Question for Simon

[Mag loop Simon]

If you have the time to read and possibly answer this???..i will try to explain...( need your help in understanding hl2 visual gain..)

Ftdx3000 vs elad duo vs hl2..

Sdrc v3.025

Getting the best out of the rx..

Using the ftdx3000 as a bench mark.. lets say on 80m..
Antenna big mag loop shared between them..as in using elad as panadapter via rx out on 3000.

Talking here about recovered audio above noise floor..Not necessary best sn ratio in db, but best audio to My ears above the noise floor white noise..less white noise the easier it is for my brain to “ pull out” the weak dx signal..
No dsp involved. No noise reduction in ( as i find it does not work for me on weak signals.)

In order of preference..ftdx3000..hl2 elad. ALL GOOD rx.. hl2 being on paper the worst.

The reason why is quite simple...
Same frequency same antenna etc.. noise floor s3 on 3000. S6 on elad ( with attenuator in.) s0-6 on hl2 ( adjustable.)
Now this means the white noise is quieter on the hl2 and 3000 than the elad..this means its much easier FOR ME to hear the weak signals in/ just above the noise..

One can really pull out the weak dx on the 3000. And the hl2 but not so much the elad..(one can not lower the noise floor on the elad like one can on the hl2 and 3000.)

Simon..the really good things about your sdrc with the hl2 on rx are..adjustable front end gain AND adjustable visual gain..both control audio out and noise floor and hence MY ability with my old ears to “pull out” the weak dx..

example..dx s6 noise s5 on elad= difficult for my ears to hear dx over the white noise
Dx s2 noise s1 on hl2 or 3000= easy for my ears to hear the dx over the Much quieter white noise..

The elad i know has no adjustable front end gain ( apart from the 10db attenuator pad.) unlike the hl2..however the visual gain on the hl2..wonderful!

How does this work?? It is very useful! Can it be incorporated into the elad sdrc??
Please tell me it can..anything to help the elad on Lf bands..( apart from more external attenuators..)

Thank you for reading..Mag loop Simon

[G4ZFQ]

Mag loop Simon,
I wonder if this is your ears?
I have quietly followed your discussion on the Elad group. Nobody understands your problem. The consensus there is that the Elad is as good as, or better than anything else. I see no problem with mine.
The level of noise displayed on a meter means nothing unless calibrated.
On LF/HF I cannot believe receiver noise can be significant. SNR will be the same. All noise comes in via the antenna. The SNR is normally quoted as measured in a 2.5KHz bandwidth. The apparent noise will vary according to the actual bandwidth used.
With current software the apparent noise is often able to be reduced considerably. Making meters read differently does nothing.
A possibility is that the Elad is overloaded by a out of band signal, the way for testing that is an extra attenuator.
73 Alan

[Simon G4ELI]

I don't like questions. If there's a problem please highlight it and add screenshots. I see no screenshots so will not reply further.

[Mag loop Simon]

Hi Alan

Yes it could be my ears..Yes agree about s meter reading relatively meaningless..its the white noise that is causing the issues..hl2 with sdrc ( brilliant!!) can remove 90% of and hence hear the real weak dx..not possible with the duo.)

An example to try to explain Alan what i mean.

Room full of people talking loud..1 person in room shouting twice as loud as others.very difficult to hear what that single louder person saying.
Same room same people but they all whispering. Same loud person now talking normal vol.. easier to hear as all the background noise has vertually gone..
This is how MY head and ears work..i have trouble with the white noise..nothing wrong with sdrc or the elad..just one can control the white noise / (background noise in above room) much better on the hl2 and 3000. Hence they work better for me..i just want to get the best out of the elad for me..

And Simon..I am trying to understand a function on hl2 sdrc has that elad duo sdrc has not.
I would like to know if its possible to add this to sdrc for elad duo?? But not understanding how this function works ( i know how to use to good effect)
I have no idea if one could add to elad sdrc..( may just not be possible)

This function is the visual gain. ( as on hl2 it also acts like a variable attenuator..helps Me alot..)

