Two rtl2832 dongles in a GRC project

GNU Radio
1

I try to make project with two dongles rtl2832+r820.

In GNU Radio Companion v3.7.6.1-58-g620817ed I made simple project with
two equal channels containing rtl2832_source block and
blocks_ctrlport_probe2. And I have an error. The output of programm is:
//////////////////////////////////////////////////////////////////////////////////////////////////////
Generating: “/home/igor/GRC_Projects/rtl_2832_block/top_block.py”

Warning: This flow graph may not have flow control: no audio or RF hardware
blocks found. Add a Misc->Throttle block to your flow graph to avoid CPU
congestion.

Executing: “/home/igor/GRC_Projects/rtl_2832_block/top_block.py”

RTL2832 Source block configuration:
??? ??Read length (bytes): 32768
??? ??Buffer enabled: yes
??? ??Buffer multiplier: 8
??? ??Buffer size (samples): 131072
??? ??Samples per read: 16384
??? ??Buffer level: 50,0%
Successfully initialised demod: “ezcap EzTV”
Skipping auto-probe with custom tuner: “r820t”
Found RTL2832 device: ezcap EzTV (tuner: Rafael Micro R820T)
??? ??Sample rate range:??? ??900001 - 3200000 Hz
??? ??Crystal frequency:??? ??28800000 Hz
[r820t] Initialised (default bandwidth: 0 Hz)
RTL2832 Source block configuration:
??? ??Read length (bytes): 32768
??? ??Buffer enabled: yes
??? ??Buffer multiplier: 8
??? ??Buffer size (samples): 131072
??? ??Samples per read: 16384
??? ??Buffer level: 50,0%
libusb error: unknown return code [-6] (int
rtl2832::demod::find_device():446) “libusb_claim_interface(devh, 0)”
Traceback (most recent call last):
?? File “/home/igor/GRC_Projects/rtl_2832_block/top_block.py”, line 146,
in
??? tb = top_block()
?? File “/home/igor/GRC_Projects/rtl_2832_block/top_block.py”, line 105,
in init
??? if self.rtl2832_source_0.create() == False: raise
Exception(“Failed to create RTL2832 Source: rtl2832_source_0”)
Exception: Failed to create RTL2832 Source: rtl2832_source_0
////////////////////////////////////////////////////////////////////////////////////////////////////
Separatly dongles are working properly. And if I run one project for the
one dongle and one more for the second one all is OK.
Please help me to what direction I have to go.
Thank You.

2

On Apr 23, 2015, at 3:32, Игорь Попов [email protected] wrote:

I try to make project with two dongles rtl2832+r820.

In GNU Radio Companion v3.7.6.1-58-g620817ed I made simple project with two
equal channels containing rtl2832_source block and blocks_ctrlport_probe2. And I
have an error. The output of programm is:
[…]
libusb error: unknown return code [-6] (int rtl2832::demod::find_device():446)
“libusb_claim_interface(devh, 0)”

I’m not familiar with this particular block you’re using, but I highly
recommend you use gr-osmosdr’s source block instead. It is widely used
and works with rtl-sdr devices, and I can confirm that it handles
multiple devices well.

With gr-osmosdr, you can use the device string to specify two RTL
dongles generically:

osmosdr.source(‘rtl=0’)
osmosdr.source(‘rtl=1’)

or using their EEPROM serials instead, which is useful for consistent
selection. (Note that most dongles come from the factory with a serial
number like ‘000001’, so you’ll have to use the rtl_eeprom tool to
rewrite them to unique text of your choice.)

–
Kevin R. http://switchb.org/kpreid/