Give us a Choice with the S Meter

Varistor

This statement about hearing below the noise floor is being thrown in way too often with no evidence or scientific rationale behind it. Not to mention that it doesn’t define what noise floor is being referred to- band/atmospheric noise or radio noise. The vast majority of the time the band/atmospheric noise is significantly higher and in urban settings it is always higher. What a radio can hear, without the help of special encoding such as FT8, is determined by the higher of the band noise and the radio’s own noise. That is, if you have band noise of -100 dbm and radio noise of -150 dbm, what you can hear is limited to -100 dbm. The laws of physics apply equally to all makes and models. The Flex has sensitivity of ~27 uV and noise floor of about -135 dbm, quite in line with other radios: http://www.sherweng.com/table.html So can someone back up such statements?

James Del Principe

S meters, we can all agree, are only on ham gear. All the time I worked at Sylvania Gov't Systems, I never once saw an S meter......nor my time in service with PRC-53s or GRC-46's......  who would have cared.???    but we in the ham community have had them in one form or another since the 30's so I guess they are here to stay.  How else could we give a DX station 5 by 9 when he is just above the noise level???   73, Jim

KY6LA_Howard

I guess for some people, the fictitious reading of an Analog S-Meter gives them great comfort when reporting a signal to their "Good Buddies" 

But if you ever work me and ask for a signal report, I will give you a real one by just looking at my Panadapter and report that your signal is hitting -63dBm (S9+10dB) or whatever it really is in dBm..

Realistically No one really expects a S-Meter reading other than 59 or 599 anymore.. and no one has asked me for a real reading in probably 5+ years except when we are playing with new antennas.

BUT Analog Meter can be pretty Eye Candy to match the spark gap transmitter and magic tuning eye on the corner self.

James Del Principe

Stan, this is a great forum and I noticed, unlike other forums, there are no personal insults.   OK, with that, let me say I agree 100% but let me throw a small wrench in the S meter by saying this. Let's say that you, as my neighbor, have a Bencher Skyhawk at 70 feet and I being your poor cousin, have a G5RV at 20 feet....   What signal report do we give the RG8U we just worked??   Which one is valid?   So the receiving station antenna will have a profound effect upon any signal report.   OK, I'm preaching to the choir here.   (both 599, right?)     73, Jim

James Del Principe

Varistor, I do not believe there is a radio on this planet that can 'hear' below the noise lever except some computer mode like FT-8.     This goes for any mode that uses human interpretation like SSB, AM or CW.   Just not possible for a human to do this.    Very Best, Jim

James Del Principe

Howard, only 10 over 9????   I am insulted that my SB200 to a dipole at 25 feet is not at least 40 over!!!   OK, let me confess that I love the eye candy on my SX-28A best and many of my BC radios have tuning eye tubes that capture my attention while I listed to THE SHADOW !!!     Best 73, Jim

Varistor

That’s precisely my point. Yet the statement that Flex radios break the laws of physics is frequently made here.

Victor Gavron

This is a neat app! IMHO, it is easier to see an "analog" meter than the horizontal bar.  I don't think precision is that important in this context.

Ken - NM9P

I think where the whole S-meter reading thing went off the rails was when people started misunderstanding the whole RST system... R is for Readability - how well can I understand you given the conditions, noise, and interference S is for Strength - NOT the S-Meter reading - but a measure of the relative strength of signal given the band, conditions, and expectations of how strong a signal might be in those conditions. T is for Tone (CW) - a 1 means nasty, with totally unfiltered AC hum, chirps, clicks, drift, or other anomalies. A 9 would be pure, perfect, smooth tone. The T was often accompanied by a qualifier - C for chirp, K for clicks, and sometimes H for hum. Somehow we have stopped teaching this to new hams, and let them absorb popular misconceptions from the Amateur and other radio services. Ken - NM9P

Robert Lonn

I decided to make my own S-meter, calibrated, for my Icom IC-R8600.. Total cost about $5.00.. Icom gives you an output on the radio for an analog meter,, so do others as well.. The meter is S-9 when at the 12 o'clock position as shown in these 2 pictures.. With all this S-meter talk of late, it would be nice if Flex could make the software display an Analog Meter rather then a Bar type meter.. I have plenty of radios with S-Meters to play with if I get the urge to go analog, like on my R-390A... Heathkit Meets Sharper Image!! :-)  And the meter is illuminated with 3 blue LED's... Looks cool at night!

KY6LA_Howard

@James

I used to listen to Hoppalong Cassidy on our Magic Eye Radio.. still loved it when it drifted off the frequency and used the eye to get it back...then it was useful

I think a DX station would be insulted if you gave him something other than 59

and a local 20 over S9

Rex K0KP

Let's not forget that ham radio is supposed to be fun!  Some of us are taking ourselves way too seriously.  This started as a suggestion *IDEA* to include a little check box in the software to emulate a relative, old style analog S Meter should the operator want to choose to use it.  Let's keep the junk science out of the idea please. 