Sorry for asking questions..am just trying to learn..cant give a screenshot of my question as a screenshot does not capture audio, or my thoughts. There is nothing wrong with sdrc..it’s brilliant..you should be proud!

Sorry if I annoy you, not meaning to.

Mag loop Simon ( qro amp, preamp,mag loop builder, mechanical engineer, artist, metal sculpture etc..just dim on sdr and writting whats in my head ( can paint it,) but trying to learn..

[jdow]

Were I a betting sort of person I'd stake a huge amount on your having your front end settings or filter selections screwed up if you really have a higher noise level relative to signals on SDRC than other SDR tools. Since I see no picture I can't read your settings to see what is going on.

You seem to be worried about visual gain. Consider it as purely a scaling factor applied to the actual A/D input values so that you can calibrate the display in dBm if you wish. It will not and can not change your signal to noise ratios or anything else as I understand it.

Note that with an SDR once the signal is applied to the A/D you do not get any changes in signal to noise ratio when you multiply levels by a constant. The digital processing does not add noise in and of itself.

With that in mind I cannot for the life of me understand what your problem is other than not experimenting to see what various controls do to reception quality. The noise level read on the spectrum scale is quite good for relative levels. It is worthless without calibration as a means of comparing SDR software.

{^_^}

[Max]

Simon (mag loop)

Visual gain is exactly that. It simply raises and lowers the received signal up and down the visual display for display calibration purposes. Yes, the audio gain changes as a result but that is totally irrelevant. If you shut your eyes, you would be in no way able to tell whether someone was turning the VG up and down or the speaker volume control. It literally changes the level out, and in no way changes the signal to noise ratio.

Your crowded room analogy....... that is signal to noise you are talking about there. Once you have noise in the system at the front end there is nothing you can do to change that actual ratio. The only way you can change the perceived noise is use of one of the digital noise reduction techniques in the RX DSP panel (NR1, NR2 etc). How I have no idea, but it is just that...... a perceived change. Every single noise reduction technique ever invented has a penalty of some sort, albeit often a very small penalty, but it will change the original signal that's for sure. Personably I prefer the sound of natural "noise" to the artificial sound of mangled signal and noise that the DSP can sometimes produce, although admittedly some of Simon's NRs on SDRC are very good when used in moderation, but for me personally on HF I generally put up with the noise, but it's a personal preference. Many rave about the NRs and that's fine. Did you try them out? Sometimes a very small amount of NR makes a surprisingly big difference. I find subtle use of NR3 works the best for me on HF if I use it at all.

But anyway, I digress. Point to make is the Visual Gain control will in no way change the S/N ratio but for some reason I think you are perceiving it as a change in S/N ratio.

Here's another analogy, and if you are "older", like me, you no doubt recall vinyl records, or discs as our US cousins prefer. Your record plays with surface "hiss" which is predominantly higher frequencies. If you don't like the hiss you can turn down the volume, and the hiss gets quieter, but oh dear, you also turned down the volume of the music. Maybe subjectively it sounds better, but as far as S/N ratio goes, you did nothing, but you might say the hiss is less objectionable, which I guess in a way it is!

73

Max

This function is the visual gain. ( as on hl2 it also acts like a variable attenuator..helps Me alot..)

[Mag loop Simon]

Hello

Thank you both for your replies.

You both however are totally missing the point I am trying to make/ explain..

I will answer fully tomorrow ( its 1am now.. need sleep, work at 6am.)

Just to say for now. I fully understand snr..not new to this.had ham licence since 1982. Built many rx and trx etc..( in the past when it was worth building one. Not now since one can not build anything comparable to a cheap modern rig.)

Yes the filters etc on the elad are correct..front end settings are correct..

I understand s meter readings are not worth paying attension to...all that matters is snr on station you want to hear..

So I ask you this ( because this is what i am trying to improve in the elad.)

S9 noise floor..dx signal s9 + 3 db..
S0 noise floor ..dx signal 1/2 s point..

What is easier to copy??

Well hopefully you will say s0....thats what beverages, active loops, flag etc antennas are sll about..

