¿ªÔÆÌåÓý

ctrl + shift + ? for shortcuts
© 2025 Groups.io
  1. QRPLabs
  2. Messages
Single Messages Topics Expanded Polls

Re: QMX and qlg2 GPS

 

Hello Wei

It isn't that straightforward.?

During the WSPR transmission the system heats up and this causes drift. If you do the calibration right before the WSPR transmission then the frequency at the start of the WSPR transmission will be accurate but at the end, it will have drifted. The WSPR drift report will be the average of these two (roughly speaking). If you calibrate right after the WSPR transmission then the frequency at the end of the WSPR transmission will be accurate but the frequency at the start won't be. The reported WSPR drift will again be the average of these two.?

So regardless: doing the cal before or after doesn't guarantee anything.?

The best way to minimize drift is to use a TCXO reference which has minimal drift with temperature. And perhaps even then put some polystyrene insulation around it to stop radiated heat at least.?

73 Hans G0UPL


On Wed, Apr 10, 2024, 11:40?PM Wei AG6AQ <wcheng95@...> wrote:
Hi Hans,

When you implement GPS calibration for QMX, Is it possible to do the calibration right before each WSPR Tx? For the kits I have(U3, U3S, QCX), the calibration happens after each Tx, and sometimes the frequency drifts a little bit after that. It's not something critical, but maybe you're willing to grant us the satisfaction of seeing "dead on" reports on wsprnet.

73,Wei,AG6AQ



On Tue, Apr 9, 2024 at 9:39?PM Hans Summers <hans.summers@...> wrote:
Hi Bill

At the moment the GPS port on QMX doesn't do frequency discipline. It hasn't been urgent to implement because the TCXO in QMX is already so precise. But I'll do it eventually.?

GPS does set the time of the real time clock, and also the Maidenhead grid subsquare in the WSPR beacon function. Setting the real time clock happens as soon as the GPS is plugged in and valid data is received. You would only see the real time clock on screen if you have enabled it, in the Display/Controls menu.?

73 Hans G0UPL


On Sat, Jun 17, 2023, 9:44?PM Bill Watkins- K0WHW <kf7yxs@...> wrote:
Hello,

I have built my QMX kit.? It seems to be operating.? I am still listening with it, and have not attempted a transmission.? I am wondering about gps discipline or at least loading the time.? I've probably missed something, so I hope someone can set me straight.? The gps is receiving the pps signal.? When I plug the 3.5mm into the QMX, I am not able to see the clock set or any reference calibration.? What am I doing wrong?? Is it because I have it in "P" mode because I don't want to accidentally transmit???

Thanks,

73 k0whw

Join [email protected] to automatically receive all group messages.