Shell Programming and Scripting

Again I have not been idle on this as some serious research has had to be done to get this to work with SoundRecorder.exe as an alternate capture source purely for CygWin.

It is SLOW and likely to be buggy but hey, it works on two installs of CygWin, using the deafult bash terminal.

The command to access it is:-

WINSOUND<CR>

It does not show up in the HELP listing yet but IF you try it you USE IT ENTIRELY AT YOUR OWN RISK.

The attached image is a whistle into the internal microphone grabbed using SoundRecorder.exe inside CygWin.

The final capture should be easier as it is for Linux ALSA and basic shell tools exist using the ALSA sound system.

PulseAudio and OSS both have a basic /dev/dsp to use and SOX is still the first choice for sampling.

Enjoy finding simple solutions to often very difficult problems...

Bazza...

EDIT:

Added a second CygWin snapshot from a laptop using an internal mic.

We are now at version 0.30.90.
Lots done here:-
1) Calibrated timebase ranges now in 1,2,5 sequence, commands 1mS, 2mS, 5mS, 10mS, 20mS, 50mS and 100mS.
2) Slowest timebase range also added to complement the Fastest one.
3) Lots of code cleanup but not using latest bash techniques, sticking rigidly to backwards compatibility as far as possible.
4) The second build, DC restorer described in the manual and usage to setup display polarity.
5) The final part of the second build to change the DC restorer to Voltage doubler ready for future use.
6) All captures now not hidden anymore.
7) Other minor things I can't remember at the moment...

Enjoy...

EDIT:
The script is now 131697 bytes in size...

Bazza...

AudioScope.sh version now at 0.31.00...

The vertical amplifier circuit at the end of the script has been modified to suit Corona688's comment about using analogue modems' isolating 600 Ohm 1 : 1 transformers. C2 is AC coupled to the transformer now and the emitter resistor is now connectd to ground.
No other changes have been done. The original circuit can still be used without modification so there is no need to alter it.

There is now a SWEEP generator built in and is used for bandwidth and LF roll-off tests.
It goes from 4KHz down to about 85Hz and back, twice. It is a poor squarewave that has a certain amount of sinewave ringing on it, this a function of 8 bit depth and 8000Hz sampling speed but was easy to implement.

Its prime objective is to quickly see how the waveform differentiates at LF and integrates at HF/MF giving a quick assessment of the total amplifier BW...

The command is SWEEP<CR> to run it...

Only three modes can play it back inside the code:-
afplay for OSX 10.7.5 and above.
aplay for Linux machines using ALSA.
/dev/dsp for CygWin and Linux machnes with OSS and PulseAudio.

It does not autorun inside a separate xterm window but is there to create the files to be run on a separate machine.

The manual has been updated to include this and the file is now 134772 bytes in size... EEK!

Enjoy...

Well I have finally decided on the method for ALTDC on AudioScope.sh.

I had a choice of three methods:-
1) Chopper.
2) VFO.
3) Freq Counter.

In the end I built a unit thst uses a chopper AND VFO, BUT, can be easily addpted to INCLUDE freq counter mode too.

As it stands at the moment the VFO is dormant but the chopper works a real treat. It can be done with just 3 transistors but mine uses 5 because of the VFO section.

Now working on the shell code to access. The command ALTDC does nothing at the moment.

It is used in tandem with the Vertical Amp and HOPEFULLY will be switched in and out as required using the earphone O/P voltage doubler trigger already built and tested. Because there is only one Mic input then the first scan will be AC and the second will be the DC and/or LF component when ALTDC enabled. After much experimentation I hope to get a bandwidth of DC to around 20KHz as flat as is possible within the limits of a(n) MBP 13 inch unit.

DC is already taken care of with Arduino but I am trying to make Arduino secondary as it requires dependencies for it to work.

On first trials this home built unit not only does DC but may even work to 200Hz, this was a surprise to me...

Photos of the ALTDC board will be uploaded soon.

@Don...

Don you are a star!

Just a little snippet from another thread solved my problem as to how to trigger the DC __adaptor__ to get both the AC and DC components into the computer using the sound system only...

This was it:-
sleep 1&

Which means that I can create a command function to switch the DC board in and call it whilst doing, one, 1 second capture for DC mode...

Exact timings are not critical but I do need to __write__ to the soundcard whilst __reading__ from it simultaneously. (Yes this is possible using shell scripting.)

Thanks for that snippet...

What's its current schematic with the VFO and chopper? I'm very curious.

Hi Corona688...

I will have to draw it in text mode so it will take a while to do however just assume a simple multivib and from one of the transistor collectors add this for the chopper...
This is 0 - +0.1V DC. Effectively 10K/Volt, worst case per cycle, for this range...
I am aware of any drawbacks but remember kids have short attention spans so the simpler and quicker to get going the better.

Code:

                               R3 = 1M
    O/P O-----------------*----/\/\/\----+ 
                          |            __|__
                          |            /////
                         === C1 = 1uF
                          |
             R1 = 1K      |
 DC I/P O----/\/\/\----*--*--+
                       |     |
                       \     o C  Q1 = BC549
                       /      \    b
             R2 = 100K \       \|__o----/\/\/\----O Square wave in from approx 2KHz multivib.
                       /       /|      R4 = 22K
                       \     |/_
                       /     o e
                       |     |
   _GND_  O----*-------*-----*--------------------O
             __|__
             /////

1uF looks rather large to me, I wonder if 0.1 would work.