S meter

KL4QG

Always reading S-4 on 20 ,S-5-6 40. S-6 on 75 meters RF not lowering it Why is it always read high Icom 7700 zero on 20 ,40 S1 average 80 S 2 Average Now when my friends talk on different bands getting their normal S reading Is their adjustment

KY6LA_Howard

Search this forum there are lots of discussions why Flex is accurate and the Icom is not correct

KL4QG

Oh will do my Ten Tec Omni 7 is close to same S meter reading as 6400M

Burt Fisher

Search this forum there are lots of discussions why Icom  is accurate and Flex is not correct

HCampbell WB4IVF

Rob Sherwood on “S-Meter Accuracy” 6-OCT-2016

While no Japanese rig has a properly tracking S meter, the following do:

  Flex 6000 series

 Apache ANAN

 Most K3 and K3S, though occasionally an individual radio cannot be calibrated properly. This includes the option to have the reading correct regardless of preamp or attenuator setting.

 Orion II once Ten-Tec updated software to allow S meter calibration. Orion II does not correct for preamp or attenuator selection.

 Eagle is good, except the S meter is microscopic and I think it quits at S9+30 dB. The Eagle reads correctly regardless of preamp or attenuator selection.

 Hilberling S meter is quite good.

 ADAT ADT-200A is very good but ergonomics in general are absurd.

 Elad DUO S meter is outstanding

 Perseus S meter is outstanding.

 With virtually all current products today having a virtual S meter, there is no technical reason the S meter cannot be programmed to read properly from S1 to S9+60 over.

When an S unit is only 2 to 3 dB, it makes QSB look much worse.*

Rob, NC0B

-------------

*Note (by DJ0IP): Most recent Japanese transceivers are using just 3 dB per S-Unit. This makes the received signal look stronger... but at the same time, the QRM, QRN, and QSB also look worse!

http://www.dj0ip.de/sherwood-forest/sherwood-sound-bytes/

Burt Fisher

The debate on S-meters is simple, Flex applies a theoretical standard whereas the rest of the ham world applies a meaningful practical standard.

In the Flex world your S-meter could read S-4 or more even if the antenna input is shorted.
In the rest of the world if you short the antenna input S0 is the result.
Of course S-meters are hardly precision meters as antenna, propagation and other variables cause the meter to be totally relative.
 

KL4QG

Burt so what does my S meter always read 4-5 with no one talking and quite band like 20 meters ?That my Question ??? It does read same S meter reading for my local contacts if they are S9 on Icom 7700 they are S9 on Flex 6400M

Lasse Moell

It's bascially due to how many dB one S-unit should be (there is only a recommendation, no standard). Usually S9 means -73 dBm at the antenna input port on the radio, and most non-JA radios then set 6 dB between each S-unit. JA seems to have 3 dB between each S-unit.
Also, remember that it reflects the amount of power in your bandpass, i.e. a narrow filter will see less noise and show less "S-units".
https://community.flexradio.com/flexradio/topics/s-meter-accuracy-of-flex-and-others-rob-sherwood

https://en.wikipedia.org/wiki/S_meter

dlwarnberg

HAHAHAHA, lets just add more confusion..

Howard says "Search this forum there are lots of discussions why Flex is accurate and the Icom is not correct"

Next replay Burt says "Search this forum there are lots of discussions why Icom  is accurate and Flex is not correct"

HAHAHAHAHA...

I would suggest another source for your information as you can see even Flex owners can't agree..
This is an excellent read.. https://community.flexradio.com/flexradio/topics/s-meter-accuracy-of-flex-and-others-rob-sherwood

KL4QG

David
I agree
It’s not normal have 4-5 S at my area on 20 meters when
no one talking I owned at 12 different HF Radios Yes receive ssb signals are accurate with my 6400M I

KL4QG

No matter if I use 1.8 to 2.8 filter or RF gain control Still 4/5 S units on 20 meters

KL4QG

Found this on your attachment this is what I want Reading Zero on Dummy load not 3-4 S units Below is from Attachment I'll make it simple when the receiver has a dummy load for an antenna I want it to read ZERO on my 6400M like on my KX3 and formally on my 7300. Currently it read S7 on 80 meters on the 6400M and slightly lower on other bands

dlwarnberg

So if you switch to RXA and narrow your slice, even put it on CW mode what do you get?  I'm assuming you have nothing attached to the RXA port..

Just an FYI... I have a flex 6500, where i used to live I had to just live with a high noise floor, it was a combination of neighbors, pool pumps, routers, switches, walwarts, etc... in my home and nearby homes causing noise..

