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Discuss RTL-SDR and cheap software defined radio
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PostPosted: Wed Oct 15, 2014 3:19 pm 
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Joined: Wed Oct 15, 2014 3:07 pm
Posts: 3
Hello

I´m running an POCSAG server on Ubuntu. I cant run more than 4 dongles at the sime time then I get "Failed to submit transfer 7!" when running rtl_fm or rtl_tcp. The number in error message is different sometimes.'
It doesnt matter on what ports I use or dongles etc. 4 dongles seems to be limit.
First I thought that motherboard was overloaded. So I bought a really good powered 7port usb hub. But its the same problem.
My instinct say that theres some software limit here.
Can rtl-sdr software handle more than 4 dongles at the same time?

I have tried different types of dongle. E4000, FC0013, lots of R820T. I have put new SN with rtl_eeprom for easier identification. Problem existed before though.

My git clones of rtl-sdr+multimon-ng are from April 30 2014



Code:
Found 7 device(s):
  0:  Realtek, RTL2838UHIDIR, SN: 8
  1:  Realtek, RTL2838UHIDIR, SN: 10
  2:  Realtek, RTL2838UHIDIR, SN: 1
  3:  Realtek, ▒▒▒2838UHIDIR00000001, SN: 6
  4:  Realtek, RTL2838UHIDIR, SN: 3
  5:  Generic, RTL2832U, SN: 77771111153705700
  6:  Realtek, RTL2838UHIDIR, SN: 2


Code:
Bus 001 Device 069: ID 050d:0237 Belkin Components F5U237 USB 2.0 7-Port Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 075: ID 0bda:2838 Realtek Semiconductor Corp.
Bus 001 Device 076: ID 0bda:2838 Realtek Semiconductor Corp.
Bus 001 Device 074: ID 0bda:2838 Realtek Semiconductor Corp.
Bus 001 Device 073: ID 0bda:2838 Realtek Semiconductor Corp.
Bus 001 Device 070: ID 0bda:2838 Realtek Semiconductor Corp.
Bus 001 Device 071: ID 0bda:2832 Realtek Semiconductor Corp. RTL2832U DVB-T
Bus 001 Device 072: ID 0bda:2838 Realtek Semiconductor Corp.


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PostPosted: Wed Feb 04, 2015 7:53 am 
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Joined: Wed Oct 15, 2014 3:07 pm
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I´ve finally found a workaround. Im now running two ubuntus paralell in ESXi.
Now I can run more than 4 USB recievers at the same time with rtl_fm + multimon on ONE computer :)

Its not a solution. But its an alternative. This is clearly a software/driver fault.


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PostPosted: Sun Mar 01, 2015 7:04 pm 
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Joined: Mon Aug 25, 2014 7:07 pm
Posts: 4
Hi Feffe,
I have been running a websdr with 4 dongles. I have more dongles but I too have the same issue and error message.
I'm not so sure it's the rtl_tcp so much as the libusb.
I'm running libusb version 1.0.17
I have tried to install 1.0.19 but although the make and install seems to work I still have the old version when I check using "dpkg --list | grep libusb".
I'm about to reboot now in the hope that it will kick in. I've had this issue for so long now that even if the upgrade worked I'm not convinced the error will go away.

Wish me luck,

Glenn

It failed.... If anyone can help me update to the latest libusb in Ubuntu 14.04 please let me know how...


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PostPosted: Sun Mar 15, 2015 6:16 pm 
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Joined: Mon Aug 25, 2014 7:07 pm
Posts: 4
Hello again,
I finally have 5 dongles running on the one machine.
I had to use 'rtl_tcp -d 4 -p 1238 -b 3 -n 1000' to fire up rtl_tcp.
It seems that reducing the buffers to 3 worked but the waterfall display on the webSDR seemed slow.
Doubling the numbe of max number of linked list buffers from 500, default, to 1000 seems to make up for redcing the buffers.
I was listening to an SSB contest on 4m today and it worked very well.

I'll attempt to add a sixth dongle, using the same technique, this week.

Watch this space!

Glenn


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PostPosted: Wed Apr 01, 2015 6:12 pm 
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Joined: Mon Aug 25, 2014 7:07 pm
Posts: 4
Just a quick note to say that six, yes SIX, dongles are running just fine.
In fact, they are all running from a single USB 2.0 port on the same powered hub.
I'll keep on adding bands until I run out of dongles... Let's see how far I can push this :o)


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PostPosted: Wed May 13, 2015 8:06 pm 
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Joined: Wed Oct 15, 2014 3:07 pm
Posts: 3
Sorry for late answer hippy1970.

Nice that you have found a solution :)
Thoose parameters doesnt work on rtl_fm though.
I dont think rtl_tcp is possible to run through multimon-ng since it operates via som sort of internal soundcard.
And I think pocsag protocol requires some bandwith to be able to transfer messages.

Listening to SSB is pretty narrow :D


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PostPosted: Sun Mar 05, 2017 9:05 am 
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Joined: Sun Mar 05, 2017 8:56 am
Posts: 1
Sorry to bump up this old thread, but I found a solution for the "Failed to submit transfer" error. I had to implement a synced output option (similar to rtl_test -S switch) for rtl_fm; which finally fixed the problem. Now it can work with up to 15 devices (don't have more at hand for further testing).

You can find the patched source for rtl_fm here: https://github.com/niofis/rtl-sdr.
If you want to read a bit more about what I did, check out this blog post http://www.eccentricdevelopments.com/patching-rtl_fm/

Regards


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