TAPR WSPR TX Shield And WsprryPi Works, But It Takes Some Work

The TAPR WSPR QRP TX Shield works with the Raspberry Pi, but it has some issues. Some users have reported that it freezes. There are support threads for WsprryPi which proved to be very helpful. With some trial and error, eventually I got mine working smoothly and it does a wonderful job with only 100mW's.



One problem I haven't been able to overcome and this seems to be a RPi3 issue, the WIFI on my RPi3 disconnects when the WSPR transmission starts. I'm using my RPi3 headless, so I loose my VNC connection until the transmissions have stopped.

One workaround I've found is to use the ethernet port, bypassing the need for my wireless connection. However, my router is in the other room.

Using an attached monitor, keyboard and mouse will work too, but that's not practical as a permanent fix in my limited space.

A touchscreen attached to the RPi3 may be the perfect solution.

Take a look at the video. Stations were spotting me all over the country and I am using a small wire antenna inside my office. Pretty amazing if you ask me and fun to experiment with.

 

Hi Richard,

I put together a Raspberry Pi/WSPR kit and went through some growing pains with it. I had problems with the Pi just losing its brains and corrupting the SD card along the way.

Turns out there are two fairly sensitive parts to the system: power supply and SD card. Your SD card must be good enough to work with the Pi. As long as it's Class 10 it should work alright.

The power supply is a different story. Power conditioning is ALWAYS a concern on any electronics and the Pi is no exception. A power glitch will take out the Pi or at least confuse it, potentially corrupting the file system (SD card) at the same time. There is no energy storage in most switching power supplies, so even a minor power glitch can mess things up. Power on and power off are major sources of trouble. Cheap power supplies are problematic.

The Raspberry Pi folks have done an amazing job designing/building the Pi. My hat's off to them. I do think they've short changed the power supply capacitor for normal Pi operation. Unfortunately, if you're demanding additional power to run a transmitter the situation is even worse.

Start with a GOOD power supply capable of delivering at least 2 amps. I picked up a couple of 5V/2.5 amp power supplies at Hamvention from MCM (http://www.mcmelectronics.com/product/28-19338). Of course, many others will work as well.

Next, try adding bulk capacitance across the 5V power supply rails (+5V on pins 2 & 4 of the header. Gnd is pins 6, 9, 14, 20, 25, 30, 34, 35, 39.) I used a 47 uF capacitor connected between pins 2 & 4 (plus) and Gnd. I tried increasing the value to 220 uF and didn't notice any difference in behavior from 47 uF.

I hope this will solve your problems. My writeup and approach is on WsprWithoutTears.com.

73,
Bruce Raymond/ND8I
nd8i@arrl.net

 

Hi Bruce,

Nice to hear from you and thanks for the information! Very important.

Yes, I ran into the same issue with the power supply. The one supplied with my RPi3 is 2.5A and it works, but I ended up using a ferrite core on the cable. This helped.

I also tried a 2A battery and it worked good.

I didn't think about the card, but I have a good Class 10 in it. It hasn't given me problems yet. Good reminder though, thank you!

On another note, I have found that when I transmit with my amplifier on SSB it will restart (shutdown) the RPi3. Too close in proximity and too much power. I haven't noticed a problem with just 100 watts or less. At least not yet.

Do you have a problem with it and wireless? Does it kill your WIFI on the Pi when WSPR starts a transmission? It takes 60 seconds or so, but it still does on mine.

I have a touchscreen attached now and it's working. Still experimenting with it though

Thanks!

 

Just follow directions on TAPR site I thought very easy. I also installed VPN so I don't need keyboard,mouse or monitor on my Pi3. I just login and startup or shut down the Pi3.

 

I'm having a lot of problems with the Lexar 300x class 10 (white/blue) SD card. The standard Lexar class 10 (black) works like a charm.

A good power supply is a must. I gave up using those wallwarts sold specifically for the RPi3. They do not provide enough juice, and the advertising claim they are 2 or 3A is questionable. I ended up buying a couple of 'pigtails' barrel connector to micro USB, and use with other power adaptors.

73 de Vince, VA3VF

 

What's the OS used? Raspbian works ok, but I would rather use Ubuntu. Ubuntu was very slow initially. I tried a couple of re-installs, and now it fails on first run when trying to expand the partition. The cards are ok, since I can install and run Raspian on them problem free.

73 de Vince, VA3VF

 

Are you using WIFI? If so, any problems once it starts the transmission?

 

I have an RPi 2 with a 20m TAPR shield and have a ton of fun with it. I have a screenshot of a confirmed 100mW Florida to New Zealand transmission on my QRZ page--obtained this year with the solar cycle at the bottom of the barrel! I ran into problems with the Pi locking up periodically and was not able to rectify the problem. In the end, I put the power supply on a cheap timer that cycles on and off every 2 hours. Effectively it reboots the Pi every 2 hours and if the Pi locks up, worst case scenario, it reboots itself 2 hours later and starts up again. Not a prefect fix, but it does work perfectly...

It runs 24/7. If I don't show up on the WSPR site, its because the Pi shares the wire in the trees with my HF rig. Sometimes I forget to switch the antenna back to the Pi after I'm done playing HF.

 

Yes I'm using Raspbian. I tried Ubuntu and still had a problem with WIFI crashing. Are you using it headless with WIFI? If so, any problems with WIFI crashing when transmission starts?

 

I'm wondering if I have some faulty hardware. WIFI crashes 60 seconds after transmission starts.

 

Thanks for the info. That's my intention, to have it run on a schedule. Eventually some DX will pick me up. It's a good way to check the Band too.

 

I never tried TXing, whether using my transceiver, or a TAPR shield, which I don't have.
I used it both headless, with a Logitech wireless keyboard/mousepad combo, and an old monitor using a VGA to HDMI converter.

73 de Vince, VA3VF

 

I don't think you have a faulty WIFI. It's likely RFI. Try using a shielded cable as the antenna, keeping only a foot or two of the shield on the RPi/antenna connector side.

73 de Vince, VA3VF

 

Thanks Vince. I'll keep trying. I have a touchscreen now, so losing the WIFI is not hurting anything. I'll keep trying because I'd like it to work.

 

Hi Richard,

I haven't run into WiFi problems with my WSPR stuff. I'm using a different setup than the TAPR unit, although not that much different. I'm not using an amplifier, so I don't really have a basis for comparison - sorry to not be of much help here. I run headless and find that my network connections seem to be fairly robust.

I tend to start look for interference and intermittent problems with power supplies and ground. It's amazing how circuits don't always work like you'd think from the schematic because ground isn't the same everywhere.

73 Bruce Raymond/ND8I