Re: Measurement examples posted on wiki

The left-hand Wiki menu doesn't seem to be linking correctly to "?? "

- Herb

Re: Measurement examples posted on wiki

Wiki corrected for minimum input frequency

Re: Measurement examples posted on wiki

On Fri, May 1, 2020 at 10:22 AM, <erik@...> wrote:

The zero hertz peak is indeed ignored
The tinySA does not have DC coupling. Below 100kHz it starts to roll off and at 10kHz there is about 8dB attenuation which is not compensated. The input capacitor is 1 microF

========================================================
Thanks for the clarification Erik,
? ?The "0 MHz to 350MHz" specification on the Wiki page threw me off.? I think the HP 8566 series spectrum analyzers were specified? down to 30 Hz but using them at less than 3 times the power line frequency was a more practical lower limit.? That and a rbw that was low enough to be useful without bumping into the 1rst LO leakage peak.

? ?I'll make a mental note of the 1uF coupling capacitor.? An un-attenuated lower limit of 100 kHz should be more than sufficient for the majority of prospective tinySA buyers.

- Herb

- Herb

Re: Measurement examples posted on wiki

#47

To clarify more:
The zero hertz peak is not caused by DC but by leakage of the 1st LO through the 1st mixer so technically it is not a zero hertz peak but a first IF peak. but given that it is positioned at zero hertz the name is understandable

Re: Measurement examples posted on wiki

#46

The zero hertz peak is indeed ignored
The tinySA does not have DC coupling. Below 100kHz it starts to roll off and at 10kHz there is about 8dB attenuation which is not compensated. The input capacitor is 1 microF

Re: Measurement examples posted on wiki

#45

Erik,
? In some of the measurement examples you provided the frequency sweep starts at 0 Hz.? In peak search functions does the tinySA ignore the internal 0 Hz signal and start its search to the right of it??

? With the dc coupling (0 Hz) of the tinySA it looks like extra care has to be taken to ensure any signals with a dc component do not exceed both the ac and dc input limit of +10dBm without attenuation.

- Herb

Measurement examples posted on wiki

#44

To help understanding the measurement capabilities of the tinySA I added some measurement examples on the wiki

One set of wide scans and one set of high resolution scans. Both from various signal sources to show the ability of the tinySA to help gaining an understanding of the various available signal sources.

Re: Request for testers for the tinySA

#43

开云体育

No problem. If any candidates drop out, I'm always willing to help.?

I'm fed up taking the 8591C out in the car :-)

Note also: Due to my long work schedule, I often don't check emails for 4 days in a row, and then answer them on my 3 days off,... hence why I did not see the request for volunteers earlier.

73

G4JMM

Sent from my Samsung Galaxy smartphone.

Show quoted text

-------- Original message --------

From: erik@...

Date: 4/29/20 6:02 PM (GMT+00:00)

To: [email protected]

Subject: Re: [tinysa] Request for testers for the tinySA

For now there are sufficient candidate testers.

Re: Request for testers for the tinySA

#42

For now there are sufficient candidate testers.

Re: tinySA IIP3

#41

开云体育

Hi Erik

Agree, removing any additional contribution on the two sideband frequencies from the two signal generators by using power combiners with isolation and other means such as isolators, will improve the displayed IIP3.

So bottom line it can only be better than what you see. However the signals must still be within the mixer linear range without compression and 0 dBm is maybe on the brink

Kind regards

Kurt

?

Fra: [email protected] <[email protected]> P? vegne af erik@...
Sendt: 29. april 2020 12:04
Til: [email protected]
Emne: Re: [tinysa] tinySA IIP3

?

But the internal generated IIP3 can not be higher then what is measured so I assume this measurement set a lower limit for the IIP3 of the tinySA, it could even be better. Correct?

Re: tinySA IIP3

#40

But the internal generated IIP3 can not be higher then what is measured so I assume this measurement set a lower limit for the IIP3 of the tinySA, it could even be better. Correct?

Re: tinySA IIP3

#39

开云体育

Hi Erik
I have a few comments/suggestions.
I do not know how you test setup was, but there is a need to ensure the IIP3 level is not influenced by cross modulation between the two signal generators. The power combiner from the two generator ought to have as high isolation as possible between the two input ports, so the test signal from one signal source is not feed directly to the ?second signal source. Next it is common practice that the level from the two signal source are identical and thus the two sidebands are more equal, too to facility the calculation as half power of side tone + the test signal level.
I used some Mini Circuit power combiners with isolation and I also did build a few as described by N2PK Paul for his N2PK VNA, going down to fairly low frequencies.

