S-meter, levels, voltages and powers
Understanding of signal strength measurement by S-meter, which is perhaps on every receiver or transceiver is a relatively little known thing. It is part of the RS report(T), which radio amateurs use every time they connect.
In year 1981 International Amateur Radio Union (IARU) Region 1 accepted the draft definition, where for KV bands the S9 level signal is defined as -73 dBm, which represents tension 50 μV on impedance 50 ohms. For the VHF band, the S-meter is calibrated differently. Level S9 is defined as -93 dBm, which represents tension 5 μV on impedance 50 ohms. Each level S then has a distance from level S9 6 dB.
S-meter for KV bands
| Signal strength | Relative level to S9 | Tension | Power on Z = 50 Ω | ||
| S1 | –48 dB | 0.20 μV | –14 dBμV | 790 aW | –121 dBm |
| S2 | –42 dB | 0.40 μV | –8 dBμV | 3.2 fW | –115 dBm |
| S3 | –36 dB | 0.79 μV | –2 dBμV | 13 fW | –109 dBm |
| S4 | –30 dB | 1.6 μV | 4 dBμV | 50 fW | –103 dBm |
| S5 | –24 dB | 3.2 μV | 10 dBμV | 200 fW | –97 dBm |
| S6 | –18 dB | 6.3 μV | 16 dBμV | 790 fW | –91 dBm |
| S7 | –12 dB | 13 μV | 22 dBμV | 3.2 pW | –85 dBm |
| S8 | –6 dB | 25 μV | 28 dBμV | 13 pW | –79 dBm |
| S9 | 0 dB | 50 μV | 34 dBμV | 50 pW | –73 dBm |
| S9+10 | 10 dB | 160 μV | 44 dBμV | 500 pW | –63 dBm |
| S9+20 | 20 dB | 500 μV | 54 dBμV | 5.0 nW | –53 dBm |
| S9+30 | 30 dB | 1.6 mV | 64 dBμV | 50 nW | –43 dBm |
| S9+40 | 40 dB | 5.0 mV | 74 dBμV | 500 nW | –33 dBm |
| S9+50 | 50 dB | 16 mV | 84 dBμV | 5.0 μW | –23 dBm |
| S9+60 | 60 dB | 50 mV | 94 dBμV | 50 μW | –13 dBm |
S-meter for VHF bands
| Signal strength | Relative level to S9 | Tension | Power on Z = 50 Ω | ||
| S1 | –48 dB | 20 nV | –34 dBμV | 7.9 aW | –141 dBm |
| S2 | –42 dB | 40 nV | –28 dBμV | 32 aW | –135 dBm |
| S3 | –36 dB | 79 nV | –22 dBμV | 130 aW | –129 dBm |
| S4 | –30 dB | 160 nV | –16 dBμV | 500 aW | –123 dBm |
| S5 | –24 dB | 320 nV | –10 dBμV | 2.0 fW | –117 dBm |
| S6 | –18 dB | 630 nV | –4 dBμV | 7.9 fW | –111 dBm |
| S7 | –12 dB | 1.3 μV | 2 dBμV | 32 fW | –105 dBm |
| S8 | –6 dB | 2.5 μV | 8 dBμV | 130 fW | –99 dBm |
| S9 | 0 dB | 5.0 μV | 14 dBμV | 500 fW | –93 dBm |
| S9+10 | 10 dB | 16 μV | 24 dBμV | 5.0 pW | –83 dBm |
| S9+20 | 20 dB | 50 μV | 34 dBμV | 50 pW | –73 dBm |
| S9+30 | 30 dB | 160 μV | 44 dBμV | 500 pW | –63 dBm |
| S9+40 | 40 dB | 500 μV | 54 dBμV | 5.0 nW | –53 dBm |
| S9+50 | 50 dB | 1.6 mV | 64 dBμV | 50 nW | –43 dBm |
| S9+60 | 60 dB | 5.0 mV | 74 dBμV | 500 nW | –33 dBm |
amtérsky KV/VKV transceiver: https://en.wikipedia.org/wiki/S_meter
