Two RF Explorer - different results

[RF Owner of Two]

Hello,

I have a unit which does great!! RF Explorer.

We purchased a 2nd one, and the signal on the new one is way off from what the 1st one is reading.

Took it to a job yesterday and couldn't use it as it was off. Same antenna and the settings seem to be the same.

Thoughts?

[RF Explorer]

Hi,

Please provide more details of models, configuration you are using, including frequency and power levels so we can better understand what you mean by "way off".

As a background information check this article https://j3.rf-explorer.com/71 for details on how to properly use the instrument for best accuracy.

Regards,

RF Explorer Team

[RF Owner of Two]

Off as the "ORG" original one was reading -96.0 and the "NEW" was reading -101.0 as an example..  majority of the readings were in the -100's and the ORG device was reading -90's.

Antenna on ORG is RFMAX RDA698/2700-1-SSM

Antenna on NEW is RFMAX RDA698/2700-1-RSM

Not sure what the RSM I didn't realize I ordered or received a different model, until I wrote this out to you.  yikes.  I've emailed the supplier for the antenna to ask the difference if there is a difference. Unless you know of a difference between them and if that could be the cause?

Thoughts?

see attached picture of settings comparison.

Thank you.

[RF Owner of Two]

I posted a reply but didn't see it in the conversation thread.  I'll try again.

I think I wrote, that the ORG unit scans and reads -94 for example and the NEW unit reads -101.  The Newer unit seems to be in the 100's a lot vs the Original unit seems to be in the -93.0 to -96 range.  during the example moment I'm referring to.

The Antenna for both is a RDA698/2700-1-SSM

see attached comparison of settings

Thank you.

On Saturday, January 14, 2023 at 8:29:32 AM UTC-5 RF Explorer wrote:

[RF Explorer]

It seems you are comparing two different models, each with different noise floor. Regardless the antenna you use, level -94dBm and -101dBm looks like noise floor, which depends on many factors, but you can expect different instruments have different noise floor. That is not an issue.

A different question would be detecting an actual signal, in a controlled environment, should provide the same signal level. If you have a reliable signal generator and a quality RF cable, do a direct connection and measure a -30dBm signal for reference, should measure the same level with the published tolerance.

Regards,

RF Explorer Team

[RF Owner of Two]

zoiks!  So different models, I guess I should return this one and get the matching model? They were called the same RF Explorer Spectrum Analyzer WSUB1G+, so which model do I ask for so it's the same as the first.

I don't have any other equipment, as I'm just an end user. No signal generator etc.

[RF Explorer]

One model is RF Explorer Spectrum Analyzer WSUB1G PLUS and the other is  RF Explorer Spectrum Analyzer WSUB1G (no PLUS).

It would not make sense to return a model to get the same noise floor, even same models may have slightly different noise floor. You can enable the internal LNA preamplifier in the RF Explorer Spectrum Analyzer WSUB1G PLUS and get a lower noise floor.

What is important to understand is the noise floor is not relevant when you are actually measuring a signal, which is probably what you are looking for. The noise floor only represents the lowest level signal you can measure.

If you do not have a signal generator, you may still have some signal source of some sort you are using to measure 855MHz, so using that you can check how both instruments detect the same signal with about the same power level.

Maybe you can describe your specific application / use case and we can help to finetune the instrument to get the same results, regardless the model.

[RF Owner of Two]

OK, how can I tune it or enable the internal LNA as you mentioned.

I'm using it to read Public Safety Radio Signal.. :)

Thanks.

[Ariel Rocholl]

Please check the user manual www.rf-explorer.com/manual for more details.

Regards,

RF Explorer Team

[RF Owner of Two]

I know there's a manual. I don't know which applies to this issue, and when I look at the table of contents, none of the items say LNA.

If there's a way to configure the device, if someone can share this with me and show me the steps to resolve my issue - that would be helpful.  

Thank you.