I used the reflection bridge PCB seen om the link ?? and I did purchase these separately as an add on although not listed as a separate item. where I used the SMD type of T1-T6 transformers. Inspiration came from

In addition a video from National Instrument is quite good to watch ??

In this video you get a method how to figure out if it is the Signal Generators are reducing the IIP3 measurements or not, by adding attenuation in front of the SA. You have enough dynamic range to use some 10dB attenuation or maybe more in front of the SA.

Kind regards

Kurt

?

Fra: [email protected] <[email protected]> P? vegne af erik@...
Sendt: 28. april 2020 11:53
Til: [email protected]
Emne: Re: [tinysa] tinySA IIP3

?

Kurt,
Can you confirm I'm doing the IIP3 measurement as it should be done?

Re: Modulation and demodulation

#38

With FM modulation the zero span graph does not show the modulation but a simple trick can help.

When you look at the close in spectrum of a FM signal using a wide but steep RBW the signal looks like this.

The top of the filters is more or less constant but the slopes show signs of changing frequencies.
By positioning the zero span precisely at the slope of the filter the modulation becomes visible

The wide FM modulation of the tinySA is indeed also a sawtooth with a somewhat higher frequency as the AM modulation.

Modulation and demodulation

#37

The tinySA can be used as a signal generator and in low output mode there are some options for modulation.
Using the AM modulation to create a 10MHz signal?

with another tinySA in zero span mode it is possible to look at the modulation as one full scan of 290 points only takes 232 milliseconds

and indeed the modulation is a sawtooth with a frequency somewhere below 1kHz
As you can see the output level still needs some calibration.

Re: Welcome and feel free to ask about the tinySA

#36

I hope you remember us little people when you become rich and famous :)
Can you share when you think the commercial version will be available?

Re: Request for testers for the tinySA

#35

Erik,

I would love to test out this TinySA and have been with the project since December of 2019 and have a version built up like you did on protoboards. I have A LOT of test equipment at hand (mostly HP and Agilent) for checkout and am knowledgeable of the design. Please do consider me for this effort - thanks,

73 de Marty, KN0CK?

RFI Source Identification Signature Storage Application

#34

Greetings Erik,

? ? ? ?A common problem for radio amateurs is the proliferation of modern day RFI sources that cause significant interference particularly to the HF bands. IMHO a portable low cost spectrum analyzer that includes some specific features intended to support tracking down noise sources would be of significant interest for many hams.

? ? ? ? Often noise sources are related to the power line frequency. It has been well documented elsewhere that because there are often multiple A/C power related RFI sources around the home and within the local hydro grid that an ability to record the time domain signature of the most offending noise is helpful for identifying the most significant cause. Once a problem is located within one's home it can usually be corrected. If a power grid problem is pinpointed it has been experienced that usually the utility will repair it expediently. Spectrum analyzers with time domain signature waveform comparison capability are now used by many utility companies for locating RFI sources.

? ? ? I found it interesting that that the tinyVNA firmware already offers a zero span mode with time domain display capability. I wonder if the time domain display could be designed to lock on to a hydro buzz type of noise and store a few cycles? If this were implemented the offending RFI?waveform signature could be compared to noise sources found in the field to help identify the source. Possibly a split screen display with the stored waveform shown within the top half and real time waveform in the bottom half would offer a convenient means for the user to compare signatures.

? ? ? ?I am interested in evaluating a tinyVNA for the purpose of tracking down RFI sources.

Best Regards,
Tom, VA7TA

Re: tinysa USB Control

#33

Erik,
? ?Once you are ready to release the full list of console commands for the tinySA, I would like to see if I can translate? the python nanovna.py class library to the tinySA (tinysa.py?).? No guarantees but I believe my Python skills have progressed to the point since using the NanoVNA that I should be able to do it.? I might have to ask hugen to clarify a few points if he is available.

- Herb

Re: Request for testers for the tinySA

#32

Hello, i can help you vs test tinySA?

? My main job is the development, repair, maintenance of aviation communications systems. Therefore, I have the opportunity to test it on various equipment (compare with other spectrum analyzers, check on various signal generators and on real radio stations).
Also can help vs software (it my hobby)

Re: Request for testers for the tinySA

#31

Hello, i can help you test tinySA

My main work is development, repair, support of aviation communication systems (i not programmer, it my hobby, but i can help vs software)

It is possible to check the required characteristics on various equipment.