Re: U4B and PuTTY Questions #u4b

Hans Summers

Hi Tony

I'm happy to hear that it is working fine! 

The reason all the U4Bs have "KM46" in them when they arrive from me is that they are all tested here before shipping. We connect an ST Link 2 programmer to flash the bootloader and lock the chip. Then use the bootloader to install the latest U4B firmware (U4B appears as a USB Flash drive and just copy on the firmware file, done!), then connect a GPS antenna and a PuTTY terminal, and run the "Hardware test" application. A "pass" is when the entire screen is white text, no red error reports. That also means it has the locator, MY locator. 

Normally even one satellite is enough to get the time, which comes in first, followed a few seconds later by the date. 3D fix requires at least 4 satellites with sufficient signal strength. 

There's also a system variable called GL whose value is 1 if a GPS fix was completed successfully in the last GPS statement, and 0 if not. You could use this to prevent transmission when there's no GPS lock. 

IF GL = 1
    WSPR blah blah blah 

73 Hans G0UPL

-------- Original message --------
From: tony.volpe.1951@...
Date: Sun, May 8, 2022, 9:30 PM
Subject: Re: [QRPLabs] U4B and PuTTY Questions #u4b
I just got my U4B today - it was delivered yesterday but I wasn't here. Up and running straight away in simple mode and getting spots from about 800 km away on a random bit of wire on 30 meter band. Looks like it will be a fun project to run it as a garden wspr tx with a couple of solar cells and a proper antenna when I get sorted.. 

When I first tried to run it, it didn't transmit for the first half hour or so even though it was powered by a 4.2 v battery. I am wondering of the GPS took a while to get enough data to get a fix. Strangely, the first two transmissions sent Hans's locator - KM46. The U4b is temporarily set up in a window and may not have had great GPS reception. It obviously had the time before it got a  proper fix on my location. 

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