[mythtv-users] Automatic antenna aiming?

[George Nassas]

On 2013-11-30, at 12:15 PM, Don Brett wrote:

> Does anyone know if there's a way  to automatically aim an antenna (i.e. move the rotor) when tuning a particular channel when using an HDHomeRun.  I ran across this antenna rotor; might be a good candidate for a blaster application?
> 
> http://www.amazon.com/RCA-VH126N-Antenna-Rotator-Remote/dp/B002GSG0CG

There are lots of those rotators around. I personally use a channel master 9521 (http://www.channelmaster.com/Best_Antenna_Rotor_Channel_Master_CM_9521A_s/63.htm) but only because that’s what my installer had when he put an antenna on my roof. The combo uses a channel master 9537 rotator controller and I lucked out and found an lirc config and rotator script for it here: http://osdir.com/ml/hardware.lirc/2004-10/msg00045.html which has been working reliably for me for six years. The script is fairly generic so whatever lirc-compatible rotator controller you have can be driven by switching a single parameter assignment near the top.

The other half is how to hook this into myth’s recorder subsystem. Analog tuners have an “external channel change script" option but there’s no such hook for devices in myth's DVB class hierarchy which includes the HDHomeRun. Instead, I connected a script to myth’s “RecStarted” backend event which tests if myth is recording on the tuner attached to the rotating antenna and then blasts direction codes based on the channel. My initial approach was custom code to add an external change script but I kept getting sideswiped whenever the recorder code got improved in some way. Using a script on a published interface insulates me from developer mayhem.

You might have questions about how to do blasting but there is lots of wisdom on that here and in the wiki. The main takeaway for antenna rotating should be make sure your rotator controller can be driven by lirc and use myth events for a reliable recorder -> rotator linkage.

- George