If I can try to explain how I HEAR THINGS in my head with My ears then prehaps you will understand my issues with the elad and will be able to help me improve things..

I really do not want to give up on the elad..its an excellent radio..

The hermes I can adjust with the excellent sdrc and remove/ lower the noise floor AND HENSE the background white noise that hinders me hearing the weak dx in the noise..LESS NOISE easier for ME to hear dx..same with the ftdx3000

I am hoping there is away to do this that i have not found with the elad..

Its as though the elad just has too much rf gain on the lower bands..

Anyway..thanks for replying..hopefully making myself more understood with what i am trying to accomplish with regards to lowering noise floor on the elad..

Best regards, stay well Mag loop Simon

[jdow]

Actually they are exactly equivalent except in the imagination of people reading S-Meters that have all the accuracy of somebody trying to predict the flight path of a butterfly. 3dB is a ratio. And it is a ratio of power levels that makes signals readable. If the S-Meter is accurate then you have described a pair of 3 dB ratios. 57 dBs0 - 54 dBs0 = 3 dBs0 - 0 dBs0.

{^_-} Stepped in it that time, you did, youngster. (Ham radio for over 60 years and worked professionally as an engineer for 50 of them. And Simon is another old timer. I do remember the aha moment when I figured out the implications of the above equality. "Aw S**T! That $25 (1960 bucks) DowKey preamplifier was pure wasted money.)

[G4ZFQ]

"S9 noise floor..dx signal s9 + 3 db..
S0 noise floor ..dx signal 1/2 s point..
What is easier to copy??"

I presume you adjust to listen at the same volume. Going by the figures, assuming 1/2 S point is 3dB and it is the same transmission, they should be the same.

It seems to me you are hearing a difference in the signal or noise quality which would indicate there is a difference in filtering.

Alan

[Mag loop Simon]

hello again..

i know you all think i am mad, or dumb..etc..but i am not..far from it..(maybe mad?..my uncle 1 designed guidance system for uk polaris neuks..uncle 2 designed the containment "bunber" for uk neuk power stations..uncle 3 worked for nasa..admittedly i am the black sheep..we do not NEED neuk power!)

anyway i degress..

what everyone trying to help me has overlooked, and i thought I had explained this enough..is that yes i theory it makes no odds in sn level wether I listening to s6 dx over s5 noise or I am listening to s2 dx over s1 noise..However it does TO MY BRAIN AND EARS..more noise floor..more white noise= harder for me to weed out dx..have said this before..My fault my ears and brain are having difficulty here..

NOW..have found the issue...if one remembers I said using sdrc and elad fdm duo the noise floor was higher than on the hl2 and the yaesu ftdx3000.this caused ME (not anyone else maybe) issues.(too much white noise, hard for me to hear weak dx against said loud white noise.)
the higher the noise floor the higher the white noise the harder FOR me to hear dx..(yesv i know sn ratio the same, but thats not the issue here..

now it appears the elad fdm duo with sdrc has an issue..

not sure how to explain this..i run elad with 10db att in..(lower bands.)..noticed if i start elad with no antenna connected with att on i have 10db up noise floor on elad..
I f i then start sdrc it also has 10db up noise floor from elads noise floor..which in the real world means s3 noise floor with no antenna..
from there switch antenna on..3 s points of noise above what the hl2 and ftdx3000 are showing and importantly giving 10db or so more white noise for my ears and brain to deal with..

to cure this I have discovered i need to switch elad and ftdx on..then go to main front panel elad menu, switch off att..then fire up sdrc..
once thts done everything is kool..elad on sdrc noise floor is as hl2 and 3000..ie my rf melted brain can cope with it..

can anyone enlighten me upon the reason why I need to do this..It makes no odds in sdrc switching the att on or off if i do not boot up this way..

screen shots below are of starting sdrc with elad att off, then using sdrc to switch on..and of starting sdrc with elad att on..note the 10db or so difference..

thank you for humouring the mad as i must be dumb g0zen whom no one on elad site understands what I am on about....(with quite obvious hearing difficulties..)

Mag loop simon. stay well everyone please..

ps both screen shots are of elad with att in.just starting differently.