[Skimmertalk] Yes...A RP-16 can be made to work over a Wi-Fi link!

Ted Gisske gisske at offex.com
Sun Aug 4 21:57:22 EDT 2019

Yep.I got it to work.


It wasn't trivial, but it is working. My skimmer is located about 150' from
my shack, with the antenna (a Cushcraft R7) up on a 50' tower. It is
"remotely" located, as I am a QRO contester, and want it to still work
during contests. It is very inconvenient to run some sort of wired Ethernet
link to my skimmer, so I explored ways to do it via radio (we are hams,
after all..).


My skimmer is in an unheated pole-shed in WI, so sees some pretty extreme
temps. I have been running the skimmer in the pole-shed for 4+ years, but
the environment is pretty harsh and have I had computer (and frequency
stability) issues over time. A GPS disciplined LO for my QS1R fixed the
stability problems, and a 802.11g Wi-Fi link got data to the shack. A lot
better idea seemed to be running just the skimmer SDR in the shed and
running the computing part of the setup in a nice cozy shack.


That wasn't easy with my QS1R, as it ran off a USB cable. I recently
upgraded to a Red Pitaya 16-bit SDR, which runs off an Ethernet link, so, if
I could get a reasonably fast Ethernet link to my remote receiver, I would
be in high clover.


That, however, was a significant challenge. The RP-16 is a promiscuous
consumer of bandwidth. A fully commissioned RP-16 (sixteen 192 kHz slices)
munches up 160Mbps. You ain't gonna get that bandwidth out of an 802.11
a/b/g/n Wi-Fi link. Further complicating the issue is that a dead-solid
Wi-Fi link is necessary, as Skimmer Server locks up on a data dropout and
you have to go thru a fairly tedious reboot sequence to get it QRV. Both
Skimmer Server and WSJT-X also get very deaf if they don't get the full 10
Mbps/slice connectivity.


It is possible to make it all work, though. A relatively new (~5 years old)
Wi-Fi standard called 802.11ac, featuring "Gigabit" speed is available at a
reasonable price. I bought a couple of Ubiquiti NanoBeam 5AC Gen2
antenna/radio modules for a reasonable price from Amazon. They form a
transparent RF Ethernet bridge from the shack to the shed. 


I put Gigabit in quotes above as that is advertising Bravo Sierra. With the
2 antennas 6" apart, I could get ~650 Mbps thruput. I can, however get the
same thruput 150' away. I can get 450 Mbps thru a window, which oddly enuf,
attenuates the link by 20dB. Either speed is plenty, though. Some folks
claim a 9 mile path works with these devices. I would not plan on 650 Mbps
at that range though.


So yah.You can run a RP-16 SDR remotely and connect it to the mothership via
Wi-Fi, if you do it right.






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