Why I dont Get Low Phase Noise Reading out of Erasynth Micro? - Page 1
Forum section: electronics / beginners

author: Mechatrommer
author_rank: Super Contributor
timestamp: December 03, 2019, 07:20:15 pm
content: i bought Erasynth Micro and it arrived. the phase noise claimed in theircrowdsupply websiteis on the left side (white background), but my measurement using Anritsu MS8609A SA is on the right side (blue background) the SA clearly has lower noise floor (last attachment, so my impression is instrument's noise floor is not and issue.. so, why? esp those spikes..

author: eevcandies
author_rank: Regular Contributor
timestamp: December 04, 2019, 07:46:01 am
content: Have you enabled some type of waveform/modulation option(s) in the generator?

author: KE5FX
author_rank: Super Contributor
timestamp: December 04, 2019, 08:10:08 am
content: You can't compare the analyzer's RF noise floor with no signal applied (in the last screenshot) with its phase noise floor, which might be showing up in the other screenshots where a carrier is actually present.Also, see if there's a noise marker feature you can use (note that the Agilent screenshots are showing marker values in dB/Hz, not dBm). If no noise marker is available, you will need to subtract 10*log10(RBW) from any marker readings to normalize them to a 1 Hz bandwidth, and also subtract the carrier amplitude if it's above 0 dBm. This will be valid to within a dB or two,ifthe noise you're measuring is well above the analyzer's LO noise floor.The spurs look like some type of modulation is enabled. Either that, or there's a problem with the analyzer or the signal generator.The 8600A series analyzers are supported by my freewarephase noise app, which can automate some of the number crunching for you if you have a GPIB adapter. I don't have any baseline data for the 8609A but I do have a baseline plot for the 8604A, and it's not exactly one of the all-time greats:Chances are that the Erasynth Micro unit is quieter than this particular spectrum analyzer model, unless the 8609A is significantly better than the 8604A. I've never actually had my hands on one of them in person (either the synthesizer or the 8600A-series analyzers.)

author: Mechatrommer
author_rank: Super Contributor
timestamp: December 04, 2019, 08:23:33 am
content: Quote from: eevcandies on December 04, 2019, 07:46:01 ami checked all of them, modulation and sweep to be disabled. i'll study more esp on KE5FX's comment. i'm newbie in this phase noise measurement.. thanks.fwiw, the measurement on the top (5KHz span) and bottom (220KHz span) are real slow measurement sweep due to i have to crank down manually the RBW or VBW down. but revealed some spikes, unlike in the middle 22KHz span (faster sweep)

author: Mechatrommer
author_rank: Super Contributor
timestamp: December 04, 2019, 08:26:09 am
content: Quote from: KE5FX on December 04, 2019, 08:10:08 amany link and info on how to get this phase noise plot for a particular instrument? say if i want to do the same on my MS8609A..got it. its in the KE5FX pahse noise app link above

author: Mechatrommer
author_rank: Super Contributor
timestamp: December 04, 2019, 08:34:38 am
content: is there possiblity of non-ideal coax cable used? (used hence cheap huber suhner cable meant for one time connection)

author: KE5FX
author_rank: Super Contributor
timestamp: December 04, 2019, 09:06:21 am
content: Quote from: Mechatrommer on December 04, 2019, 08:34:38 amAnything's possible if the ground is open. But Huber+Suhner is among the very best manufacturers of that sort of thing.