In article , Dave Plowman (News)
wrote:

Accurate pink noise sources are not so easy to find and the reading
will take some time to average out.

Perhaps a suitable prog. would generate the required pink noise too.

A snag with pink noise is that you tend to have to choose a LF limit to
avoid infinities Which may then put a roll-off into the LF end of
measurements. Given that standard FFTs tend to produce uniform bins I've
never really bothered with pink noise.

OTOH, for most audio electronics items, a sine / square wave generator
plus scope is WAAYYYY better than either for response testing.

I want something which gives a quicker way of doing a simple check.

This thread prompted me to check and I found that I had written a
"!USBScope" application for RO when using my ARMiniX machine. Not checked
yet if it will run on my ARMX6 without modifying. I fear it wouldn't work
on a RPC though, which - IIRC - is where you stopped for RO hardware. But
it did provide an FFT display. Works with USB audio ADC interfaces that
adhere to the class specs. Does much the same as the USB audio programs I
wrote for Linux.

I was thinking at the time of developing a combined source and scope/FFT,
but moved on to other things. The equivalent Linux apps I wrote as a signal
source and for capture / analysis will run in parallel.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics https://www.st-andrews.ac.uk/~www_pa...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

On 25/10/2017 9:12 PM, Dave Plowman (News) wrote:
In article ,
Trevor Wilson wrote:
On 24/10/2017 12:05 AM, Dave Plowman (News) wrote:
Anyone know of (hopefully free) software which will give a real time
display of energy bands?

If say you fed white noise into an amp and the output to the PC, it gives
a graphic of the energy at different frequencies - a sort of instant
frequency response trace.

Thing like Audacity can analyse a recorded sample afterwards - I was
looking for something which will do it in real time.


**If you have a 'smart 'phone' then there are lots of free apps that
will do what you want. Obviously, such software will probably run on a
tablet too. Ah, the joys of having the power of a 1970s Cray
supercomputer in one's pocket....

I want something a bit better and more convenient than a smart phone can
do. ;-)


**"More convenient than a smart 'phone"? You're kidding, right?

--
Trevor Wilson
www.rageaudio.com.au

Dave Plowman (Rabid NUTTER)wrote:

----------------------------


Anyone know of (hopefully free) software which will give a real time
display of energy bands?

If say you fed white noise into an amp and the output to the PC, it
gives a graphic of the energy at different frequencies - a sort of
instant frequency response trace.


** That job is much better done with "pink noise" - having equal energy
per octave or part thereof results in a flat spectrum.

True. Hence my using 'say white noise' As the basic principle is the same.


** ********.

Accurate pink noise sources are not so easy to find and the reading will
take some time to average out.

Perhaps a suitable prog. would generate the required pink noise too.


** Won't solve prob #2.


OTOH, for most audio electronics items, a sine / square wave generator
plus scope is WAAYYYY better than either for response testing.

I want something which gives a quicker way of doing a simple check.


** So you don't understand square wave testing of audio ?

PLUS you have not defined your actual need making it impossible to answer you dumb Q.

FYI:

Checking that a response that should be flat IS flat is done accurately in seconds with a square wave test using a few spot frequencies.

Also, one can similarly check the operation of tone controls, graphic eqs and cut/boost switches by observing the effect on a square wave.

For items where the ideal response is not flat, a log swept, audio band sine wave plus modern DSO to store and view is gonna beat using pink noise hands down.


..... Phil