[Dprglist] Fwd: Roborama & wireless networking

John Swindle swindle at compuserve.com
Sun May 13 14:18:12 PDT 2018

Are the dedicated video radios that connect TVs in homes suitable? Parts Express and Frys have them. Sorry I don't have a part number to refer you to. Seems they would grab a channel that is all theirs. Maybe physically too large.
Sorry I was out of town and couldn't see the competition yesterday.
Later,John Swindle

-------- Original message --------From: Carl Ott via DPRGlist <dprglist at lists.dprg.org> Date: 5/13/18  1:26 PM  (GMT-06:00) To: DPRG <dprglist at lists.dprg.org> Subject: [Dprglist] Roborama & wireless networking 
Thanks to everybody who came to RoboRama yesterday - it seems that everybody had a good time, we met new visitors & old friends, and we had a well received contest!
We also had Wi-Fi issues - leading to questions...
Can anybody offer suggestions for the Wi-Fi issue some of us observed yesterday?
The issue was that as the day went on, and more people surfaced in the Makerspace, the Wi-Fi environment went from almost tolerable to ***difficult for some - won't work at all for others***.
This forced several of us to use personal access points - which definitely helped - at least for those using the connection more for telemetry than 'in the loop communication'.  However, I was not able to run at all due to apparently tight latency/jitter requirements, which became unmet as the makerspace filled up.  This becomes apparent for my robot when one video stream receiver (whatever Chrome uses) behaves much better and more consistently as the environment degrades (still ultimately failing), but another codec viewing the same stream (ffmpeg + whatever plug-in adapter RoboRealm uses for RTSP) fails much sooner - 'at the drop of a hat / network-packet' - completely breaking my control loop, yielding grumpy scowls and a very still and boring robot...
My question is this - what options should I consider beyond the obvious?
The obvious options are
a) keep processing local, get the network out of the loop
b) flip the personal access point an unused Wi-Fi channel---> e.g. on 5 GHz---> ie. requiring adding a 5 GHz dongle to R-Pi Zero W (depends on finding one with compatible driver)---> or requiring swapping R-Pi Zero for e.g.R-Pi 3 B+ (with built-in 5 GHz, entails considerably more hardware rework to existing robot platform)
c) find an alternate radio strategy
d) give up
Currently, options a and d are off the table, and next steps focus on option b.
So my questions for DPRG land:
1. for option b: can anybody recommend an R-Pi Zero W compatible Wi-Fi dongle with 5 GHz?   If no better out there, I'm gonna try an older / slightly larger version of this: https://www.amazon.com/gp/product/B01MY7PL10/ref=ox_sc_mini_detail?ie=UTF8&psc=1&smid=ATVPDKIKX0DER, with what appears to be a R-Pi compatible open source driver recommended by the vendor...

for option c: 

can anybody recommend something small other than Wi-Fi that can carry low jitter / low latency /

 low video resolution (e.g. 160 x 120)  network packets, and interface cleanly to both R-Pi Zero and Windows?

for option c: 

has anybody dabbled with network packet data over HAM frequencies?
carl.ott.jr at gmail.com

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