If it was properly calibrated you would have a realistic idea of what the noise level at your QTH is. Unlike the 10,000 dollar radio manufacturers who deliberately compress the bottom end of the S-meter scale so it looks like you have a
low noise QTH. A calibrated S-meter would also would give you a true indication of galactic noise on the higher bands which on a dipole antenna in 2.4khz bandwidth should be something from S3 to around S1 on a calbrated S-meter.
Radios should have their pre-amp settings with labels like Quiet Rural, Suburban, City, and Industrial. This way you can set the gain of the receiver to the noise floor of the location using just the right amount of sensitivity.
The worst feature of modern radios is the excess gain on the lower bands that is really not needed or cant be realistically exploited. Its pointless amplifying galactic noise and QRM.
Talking about antenna factor and other factors. If the receivers did have calibrated S-meters, Antenna factor offset, EMC 9khZ bandwidth plus Quasi peak detectors we could use our radios as legitimate EMC receivers for measuring
radiated emissions and reporting these levels. We have 10,000 dollar radios with useless S-meters that are as bad as 50 dollar CB radios, why are we paying such high prices for expensive junk? I can buy a Rigol spectrum Analyzer for 2000 US dollars that is accurate to within 0.3db with a color screen. Why do useless radios like the Icom IC7700 and IC7800 cost so much and are nothing more than useless toys with a meter that us totally useless?
Calibrated S-meters are very handy if designed and implemented correctly to be a true reference 50 ohm source impedance level meters. This should be easily accomplished in software defined radios.
It would be nice having S-meter in radios that can be switched to the commonly used scales such as Dbm, DbUv, S-units, Uv. Just about every commercial radio that I have used has an RSSI(received signal strength indicator) that is calibrated. Only hams buy 10,000 dollars pieces of equipment with 10,000 % inaccuracy. We should demand better.
The ADAT radio has the most accurate S-meter that I have ever used. The K3 is reasonably good, however its resolution is limited to chunky S-units. All my SDR receivers, Perseus and Winradio have super accurate S-meters
The is absolutely no reason why a Analog S-meter cannot be made to closely match a LED bargraph for level indication. High speed wide bandwidth op amps are cheap these days. But I suppose it depends what you are actually measuring, deep fades of 20 db or following voice peaks, it depends on the application. With the appropriate sampling and detection algorithms, every possible measurement should be able to be plotted and displayed.
Anyway dont expect calibrated S-meters from ham companies any time soon, they committed to delivering the same radios with poor TX IMD, poor receivers and uncalibrated S-meters year after year. Its only because hams
appear to be consumer suckers. We really deserve what we get because we dont complain about anything and just take the junk that they manufacture.
You have more chance of getting decent ham equipment from groups such as the HPSDR groups who understand these issues more than the manufacturers who are just in it for the money and not the science.
Its a real pity ADAT is not more proactive about marketing its radio. In my opinion this one of the best pieces of equipment a ham can buy for the money, its a true test receiver. Its transmitter is almost perfect with very low TX IMD.
They have such a good product, I dont know why they dont point a good marketing company like DXENGINEERING in the USA to market their products. I am sure it would be top seller in the USA. The S-meter is godly accurate.
Even if it is well calibrated, unless you know the applicable antenna factor, it doesn't really tell you very much.