Boosting Raspberry Pi 3 WiFi

[kbrown]

In the past I've been using a Raspberry Pi 2 with a USB WiFi dongle to run INDI server and lin_guider and it has been okay for long exposure imaging. Recently I wanted to be able to do planetary imaging too but I was getting poor FPS out of the system (< 4 FPS). I first thought the bottleneck would be the SD card but It turned out to be the USB WiFi dongle causing too much I/O together with the image streaming no matter what I tried.

I ended up upgrading to a Raspberry Pi 3 which I had lying around.  By using its internal WiFi I was able to free up some USB bandwidth and got around 25FPS. Still not as fast as the camera (QHY5L-II mono) would be able to do but much better. The problem with this is the range of the internal WiFi. A friend of mine shared this link with me and I decided to give it  a go: https://www.dorkbotpdx.org/blog/wramsdell/external_antenna_modifications_for_the_raspberry_pi_3

Just about got it done but it took several attempts. Not an easy job at all. I almost gave up while trying to solder the U.FL connector. One I simply lost, two of them I managed to melt and on two I got solder in the wrong place. Was probably the 6th connector which finally went where needed.

To finish the mod off I printed an enclosure that holds the new connector for the WiFi antenna and also a tiny 12V to 5V step down converter so I can power it the same way as my other devices.

[Demonperformer]

Sounds fiddly. What frame rate are you getting now?

[Dr_Ju_ju]

You may still get frame limiting, even though you've boosted the connection signal strength back to your WiFi router, that doesn't equate to a faster data throughput.

A lot will depend on which router you are using, how many devices are using the router etc. Domestic routers are not that good and provide 'adequate' service, whereas pro office systems will give better performance, but at added cost.

For me, to get the performance, I use all wired connections; I'm running power to the devices anyway, so what's one more cable. 

[kbrown]

2 hours ago, Dr_Ju_ju said:

You may still get frame limiting, even though you've boosted the connection signal strength back to your WiFi router, that doesn't equate to a faster data throughput.

A lot will depend on which router you are using, how many devices are using the router etc. Domestic routers are not that good and provide 'adequate' service, whereas pro office systems will give better performance, but at added cost.

For me, to get the performance, I use all wired connections; I'm running power to the devices anyway, so what's one more cable. 

Yes the faster data rate doesn't come from boosting the signal. It comes from not having a WiFi dongle sharing the USB data bus like it was before I swapped to RPi 3. The signal boost is merely for extended range. 

[Dr_Ju_ju]

Unfortunately, even the RPi3 is a mixture of compromises and their limitations. I accept that it works for some, and I have a number of them doing sterling work on printers etc. but for intensive processing\high data rates I've switched over to the Pine64 (https://www.pine64.org/?page_id=1194)

[Gina]

I'm thinking of getting the Rock64 "from the same stables" for Ha solar imaging.  An RPi 3 isn't fast enough - alright for DSOs but not solar or planetary.

[kbrown]

2 minutes ago, Dr_Ju_ju said:

Unfortunately, even the RPi3 is a mixture of compromises and their limitations. I accept that it works for some, and I have a number of them doing sterling work on printers etc. but for intensive processing\high data rates I've switched over to the Pine64 (https://www.pine64.org/?page_id=1194)

Yes the RPi3 has its limitations but I'm sure it will be enough for my purposes. For DSO imaging and guiding even the RPi2 was good enough. The swap to RPi3 was the easiest option for me as I already had it and it has the same footprint as the RPi2 so I didn't have to modify the rest of my setup.

I'm curious what are you running on your Pine64?

[Dr_Ju_ju]

It's for a mobile system, where I run all the Indi stack, Kstars, Storage, Heater controls etc. and lives at the mount. All I need then is a power source, and for me, a network cable, so I run it all remotely (in warm tent).

[kbrown]

35 minutes ago, Dr_Ju_ju said:

It's for a mobile system, where I run all the Indi stack, Kstars, Storage, Heater controls etc. and lives at the mount. All I need then is a power source, and for me, a network cable, so I run it all remotely (in warm tent).

My setup is a similar mobile system too but differs in two ways. I opted for WiFi instead of a cable as in many cases I'm too far away from the scope to run a cable. The other thing is I run Kstars on my laptop. Initially I ran it on the RPi over VNC but I found it to be a bit too sluggish to use and plate solving was slow too. Your Pine64 probably handles these better though.

[stash_old]

I think I am still right saying all RPI's still share the USB data bus between USB devices and Ethernet (wired or wireless) even if the RPI3 has its own wireless outlet built in - £32 bargain but limited

[stash_old]

4 minutes ago, kbrown said:

I'm too far away from the scope to run a cable

How far ? wired limit is 100m without extra h/w

[kbrown]

18 minutes ago, stash_old said:

I think I am still right saying all RPI's still share the USB data bus between USB devices and Ethernet (wired or wireless) even if the RPI3 has its own wireless outlet built in - £32 bargain but limited

That's what I thought too but for me taking the usb wifi dongle (Brostrend AC1200) out of the equation made a big difference even on the same RPi3. Maybe the dongle or it's driver is to blame but the difference was huge.

