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Andy,
I am using a Kenwood TS440 where the AGC cannot be disabled. Strong signals and/or QRM-QRN ofter affect the AGC, but far less at 270Hz bandwidth.
Maybe the AGC action affects on the reported SNR values.
I believe that Andy (F6CNI) also is on the reflector, so he might reveal the secret.
73, Rik ON7YD - OR7T
All the critical filtering is done in the software, and results in a 1.46Hz noise bandwidth - which is what the software measures and reports upon.
Your observation that a narrower IF bandwidth is interesting. Its most likely based on the fact that typical signals are corrupted by pulsed non-gaussian noise which upsets the frequency bin detection process, and upsets sync recovery.
Andy
www.g4jnt.com
This email has been scanned for damaging side-effects by the health and safety police, is guaranteed to contain no substances hazardous to health, but may contribute to dissolving the nether and polar regions
2010/1/27 Rik Strobbe <[email protected]>
Andy,
maybe the "magic" lies in a narrow filter (either IF or audio).
If I switch from a 2.5kHz (SSB) filter to a 270 Hz filter I also get a significant increase in SNR values reported by WSPR.
Unfortunaely it hardly affects the decoding level (minimal SNR needed to get a positive decode), that rises by almost the same amount.
73, Rik ON7YD - OR7T
Has F6CNI managed some sort of magic noise reduction system, or is it a just a case of being in a very quiet location...
These are pretty impressive S/N values
| 2010-01-27 20:14 |
G4JNT |
0.503875 |
+13 |
0 |
IO90iv |
+23 |
0.200 |
F6CNI |
JN19qb |
391 |
243 |
| 2010-01-27 20:08 |
G4JNT |
0.503875 |
+10 |
0 |
IO90iv |
+23 |
0.200 |
F6CNI |
JN19qb |
391 |
243 |
| 2010-01-27 20:02 |
PA0A |
0.503900 |
+15 |
0 |
JO33de |
+37 |
5.012 |
F6CNI |
JN19qb |
502 |
312 |
| 2010-01-27 20:00 |
G4JNT |
0.503875 |
+14 |
0 |
IO90iv |
+23 |
0.200 |
F6CNI |
JN19qb |
391 |
243 |
| 2010-01-27 19:54 |
G7NKS |
0.503920 |
-5 |
0 |
IO92ub |
+20 |
0.100 |
F6CNI |
JN19qb |
422 |
262 |
| 2010-01-27 19:54 |
G4JNT |
0.503875 |
+14 |
0 |
IO90iv |
+23 |
0.200 |
F6CNI |
JN19qb |
391 |
243 |
| 2010-01-27 19:44 |
G4JNT |
0.503875 |
+10 |
0 |
IO90iv |
+23 |
0.200 |
F6CNI |
JN19qb |
391 |
243 |
| 2010-01-27 19:40 |
PA0A |
0.503900 |
+15 |
0 |
JO33de |
+37 |
5.012 |
F6CNI |
JN19qb |
502 |
312 |
|
