Re: GPS/U3S generated Noise
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Hi Bruce
A digital signal changing at a rate of 9600 baud will generate noise. Whether or not that noise is radiated enough to be troublesome, or conducted through power supply lines or ground enough to be troublesome, depends on a lot of different factors. Shielding, grounding, location, both for the GPS and for the receiver. And how sensitive your receiver antenna system?is to local noise. So tends to be different every time.?
Two things you can try (and I have heard helped) to make it better:
1) Disconnect the yellow LED. The easiest way to try it, is to left one end of the series resistor R4.?
2) Put a 1K resistor in series with the data line between QLG1 and GPS
73 Hans G0UPL
Hi, Andy -
Thanks for the reply.? I was interested to see that you have the noise problem with one QLG1 and not with the other.? Assuming that your two GPS units are pretty much identical, I'm wondering what's different on the other end of the line.
I've opened up the VFO/SigGen and tried (1) pulling the serial data line off on the VFO end (still heard noise) so then (2) tried wrapping various leads in the VFO case through a toroid, on the assumption that the serial data line noise was being picked up in the case ... but no luck.
Since Hans has apparently not seen this behavior, and there were just a few respondents to your post (or this one), either QLG1 users have been ignoring it or there is some tweak I can do to clean it up, i.e., something on the VFO end.
Best -
Bruce K1FFX
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