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Re: [Discuss-gnuradio] Tx/Rx using one USRP board
Hi,
I am facing a few problems in making USRP work as relay.
I use rx_voice.py and tx_voice.py for reception and transmission of audio
files.If i transmit at 910MHz and relay it at 950MHz then after relaying , very
few packets are received on another node. Infact, most of the packets are not
received.
What i know is that the usrp is working as a relay to some extent because if i
transmit a sine wave using usrp_siggen.py and see the wave after relaying then
i do observe the sine wave. But, the sine wave has a lot of variation. i.e it
is continuously changing its amplitude .I observed it to change from 2500-15000
on oscope. The original wave was at a perfect amplitude of ard 15000. Now, is
the problem in reception of packets coming because of this kind of variation??
Or is it that the USB is playing the limiting factor role. The data rates used
in audio transmission is
Bitrate- 50,000
Samples per symbol = 5
Also, Even if i receive a few packets then, i get the error message
terminate called after throwing an instance of 'std::runtime_error'
what(): msg length is not a multiple of d_itemsize
Aborted (core dumped)
Please tell me how to handle the above problems.
Thanks
Pratik Hetamsaria
On Wed, Aug 01, 2007 at 05:52:56AM +0100, pratik hetamsaria wrote:
hi,
I am posting this again as i havent got any concrete replies.I have
been stuck making the usrp work as a relay for a very long time. I
am giving the code which i am using for making it work as a
relay. Can somebody please point out where is the mistake. I am
trying to receive a signal sent by usrp_siggen.py at 910MHz and
retransmit it at 950MHz. However, when i view the signal at 950MHz
using usrp_oscope.py then i am able to see only noise. There is no
sine wave present at that frequency. I am not able to understand
what is the usrp transmitting at 950 MHz then. What i know is that
the usrp does receive the sine wave at 910MHz.
Are you using one or two daughterboards?
What kind of daughterboard(s)?
Is your rx-subdev-spec the same as tx-subdev-spec?
Checking to see if r is None is highly recommended.
If you're using a RFX-900 for TX, is the saw filter still in?
(It comes with a 902 to 928 MHz ISM band filter.)
Does the data in usrp_data_receive.dat look reasonable?
What are the min and max values that you see?
What's your tx-amplitude?
Depending on the tx daughterboard, you may need
dst.set_enable(True)
If you're trying to use a single RFX-* daughterboard, you'll need to
set the RX to receive from the RX2 antenna port, not the TX/RX port:
rx_src.select_rx_antenna('RX2')
Eric
PLease point out where is the mistake in my code.
Thanks
Pratik Hetamsaria
_
class my_graph(gr.flow_graph):
def __init__(self):
gr.flow_graph.__init_ _(self)
parser = OptionParser(option_class=eng_option)
parser.add_option(-R, --rx-subdev-spec, type=subdev,
default=None)
parser.add_option(-d, --decim, type=int, default=256)
parser.add_option(-f, --freq, type=eng_float, default=910e6)
parser.add_option(-g, --gain, type=eng_float, default=45)
parser.add_option(-T, --tx-subdev-spec, type=subdev,
default=None)
parser.add_option(-a, --tx-amplitude, type=eng_float,
default=32000)
parser.add_option(-q, --tx-freq, type=eng_float, default=950e6)
parser.add_option(-i, --interp, type=intx, default=512)
(options, args) = parser.parse_args()
rx_src = usrp.source_c (0, options.decim)
rx_subdev_spec = (0,0)
rx_src.set_mux(usrp.determine_rx_mux_value(rx_src, rx_subdev_spec))
subdev = usrp.selected_subdev(rx_src, rx_subdev_spec)
r = rx_src.tune(0, subdev, options.freq)
self._tx_amplitude = options.tx_amplitude
self.amp = gr.multiply_const_cc(0)
self.amp.set_k(self._tx_amplitude)
dst = usrp.sink_c(0, options.interp)
if options.tx_subdev_spec is None:
tx_subdev_spec = usrp.pick_tx_subdevice(dst)
dst.set_mux(usrp.determine_tx_mux_value (dst, tx_subdev_spec))
subdev = usrp.selected_subdev(dst, tx_subdev_spec)
r = dst.tune(subdev._which, subdev, options.tx_freq )
filename = /home/polytech/Desktop/usrp_data_receive.dat
destination = gr.file_sink(gr.sizeof_gr_complex, filename)
self.connect(rx_src, destination)
self.connect(rx_src, self.amp, dst)
if __name__ == '__main__':
try:
my_graph().run()
except KeyboardInterrupt:
pass
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Re: [Discuss-gnuradio] Tx/Rx using one USRP board
Hi,
Thanks very much for your info. i finally got the relay working.. :) ...the
basic problem was probably in the selection of the antenna.
