Does anyone happen to know where there is a circuit diagram for a home
brew SINAD meter ?

Owen Duffy wrote:
On Thu, 13 Oct 2005 17:27:14 -0700, crb wrote:


Is it only valid for AM and FM measurements?

I know its receiver sensitivity.

Is it Signal divided by Noise with distortion??

12 dB SINAD means what? The signal is 12 dB greater than noise and
distortion or
is it more complicated than that?


Thats about it.

It is the ratio of signal to noise and distortion, and it is measured
by setting up a test where the receiver produces output from a SSG
(typically for a 1KHz audio output) and notching out the 1KHz output
to measure the noise and distortion wrt the filtered 1KHz output.

I wrote a handy little calculator for converting rx senstivity
metrics, it is at http://www.vk1od.net/sc/RxSensitivityCalc.htm . The
conversions assume that the signal distortion component of the
Noise+Distortion is zero, in other words that the demodulation and
amplification process is linear.

SINAD is used widely to express the sensitivity of AM, FM and SSB
receivers. It is a much better method of measuring FM receivers than
the older "quieting" measurement.

Owen
--

On Fri, 14 Oct 2005 01:03:00 GMT, David wrote:

Does anyone happen to know where there is a circuit diagram for a home
brew SINAD meter ?

You should also consider searching the net for software that will use
the PC sound card to make a SINAD measurement.

Owen
--

I use Baudline (http://www.baudline.com - Linux) for doing measurements
like that. Works well.

One should calibrate the soundcard first though.

There are a host of others..

Cheers Bob VK2YQA

Owen Duffy wrote:

On Fri, 14 Oct 2005 01:03:00 GMT, David wrote:


Does anyone happen to know where there is a circuit diagram for a home
brew SINAD meter ?


You should also consider searching the net for software that will use
the PC sound card to make a SINAD measurement.

Owen
--

"David" wrote in message
...
Does anyone happen to know where there is a circuit diagram for a home
brew SINAD meter ?


While not homebrew , here is where you can find a manual and schematic for a
sinad meter.

http://www.repeater-builder.com/other-mfrs/sinadd.pdf

Thanks, that's what I was after.

Ralph Mowery wrote:
"David" wrote in message
...

Does anyone happen to know where there is a circuit diagram for a home
brew SINAD meter ?



While not homebrew , here is where you can find a manual and schematic for a
sinad meter.

http://www.repeater-builder.com/other-mfrs/sinadd.pdf