soundcard does matter !

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f6irf
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Joined: 2008/04/18 - 12:24
soundcard does matter !

Feeding two PC's with the same RX-audio, I can notice differences in the reported levels: I tested the 3 sound devices available here.

- my main sound device, is the microham MK2R+. With the built-in soundcard (USB-audio) I almost never get false decodes (or phantom signals on a strong station)
- with my laptop PC (IBM thinkpad), I often get false phantom signals on strong stations, false callsigns or false CQ or reports. In general the reported levels are 3 to 4dB lower than they are on the main sound device, while they almost match (+/- 1dB) on strong or very weak signals. Must say that this soundcard only has a mic input.
- On my desktop soundcard (using line input through a microkeyer 1), I get almost no decoding (or only very strong stations reported at low level). What is amazing with this device (and the same level settings) is that WSJT7 (in WSPR-mode) works perfectly and provides reports matching closely the reports provided by the main sound device (I reported this pbm to Joe).

Just to spot that: Yes the soundcard does matter and may affect the reported signal levels... or in the worst case may even provide no decoding at all...

Pat

Following is an example of the differences that can be seen, using 2 PC's fed from the same RX audio

MK2R+ USB audio soundcard
080924 1006 35 5 1.2 10.140205 DH8SA JO53 37 -1 1 0
080924 1014 28 -4 1.2 10.140146 EB1APK IN73 40 1 1 0
080924 1016 36 5 1.1 10.140205 DH8SA JO53 37 -1 1 0
080924 1018 16 -19 1.5 10.140110 OK1DST JN79 33 0 2 0
080924 1018 22 -10 0.6 10.140142 IV3GTH JN65 37 0 1 0
080924 1024 34 2 1.1 10.140146 EB1APK IN73 40 1 1 0
080924 1024 5 -28 0.9 10.140245 K1JT FN20 37 0 39 0
080924 1026 28 -3 1.7 10.140126 IQ3AZ JN65 37 2 1 0
080924 1026 36 5 1.2 10.140205 DH8SA JO53 37 -1 1 0
080924 1030 14 -18 1.6 10.140110 OK1DST JN79 33 0 1 0
080924 1032 29 -4 1.1 10.140147 EB1APK IN73 40 0 1 0
080924 1034 9 -20 0.4 10.140142 IV3GTH JN65 37 0 5014 0

IBM thinkpad laptop built in soundcard
080924 1006 35 6 1.2 10.140205 DH8SA JO53 37 -1 1025 0
080924 1006 3 -29 2.3 10.140186 DH8SA JO53 37 -1 1025 -61
080924 1008 3 -23 0.7 10.140288 TS4AEZ (BadMsg) 0 16986 7
080924 1008 3 -28 0.3 10.140298 814SSR <...> R S6 -3 4610 -5
080924 1008 1 -33 6.1 10.140273 814SSR <...> R S6 -3 14766 -4
080924 1014 26 -7 1.1 10.140146 EB1APK IN73 40 1 1 0
080924 1016 35 5 1.1 10.140205 DH8SA JO53 37 -1 1 0
080924 1018 11 -23 1.4 10.140110 OK1DST JN79 33 0 1 0
080924 1018 17 -14 0.5 10.140142 IV3GTH JN65 37 0 1 0
080924 1024 34 2 1.1 10.140146 EB1APK IN73 40 1 1 0
080924 1024 3 -27 0.9 10.140245 K1JT FN20 37 0 12753 -4
080924 1026 25 -5 1.6 10.140127 IQ3AZ JN65 37 2 1 0
080924 1026 35 4 1.0 10.140205 DH8SA JO53 37 -1 1 0
080924 1030 10 -22 1.5 10.140110 OK1DST JN79 33 0 1 0
080924 1032 24 -8 1.1 10.140147 EB1APK IN73 40 0 1 0
080924 1034 7 -23 0.5 10.140143 IV3GTH JN65 37 0 1975 0