But, other things have cropped up. I am transmitting a sine wave from one of
the usrp and after the relay ,when i receive it on another 3rd machine at say,
950MHz, thne there is a lot of amplitude variation and i am not able to see a
clear sine wave.Moreover, changing the tx_amplitude introduces a lot of
variation in the signal. The best sine wave is viewed when i keep its value
1.Increasing its value introduces more signal distortion in the signal. Please
tell me what are the values which should be kept for tx_amplitude.
Moreover, I have to work with tx_voice.py and rx_voice.py for transmission and
reception of audio files. After relaying, when i try to receive, after a
reception of few packets, i get the following error message:
terminate called after throwing an instance of 'std::runtime_error'
what(): msg length is not a multiple of d_itemsize
Aborted (core dumped)
Going through pkt.py and packet_utils.py , and printing out the message length
, i have figured out that the above error doent appear whenevr, the msg length
has some difference of 33.For eg. it runs perfectly fine if the msg length is
1687 or 1720 (difference of 33). But at the relay node , it arbitrarily goes to
some different msg length(different values seen in my case is 1542,1592
etc).There is no problem in reception of signal in the relay because i can see
that the packets are demodulated properly by passing the file
usrp_data_receive.dat to the demodulator. I do not know how to control this
change in the message length in the relay code. So, could you please tell me
how to resolve this issue.
Thanks
Pratik Hetamsaria
Eric Blossom [EMAIL PROTECTED] wrote: On Wed, Aug 01, 2007 at 05:52:56AM
+0100, pratik hetamsaria wrote:
hi,
I am posting this again as i havent got any concrete replies.I have
been stuck making the usrp work as a relay for a very long time. I
am giving the code which i am using for making it work as a
relay. Can somebody please point out where is the mistake. I am
trying to receive a signal sent by usrp_siggen.py at 910MHz and
retransmit it at 950MHz. However, when i view the signal at 950MHz
using usrp_oscope.py then i am able to see only noise. There is no
sine wave present at that frequency. I am not able to understand
what is the usrp transmitting at 950 MHz then. What i know is that
the usrp does receive the sine wave at 910MHz.
Are you using one or two daughterboards?
What kind of daughterboard(s)?
Is your rx-subdev-spec the same as tx-subdev-spec?
Checking to see if r is None is highly recommended.
If you're using a RFX-900 for TX, is the saw filter still in?
(It comes with a 902 to 928 MHz ISM band filter.)
Does the data in usrp_data_receive.dat look reasonable?
What are the min and max values that you see?
What's your tx-amplitude?
Depending on the tx daughterboard, you may need
dst.set_enable(True)
If you're trying to use a single RFX-* daughterboard, you'll need to
set the RX to receive from the RX2 antenna port, not the TX/RX port:
rx_src.select_rx_antenna('RX2')
Eric
PLease point out where is the mistake in my code.
Thanks
Pratik Hetamsaria
_
class my_graph(gr.flow_graph):
def __init__(self):
gr.flow_graph.__init_ _(self)
parser = OptionParser(option_class=eng_option)
parser.add_option(-R, --rx-subdev-spec, type=subdev,
default=None)
parser.add_option(-d, --decim, type=int, default=256)
parser.add_option(-f, --freq, type=eng_float, default=910e6)
parser.add_option(-g, --gain, type=eng_float, default=45)
parser.add_option(-T, --tx-subdev-spec, type=subdev,
default=None)
parser.add_option(-a, --tx-amplitude, type=eng_float,
default=32000)
parser.add_option(-q, --tx-freq, type=eng_float, default=950e6)
parser.add_option(-i, --interp, type=intx, default=512)
(options, args) = parser.parse_args()
rx_src = usrp.source_c (0, options.decim)
rx_subdev_spec = (0,0)
rx_src.set_mux(usrp.determine_rx_mux_value(rx_src, rx_subdev_spec))
subdev = usrp.selected_subdev(rx_src, rx_subdev_spec)
r = rx_src.tune(0, subdev, options.freq)
self._tx_amplitude = options.tx_amplitude
self.amp = gr.multiply_const_cc(0)
self.amp.set_k(self._tx_amplitude)
dst = usrp.sink_c(0, options.interp)
if options.tx_subdev_spec is None:
tx_subdev_spec = usrp.pick_tx_subdevice(dst)
dst.set_mux(usrp.determine_tx_mux_value (dst, tx_subdev_spec))
subdev = usrp.selected_subdev(dst, tx_subdev_spec)
r = dst.tune(subdev._which, subdev, options.tx_freq )
filename = /home/polytech/Desktop/usrp_data_receive.dat
destination = gr.file_sink
[Discuss-gnuradio] Tx/Rx using one USRP board
