with display that doubles up as an audio spectrum analyser and phone. :D Arguably more useful than a Raspberry Pi, and certainly cheaper.


just for the fun of it too, i got a few pieces 4 wire resistive touch panel for 2.8 inch displays for some old sony ericsson phones for around $1.50, after i ordered that i did a search now, the availability is literally extinct, OMG, the rest are all 3.5", 5", 7" resistive touch panels and cost quite a bit more (i got some ILI9341 without touch only to find out after i receive them, so i made up for that old goof with a new goof) :lol:
http://www.ebay.com/sch/i.html?_from=R4 ... el&_sop=15

there are tons of touch panels for the modern smart phones hi-tech capacitive (multi) touch often with the controller
http://www.ebay.com/sch/i.html?_odkw=4+ ... l&_sacat=0
the only trouble is that often a google search for how to interface them tend to turn up a blank

hope someone can pester some of the manufacturers to release the specs then all our arduinos would become capacitive multi touch as well and cheap :lol:

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Re: Andy's Postbag and random ebay links

Postby ahull » Fri May 12, 2017 10:38 pm

ag123 wrote:
ahull wrote:
ag123 wrote:wow, @ahull, it seem that the screen suffer quite a bit of violence, the vocals cracked the glass? :lol:

There is a reason why this one only cost £1 on ebay (plus postage) :P

The smashed digitizer is actually pretty easy to fix. if you can wield a small screwdriver and a hot air gun, it comes away clean without damaging the LCD below. Replacements only cost a couple of quid. In the case of this phone, (a Galaxy Ace 2), the digitizer is £3.49 shipped from the usual suspects. So for <£10 plus a little time spent rooting it and installing Cyanogenmod, you have a small wifi enabled Android/linux box with display that doubles up as an audio spectrum analyser and phone. :D Arguably more useful than a Raspberry Pi, and certainly cheaper.


just for the fun of it too, i got a few pieces 4 wire resistive touch panel for 2.8 inch displays for some old sony ericsson phones for around $1.50, after i ordered that i did a search now, the availability is literally extinct, OMG, the rest are all 3.5", 5", 7" resistive touch panels and cost quite a bit more (i got some ILI9341 without touch only to find out after i receive them, so i made up for that old goof with a new goof) :lol:
http://www.ebay.com/sch/i.html?_from=R4 ... el&_sop=15

there are tons of touch panels for the modern smart phones hi-tech capacitive (multi) touch often with the controller
http://www.ebay.com/sch/i.html?_odkw=4+ ... l&_sacat=0
the only trouble is that often a google search for how to interface them tend to turn up a blank

hope someone can pester some of the manufacturers to release the specs then all our arduinos would become capacitive multi touch as well and cheap :lol:


The touch panel controller is integrated in to the touch panel in this case (that black square on the fpc cable).
The code to drive it will be in the Cyanogenmod/Android kernel source.
- Andy Hull -

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Re: Andy's Postbag and random ebay links

Postby ag123 » Fri May 12, 2017 10:46 pm

that's a nice finding :D

back on the topic of the dropper shift, my example of a car at supersonic speeds shows that the tyre noise FFT isn't quite accurate enough to tell the speeds of the vehicle. i've originally thought that when the vehicle is approaching u'd get 1000 hz, and when it is moving away u'd get say 900 hz, but the calcs create 'supersonic' cars with these estimates. hence, the real dropper shift is possibly only a couple of hz difference

and those 900hz peaks are large trucks and 1000hz are cars (the tyre thread width accounts for that difference in pitch). this finding is useful, as now arduino boards or android phones can now 'count cars and trucks' simply 'listening to it'

my guess is tracking the rate of change would be somewhat more tricky and difficult, it is quite observable that the peaks changes in shape and intensity say around a central of 1khz as the vehicles approaches and move away, but the band varying around it is probably a couple of hz to tens of hz
:lol:
Last edited by ag123 on Fri May 12, 2017 11:22 pm, edited 4 times in total.

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ahull
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Re: Andy's Postbag and random ebay links

Postby ahull » Fri May 12, 2017 10:51 pm

ag123 wrote:that's a nice finding :D

You will of course need to find a suitable fpc connector, or solder direct to your own PCB. If that is not an issue, then they are an inexpensive option. The Galaxy Ace digitizes (and a few others) are a similar price.
- Andy Hull -

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RogerClark
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Re: Andy's Postbag and random ebay links

Postby RogerClark » Fri May 12, 2017 11:58 pm

ahull wrote:

We also know that when the volume peaks, it is at its closest, so we should therefore be able to figure out that it is travelling at one of two speeds, depending on which distance it passed at, even if we don't actually know which lane it is in.

With two microphones at 45 degrees to each other, we should even be able to figure out the direction of travel.. but can we figure this out with only one microphone I wonder?


Yep.

I think the volume peak may be important, its only at that point can you assume its directly in front of the detector in either of the 2 lanes.

So if you can use 2 different mics, and compare the volume, you should be able to detect the direction and hence the lane and hence the distance from the main sensor (or one of the direction sensing mics)

I wonder if having 2 mics may also help in other ways.. (I'd need to think about that one)

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Re: Andy's Postbag and random ebay links

Postby zmemw16 » Sat May 13, 2017 3:16 am

iirc wasn't there a discussion about using 4 mics to derive a sources position on the forum ?
stephen

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Re: Andy's Postbag and random ebay links

Postby RogerClark » Sat May 13, 2017 7:04 am

zmemw16 wrote:iirc wasn't there a discussion about using 4 mics to derive a sources position on the forum ?
stephen


Yes. I recall someone doing that, but from what I recall, the sounds they were detecting where discrete "taps" or "knocks", and not the complex sounds that andy would need to detect.

I guess it may be possible to record from 2 ADC channels via DMA into 2 buffers and perhaps run some matching algorithm, to determine the time difference between the 2 waveforms. But I have a feeling the amount of processing power that would be required would be beyond the F103, but possibly not beyond the F407. I suspect you'd need a FPU for the maths.


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