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Awhile back I exchanged computers in my VHF VARA FM shack from a laptop to a solar powered Bmax B4 mini PC.

Right away I noticed the 4 signal "dots" in the diagram display went from being tight centered dots to somewhat splattered "dots" when I was connecting to the gateway.

I wasn't able to adjust it out and just assumed it was the new normal for this PC.?

Also, it didn't seem to affect performance as it was before the Willmar gateway was connected to the Internet.

After we got on line and it was easy to order up large attachments to download from the catalog, I noticed the throughput from the gateway to my station wasn't as fast as I remembered it.

Since around 40k/minute is pretty fast anyway, I didn't worry about it.

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Fast forward to this past week. As a solar operator I call it "h_ll week" because the days are the shortest and it's often cloudy.

This tests the system and I found 3 days was where I ran outta gas if the station(s) were operating 24/7.? Good to know.

Today being the 4th day had me switching my hardware over to the grid so I could continue to operate... Ok, play.? :)

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The first thing I noticed when I useded the mini PC on a wall wart was the dot's in the signal diagram were round and very tightly grouped again when connecting with VARA FM.

Hmmm.

I ordered up a 50k weather file and was blown away at how fast it downloaded from the gateway - 120k/min!!? I did a few more to prove it wasn't a fluke. Nope, no fluke.

The other thing I noticed was how the diagram had 32 squares instead of 16.? VARA figured out my system had better hearing and used it.

I swapped power sources back and forth til I narrowed it down to a undersized, unshielded, too long cable powering the mini PC.?

Moral of my story - learn to trust your visual indicators.

In this case power supply noise was going out the mini PC USB to the Digirig, raising it's noise floor dramatically. This was like tatters in it's ears.

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73

Mike N0QBH

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After reading over my previous post I could almost hear my old elmer Roger W0WUG (sk) saying "kind of ambiguous don't you think?".

Four fuzzy dots?? Umm, there's a signal to noise meter right next to the diagram that spits out real numbers!

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With that in mind, the noisy power SNR was in the low 20 dBs and with the factory wall wart it was almost buried at +30 dB.

Mind you, my station is 8 miles away and it's antenna has a view of the gateway on the southern horizon.

Your location and antenna will determine the SNR, but a higher number is better.

Also, I miscounted the diagram squares in my 1st post.? They went from 16 to 64 which represents the number of octaves used.?

I don't claim to understand this any better than you do. All I know is it's blazing fast with good signals.

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73

Mike N0QBH

This is very enlightening info!!? I only see 4 squares on my display and I don't really pay attention to the signal level.? I will now take a closer look and probably work to reduce Wall Wart noise in my shack.

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WD0HXV

I would add that you usually see the octaves (multiple carriers as squares) when VARA is receiving a large file.

When it first connects and you see the 4 squares, it's measuring the SNR (signal to noise ratio) to determine what speed to use .

Then, depending on how much data it has to move, it sort of shifts gears.

When a packet is missed, it downshifts for awhile then tries to find it's best speed. Adaptive I believe they call it.

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Anyway, lots of things can affect your SNR.? In my case the computer's power supply was noisy.

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73

Mike N0QBH