hi, I am posting this again as i havent got any concrete replies.I have been stuck making the usrp work as a relay for a very long time. I am giving the code which i am using for making it work as a relay. Can somebody please point out where is the mistake. I am trying to receive a signal sent by usrp_siggen.py at 910MHz and retransmit it at 950MHz. However, when i view the signal at 950MHz using usrp_oscope.py then i am able to see only noise. There is no sine wave present at that frequency. I am not able to understand what is the usrp transmitting at 950 MHz then. What i know is that the usrp does receive the sine wave at 910MHz. PLease point out where is the mistake in my code. Thanks Pratik Hetamsaria _ class my_graph(gr.flow_graph): def __init__(self): gr.flow_graph.__init_ _(self) parser = OptionParser(option_class=eng_option) parser.add_option(-R, --rx-subdev-spec, type=subdev, default=None) parser.add_option(-d, --decim, type=int, default=256) parser.add_option(-f, --freq, type=eng_float, default=910e6) parser.add_option(-g, --gain, type=eng_float, default=45) parser.add_option(-T, --tx-subdev-spec, type=subdev, default=None) parser.add_option(-a, --tx-amplitude, type=eng_float, default=32000) parser.add_option(-q, --tx-freq, type=eng_float, default=950e6) parser.add_option(-i, --interp, type=intx, default=512) (options, args) = parser.parse_args() rx_src = usrp.source_c (0, options.decim) rx_subdev_spec = (0,0) rx_src.set_mux(usrp.determine_rx_mux_value(rx_src, rx_subdev_spec)) subdev = usrp.selected_subdev(rx_src, rx_subdev_spec) r = rx_src.tune(0, subdev, options.freq) self._tx_amplitude = options.tx_amplitude self.amp = gr.multiply_const_cc(0) self.amp.set_k(self._tx_amplitude) dst = usrp.sink_c(0, options.interp) if options.tx_subdev_spec is None: tx_subdev_spec = usrp.pick_tx_subdevice(dst) dst.set_mux(usrp.determine_tx_mux_value (dst, tx_subdev_spec)) subdev = usrp.selected_subdev(dst, tx_subdev_spec) r = dst.tune(subdev._which, subdev, options.tx_freq ) filename = /home/polytech/Desktop/usrp_data_receive.dat destination = gr.file_sink(gr.sizeof_gr_complex, filename) self.connect(rx_src, destination) self.connect(rx_src, self.amp, dst) if __name__ == '__main__': try: my_graph().run() except KeyboardInterrupt: pass - Download prohibited? No problem. CHAT from any browser, without download.___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] USRP as relay
hi tarun, I have been looking at those links only.Rather the entire code which i have made is based upon that. I came to know how to declare the usrp as source and sink from the archives. But making it as a relay is somehow not working and i don't have any idea where can be the possible mistake. It would be very helpful if you can point out where i am making the mistake. Thanks Pratik Hetamsaria Tarun Tiwari [EMAIL PROTECTED] wrote: Hi Pratik, I hope this would help you http://lists.gnu.org/archive/html/discuss-gnuradio/2006-04/msg00196.html regards, Tarun On 7/18/07, pratik hetamsaria [EMAIL PROTECTED] wrote: hi.. I want to make the usrp function as a relay for audio files. Apart from working on rx_voice.py for getting the relay function to work(i have written about the problem faced by me in my previous mail) http://lists.gnu.org/archive/html/discuss-gnuradio/2007-07/msg00203.html i just made up a simple code which would do the same.I am attaching the code for reference. I am able to see that the usrp reads the data coming at 910MHz(in my case) which is transmitted by tx_voice.py by writing the data onto a file and then passing it to the demodulator(i am able to see the packets by passing the file as input to rx_voice.py). But, after retransmission at 950MHz , at another machine i am not able to receive any packets. I am able to see that the usrp does transmit something at 950MHz because i can see a spike in a spectrum analyzer at that frequency. I am not able to get what can be the possible problem. Kindly point out if there is any error in my code. Is there any fundamental mistake which i am doing. I have been mailing quite a lot regarding this but not getting any response. Please help. Thanks Pratik Hetamsaria ___ class my_graph(gr.flow_graph): def __init__(self): gr.flow_graph.