Living on the edge

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OZ2M's picture
Last seen: 4 hours 34 min ago
Joined: 2013/02/01 - 16:49
Living on the edge

Recently a fellow ham had zero decodes despite being GPSDO controlled, and transmitting on a "valid" frequency, 7 040 000 Hz. This made me run three simple tests last night on 40 m using my RFzero. Without making exact counts, which may not be relevant anyway since the transmission did not happen at the exact time, the rough number of decodes were:

-10 Hz: 30 (i.e. effectively outside the nominal 1400 Hz to 1600 Hz AF band)
0 Hz: 30
+10 Hz: 60

I.e. about twice as many decodes when being well inside the lower band edge. Of course if the RXing stations have an unintended offset, it may increase or decrease the number of decodes depending on the sign of the offset. The same probably applies to the high end also.

The bottom line is that if a station is not referenced locked, it will make a lot of sense to perform some kind of calibration to ensure the rig is not way off since 10 Hz may have an impact. Otherwise the number of stations decoded will be less.

Bo ::