just learning to fly with sdr ... and hit a 64-bit snag

Gary Lawrence Murphy garym at teledyn.com
Thu Aug 9 18:05:32 UTC 2012


First off, this is my first post to the group and I want to thank everyone
who has worked to get this kit as far as it is; I was deathly worried that
I might be stuck with unusable hardware, and it is still unusuable, but
there seems to be light at the end of the SDR tunnel and I'm hoping this is
the right forum for asking newbie questions :)

Here's where I am so far:  I have the Hama Nano DVB-T+DAB+FM with the
Elonics E4000 tuner and my goal is really very modest (I hope) in that I
only want to tune in one ordinary analog FM station, the FM transmitter in
the next room that supplies our house with music from our MP3 collection.
 Rather than pay $40 at walmart for a radio for my lab, I thought I'd spend
$20 on the USB device and have some fun in the process.

And it's been fun: I found the recipe for the rtl_fm using the alsa aplay,
and I assume the examples were concerned with some other sort of radio
(shortwave?) because the recommended 48k sampling sounded like a taxi
radio!  Not really Easy Listening sort of audio.

with some experimenting I found a formula that is still heavily distorted,
but recognizable as music:

rtl_fm -f 96.3e6 -s 192000 -l 5 -| aplay -t raw -f s16_le -r 192k -c 1

the trouble was that it wouldn't play continuously on my 3300-bogomips
netbook, so I moved the code over to my 64-bit dual-core laptop and that's
where a strange thing happened: when run as a regular user, the code aborts
giving strange (unicode?) gibberish as the device name, but when run as
root, the name is correctly reported although the program aborts.

~/Work/dev$ rtl_fm -f 96.3k -s 192000 - | aplay -t raw -r 192k -f s16_le
Found 1 device(s):
  0:  , mX��, SN: ��z�

Using device 0: Generic RTL2832U (e.g. hama nano)
usb_open error -3
Failed to open rtlsdr device #0.

~/Work/dev$ sudo rtl_fm -f 96.3k -s 192000 - | aplay -t raw -r 192k -f
s16_le
Found 1 device(s):
  0:  Generic, RTL2832U, SN: 77771111153705700

Using device 0: Generic RTL2832U (e.g. hama nano)
usb_claim_interface error -6
Failed to open rtlsdr device #0.

on the 32-bit platform, the *Using device* line is followed by

Found Elonics E4000 tuner
Oversampling input by: 6x
Oversampling output by: 1x

is there perhaps some simple config setting that I've overlooked in the
64-bit box? Both are running Ubuntu 12.04

here are the kernel messages on loading the device on 64bit

Aug  9 13:47:58 strata kernel: [200306.632008] usb 3-1: new high-speed USB
device number 3 using xhci_hcd
Aug  9 13:47:58 strata kernel: [200306.663830] usb 3-1: ep 0x81 - rounding
interval to 32768 microframes, ep desc says 0 microframes
Aug  9 13:47:58 strata kernel: [200306.669822] dvb-usb: found a 'RTL2832U
DVB-T USB DEVICE' in warm state.
Aug  9 13:47:58 strata kernel: [200306.669840] dvb-usb: will pass the
complete MPEG2 transport stream to the software demuxer.
Aug  9 13:47:58 strata kernel: [200306.671500] DVB: registering new adapter
(RTL2832U DVB-T USB DEVICE)
Aug  9 13:47:58 strata kernel: [200306.689815] RTL2832U
usb_init_bulk_setting : USB2.0 HIGH SPEED (480Mb/s)
Aug  9 13:47:58 strata mtp-probe: checking bus 3, device 3:
"/sys/devices/pci0000:00/0000:00:1c.3/0000:09:00.0/usb3/3-1"
Aug  9 13:47:59 strata kernel: [200306.972506] RTL2832U check_tuner_type :
E4000 tuner on board...
Aug  9 13:47:59 strata mtp-probe: bus: 3, device: 3 was not an MTP device
Aug  9 13:47:59 strata kernel: [200307.552737] DVB: registering adapter 0
frontend 0 (Realtek DVB-T RTL2832)...
Aug  9 13:47:59 strata kernel: [200307.553116] input: IR-receiver inside an
USB DVB receiver as
/devices/pci0000:00/0000:00:1c.3/0000:09:00.0/usb3/3-1/input/input15
Aug  9 13:47:59 strata kernel: [200307.553243] dvb-usb: schedule remote
query interval to 287 msecs.
Aug  9 13:47:59 strata kernel: [200307.553251] dvb-usb: RTL2832U DVB-T USB
DEVICE successfully initialized and connected.

I notice that it DOESN'T say "*will pass the complete MPEG2 transport
stream to the software demuxer"* as it does on the 32bit side.

Also, what is the syntax for the -g switch?  I have tried integers,
decimals and the string -3dB and in all cases I get the message *Warning:
Failed to set tuner gain* -- could the gain control simply be unsupported
by my device?

Lastly, I'd like to ask the hard question: are my goals here feasible?  Is
this an appropriate device for listening to FM broadcasts at the computer
or is this more a hobbyist's SDR playground and, like a dancing bear, the
bear doesn't dance amazingling, it is only amazing that the bear dances at
all ;)
-- 
*Have Blog, Will Travel: blog.teledyn.com*
*A Serviceable Substitute: post.teledyn.com*
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osmocom.org/pipermail/osmocom-sdr/attachments/20120809/ab91b0f9/attachment.html>


More information about the osmocom-sdr mailing list