/posts/ 2015/dvbt_and_sdr

DVB-T and SDR with the RTL2632

I spotted a Youtube video the other day that talked quickly about SDRs (Software Defined Radios) and how you can pick up one for $20, which is a massive difference from the £300-400 devices I spotted a few years ago. Of course, I decided there and then that i’d grab one to experiment with and searched Google for the mystical device. As it turns out its the Realtek RT26832 based devices which allow SDR type functionality, and while a lot of devices out there are higher than the magical $20 due to them being advertised as a SDR it was quite easy to find one of these generic DVB-T tuners with the right chipset on Amazon for a grand total of £9. With the order being eligible under Amazon Prime I ended up ordering the item yesterday (Saturday) and it was delivered today (Sunday).

So, straight out of the box and into my Debian Jessie test system and everything worked, no tweaking or hassling, within seconds I had a working DVB adapter and I used the standard DVB tools to scan and create a channels.conf within a minute or so. My last experience with the LinuxDVB stack was around 2005-2006ish with MythTV, the drivers “sort of” worked and everything was a little rough round the edges, it seems the last 10 years have really cleaned up the stack. With that in mind its not really worth posting about getting the DVB-T tuner to work, because it just did…

SDR required a little extra work. I’ve not spent a large amount on time trying to get the full toolset to work on Debian, the rtl-sdr toolset is available as a package with Jessie and can be easily install, the biggest problem was that because I was using my test system I didn’t have a X session running to run anything on. I got everything installed and spun up a rtl_tcp instance without much incident, the biggest roadblock was that you can’t have the DVB kmod inserted at the same time as using the rtl-sdr package tools, but a quick rmmod and blacklist sorted that out, the tools are very quick to point out exactly what needs to be done.

Instead of working on Linux I got everything up and running on my Macbook Pro running OS X Yosemite, while OSX doesn’t have the full suite of tools available a few good ones have been developed for the platform. I found that CubicSDR was by far the easiest to get rolling with, no messing with MacPorts or any other third party packaging tools, just a DMG and a pre-packaged application. While it isn’t as feature complete as some of the other packages out there it does cover the basics to go poking around. Their todo list does looks interesting, especially with the target of having digital demodulation built in.

Quick overview done and i’m now looking for a better antenna. While not being used as a SDR the stick itself will be happily serving as a DVB-T source for my Plex system using TVHeadEnd and with a quick MCx to Coax adapter you can have it plumbed into the household aerial without much issue.

[Update - 2015/08/31]

Regarding the links earlier on in this post, it turns out that the two tuners are actually different, with the Nooelec it includes an improved tuner chip (the R820T2). As it turns out it is worth investing the few pounds more for this version as its more sensitive and also includes a more stable crystal that won’t require much adjustment.