__init_ _(self) parser = OptionParser(option_class=eng_option) parser.add_option(-R, --rx-subdev-spec, type=subdev, default=None) parser.add_option(-d, --decim, type=int, default=256) parser.add_option(-f, --freq, type=eng_float, default=910e6) parser.add_option(-g, --gain, type=eng_float, default=45) parser.add_option(-T, --tx-subdev-spec, type=subdev, default=None) parser.add_option(-a, --tx-amplitude, type=eng_float, default=32000) parser.add_option(-q, --tx-freq, type=eng_float, default=950e6) parser.add_option(-i, --interp, type=intx, default=512) (options, args) = parser.parse_args() rx_src = usrp.source_c (0, options.decim) rx_subdev_spec = (0,0) rx_src.set_mux(usrp.determine_rx_mux_value(rx_src, rx_subdev_spec)) subdev = usrp.selected_subdev(rx_src, rx_subdev_spec) r = rx_src.tune(0, subdev, options.freq) self._tx_amplitude = options.tx_amplitude self.amp = gr.multiply_const_cc(0) self.amp.set_k(self._tx_amplitude) dst = usrp.sink_c(0, options.interp) if options.tx_subdev_spec is None: tx_subdev_spec = usrp.pick_tx_subdevice(dst) dst.set_mux(usrp.determine_tx_mux_value (dst, tx_subdev_spec)) subdev = usrp.selected_subdev(dst, tx_subdev_spec) r = dst.tune(subdev._which, subdev, options.tx_freq ) filename = /home/polytech/Desktop/usrp_data_receive.dat destination = gr.file_sink(gr.sizeof_gr_complex, filename) self.connect(rx_src, destination) self.connect(rx_src, self.amp, dst) if __name__ == '__main__': try: my_graph().run() except KeyboardInterrupt: pass - Get the freedom to save as many mails as you wish. Click here to know how. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio - DELETE button is history. Unlimited mail storage is just a click away.___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] USRP as relay
hi.. I want to make the usrp function as a relay for audio files. Apart from working on rx_voice.py for getting the relay function to work(i have written about the problem faced by me in my previous mail) http://lists.gnu.org/archive/html/discuss-gnuradio/2007-07/msg00203.html i just made up a simple code which would do the same.I am attaching the code for reference. I am able to see that the usrp reads the data coming at 910MHz(in my case) which is transmitted by tx_voice.py by writing the data onto a file and then passing it to the demodulator(i am able to see the packets by passing the file as input to rx_voice.py). But, after retransmission at 950MHz , at another machine i am not able to receive any packets. I am able to see that the usrp does transmit something at 950MHz because i can see a spike in a spectrum analyzer at that frequency. I am not able to get what can be the possible problem. Kindly point out if there is any error in my code. Is there any fundamental mistake which i am doing. I have been mailing quite a lot regarding this but not getting any response. Please help. Thanks Pratik Hetamsaria ___ class my_graph(gr.flow_graph): def __init__(self): gr.flow_graph.__init__(self) parser = OptionParser(option_class=eng_option) parser.add_option(-R, --rx-subdev-spec, type=subdev, default=None) parser.add_option(-d, --decim, type=int, default=256) parser.add_option(-f, --freq, type=eng_float, default=910e6) parser.add_option(-g, --gain, type=eng_float, default=45) parser.add_option(-T, --tx-subdev-spec, type=subdev, default=None) parser.add_option(-a, --tx-amplitude, type=eng_float, default=32000) parser.add_option(-q, --tx-freq, type=eng_float, default=950e6) parser.add_option(-i, --interp, type=intx, default=512) (options, args) = parser.parse_args() rx_src = usrp.source_c (0, options.decim) rx_subdev_spec = (0,0) rx_src.set_mux(usrp.determine_rx_mux_value(rx_src, rx_subdev_spec)) subdev = usrp.selected_subdev(rx_src, rx_subdev_spec) r = rx_src.tune(0, subdev, options.freq) self._tx_amplitude = options.tx_amplitude self.amp = gr.multiply_const_cc(0) self.amp.set_k(self._tx_amplitude) dst = usrp.sink_c(0, options.interp) if options.tx_subdev_spec is None: tx_subdev_spec = usrp.pick_tx_subdevice(dst) dst.set_mux(usrp.determine_tx_mux_value(dst, tx_subdev_spec)) subdev = usrp.selected_subdev(dst, tx_subdev_spec) r = dst.tune(subdev._which, subdev, options.tx_freq ) filename = /home/polytech/Desktop/usrp_data_receive.dat destination = gr.file_sink(gr.sizeof_gr_complex, filename) self.connect(rx_src, destination) self.connect(rx_src, self.amp, dst) if __name__ == '__main__': try: my_graph().run() except KeyboardInterrupt: pass - Get the freedom to save as many mails as you wish. Click here to know how.___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] USRP as relay