[Ariel Rocholl]

The user manual page 22, section ATTENUATOR MENU describes the option Input so you can easily select LNA.

Regards

[RF Owner of Two]

Ahh right, but I indicated (by not indicating) on the attachment with my settings, that there was no Input mode on the NEW device.  

How do I get the Input filed to appear.

[RF Explorer]

The manual clearly indicates the Input is only selectable in the PLUS models. Your new device (which is actually an older lower cost model than the PLUS model) is not a PLUS model.

As you are getting reads of lower noise floor in the new unit, what you need to do is to enable LNA input in the ORG model, so you get about the same noise floor in both. As you are interested in getting the same noise floor read, we are suggesting to enable LNA.

[RF Owner of Two]

ok thank you for explaining that detail. 

I feel the older model is the more correct/accurate reading, so no don't want the same floor read, would like the reading of the frequency which I'm reading.  

Is there a way to get the new unit to work the same as the older one. I'm feeling like sending back the new one and getting the right model is the answer. I was willing to try and make the new one work, but seems like it's not going to be able to set and work the same as the + model.  

Probably when searched wsub1g+ the search field dropped the + and I didn't realize/notice. 

[RF Explorer]

If you want the two units to work more closely the only option is to use the same model. But that is not related to accuracy of the signal measured, only to noise floor, so if that is important to you then use PLUS models only.

Regards,

RF Explorer Team

[Nuts About Nets]

I've been following this particular thread and, until now, resisted posting -- but now I can't help myself...

To 'RF Owner of Two' -- there is a simple way to do what you want and there is a difficult one. The difficult approach involves trying to get different instrucments to display the same noise floor -- either by fiddling with settings or returning one of the instruments and purchasing another one.  Plus there is the issue of antennas, frequency span, and more.  The simpler approach -- which was already suggested by the RF Explorer team -- is to take a few minutes to learn / understand what SNR (Signal-To-Noise Ratio) is -- it's not rocket science.  In fact, for almost any RF application, absolute amplitude readings are irrelevant.  All that matters is SNR...

[RF Owner of Two]

ok, I appreciate that, reassurance that the device can work, let me look in to the SNR and see what I can do. Thank you for chiming in. :D   I know it's sometimes much safer to stay out of things. I just LoLed out oud. 

Thank you.

[Nuts About Nets]

Thanks for taking my response in stride.  To be clear -- SNR is **really** simple.  SNR is simply the "delta" -- i.e. difference -- between the noise floor and a peak.

[Nuts About Nets]

Here's an analogy -- the height of your house.  Los Angeles is at sea level, whereas Denver is a mile high.  Technically, the absolute height of your house is much taller in Denver.  However, we don't measure the height of a house in absolute terms (i.e. from sea level) -- rather, we measure the height from "ground level".  The ground level altitude is different in Los Angeles and Denver.  However, the distance between ground level and the house roof is the same in Los Angeles and Denver.  "Ground level" is analogous to "noise floor".

[RF Owner of Two]

ok, took some time to look at video s on SNR.. I get that (I think ) it's the difference between the floor (background noise the device doesn't know what to do with or process..) and then the "useful" signal and the SNR is the ratio between the signals.. let's say, -110 the floor, and -90 or -93.5 range for the useful.  so 20-23 difference. 

so.... now what? I still don't see how this relates or factors in to the settings of the Explorer to make it read right..  the Original device is reading cleaner..  this is what I see:

ORG:

87 95 98 96 97 96 95 97 94 96 95 99 97 100 93 95 96 92 95 98 95 94 96 94 93

NEW beside each other.

95-98-100 101 102 101 102 103 104 0103 102 101 100 102 102 103 103 102 101 100 101 101 100 101

soo.. what settings do I need to se to make them read the same readings... if that makes sense.  I look at the settings as set in the screenshot and they are set the same.

The videos and things I read about SNR explains the theory and noise.. but nothings says, set "this" setting up or down +/- 2  and what the 1,2,3,4 change in value means.