Some problem with my USRP N210

GNU Radio
1

Hi everyone,

I am a new user of GNU radio. I am trying to communicate between Tmote
Sky
sensor node and USRP N210.

I use the Tmote Sky sensor node as transmitter to broadcast messages by
flashing the example code into the node. The messages are broadcast in
radio
channel 26. (The code is this one
“./contiki/examples/ipv6/simple-udp-rpl/broadcast-example.c”)

I use USRP N210 as the receiver. I just want to test whether my USRP can
receive the broadcast messages or not. So I made a small receiver in
gnuradio-companion which just has a USRP Source, a Scope Sink and an FFT
Sink. I set the sample rate to be 4M, center frequency to be 2.48G,
Channel
gain to be 15dB.

However, in the scope sink and fft sink, I cannot find any signal except
the
noise.

I am sure the sender works successfully because I have a receiver
implemented on another Tmote Sky sensor can receive the broadcast
messages.

I just want to make sure my USRP N210 can receive the signal so that I
can
make a 802.15.4 receiver on it in the next step.

I hope someone could give me some suggestions that I can make it work.

Thanks in advance,

Su

broadcast-example.c
http://gnuradio.4.n7.nabble.com/file/n50723/broadcast-example.c
top_block.py http://gnuradio.4.n7.nabble.com/file/n50723/top_block.py
Receiver.png http://gnuradio.4.n7.nabble.com/file/n50723/Receiver.png

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2

If there aren’t any GR-specific issues, you might consider moving this
to
the UHD-users mailing list.

  • Presumably, you’re using an SBX?
  • Is there any chance the bursts are just very short? Experiment with
    the trigger settings on the scope to see if you can catch any bursts.

-John

3

Hi John,

Thanks for your reply.

I am using RFX2400 2.3-2.9GHZ RX/TX

I increased the message length from 4 to 100 at the sender. But I still
can
not observe the signal. (Maybe because of the power of signal is too
small?)

The USRP N210 can receive signal at frequency around 2.9GHz. So I think
the
hardware of USRP still works. But I cannot make it work now.

Thanks for your help.

-Su

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4

Hi,

On 10/09/2014 05:43 PM, liisuu wrote:

I use USRP N210 as the receiver. I just want to test whether my USRP can
receive the broadcast messages or not. So I made a small receiver in
gnuradio-companion which just has a USRP Source, a Scope Sink and an FFT
Sink. I set the sample rate to be 4M, center frequency to be 2.48G, Channel
gain to be 15dB.

However, in the scope sink and fft sink, I cannot find any signal except the
noise.

Maybe you want to try gr-fosphor [1]. AFIAK, it uses all samples to
calculate the FFT, so it will be easier to spot the bursts.

I am sure the sender works successfully because I have a receiver
implemented on another Tmote Sky sensor can receive the broadcast messages.

I just want to make sure my USRP N210 can receive the signal so that I can
make a 802.15.4 receiver on it in the next step.

There is already a transceiver that is tested with TelosB motes [2]. It
also implements parts of the Contiki RIME stack.

Best,
Bastian

[1] Fosphor - SDR (Software Defined Radio) - Open Source Mobile Communications
[2] GitHub - bastibl/gr-ieee802-15-4: IEEE 802.15.4 ZigBee Transceiver

5

4 to 100? What are the units? How long is the actual burst? Just
guessing - a ~100 byte packet at the lowest datarate (250 kbps) of the
CC2420 chip means the packet will e about 3.2 ms. If you’re using the 2
mbps rate, obviously it’ll be much shorter. Unless you’re sending these
packets with very high duty cycle, you won’t really see anything in the
FFT
sinks…

Did you experiment with setting triggers in the scope like I suggested?

-John