S-Meters – Comfortable Lies or Accuracy? – The Whisper of Sweet Nothings

In the FlexRadio Community a poster complained that his Flex-6700 reported S-2/3 noise most of the time.

He wanted his radio to “Whisper Sweet Nothings” report S-0 if disconnected from an antenna – basically setting aside the noise the sensitive Flex-6700 was actually hearing.

He never disclosed if his feedline and antenna switches were still in line, if they were grounded when antennas were deselected, or whatever other RF his radio was experiencing.

He also didn’t tell the community if he had his Flex-6700 narrowed down to a specific frequency, opened wide in a wide band receiver configuration, or how his radio was configured.

“He” is actually several posters who have some been part of this discussion before, some new to FlexRadio, and all who hadn’t looked for older threads on the issue.

I commented:

This has been discussed at length before.

In the traditional approximations vs closer to theoretical measurement, FRS has been consistent with their philosophy of using the available technology of their platform by adopting the closer to theoretical approach.

The former compromises over time became a “availability heuristic” (basically a rule of thumb based on availability and experience, rather than correctness) but as we know were never truly accurate nor perhaps even appropriate if we’re after true signal strength.

The FRS approach plays closer to theory, and yes that includes faithfully observing the noise from empty ports. This is more accurate than our generally accepted rule of thumb approach that an open port is silent by ignoring the observable noise.

The contrived S-meter scale many of our favorite receivers from the past are amateur radio market engineered-marketing that everyone knew was “feel good” rather than factual.

We exacerbate the S-meter scale nonsense by tradition, especially the everyone is “59” or “5NN” when contesting or in a hurry.

Is the FRS implementation lab grade perfection? Will it toe up and hold the line with your professional grade station monitor? Depends, though you can know it will be closer to lab grade than the approximations of legacy radios.
In prior discussions community members suggested implementing an alternative scale making SmartSDR report to them S-numbers they are happy with, rather than accurate. FRS didn’t take up the suggestion. Truly what manufacturer would willingly “fake it” when they have the real goods because yesterday’s market products were actually wrong?

So yes your Flex-6000 is going to tell you about the noise it actually hears, rather than ignoring that noise.

On one of my older cars with a KM only speedometer is a KPH to MPH conversion chart – so you know that 55 MPH is 88 KPH and so on. If your ham radio enjoyment depends on having a vintage pseudo-S-meter you could make yourself a similar chart.

Truly it was amazing to see people post that they wanted – so strongly that they were unhappy about it – for their expensive $6,000+ Flex-6700 to purposely lie to them – to “Tell them Sweet Nothings” – even when they had this near lab-grade equipment properly observing S-2/3 level noise & signals.

Even when confronted with the test data explaining that their familiar old school radios did an approximation of S-signals, each with a different range, scale and even different sampling methods they somehow wanted Today’s-Technology with Yesterday’s-Lies.

It is almost like asking a construction laser-level manufacturer to purposely put in a wobble in their levels to reduce accuracy to the old physical level-line accuracy.  Or asking a laser digital tape measure to not report the device’s ultimate accuracy, but approximate to a nearby 1/4 increment on an unpredictable basis.

Better Tools demand Better Craftsmanship.  In keeping having more accurate and theoretically more correct measures of S-unit Levels requires us to up our game as operators, so be it.



Blog: https://k9zw.wordpress.com

2 thoughts on “S-Meters – Comfortable Lies or Accuracy? – The Whisper of Sweet Nothings

  1. Ross Stenberg K9COX says:

    Forgive them. Some of the old receivers gave most signals something above 30 over S9. An S9 signal was just above the noise.

    Another sore point is the fact that the meter readings do not increase with preamp gain, however the noise floor will drop if you are lucky.

  2. Mike Coslo N3LI says:

    Many people are simply not ready for what the Flex is. They bought it based on specs, yet want it to act like a legacy radio. And if their legacy radio reads something false, they want their SDR radio to read falsely as well. It is hard to fathom, I was really happy to have an accurate S-Meter, Wattmeter, and Power meter. I’d say different strokes for diifferent folks, but it is hard to defend plain old wrong, and harder to defend people that demand wrong.

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