Data receiving failed

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Bulova
Posts: 111
Joined: Fri Jan 09, 2015 6:07 pm
Location: Babenhausen/Germany

Data receiving failed

Post by Bulova » Mon Oct 05, 2015 4:30 pm

Hello,

I did not use my RP for some months. But I remember, that there was sometimes a problem on each APP after some seconds after starting the APP. It is the message "Date receiving failed". Then I had to press Retry or Restart (which forces me to set the parameters once more), and for 50% the APP ran again, for another 10 seconds or so, and then the error came again. Sometimes the RP ran without any problem. But now -- I am not sure if there is a coherence to the updates I made -- but I have the impression, that the malfunction happens much more often than before.

I read posts about the same problem, but I cannot confirm, that I could solve the problem by changing the power supply. I tried both, a 1A and a 2A device (by the way, the 2A is to cover loads of the generator's outputs and others, which I don't have in my tests). It is independently the same problem. At the moment, this frequent occurence I have now is unacceptable and I cannot use the RP that way. I wanted to use it in an automatic measring system, but it is useless.

Dieter

Bulova
Posts: 111
Joined: Fri Jan 09, 2015 6:07 pm
Location: Babenhausen/Germany

Re: Data receiving failed

Post by Bulova » Wed Oct 07, 2015 7:48 am

Hello,

I think I can response to myself, as I did some analysis. Test criterion was the streaming data for the Spectrum-Analyzer-APP, which can be observed at the refreshed noise carpet.

I placed the RP close by the WLAN router (FritzBox 7312), in about 20 cm distance. The test duration was 1/2 h, and no problems occured. Then I put the RP on my desk again, where the distance to the router is about 2,5 m, but partly have to go through the table. Now I got problems as described before, almost no way for a reasonable working without interruption by error messages "Data receiving failed". The third test was made by putting the RP onto a chair, which was in free vision in about 2,5 m distance. Mostly good streaming, sometimes sticking, but not long enough to exceed the timeout and initiate the error state. Increasing the distance to about 3 m the problem was there again. It seems that in this distance the field strength of the Edimax is too less to maintain a sufficient connection quality.

So it seems the problem is caused by poor transmission quality of the WLAN dongle. Maybe there is a better one than the EDIMAX EW-7811UN.

Dieter

Bulova
Posts: 111
Joined: Fri Jan 09, 2015 6:07 pm
Location: Babenhausen/Germany

Re: Data receiving failed

Post by Bulova » Sat Oct 17, 2015 5:58 pm

Hello,

found out another thing, which could be seen as the root cause of the whole problem. I placed the RP again to the same place, where it caused connection problems before. But lo and behold this time there were no problems at all, the data streaming to keep alive the analyzer noise carpet was without any sticking. So apparently the same situation, but no WLAN problems. How could this be? I tested my WLAN by the WiFi analyzer of my tablet computer, and my WLAN was shown with a good signal on channel 1. A later test, where the problems occured again, I tested the WLAN again with the tablet PC, and I saw this time the channel was 11. Then I switched my FritzBox from automatic channel to the fixed channel 1, where the problem disapperaed again. There and back from channel 11 to channel 1 -- everytime the problem came and disappeared reproducible. So it seems the EDIMAX does not work very well on higher channels (where I am not sure, how the RP system does make the scanning of the channels). I tested the channels from 1 to 3 and this range works without any problem with the RP.

Dieter

tony1tf
Posts: 33
Joined: Mon Sep 21, 2015 10:49 am

Re: Data receiving failed

Post by tony1tf » Sun Oct 18, 2015 8:43 am

Hi Bulova
You are posting some really interesting stuff here. I hope Nils has a system for scraping this into the wiki.
I have seen similar problems and have changed from the previous 0.92 to 0.94 OS.
It is very difficult to remember the things that happen in a plug and play system showing inconsistencies.
0.94 by default creates a wifi router and can connect at the same time to your existing router to access the external site AFAIK - it is difficult to remember since it is several days since I did this. I use an Android application on my phone to list connected devices (Fing). I have an Edimax repeater in my WiFi which throws a curved ball into the system due to NAT. Fing correctly lists other addresses that the repeater serves. I have not yet found what commands to put into the RP serial terminal to stop the Router, and make it a normal passive device receiving it's address via DHCP.
I think I managed to do that on 0.92 with a fixed address on the Ethernet connection, but had problems getting it to log into my home router. With 0.92 I use the Ethernet connection on my Mac as an Internet share, but this is also inconsistent. At the moment with 0.94 acting as a router, I have to keep logging into either my home router or RedPitaya - when on the latter I can't see the outside world from my Mac, but can get data from the RP.
Those of us who are reasonably knowledgeable but not really IT/Linux experts are probably struggling with the complexities of this device.
I'm sure Nils is trying his best to service our individual problems.
Mini rant over for now.
Tony

tony1tf
Posts: 33
Joined: Mon Sep 21, 2015 10:49 am

Re: Data receiving failed

Post by tony1tf » Sun Oct 18, 2015 10:48 am

Important Correction - see what happens when you try and remember ;-) Rather than 0.94, I meant Pavel's new distro based on Jessie. We have previously posted that 0.94 doesnt seem to work with the approved WiFi USB device.

Tony

Nils Roos
Posts: 1441
Joined: Sat Jun 07, 2014 12:49 pm
Location: Königswinter

Re: Data receiving failed

Post by Nils Roos » Sun Oct 18, 2015 10:18 pm

I hope Nils has a system for scraping this into the wiki.
I don't have editing rights on the wiki.
I'm sure Nils is trying his best to service our individual problems.
Thing is, I'm not much of an expert when it comes to wifi configuration and I don't actually own one of the approved adapters. So, I'm always glad when somebody more knowledgable picks up those topics.

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