[mythtv-users] OT: Addressable Antenna Switch

[Dennis Cartier]

On Sun, Sep 6, 2009 at 11:15 PM, drew einhorn <drew.einhorn at gmail.com>wrote:

> Hmm, I wonder if the diseq switches that are typically used to select which
> LNB signal is fed from the satellite dish to the satellite receiver
> could be adapted
> for this purpose.
>

I had thought of this. I even have some switches laying around from days
past. I am a bit worried that I would not be able to safely inject the
supply voltage and not to mention the DiSEqC control signals onto the coax
and have it not interfere ... fry or otherwise hamper the ATSC
signal/tuners/etc. I am fairly analog challenged.

Going back over the plan, I realized that the HDHR interface in Myth does
not have the ability to run a script on channel change. Doh! Then it hit me,
I had a similar problem while trying to orient the second antenna this
weekend. Rather than climbing up and down the tower to check the signal
output from the HDHR after every adjustment, I created a script that mailed
the output to my Blackberry every 30 seconds. That way I could stay on the
tower and get instant feedback. Well almost instant. I could use a similar
method of having a script watching the status output of the HDHR devices and
then switch the required antenna in depending on the channel it was tuned
to.

The next hurdle is how to communicate to the location where the HDHR devices
are located. I have them installed in a workshop at the base of the tower
and I would like the signals to use the existing ethernet network to control
the switching. Hmm,I would rather not require a PC for this function so ....
I need a print server. I know what you are thinking, a print server??? For
what? Simple, to be the network interface for the antenna switch. An older
style parallel print server should be perfect to interface a micro
controller to. Sending the the commands will be as easy as echoing to lpr.
You may even be able to do it without the micro controller just by creating
a simple latch from discrete components but why pass up the opportunity to
do something neat with a MCU.

All that is left to work out is how to actually switch the signal. I was
thinking perhaps a lobotomized DiSEqC switch might work, but I had better
consult the OTA DigitalHome forums where the real antenna geeks hang out.
They will know how to accomplish this.

Dennis
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