Can someone explain why the following happens:
I generator a 400mhz carrier FM modulated with a 1Khz tone and feed it into the DSA715 SA
I see the signal displayed.
I turn on DEMODULATE, plug in a headset and I hear the tone go on and then off and repeater (a pulse).
I then tuned the SA to a local FM broadcast, did the same thing and heard the broadcast station in the same way (1/2 second on, 1/2 second off).
I played with "demod time" but it didn't get rid of the on/off pattern.
What am I doing wrong?
Thank you!
You're doing nothing wrong, the spectrum analyzer is "sweeping" a single frequency. Even if the frequency isn't changing it is effectively restarting the sweep each time at an interval determined by the "demod time".
Moral of the story - a spectrum analyzer isn't a standard receiver.
You're doing nothing wrong, the spectrum analyzer is "sweeping" a single frequency. Even if the frequency isn't changing it is effectively restarting the sweep each time at an interval determined by the "demod time".
Moral of the story - a spectrum analyzer isn't a standard receiver.
Unless it is an old analog HP,which will happily act as a receiver.
I see!
So even at zero span, it's restarting it's measurement at the interval that "demod time" is set to.
Thank you so much!
You're doing nothing wrong, the spectrum analyzer is "sweeping" a single frequency. Even if the frequency isn't changing it is effectively restarting the sweep each time at an interval determined by the "demod time".
Moral of the story - a spectrum analyzer isn't a standard receiver.
Unless it is an old analog HP,which will happily act as a receiver.
What models would constitute an old analog HP (where is the demarcation in their models between old and new?)
Any of the HP 8590 series will give you excellent audio either AM or FM. Just make sure it has option 102, which is the AM/FM demodulator board. No matter what the scan you will hear a constant good signal on AM or FM, and you can do Zero Scan as well with the same results.
I had a new DSA815 and sent it back for that exact reason. Also the Rigol front end sensitivity was not anywhere near as good as the HP 8595E that I purchased to replace it. You can purchase one of the 8590 series HP SA's for about the same price, or less than the DSA815.
Hope this helps..............