RF Explorer

[eurofox]

Hi,

Someone test this one?

What is the specific Frequency Accuracy in RF Explorer?
Frequency accuracy of the crystal used is +-10ppm, that is +-4.3Khz in 433Khz band or +-24Khz in 2.4Ghz band.
The aging factor of the crystal is +-3ppm/year.
You can get detailed specifications of the crystals used below:
For all models under 1Ghz: 7M-30.000MEEQ-T
For 2.4Ghz model: NX3225SA-26.000000MHZ-G4
Frequency stability over temperature and voltage is within +-10ppm.
Unfortunately crystal tolerance is not the only factor that has influence in the initial accuracy of the unit. PCB parasitic capacitance and manufacturing tolerance plays an important role at these high frequencies. Due to this, you may expect up to +-100ppm initial value tolerance when uncalibrated.
However, aging and stability is maintained within +-10ppm, in this case the crystal is the dominating factor (the parasitic capacitance is a manufacturing error and is not influenced by age or temperature).
 

http://micro.arocholl.com/

Eurofox

[Marc M.]

I just did a quick comparison between my RF Explorer (2.5 GHz Version) and my Rigol DSA815-TG.  The output of the generators simply ran to a tee connected to both analyzers at the same time effectively halving the impedance the sig. gen. was seeing (both have 50 ohm inputs).  The first signal was 30 MHz sine out of a Rigol DG4162 @ 400 mVpp.  Both analyzers were set for a center of 30 MHz with a 5 KHz span and averaging set to 25.  I had the RBW of the Rigol set to 30 Hz, I'm not sure what it is for the RF Explorer.





Next was a Rohde & Schwarz SMS sig. gen. set to 500 MHz @ -10 dBm:





The R&S, DG4162, and DSA815 are all running off a Rubidium standard pumped thru a HP2087A distribution amplifier so they are within a few hundredth's of a Hz (cross checked against 2 other rubidiums).  The RF Explorer frequency was just about spot on at both frequencies (it's about 1 year old).  The amplitude on the other hand is off quite a bit and I'm not sure why.  I checked to make sure there was no offset set in the RF Explorer and it was 0.  I normally use the RF Explorer in the field as a relative device anyway so it's exact amplitude accuracy isn't that important, but I think it's supposed to be better than that.  When I get more time I'll try to delve into that further.

[eurofox]

Hello Marc,

Thanks for this test, I'm anyway surprised that this rater cheap instrument give a good picture of the signal, with use of the Windows client it should look better.

With respect to the level maybe it need some calibration, Rigol as well is not perfect if we can accept the the generator is the reference.

Eurofox

[Marc M.]

Actually the Rigol checks out pretty close across the 500 MHz range of the R&S Generator.  With a direct connection between the 2, the Rigol shows under 1 dBm deviation across the range of 10 - 500 MHz when set at -10 dBm.  The RF Explorer on the other hand isn't exactly a precision instrument.  But given the cost, it's rather decent.  I use it mainly for checking WiFi channel activity and as a RF field strength meter when playing around with antennas for which it works very well.  And you are correct, the RF Explorer display is greatly improved when using the PC.  It also adds a bit a functionality as well.  There's a waterfall display that's great for analyzing WiFi traffic. 

[G0HZU]

The amplitude on the other hand is off quite a bit and I'm not sure why.  I checked to make sure there was no offset set in the RF Explorer and it was 0.  I normally use the RF Explorer in the field as a relative device anyway so it's exact amplitude accuracy isn't that important, but I think it's supposed to be better than that.  When I get more time I'll try to delve into that further.

At 500MHz it's generally not a good idea (in the real world with real devices) to use a basic T piece to connect the 3 devices like this because it will give very uncertain results. This is because the impedance seen (looking into the network) at each port could be markedly different from what you might expect. A lot depends on how long each cable is though. Shorter is better but even a 15cm cable will give problems.

It's therefore not unrealistic that you could easily see maybe 6dB of passband ripple across VHF and UHF. On some frequencies one device could see more drive level  than the other because the system won't be balanced due to the imperfect port impedances of all three devices.

So you could see some very confusing results. It's better to use an RF splitter that has high port isolation so the above effects will be minimised. Even better still would be to simply test each device in turn with no need for a splitter.

[Fraser]

UPDATE:

RF Explorer new update released with 2D and 3D display modes.

http://micro.arocholl.com/index.php?option=com_content&view=article&id=52:rf-explorer-downloads&catid=40:article&Itemid=64/

Claimed to be the only open source 3D display released for such a use.


Ariel's email:

RF Explorer for Windows – client tool version 1.11.1311 is available. It comes with some great new features including a high performance 2D/3D Waterfall view.

A powerful waterfall screen is very useful feature in detecting spurious signals, dynamic spectrum environments and interference analysis.

Some spectrum analyzer brands offer this advanced feature as an option with costs in the range of $1000-2500; some offer a pseudo-3D graphic view and some other spectrum analyzer brands don’t even offer it at any price. RF Explorer is now offering a fully capable 2D and 3D configurable Waterfall for free, thanks to the continuous support of our user community who spread the voice, increase the customer base and makes it a better product everyday.

In addition to this powerful 3D feature, the new release include many improvements including filled signal graphs for even easier visualization at any condition, make sure to check the release notes for more details, and the RF Explorer for Windows user manual online.

You can get it on the download area. As with all earlier versions, this is free upgrade for all RF Explorer users.

If you are interested on some background of the Waterfall development, in earlier releases, the tool included a basic 2D Waterfall contributed by user Josef Jahn – we want to thank Josef very much for making this available to the community indeed!

In the meantime, we were exploring different ways to add a more capable, high performance 3D Waterfall and, after testing all commercial options we found no one would really offer the flexibility we need. In addition to that, adding a commercial library of any kind would prevent us from granting the code in open source mode as we currently do – and this has been of phenomenal help to many users and several companies to develop their own customs solutions – there is no other general purpose spectrum analyzer offering the code open source, and we want RF Explorer to keep it that way.

So we contacted David Cortes, a seasoned 3D graphics professional consultant to see if he would be interested in this project and he was actually really happy to be onboard.

David works currently as a software consultant, has over 20 years of programming experience in UI, graphics (2D/3D) and multimedia programming, using different APIs: GDI and GDI+, Leadtools Raster and medical packages, DirectX, OpenGL, WPF. Working in the field of medical imaging for the last 12+ years with Dolphin Imaging, has been working with DICOM standards and Volumetric 3D scans (ConeBeam technology mostly). Developed a specific morphing of 2D images based on feature lines, taking as starting point cephalometric information, which got him a patent in the U.S. for the technology.

Therefore we can now include an open source, free high performance Waterfall display screen that integrates just perfectly with RF Explorer for Windows. Not only that, even more interesting is the fact that it works on top of OpenGL portable standard so we can migrate it to other platforms in the future with moderate effort.

We want to thank the beta testers crew (Jose Gavila, Guillaume Desbois, Honza Vrbka, Diego Mayán, Kean Maizels, Giorgio and FredomFighter) who validated the tool in different configurations and environments, provided feedback and helped on resolving several issues.

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