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Messages - possum

Pages: [1]
IOScope / Re: Block diagrams of I/O
« on: October 29, 2012, 05:59:46 PM »
Thanks Ben,

It looks like we crossed posts.  Yeah, I figured out the iPhone I/O share a common ground.

It seems like the iPhone is not happy with inputs exceeding 1 Vrms, which also makes using a power amp dangerous if speaker impedance and sense resistor values are not carefully considered.

Do you know of issues with the missing Ch2-Ch1 input option with the Line6 Mobile In and/or iPod touch 5G combination ? 


IOScope / Re: Block diagrams of I/O
« on: October 29, 2012, 05:51:42 PM »
here is how I understand the I/O block diagram for measuring loudspeaker impedance based on your video tutorial.

I'm using the following equipment;

iPod touch 5G with 30pin to lightning adapter
Line 6 Mobile In

one observation with this setup; I'm not seeing the option for (Ch2-Ch1) input, just Ch1 and Ch2 independently.

Would using a power amplifier be advisable to take some current load off the iPod/iPhone/iPad headphone output ?

Are you aware of any iPhone/iPod/iPad compatible USB input devices that have floating inputs ?



IOScope / Block diagrams of I/O
« on: October 29, 2012, 08:00:27 AM »
Hi Faber,

In the hopes of better understanding how the I/O is routed through the iPhone headphone jack, do you have a block diagram of what is going on, including grounding ?

I'd like to avoid blowing up my headphone outputs again the next time I try to measure something.



SignalScope Pro / Re: .mat file export sample rate errors
« on: January 02, 2012, 01:34:14 PM »
little bump for the new year.

In regards to your original questions:

Are you connecting/disconnecting any audio input devices (e.g. a headset mic or dock connector interface)? 


Are any other apps running that might access audio inputs/outputs on your iPod?


Just wondering if I can provide any more info on the Matlab export issues.


SignalScope Pro / Re: .mat file export sample rate errors
« on: November 30, 2011, 12:25:31 PM »
Hi Ben,

I just tried repeating the .mat file export with a speaker playing a 1kHz sine wave.  SSPro reported the correct frequency on the graph.  I exported a .mat file, and when I was returned to the FFT analyzer screen (which was still running), the sine wave frequency peak drifted down from 1kHz (presumably 44100/48000 * 1kHz).  I tried exporting that curve as a .mat and SSpro crashed on me.

Restarting SSpro, I could see the frequency was correct again, but I can no longer export a .mat file, as SSpro continues to crash each time I try. Even after clearing SSpro from the background and restarting the iPod Touch, SSpro seems insistent on crashing every time I try to export a .mat file.

I tried exporting to PDF with the same results, SSpro crashes after one successful export.  I was able to capture a screenshot of before and after a .mat export to highlight the 1kHz frequency peak oddity.

I was getting the same results with and without my external headset mic plugged in.

During this session today I was careful to not be running any additional apps, audio or otherwise.  This was confirmed by checking background processes by pressing the home button twice to bring up the background screen.

Let me know if you have any questions.


SignalScope Pro / .mat file export sample rate errors
« on: November 23, 2011, 10:07:12 AM »

I've saved a series of .MAT files from the FFT analyzer using the default settings and when I look at the data in Matlab I get sample rate errors.

Here is what MATLAB reports for sample rate from 6 files I read in from SSPro;

ans =
>> case4_top_9v.Parameters.SampleRate
ans =
>> case4_top_8v.Parameters.SampleRate
ans =
>> case4_top_7v.Parameters.SampleRate
ans =
>> case4_top_6v.Parameters.SampleRate
ans =
>> case4_top_5v.Parameters.SampleRate
ans =

The data looks correct when I assume a 48kHz sample rate.  Any reason why the MATLAB export would report the incorrect sample rate when saving to the structure ?

If I can provide more info please advise.

SignalScopePro, iPod Touch 4G, iOS 5.0.1 (9A405), Matlab 7.11.0 (R2010b), WinXP.



SignalSuite / Re: SignalSuite and iOS4
« on: July 02, 2010, 05:21:16 AM »
Thanks Faber, the update works great!


SignalSuite / SignalSuite and iOS4
« on: June 23, 2010, 06:50:35 AM »
Anyone else having trouble getting SignalSuite running under iOS4 ?

I upgraded my iPhone GS last night and this morning SignalSuite wouldn't run.
It would show the start screen for 20 seconds then bounce back to the desktop.

SoundMeter and SignalScope seem to run just fine under iOS4.


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