I recently moved, out in an area where I see one neighbor, on 2 acres of land now and very little noise.. I can now pick up a electric fence about 1/4 mile away and my 4 Square Receive array will light up with signals.

KL4QG

Not thing on RXA port I’m new and not afraid admit I’m learning narrow slice ? What is Slice??? Had radio 6 days at work now

dlwarnberg

Just to give you an example and my opinion.... I recently had the electrician put in a 50 amp RV outlet on the other side of the house, if I turn on the breaker I see my noise floor go up and I hear the RV causing RF on 80 meters...  In my opinion several radio manufactures have designed radio's that account for higher noise levels and adjust them accordingly thus making is seem like brand A has a lower noise floor with the same given conditions as brand B Radio.  To back this up, my Flex 6500 hears the RV, where as my Yaesu QRP rig I do not hear it nearly as pronounced as I do on the flex, it's still there but it's very faint.

Lasse Moell

Of course the difference of going from 2.8 to 1.8 kHz is small, it's less than 2 dB. Remember Flex has chosen 6 dB for each step, i.e. you need to go fron 2.8 down to 0.7 kHz to have one S-unit less, IF you only have noise in the passband.

One way of pleasing most users would be a user defined table, mapping the received power to shown S-units. Purists may say this is wrong, but then S-units are only a recomendation no standard. Some do get their knickers in a twist when the S-meter stays the same when invoking pre-amp, or even get crazy when the S-meter shows reduced numbers... it all falls back to lack of understanding of power, noise, noise factor and what you accually measure

dlwarnberg

Joe... it's really the width of the pan adapter / water fall you are looking at.. zoom in

Michael N3LI

Hi Joe, I think you might have to get a different radio to give you the S-Numbers you want. Spreading out the Panadpter and cuttung the bandwidth might help as well. 

I think (and someone please correct me if I'm wrong ) the Flex samples the background using  digital "bins" based on how big a slice of frequency you are using If I have my radio on CW, 50 Hz, and on a Dummy load, I'm ~ -140 SWR measures something less than 1. PLacing it on the antenna this morning it's between 1 and 2. 

Now changing that to 3K Bandwidth, same mode, Signal goes to ~ -120, and S is ~5 with antenna, and a tad over S3 on the Dummy load. 

The interesting thing is that the bandwidth doesn't do a thing to the noise floor. The difference is because some of those noise peaks hit the bins.

If you look at the S-Meter, and at the noise floor, you will see that the noise is not steady. Looking at my S meter I can see the level going between 1 and nearly 0 as the noise floor at the 50 Hz slice varies. 

Anyhow, please gurus, correct me if I'm just blowing hot air. 

In the end, S-Units are a terrible way to determine signal strength. Some radios use 3dB per S-unit, while the "standard" is 6. So a inherently innacurate signal strength measurement is made worse by the 3 versus 6 dB variance. 

I suppose it takes some getting used to. But It isn't likely that Flex is going to make their S-Meter less accurate. 

KL4QG

I don’t want different radio I use Flex 6400M I’ll try different pan h widths next I just want meter read Zero on dummy load. not 3-4

dlwarnberg

Mike you are spot on... example, right now.. 20 meters, RXA wide slice, I show S2 but a noise floor of -130... zoom in, narrow the slice... my noise floor will drop to -140 but the S meter still shows S2

KL4QG

Nice comments enjoy all help

KL4QG

I’ll try few things when I get home after work and report back here

KY6LA_Howard

Joe

If your radio is only capable of receiving -117dBm on say 40M then the correct S Meter Figure is S2 not S0 (-127dBm) even though you are connected to a dummy load

Basically the Japanese use an ancient circuit that integrates the voltage on the AGC circuit to give some sort of imaginary number of relative signal strength - Hence it gives you an absolutely meaningless S0 with a shorted antenna because the AGC voltage is zero even though the radio may be hearing better or worse than S0-

On the Other Hand, Most modern SDR radios actually measure the actual noise power in the bandwidth of the received signal...shorting an antenna does not make the radio hear any better or worse hence there is no change.

Be thankful that you finally own a radio that gives you real lab grade Signal Strength Measurements rather than the meaningless nonsense from that 7700.

Personally I have long since stopped give S Reading to DX Stations and now only give out readings in dBm - most sophisticated DX stations appreciate the much more accurate and realistic report than the usual  59

Dudley WA5QPZ

Joe,

Move your receive bandwidth to 10 HZ  (yes it will go that small)  that way you are only measuring the power within 10 HZ,  you should see near zero.   It's the power of the noise with in the bandwidth.    You will also notice that the band level will drop with each additional preamp setting added,  this is correct too,  giving you a better signal to noise ratio that a conventional radio can't do or show on the S-meter.   

