RSA306B What is the physical setup required to measure SINAD?

I'm new to SINAD measurements and never taken one before. I need help setting up my Tektronix Spec. An. to measure SINAD values. This procedure is not stated in the manual.

The problem is, I have a radio my company develops that, when powered on, desensitizes another brand of radio in the vicinity. I'm trying to measure SINAD to determine if the changes we're making to our radio are having an effect on the desensitization in a measureable way.

I have a Tektronix RSA306B Spectrum Analyzer. I am using the Tektronix SignalVu-PC software with the spec. an. I see, via an optional software module, that I'm able to measure SINAD (Module: Audio Analysis). I have the Audio Summary - EM display up, showing me SINAD and I have an appropriate antenna for the spectrum desired hooked up to the device. 

From what I understand, to measure SINAD you adjust the power output of an RF frequency generator until you reach 12dB SINAD. How do I hook up an RF frequency generator to the spec. an.? To the Ref in port? Or perhaps to the type-N Input Connector? I have the antenna hooked up there. Note that "The input signal frequency range is 9 kHz to 6.2 GHz" according to the documentation and that and from what Ive read, SINAD is measured with a 1kHz signal injected. 

Hi John,
 

SINAD (signal to noise and distortion ratio) is a rather simple measurement of signal quality.
In the radio industry it is used as a standard for measuring input sensitivity of receivers. This is done by choosing the minimum acceptable output SINAD (generally 12 dB) and a signal frequency (1 kHz was mentioned in your post but the RSA306B cannot go that low, a frequency between 9 kHz and 20 kHz must be used instead).

With that information and with equipment monitoring the output of your test receiver, a signal is fed into the receiver and its power level is decreased until the SINAD measurement goes down to 12 dB.
So, for example, if the receiver reached 12 dB SINAD at 0.5 uV, that is its sensitivity. It's the lowest power input level for which the receiver can still output an acceptably clear audio signal.

So, to summarize: the RF frequency generator should be connected to the input of the receiver you are testing, and the output of that receiver to the RSA306B.

In addition to Afonso's comment, you will need to connect the signal to the RF input (type N connector) on the RSA306B.  The Ref In port is for connecting an external 10MHz refrence clock if desired.    

Another question, and I understand if you can't answer this, you'd have to know my radio; is it safe to connect the function generator directly to the radio's antenna port? Do I need a subcircuit inbetween the two to protect them?

Hi John,

As you suspected, I would have to know your radio and signal generator to answer that concretely.

Generally, one would look at the power rating of the signal generator's output and the receiver's input to determine that. The characteristic impedance of each is also important.
If the power rating is too high, attenuators can be used. If there's an impedance mismatch, a matching network might be needed.

Those are the most typical specifications to look at for such considerations.