17 minutes ago, stash_old said:

How far ? wired limit is 100m without extra h/w

Probably less than 100m. Maybe I should try with a cable to see if I gain anything. Thanks!

[stash_old]

4 minutes ago, kbrown said:

Maybe I should try with a cable to see if I gain anything

Just use "Outside/external" quality cable which stands up to the weather better or put it in some cheap plastic ducting - a bit more expensive than std Cat5/6 cabling and slightly harder to crimp due to thickness of outer sleeve .

8 minutes ago, kbrown said:

Maybe the dongle or it's driver is to blame but the difference was huge

Yep totally agree. 

[GuLinux]

Not sure exactly what your software setup is..

Anyway, just FYI, the application I made for imaging (PlanetaryImager: https://github.com/GuLinux/PlanetaryImager ) explicitly supports a networking mode.

You run the (headless) server daemon application on the raspberry, and it will send data to the remote client on your desktop. The network frame rate is relatively low to save bandwidth, but recordings are saved on the server at full FPS speed.

Just one problem though: QHY support is currently very bad. I need to work on that (whenever I get the time..  )

 

[kbrown]

2 minutes ago, GuLinux said:

Not sure exactly what your software setup is..

Anyway, just FYI, the application I made for imaging (PlanetaryImager: https://github.com/GuLinux/PlanetaryImager ) explicitly supports a networking mode.

You run the (headless) server daemon application on the raspberry, and it will send data to the remote client on your desktop. The network frame rate is relatively low to save bandwidth, but recordings are saved on the server at full FPS speed.

Just one problem though: QHY support is currently very bad. I need to work on that (whenever I get the time..  )

 

Sounds very interesting. I'll definitely check it out.

[kbrown]

2 hours ago, Gina said:

I'm thinking of getting the Rock64 "from the same stables" for Ha solar imaging.  An RPi 3 isn't fast enough - alright for DSOs but not solar or planetary.

Layout looks similar to RPi. Do you know if it would fit in an RPi enclosure?

[Gina]

No, I don't know - I 3D print my own enclosures.  I haven't got as far as ordering a Rock64.  I use KStars/Ekos/INDI with ZWO cameras on RPi 3, which are well supported.

[Dr_Ju_ju]

38 minutes ago, kbrown said:

Do you know if it would fit in an RPi enclosure?

No it won't, its a different layout.

I'm using a DIN rail system, that I found on Thingiverse e.g. https://www.thingiverse.com/thing:2610621  which allows for mounting just about anything you can think of, and will fit inside a standard DIN rail enclosure...

[kbrown]

Thought I'd share how I was able to double the WiFi speed I was getting with a simple configuration tweak. I went through my RPi3 WiFi hotspot settings using RaspAP after reading a few articles about the security/encryption settings affecting the WiFi speed. I monitored the network performance using iperf running as server on the RPi and doing 30s tests from my laptop.. With default settings I was only getting about 21-22 Mbits/sec. The best performace I was able to get was with Security Type: WPA+WPA2 and Encryption Type: CCMP. With these the speed jumped up to 49.6 Mbits/sec.

[Gina]

That sounds useful ??

[sloz1664]

I was given a Raspberry PI 3 as a present, downloaded Ubunta Mate and followed Gina's blog to load kstars. Any input into increasing the potential of the RPI is great in my eyes. Thanks for your input into upgrading the wifi.

Steve

[kbrown]

2 hours ago, sloz1664 said:

I was given a Raspberry PI 3 as a present, downloaded Ubunta Mate and followed Gina's blog to load kstars. Any input into increasing the potential of the RPI is great in my eyes. Thanks for your input into upgrading the wifi.

Steve

I run Kstars on my laptop and connect it to the indiserver running on the RPi. This way the RPi has more spare cpu cycles to do things like streaming as is the case here.

In my particular case I have now learned that the biggest bottleneck for getting more acceptable FPS from my QHY5L-II is not the hardware or INDI/Ekos but the QHY SDK the indi driver is built on. I have a thread about that going on in the indi forum if you're interested.

The reason why for example oaCapture is able to achieve much better frame rate is because it does not use the QHY SDK. I'm now contemplating whether I should have a closer look at oaCapture source code and see if I could write my own indi ccd driver based on that...

[Gina]

Do you write INDI drivers, Steve?  If so I may have a question or two ?

[kbrown]

Just now, Gina said:

Do you write INDI drivers, Steve?  If so I may have a question or two ?

Was that question aimed at me (Kari)? If so then yes. I'm not super experienced but I have written a couple of drivers for my own arduino based devices (a focuser and a filter wheel).

[Gina]

Oops, sorry, my mistake - read the name in the quote - must be bedtime...  Yes, it was aimed at you, Kari   Good, I've modified some but there are one or two things that puzzle me.  I'll get back to you, if I may, next time I have a problem.  Thank you.