Dudley
WA5QPZ

KL4QG

I not concerned about stations S reading at all-
I would like upgrade from Flex to give us a way lower
The Meter reading noise levels to Zero without affecting stations S reading
I am very thank full for Flex Radios

KL4QG

Ok I’ll try 10 HZ I seen that below that was my next question thanks You will also notice that the band level will drop with each additional preamp setting added, this is correct too

Michael N3LI

Here's some S-Meter information:
http://www.voacap.com/s-meter.html

http://www.giangrandi.ch/electronics/radio/smeter.shtml

http://wb9kmw.com/WB9KMW/Research/articles/article_S_meter.pdf

It is also pretty important to note that there really is no S-0. Well perhaps when the radio is off. DBM readings are the way to go, not the uncalibrated and pick-a-winner 3 or 6 dB per S units variables in use. 

Lasse Moell

Trying to find the specs for the 6400 receiver I failed and using the numbers from the 6300/6500. It states that -121 dBm is the MDS of the radio with pre amp OFF and 500 Hz filter. Assume you are looking at SSB, this translates to -114 dBm with 2,5 kHz BW (remember this is 6500 I do not have the numbers from the 6400). This is slightly more than S 2 accordingly to the recommended levels by IRAU. All these numbers seems to translate to a receiver NF of 26 dB, which is a bit high in my book, but real world testing shows I only need to activate the pre-amp on the higher bands, as the atmospheric noise is usually higher on lower bands.  Remember that the s/w compensate for the additional gain and the user will only see lower S-numbers if the amospheric noise is lower than the radio sensistivity. It bottoms out to if you want the S-meter to read lower numbers when you have your dummy load attached (it may read S 2-3), do invoke the preamp. You will see lowest number with the pre amp at the highest setting. This will give your receiver lowest noise factor. But it is wasted if the noise from the antenna is higher, and the price you pay is less ability to handle multiple strong signals (i.e. dynamic range).

All these numbers may be confusing for some... but the bottom line is: If you want your radio to adhere to the IRAU recommendation, you will have your S-meter showing higher than zero even when using SSB bw and a dummy load with the pre-amp off. Like it or not

Lasse Moell

Even though I use dBm when I do my own measurement using my receivers, it is still not really a meaningfull way of reporting the received signal. The proper way would be field strengh, which also take in account thé antenna used by the receiver, but that's another can of worms...  I pretty much resigned giving out "meaningful" strenght reports,  it's really either I hear them or not

Duane N9DG

"Personally I have long since stopped give S Reading to DX Stations and now only give out readings in dBm - most sophisticated DX stations appreciate the much more accurate and realistic report than the usual  59"

+1000

I tell stations who want to know there signal strength at my location in dBm too. I can't remember when I last told someone an S unit reading for their signal strength.

If the propagation path is stable, as it can often be, or a path that isn't subjected to propagation modes. Then doing back to back readings in dBm will accurately reflect the change reasonably accurately between one antenna vs. another configuration, or the amplifier on or off scenarios.

So the notion that propagation variability always makes those kinds on on air signal comparisons impossible is nonsense and is just rationalizing and a lazy excuse for accepting inaccurate signal strength metering.

Nothing more funny than hearing two stations comparing different antennas or amplifier an vs. off and then using S units to compare the differences. They do do the mental gymnastics of 1 S unit = 6dB to come up with a dB difference in signal strength, but will still be totally off because the legacy technology radios and current SDRs that emulate legacy radio technology the dB per S unit are anyone's guess.

Duane N9DG

"Personally I have long since stopped give S Reading to DX Stations and now only give out readings in dBm - most sophisticated DX stations appreciate the much more accurate and realistic report than the usual  59"

+1000

I tell stations who want to know there signal strength at my location in dBm too. I can't remember when I last told someone an S unit reading for their signal strength.

If the propagation path is stable, as it can often be, or a path that isn't subjected to propagation modes. Then doing back to back readings in dBm will accurately reflect the change reasonably accurately between one antenna vs. another configuration, or the amplifier on or off scenarios.

So the notion that propagation variability always makes those kinds on on air signal comparisons impossible is nonsense and is just rationalizing and a lazy excuse for accepting inaccurate signal strength metering.

Nothing more funny than hearing two stations comparing different antennas or amplifier an vs. off and then using S units to compare the differences. They do do the mental gymnastics of 1 S unit = 6dB to come up with a dB difference in signal strength, but will still be totally off because the legacy technology radios and current SDRs that emulate legacy radio technology the dB per S unit are anyone's guess.