Saturday, February 18, 2012

16:49utc pass


pre-amp : update

Another couple of similar before and after passes:

With pre-amp (05:22UTC today)





















Without (04:53UTC  11/02/12)


















AOS and LOS seem respectively much earlier and much later - consistent with a few extra dBm arriving at the RX.

Definitely time to think about servicing the antenna and possibly getting the preamp up to masthead. I should really uprate the coax too - its only RG58.

Thursday, February 16, 2012

Pre-amp

Ive noticed a lot more noise on the NOAA15 passes recently, and looking back through the archive it seems that over the last two years the signal strength has been slowly dropping - probably down to it being time to get up on the roof and service the antenna.

This isn't an easy job, due to the WX sat turnstile being on the northernmost chimney here @ the 'NBP QTH, which is not directly accessible via ladder as it has a fragile sloping roof directly below it. Access is gained by climbing up to the apex, and then by walking the ridge to the chimney itself - scary stuff!

Im due for some roof work soon anyway - so will wait until there is some scaffolding up, then I think I may re-site the antenna to a more accessible location - at the expense of partially obstructed sky to the south.

Anyway, in a bored moment this afternoon, I quickly tacked a Garex 137MHz pre-amp into the case of the RX - yes I know it should be at masthead - did you not read the last few paragraphs??   ;)

Sigs on the most recent pass - northwards over the Azores, up towards Greenland still shows a little patterning, but is a much more solid signal than previous passes at similar times.


Pass with Pre-amp
















Similar pass without pre-amp












In both of these passes NOA15 isnt much above 15 degrees over the horizon at its highest. As can be seen I have much more coverage north-south now.

Best passes are typically 90 mins before - so watch out for images between 15:30 and 17:00