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TOPIC: S-Meter calibration to IARU standards

S-Meter calibration to IARU standards 21 May 2021 20:28 #1

  • N1KIN
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Summary: S-9 meter calibration on 6M in ExpertSDR does not conform to IARU standard. All other HF bands are correct, as is 2M standard operation. Confirmed on both SunSDR2-DX and SunSDR2-Pro running 1.3.1 Update 8.
More detail:
According to IARU convention, -73 dBm is the standard for an S-9 signal level on HF bands up to 30 MHz. The standard also indicates that above 30 MHz, the standard changes to -93 dBm. Though the software seems to calculate this properly for 160-10 Meters (S-9= -73 dBm), and 2 Meters (S-9 = -93 dBm), the 6M band seems to be calibrated to the standard HF -73 dBm level, vs, -93 dBm. The confusion may come from the fact that 6M band straddles the line between the old standard HF band, and the beginning of what is considered the beginning of the VHF band. To further confuse things, some manufacturers go one way and some go the other. Regardless of what manufacturers are calling the 6M band for marketing purposes, the IARU standard is specific... for the purpose of S-Meter calibration, operation above 30 MHz falls under the -93 dBm rule. See the IARU text: raag.org/wp-content/uploads/2021/03/VHF_Handbook_V9.01.pdf
(See section 4.1.1)
Would it be possible to either correct ExpertSDR to be IARU compliant, or at least add an option for metering to allow for a "6M band S-Meter = -93dBm/-73dBm" choice?
Thanks! -- N1KIN
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S-Meter calibration to IARU standards 25 May 2021 11:12 #2

  • Rome
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Hello,
We know that, and once, a long time ago, we even changed 6M calibration to a unified standard but got so much negative in return, so changed it back and never touched again.
We might implement a switch for a 6M S-meter at some point in the future, but not any time soon since we are busy with other tasks.
Роман, Roman
Expert Electronics
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