[Amps] Remote monitoring of SSPA

[Manfred Mornhinweg]

Conrad,

> I have been asked to look into the possibility of remote monitoring an 
> SSPA at a distance of a little over 50m. My feelings are that ethernet 
> is the way to go. 

That would be overkill, but maybe it's cheap enough to be acceptable 
despite that.

 > I will need to monitor supply voltage and current,
> forward and reflected power, drive power and a few fault conditions.

For such little data, a plain old RS-422 serial link is plenty. Even 
RS-232 will typically work fine, at the slower speeds, despite your 
distance being above that standard's specs. Using such a slow link has 
the advantage of creating almost no RFI, and being quite imune to 
receiving any. Ethernet instead typically has lots of RFI problems. Also 
it's far easier to send out data in such a standard when using a small 
microcontroller in the amp, than sending in ethernet protocol.

> I do not expect there to be problems with RF fields as it is a 1kW on 
> 23cms and there should not be much spill over from the dish. Of course 
> it must be quiet so as to not disturb the weak signal RX.

If you happen to get RFI problems, regardless of which standard you use, 
there's the option of making the link over fiber optics instead of wire. 
That also takes care of ground potential differences, lightning 
protection, and many other issues you might otherwise have. Optical 
transceivers are widely available for ethernet and for the serial 
protocols I mentioned. Those that use thick (plastic) fiber are very 
easy to set up, without requiring any special tools or expertise. Such 
plastic fiber is plenty for the distance you need.

Manfred

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