[Dprglist] Roborama & wireless networking

Doug Paradis paradug at gmail.com
Sun May 13 11:47:35 PDT 2018

    I know very little about radio. I also do not know what amount of info
you need to push to the robot. So my question to you is, could you use
something like a Wixel or a 433MHz radio? Wixel is dead easy. I generally
use 56700 Baud rate. I am exploring 433MHz radios also for another project
(interfacing with the rain gauge you gave me). If you make sure to buy the
right 433MHz radios, not the cheapest, they seem easy to use. Radio cost is
low. There is also, Xbee and some other radio systems that might be useful.
You only need to communicate within a few feet. Bluetooth also might be a
possibility if you are only sending, move, X and Y coordinates to the
robot. The camera characteristics might be able to be sent on one of the
FPV cameras used by drones.

   Since I know so little about radio, I am not sure these ideas are even
viable. Just a thought...

Doug P.

On Sun, May 13, 2018 at 1:26 PM, Carl Ott via DPRGlist <
dprglist at lists.dprg.org> wrote:

> 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...
> *2. **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?
> *3. **for option c:*  has anybody dabbled with network packet data over
> HAM frequencies?
> Thanks!
> Carl
> carl.ott.jr at gmail.com
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