RTL-2832 and Raspberry Pi for ARPT and FUNcube

RTL-2832 and Raspberry Pi for ARPT and FUNcube

Last year I was playing with a cheap USB dongle for weather satellite reception. Eventually though I gave up on it, as although I could receive reasonable pictures with it, the device kept causing my machine to freeze.

Anyway, I recently dropped a raspberry Pi in the shack to act as a router between my shack and my wireless network. It got me wondering as to the possibilities of running the dongle via it. Turns out, it was as easy as… pi! (Sorry… 🙂 )

It really only takes a few simple steps:

  1. Download the rtl tools source code via git from OsmoSDR
  2. Build up the tools (make sure you’ve installed the build-tools package on your pi)
  3. Make sure you unload an DVB kernel modules with rmmod (after checking with lsmod)
  4. Run rtl-tcp on the raspberry pi
  5. And then connect via TCP from something like SDRSharp

Doing this I’ve had no problems with anything freezing, and have captured images with as much ease as I did before – although I have a dodgy coax cable I need to fix.

Further, I’ve gone on to receive beacons (6m, 2m and 70cm) as well as the FUNcube telemetry. Actually, to my surprise I’m the only VK7 to have recorded reception of any telemetry (according to the FUNcube Upload Ranking page).

To finish, here’s a couple of images received via this setup (one from NOAA-15 and one from NOAA-19). And the title picture of New Zealand is from NOAA-19.

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Improved NOAA-19 Reception

Improved NOAA-19 Reception

This week, my ebay ordered RTL2832U based USB digital TV receiver dongle arrived! I’ve been working through a bit of a cold, but that wasn’t going to stop me going down to the garage and having a play. I was too excited at the possibilities!

With no time at all I had my RTL-SDR solution up and running with SDR#. All that was needed was a custom driver install and then a couple of very minor mods to SDR# and all was working. Other than that, I connected the antenna socket out via my access panel to the Diamond X-50 on the roof. Before I knew I had local WFM radio stations playing on my computer.

The main purpose though for even trying all this, was the hope that it’d improve on my weather satellite reception as per my previous attempt. My thinking was that the main limiting factor was the narrow bandwidth of my receiver.

With using an SDR setup, I should be able to have as wide a bandwidth as needed (and more if wanted). However it required one extra bit of software, and that was a virtual audio cable to route the audio out of the SDR software into the audio in of WxtoImg. For this I chose VB-Audio Virtual Cable. It’s free and couldn’t be easier to use.

NOAA-19 @ 0446 UTC - Both Channels

NOAA-19 @ 0446 UTC – Both Channels

After getting past some recurring computer freezes (think I need to rebuild my PC) I was able to play with an initial pass to play with some settings. But before even changing anything things were looking drastically different. Then on turning the gain in SDR# up full and increasing the AF Level slightly things were looking (to my eye) perfect!

So with all trimmed and ready to go, I  keenly awaited 0446UTC for the next NOAA-19 pass. The results were amazing – the best by a long shot that I’ve every received. These can be seen in the first NOAA-19 image with both channels,  and you’ll notice only a few spots of noise which I believe was mainly due to physical obstruction.

To consider this was achieved with essentially a $25 receiver and some free software is amazing. Considering further I’m still just using the Diamond X-50 and haven’t even bothered to consider the circular polarisation. And further, this was from the West were I do have far less of a view – South/East is the preferred approach.

With that success, what now? Well, I’ll keep trying some more receives (hopefully my PC will stop freezing) and I might try some of the other SDR# features/plugins so that I can attempt to switch frequency for each of the three active NOAA satellites. That way I can aim for a full set of images!

Further, I’m also interested to see how some of the other SDR software offerings go and then I can also start to look at all the other possible items to receive out there – considering this dongle (with the FC0013 chip) covers from just below 30MHz to just up over 1Ghz. So many options! Oh, and then there’s the idea of an upconverter for all the offerings below 30MHz!

Dongle SDRs

With my recent attempt at NOAA weather satellite reception, I’m keen to get a receiver that has support for WFM. Having such would in theory allow me fair better reception – as APT uses 32kHz bandwidth and then there’s also doppler shift to accomodate for (which WxToImg does itself, if you’ve got enough bandwidth). Currently, my Yaesu radios only have support for NFM on 137Mhz and thereby only around 9kHz bandwidth.

A solution for this would be an SDR receiver that covers VHF. There’s been a lot of coverage in magazines lately (namely Silcon Chip and Practical Wireless) on the use of DVB-T/DAB+ dongles for SDR. With these being so cheap (delivered from eBay for ~$30), this definitely looks like a good starting place. If you’d like to know more on this, than simply look up RTL-SDR or start at http://www.rtl-sdr.com/.

However, for it’s price the FUNcube Dongle really appeals compared to some other dedicated SDR offerings. With LF to UHF coverage it’d be great for both work in the 630m band as well as most other amateur bands, and then also for doing weather satellites. (Unfortunately the RTL-SDR idea will only provide for VHF and UHF, however it also about  20% the price).

Here’s a nice video on the FUNcube dongle:

But that said, as a starting point the RTL-SDR (especially at it’s price) will be where I’ll start with attempting to improve my weather satellite reception. And hopefully in the future, I’ll grab a FUNcube dongle. I found these two videos interesting for a comparison of the two options:

Part 1:

Part 2:

SoftRock Complete and Working

Well, I've completed my SoftRock Lite II for 40m. It may have taken me some six months to start building it, but it was pretty straight forward in the end. A couple of hours a night for a couple of nights and all was done. It was my first time doing SMD components, and I was surprised at the success I had. No need for all the procrastination. It's also the first receiver and the first amateur radio kit I've built – well, aside from a crystal radio kit. 😉

Looking forward to playing with it more, but so far I've been impressed with the reception it's achieving (but VK and DX). I'm hoping eventually to set it up with WSPR and see how that works.

Enjoy the pics.

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