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… ūüôā )

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.

WSJT-X Going the Distance – 16,900 km

JT65 QSO with AB1J at some 16,917 km.

JT65 QSO with AB1J at some 16,917 km.

After successfully getting WSJT-X 1.3 up and running last night, I decided to throw out a quick CQ on JT65. Even though my waterfall was showing some interference I still managed to pick up a contact way out over on the West Coast of America some 16,900 kms away!

Other than being my longest QSO to date, what really surprised me was:

  • The fact the QSO was achieved with such high level of interference with¬†the signal barely visible on the waterfall (see below); and
  • That this was with JT65, so imagine what could be achieved with JT9 – shame the majority of activity of the two is JT65!

Looking forward to doing more with WSJT-X!!

Waterfall showing QSO with  AB1J. Note the interference and how weak (visually) the successfully received signal was.

Waterfall showing QSO with AB1J. Note the interference and how weak (visually) the successfully received signal was.

WSJT-X and Windows XP

As mentioned in my post about my first experiences with WSJT-X and JT65/JT9, I had issues getting any version other than 1.1 to successfully decode. A bit more searching and some playing around last night and I now have successfully decoded with 1.2.1 and 1.3 on Windows XP.

My solution in the end was to simply open up wsjtx.ini in the install directory, and then add the following lines at the very end:

[Tune]
Audio\DisableInputResampling=true

This (I understand) has the effect of returning the¬†sampling methods back to what was in version 1.1 – which essentially uses 12kHz sampling rather than 48kHz. There is another option however this is sound card driver specific, and that’s to set the default sampling rate (via the control panel, etc.) to 48kHz. However, for my sound card (Audigy 4) I was unable to find this setting so went with the above solution.

I hope this helps others who may have been stumbling on this. Albeit, I do now realise it’s documented in two places:

  • The above solution is in the manual’s FAQ section – however currently the formatting is a bit askew in the manual; and
  • The details about making sure your sound cards default sampling is set to 48kHz is specified in the Windows install instructions in the manual.

Good luck!

An easy 15,800 with JT9

An easy 15,800 with JT9
JT9 QSO with K8TLC at some 15,813 km.

JT9 QSO with K8TLC at some 15,813 km.

I was passing the shack’s computer last night before dinner and I noticed JT9 showing a very clean waterfall. I saw someone calling but it was really on the edge of my filters passband. So in case someone else was about I threw a CQ out up in a stronger section of my passband.

To my surprise the other caller (K8TLC) saw it and immediately replied. This resulted in a full QSO at some 15,813 km. Full exchange can be seen in the screenshot.

I’ve also found some information on getting WSJT-X versions 1.2 and up working on Windows XP. Seems in my haste I missed the pertinent information in the manual. If all works out I’ll be sure to share.

WSJT-X and DX with JT9 and JT65

Last week I came across JT9 as a mode for DX on HF. I’d not come across it before (possibly being side tracked with WSPR), but before I knew it I was downloading WSJT-X, reading the tutorial and running it up.

However, first attempts to receive were a complete fail. I was sure of success as it was when there was no interference (for once) and I had heaps of JT65 signals roaring in and system time was in sync to ~100 milliseconds. But not a single decode.

I then proceeded to just give it time and let it run some 24 hours. But still nothing…

A bit of searching around the net revealed I wasn’t the only person who had troubles decoding with WSJT-X. Further, it seemed maybe that for those who had troubles all used to work with version 1.1 of WSJT-X.

I proceeded to download WSJT-X 1.1 and lo’ an’ behold suddenly I was decoding signals left right and centre. Both in single JT65 mode (for which there seems greater activity) and also in split mode decoding both JT65 and JT9 transmissions.

Since then I’ve tried again with version 1.3 and also 1.2.1 (a couple of times), but for the sake of me I can not get decodes with either – oh, except a single decode once… And looking on pskreporter (a¬†great site BTW) it would seem very few are using the latest version of WSJT-X. Further, looking at a¬†WSJT-X changelog I note there were changes starting with 1.2 about how the sound hardware was accessed. So I wonder if maybe that’s had a flow on effect to those running on Windows XP (such as my shack PC).

Anyway, at least I have a version that works (just a shame some nice waterfall improvements came in in version 1.2) so I proceeded to try some contacts. My first was with VK5HAM but I made a fair mess of things as I wasn’t as comfortable with the UI as I thought I was. Anyway, the one I was most impressed with was with HA1AD. Details were:

Their grid square: JN87
My grid square: QE37
Mode: JT9
Freq: 14.078850 MHz
Report sent: -06
Report received: -09
Distance: ~12,995
My power: 5W

That is indeed my first true (ie. bi-directional) DX contact.

After that, I was hooked and tried a few more, but often shooting too far (15,000+ kms). It’s amazing how quickly the time passes by with these modes.

So, if you’re yet to try these¬†modes then I highly recommend them. They take WSPR a step further, and with reverse beacon networks such as PSK Reporter you’ve got everything you need (ie. WSPR beaconing but with option for proper QSO contacts)!

One last thing though before I go. Later on my interference returned, but to my surprise WSJT-X kept on decoding. The following two images show WSJT-X picking signals out of the noise. If you take a look at the waterfall @ 23:23 and then just near 1200Hz you can see the signal (just) from ZL3HAM, but at the same time you can see the wonderful interference I enjoy.

Although an extreme example, I have actually had QSOs in amongst lesser interference with WSJT-X this week-end. Something I would have struggled with voice and many other digital modes.

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!