Hi John/Graham/Paul/Lee,
I'm also not an 'Expert' on SkyEcho2, but in view of my previous experience with SkyEcho1, and PAW Testing in general, I am not at all surprised at your findings.
I don't have a SkyEcho2, but have had a SkyEcho(1) since they first came out, which I used extensively at the time for testing. I also know several others who have SE1s. In my experience, it is not at all unusual for nothing to be received from SkyEcho (1 at least) when it is not actually 'in the air' (even when the unit is 'moving' - see below).
When I first got my SE1, I was as you will imagine, keen to try it out, so charged it and after reading through the 'Manual' and doing the initial programming input, powered it up at home in my living room (inside the EGPH CTR), but couldn't see anything from it at all on two separate 'test' PAWs, despite the SkyEcho reporting a solid GPS fix. On further investigation, I found the SkyEcho 'Vso' setting (basically minimum landing or 'stall' speed as reported by Lee). I therefore tried setting the Vso to varying speeds - but even with it right down to '0' Knots, there was still no sign of any transmissions from the SE1. I then tried putting the unit in my car and belting round the local bypass at speeds up to 70 mph, with Vso set to varying speeds between 0 and 40 Knots, but this also gave no indication whatsoever that the unit was transmitting. My conclusion therefore was that there must also be some sort of tie-in with a minimum height above ground, climb rate or whatever before the SE starts to transmit, but nothing like this is mentioned in any uAvionix documentation I have seen and the only 'confirmation' I have (from subsequent testing), is that my SkyEcho1 certainly transmits when in a plane in the air (though I can't legally use it in my own as I already have ADSB-Out via my transponder).
Thinking further about this, it makes sense - after all the authorities wouldn't want people randomly powering up SkyEchos and gaily transmitting 'aircraft positions' on the 'official' 1090MHz band when the unit isn't in an aircraft in the air - (or in my case even in an aircraft). None of this however (apart from the 'Ground Mode Only when below Vso') is mentioned in the uAvionix documentation, or explains why I could never get the unit to transmit when still on the ground but well above the selected Vso. It would certainly be worth an e-mail to uAvionix Support to ask them to clarify the position.
If you find anything out, please let us know.
Best Regards
Peter
p.s. Not an 'expert' on Ground Mode either, but previous exhaustive testing in the vicinity of my local airport certainly seems to indicate that CAT traffic in 'Ground Mode' only transmits 'Mode-S' NOT ADS-B. If this is the case, then the SkyEcho obviously won't transmit anything in 'Ground Mode'. Paul - any knowledge of this in relation to CAT?