PS Stopped at Radio CIty yesterday and they fired up the IC7610, and without an antenna the S meter read S 0.  I only bring this up because apparently there is a way to ignore the empty FFT bins when feeding data to the S meter.  

Rex K0KP

PS above is not meant pointed to any particular person, just a note about the conversation taken as a whole.  

Rex K0KP

PPS Perhaps I need to remember my first point too, ham radio is supposed to be fun.  hahahha  ;-)

Bill -VA3WTB

It is likely I am not being so clear about what the Flex can hear,
this is a part of a reply that Steve Hicks made.

When people talk about noise floor in ham radio they are generally talking about the noise level with a 500Hz bandwidth. When the panadapter is zoomed in to the max level, the bin size today is about 5.8Hz. This is a 19dB difference in noise from where a ham would say the noise floor is to what you can see on the panadapter. This means that the panadapter can see 19dB below what most hams would call the noise floor. Your ear and brain are also able to hear below the noise floor in 500Hz because of how they work. But there are limits to how well you can hear. If you've ever worked JT65 or another long-term integrating mode, you have noticed that your computer can copy signals that you cannot hear. 

And
How it possible that the panadapter is so much better than PowerSDR?  The thing about PowerSDR is that it does only one FFT at the sampling rate you have selected.  So let's say that you are at 192kHz sampling rate in PowerSDR.  The bin size will always be 23.43Hz.  When you zoom in, you are just spreading the bins available over more pixels, but you get no better resolution...  Since we can see down to 1.46Hz bins in SmartSDR on a FLEX-6700, we have a 12dB visual advantage over PowerSDR.  The panadapter literally sees 12dB further into the noise.  By always adjusting the sampling rate in SmartSDR, we can keep showing you better and better data in the panadapter and also allow you to see wide bandwidths when you want to.

KY6LA_Howard

@Rudy

It's a confusion/conflation of terms...

Noise Floor is as per the chart I posted above- the Atmospheric and Urban Noise at a particular Frequency... say -110dBm (about S3) @14MHz at my so called Suburban House near a mountain top near 18 TV Towers

Minimum Discernible Signal (MDS) is the weak signal that a radio can copy in a perfect environment - say -120dBm (about S1) at 14MHz with the preamps off.

So technically the Flex can hear below the Noise Floor by 10dB at my house without preamps and by 30dB with Preamps ON (about S-2.5)

However you are 100% correct, that no one will actually copy any signals below the Noise floor unless they are using a digital mode such as FT8 which can do.

So to misquote Sherwood a bit.. All modern radios hear far too well.

That said.. I have a great laugh every time someone quotes that a K3 will copy weaker signals (0.02micro volts = -140dBm) than a Flex especially since the Noise Floor on ALL HF Bands NEVER gets below -132dBm - so it copies 8dB of Noise

KY6LA_Howard

@REX

What you are seeing on the IC7610 is a FICTIOUS Reading Calibrated to be meaningless like all ICOM analog S-Meters.   It's designed to show S0 when an antenna is disconnected.... But is the signal on the antenna really -127dBm if the MDS on the radio is not -127dBm

Bill -VA3WTB

And it has no FFT bins to sample..lol

Rex K0KP

@Howard

I appreciate and welcome your thoughts, on this though you miss the point.  We all know that the S Meter is a relative reading device, not a precision measurement tool.  And that's OK, nothing wrong with it. 

That said I do postulate that ANY measurement taken by ANY equipment and interpreted by anyone's brain is in fact fictitious!  Measurements are only guesses or approximations at best per quantum physics, Check out the wave or particle experiments performed on light.  For heck's sake, in the big picture scientists are debating if our universe may be emulated or even if reality can even exist without the consciousness of the soul.   Yet here we are, this little spec in the universe, taking ourselves seriously?  Live, love, laugh, be kind, and have fun before it ends!

James Whiteway

So, if S Meter readings are meaningless, then what is the point of this discussion?

Other than saying my  S Meter/ DBM meter, is better than yours, as has been going on here. None of this will actually matter. As has been mentioned a ton of times, no one really cares about a REAL signal report beyond "Your 59 QRZ" anymore.

