Bill,
Be careful. I basically made it say what I wanted to by fooling
with the gain, filters, and FFT bin size. I could be fooling us
both. Let me do one more test. I’ll get it back to the
configuration I just sent to you and then I’ll feed it a 10 MHz signal
from my two synthesized signal generators. I’ll report back…
(I should have picked a noisier oscillator so I could match it up with
the 8566B too).
The oscillator is manufactured by Bulova Electronics. The label
says:
Model: PCOXO-HP22
Freq: 10.000 MHz
Osc. Volt: +20V DC
Oven Volt: +30V DC
Part No. 0960-0151
I yanked it out of an HP8660C organ donor.
Juan
-----Original Message-----
From: Bill Ress [mailto:[email protected]]
Sent: Wednesday, July 11, 2007 5:25 PM
To:
Cc:
Subject: Re: 10 MHz Phase Noise
Hi Juan,
Thanks for collecting the data. Now I'm flat amazed!!!
Assuming, as you say, that the signal is referenced to 0 dBm in the
SDR-IQ then it is essentially repeating the data at 10 Hz and 100Hz
that
you got for the 10 MHz oscillator on the HP ES5500. That is really
super! I'm putting an SDR-IQ in the budget. Using clean heterodyne
sources, the SDR-IQ will make a great back end for a VHF-microwave
phase
noise test set (unless I'm missing something).
I don't remember the schematic for the SDR-IQ but I think the reference
oscillator is just an ordinary crystal oscillator - right? If so that
accounts for the center frequency drift.
Do you have a HP part number for the 10 MHz oscillator?
Regards...Bill - N6GHz
Juan Rivera wrote:
>
> Bill,
>
> I’m sending you my preliminary phase noise results. As you
recall, I
> constructed a battery-powered 10 MHz oscillator by grabbing a junked
> reference oscillator from an old HP signal generator and mounting
it
> in a box with two 9-volt batteries, a switch, and a BNC. That
allowed
> me to bring it into work and use the Agilent ES5500 Phase Noise
> Measurement System on it. Then I brought it home as my
poor-man’s
> phase noise source. Here’s the test results on the
oscillator and the
> first look at the SDR-IQ:
>
> *Phase noise of the battery-powered oscillator*
>
> Here’s the same oscillator captured with the $400 SDR-IQ.
The SDR-IQ
> drifts in relation to the device under test so the signal average
is
> artificially low. It’s really at 0db on the scale. With the
IF and RF
> gain set to their lowest settings I think this lines up pretty
well
> until the level drops down to the SDR-IQ baseline noise level at
about
> the 100 kHz point. The 120 Hz bump has to be coupling from the PC
via
> the USB port where it gets its power. I was able to rid the SDR-14
of
> that by tossing the wall wart and using a lab bench supply. For
now
> I’ll just ignore this one.
>
> What do you think?
>
> Juan
>
> -----Original Message-----
> From: Bill Ress [mailto:[email protected]]
> Sent: Tuesday, July 10, 2007 7:27 PM
> To: Juan Rivera
> Subject: 10 MHz Phase Noise
>
> Hi Juan,
>
> Really sorry you couldn't transmit this evening. I always enjoy
your
>
> keen comments.
>
> Thanks for the 10 MHz phase noise data. What is the model number
for the
>
> HP oscillator? It's probably a version of the one I use.
>
> Now - - - - I'm really interested in what you read on your SDR. On
the
>
> 8566B you'll just be looking at its internal LO's phase noise
floor but
>
> it will be very interesting to see what your SDR phase noise floor
is.
>
> Your test results will be the key data point in my decision to buy
one.
>
> Again - much thanks for you fine work.
>
> Regards...Bill - N6GHz
>