Chasing and recovering with powered raspberrypi

[Fernando Fdez.]

Hi,

Whenever you go on chasing a sonde, the auto_rx and chasemapper combination is a really good tool that allow us to follow the payload and get the predictions very accurately. Using this method implies that you have to carry a permanent powered RaspberryPi and a computer or mobile phone to connect to chasemapper website. 

I am just asking if someone has found an effective method to power the Raspberry when you are not on your car and walking in field trying to receive the signal and last coordinates. 

External powerbank usually don't have enough power to keep the Raspberry and SDR working with a lot of voltage alerts. On the other hand I have bought several of those popular UPS for Raspberrypi but even do they work right to do some tasks, they feed some kind of interference or  spurious signals that avoid the SDR and so the auto_rx to receive and decode correctly. It is quite noticeable, just connecting the UPS the decoding process stops inmediatelly, once you power off the UPS (while the Raspberry is feeded by its USB power connector) it begins to decode right away. I still haven't found how to filter the power signal from the UPS and I think I am not going to find it out, any ideas are welcome.

Anyway, what do you all use for chasing the radiosonde once you get off the car and start walking trying to intercept the radiosonde?

Regards!

Fernando

[Mark Jessop]

The RX system in my car is quite sensitive - I run a 1/4-wave monopole on the roof of the car, with a PSA4-5043+ preamp.

Usually I am near enough to track the sonde down to either the ground, so I often just plug the coords into my phone for the last bit of the hunt. If i'm further away I can still usually track down to a few hundred metres, low enough that I can drive to the area and often start decoding again, though sometimes I need to switch to a higher gain antenna.

I'll sometimes resort to traditional DF techniques if necessary (in my case a 7-element yagi + IC-R10), but most of the time I can use the yagi to get a decode. The new feature to manually start a decoder (look for the advanced controls in the web interface) can help get that decode when its on the ground.

Also worth noting that the open source rdz_ttgo_sonde software ( https://github.com/dl9rdz/rdz_ttgo_sonde ) which runs on the cheap TTGO units will now contribute data to the SondeHub tracker. These can be useful to decode telemetry if walking in more than a few hundred metres.

73

Mark VK5QI

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[Chandler Heath]

Hi Fernando,

I use a 12v battery pack and use a DC to DC converter to bring it to 5V using this: https://www.amazon.com/dp/B086KTGRH1/ref=cm_sw_em_r_mt_dp_F7WJCF72X42RQHY8WET7 My setup in the car and at home I use these without any issues :-)

Chandler

[Jim Langsted]

In the car I use a separate 12V deep-discharge battery (no voltage bumps when the car is started), a 110V inverter, and an official Raspberry Pi 3A wall charger. This seems very stable. Like Mark indicated, drive around until you get a signal from the radiosonde on the ground, and then walk in with a hand-held GPS. I run my Raspberry Pi system disconnected from the internet, then I do not have problems when we get out of cell phone range. I have downloaded map tiles using Foxtrotgps (about 2.5GB for my recovery area) and can run independently.

Jim

KC0RPS

[Jim Langsted]

And I download the current wind data in the morning before heading out. If the data is too old (I'm not sure how old that is), Chasemapper will not generate predictions, which makes chasing MUCH harder.

Jim

[Fernando Fdez.]

Thank you all for your answers and details, always very useful.

In my case, I made up a small project based on a RaspberryPi, one UPS attached and small 3,5" screen. I designed the box and 3D printed. Powered by 2 18650 Lithium batteries it gives the whole pack about 4 hours autonomy with a single rtlsdr connected, I love it!!. It is very convenient and easy to carry because is totally autonomous, not needed to be connected to any power source if previously you charged the batteries, anyway it can be charged and running at the same time. The problem is what I explained, the UPS do something bad to the signal received and unless the signal is very powerful, it cannot decode so I thing it interferes in a way that I don't know. I will try some other UPS trying to improve the receive signal and...let's see if it works!

[Michael Hojnowski]

I run with a 10,000 mAh power brick - https://www.amazon.com/gp/product/B07XFBN7HX/ref=ppx_yo_dt_b_asin_title_o07_s00.

This will run my chase computer for about 4 1/2 hours.  I use a Pi 3B+ with a 7" touch screen display and case.  I integrated the SDR and Preamp into the case, to make it fairly modular and robust to stick on my car's dash board.  It's got an SMA Barrel connector coming out of the case, so I just have to screw in an external antenna, power it up and go.  This is an old picture, and I was plugged into my car outlet.  Now the wires just go to the power brick, that's velcro'd to the back of the case.  The little orange box is a .98" OLED display that displays the IP address of the Pi at the top, and scrolls the time and altitude.  That way, I have the IP handy to use with my phone, and an easy to see scrolling display showing me packets as they come in.  I got a bunch of those little OLEDs for like $3 each, so I thought it would be fun to add it.



To be honest, I don't really love the touch screen display.  It's sluggish on the Pi.  Mostly, I use it as backup, and connect to chasemapper from my phone instead.

Mike / KD2EAT

[Fernando Fdez.]

 Wow, Impressive Mike. Just one question, Is there any documentation about how to connect this little to the Raspberry and show the info you want?  Ip address is a good idea, or even the landing predicted coordinates, etc. I can figure out that you use some kind of python programming but I am not a expert...   Any clues are welcome :-).