Some people like the look of an analog meter.So, having a choice of the display in SSDR and being able to customize it, in a way that an individual might enjoy having, there's no real reason to not have choices as far as Meters. (or any other parts of SSDR as well) After all, Eye Candy does sell.

james

WD5GWY

James Del Principe

OK, Howard, you and a few others seem to know a great deal about the operation of the Flex so I have a basic question that has me puzzled by the display of my 6500. I have owned this for some time but still don't know how to explain it.
In a nutshell, the 'S' meter in DBM does not match the level on the panoramic display with regard to noise floor. Just for example, with the antenna shorted and 6 KHZ bandwidth, SAM on 80 M, the 'S' meter reads -105.5 DBM but the average noise displayed is 130 with no preamp. With +10 DB preamp, the dosplay says 140 and with +20 DB preamp it is 150. This happens without regard to mode and selected bandwidth. It holds true for SSB at 2.7 KHZ bandwidth as it does for CW at 400 cycles bandwidth.   So first, why do the values not match and second, why would the apparent noise floor seem to drop?   The sound of the noise in the receiver does increase with the addition of the pre-amps.     Jim

KY6LA_Howard

@Rex

S-Meters have a precise definition of S9=50 Microvolts @500Hz bandwidth

You are conflating Quantum Mechanics sized measurements and the Heisenberg Uncertainty Principal with real world measurements.   The S-Meter and especially the Panadapter show readings on a Flex can show a fairly close to Lab Grade precision measure of the received signal.

For those who really like Eye Candy, I posted a link earlier in this thread to the Woodbox Radio Analog Style S-Meter that works perfectly with Flex and gives one the swinging needle effect so beloved by many..

Bill -VA3WTB

@James, you must not have been following along. the reason for this discussion is that Rex has asked for a old style meter found on many older rigs were the meter is reflective of the AGC action  and just bounces around meaning nothing.

In order to even make something like that work on a Flex would not be a small task because the Flex does not share any radio circuitry with non SDR radios.

Rex K0KP

@Bill
Sorry I retract the empty FFT bins statement.  But then let me say apparently there IS a way to make an SDR receiver with an S meter that reads S 0 at the practical noise floor rather than S 4 or 5.  I really do not want to criticize Flex at all.  I want Flex to succeed, grow, and prosper as a North American company.  Heck yes.  However, please don't make me have to say something when it is posited by the few as the Holy Grail.  Please don't ask for ideas and then demean what customers might feel are important to them.   That said, what I stand by is Flex is a very good radio, a very, very good one worthy of pride of ownership with impeccable performance.  Can't it be that and have the option to click on an analog looking relative S meter like we all have used for decades?  And one that doesn't read S4 with no signal tuned in? And yes a little eye candy is nice.  This is my final post on this topic.  ;-)

Varistor

Personally, I couldn’t care less if there is a S meter or not. As it has been stated by many the S meter is useless. That said, my view is that displaying the noise of the ADC/thermal noise that is present in any material with temperature higher than 0K is just silly. We don’t need to spend time analyzing the math behind FFT as at the end of the day the noise we are discussing is generated by the ADC and the other components in the RF path before the ADC. It’s that simple. It’s even more silly to argue that this is some sort of an advantage and that everyone else does it wrong. Measuring and displaying the thermal noise of the ADC has no practical use unless you want to see what the exact noise floor of your own radio is.

James Del Principe

Rex, I am sorry you feel that way because this has been a very stimulating thread in which I learned a great deal.   I for one, am glad you posted it. My FT2000 will read S-0 with the input shorted and some amount, usually S-4 with the antenna connected and just listening to background noise. I think that is what you are looking for in a meter, As for representation, I think it is just a matter of graphics to go from a bar to a meter if the behavior is the same as it currently is. I have a friend with a Flex 1500 running a version of Power SDR and it has analog style meters. They honestly look great!   Of course we all know the reading is meaningless but I love it! HI HI.   So, bottom line, please hang in here, bear with the comments and learn along with me.   Jim

Bill -VA3WTB

I understand Rex, I'm simply asking you to think about how an S meter works on an old non SDR radio, what makes it bounce, where does it get it's signal from. Now think about how the Flex is made to work and how the Meter in the flex works. given the huge differences in the way they work I don't even know it it's possible to produce such a thing IN SSDR.

Bill -VA3WTB

@visitar, I agree with you. The way Flex does it is the standard witch all Lab equipment uses. as Steve Hicks says.  I don't know if that is right or wrong to have a ham radio work in this manor. And it confuses the **** out of customers that are not so inclined to read up on it. Flex brought SDR to ham radio in the first place, who am I to question? I'm just explaining to some folks how their Flex radios work in this regard as the question crops up time to time.

Almost all contacts I make out side of contesting people ask and give signal information. It is the standard to find out how our stations are working, witch is sort of silly considering our signals rely on propagation...anyways

Varistor

This is not the standard for lab equipment. Lab equipment is measured and calibrated to compensate for the built-in error of the piece of equipment. So if Flex were lab grade, the noise profile of each and every radio would be captured and removed from the FFT calculations. In other words, just like the 7610, the S meter would read 0.

Bill -VA3WTB

@Varistor..lol you are really having trouble wrapping your head around around this stuff,,don't worry your not the first one...
All spectrum analizers read RF the same way the Flex does.

I know you think Steve Hicks is wrong and misinformed, lets just leave it at that. This is the way the Flex works thank God.