hi I have been trying to make the USRP work as a relay for quite some time and not been able to do so. I want to transmit whatever data the USRP has received. I have been working on rx_voice.py for reception of my audio files.The flow graph is connected like : self.u = usrp.source_c(0,decim); fg.connect(self.u, self.chan_filt, self.packet_receiver) The reception of packets is perfectly fine in this case. Now, the curious thing which is happening is that when i also make the usrp as the sink and connect the flow graph as self.dst = usrp.sink_c(0,interp); fg.connect(self.u, self.chan_filt, self.packet_receiver) fg.connect(self.u, self.dst); then i also stop receiving any packets. I am not able to understand why is this happening. At least the reception of the packets should not have changed, leave aside the retransmission part. I am using a single Flex 900 board so i dont think that might be causing the problem.I dont think that making the connection as Data from usrp Data to usrp is wrong. If its so,then let me know and is it necessary to put some kind of filter between the 2 to make it working. Also, i dont think that making the flow graph as Data from usrp data demod - data remod -- Data to usrp would make any difference. I also want to retransmit at a different frequency. So, is it necessary to demod and remod or whether just setting the usrp at that retransmission frequency would solve my purpose. Reading from the previous archives i have found that it should not be much of a problem in making such a thing work but somehow its not working in my case. I would be very grateful if somebody could help as its been quite long since i am stuck onto this problem. Thanks Pratik Hetamsaria - Heres a new way to find what you're looking for - Yahoo! Answers ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Reducing the samples from ADC
hi.. i am working on tx_voice.py and rx_voice.py. I have to capture data directly from usrp and write onto a file and process that. The problem is that the file which is made by the data coming from usrp is very big so basically i am not able to process that. Is there any way by which i can reduce the size of the file without affecting my audio quality much. The rates which i am presently using on the tx_voice.py are: Bitrate- 50,000 samples per symbol - 5 interpolation - 512 Rates which i am using on the rx_voice.py are: Bitrate- 50,000 samples per symbol - 5 decimation - 256. Moreover, i have tried using gr.fir_filter_ccf (for decimatio in software)in the following fashion chan_coeffs = gr.firdes.low_pass (1.0, # gain self._samples_per_symbol, # sampling rate 1.0, # midpoint of trans. band 0.1, # width of trans. band gr.firdes.WIN_HANN) # filter type self.chan_filt = gr.fir_filter_ccc(sw_decim, chan_coeffs) and making a connection as fg.connect(self.u, self.chan_filt, self.packet_receiver) fg.connect(self.chan_filt,destination) where destination refers to the file onto which i want to write.Now, this works fine as long as sw_decim =1. But, if i change the value to 2,4 ,8 or any other then i dont receive any packet. The file size does change as required (i am able to observe that as the usrp is always sending data). what i have understood is that because of the decimation i am missing samples and thus not able to receive packets.So, can somebody please explain how to get around the situation. Thanks for all the help. Pratik Hetamsaria - Why delete messages? Unlimited storage is just a click away.___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Demodulation problem
hi.. i am working on rx_voice.py for transmission of audio files. In my application, i need to capture directly the usrp samples and write them onto a file. Now, i further want do some processing on them using MATLAB. Next, what i want is that the file be passed to the python code where i can demodulate them as it is done in receive_path.py . I have been able to capture the data directly from USRP and write it onto a file by making the connection: fg.connect(self.u,self.dst) where self.dst refers to the file. I also do the processing using MATLAB and again write it onto a different file. Now, the problem is that how should i pass the new file back to the code so that it gets demodulated. I have tried running the rx_voice again wherein i make a connection as follows: fg.connect(self.dst,self.chan_filt,self.packet_receiver) where self.dst refers to the new file which i want to demodulate. But, nothing happens on making such a connection. Maybe the problem is because of the way in which the samples from USRP and files are read. The other option which i have thought of is to demodulate the entire signal in MATLAB .But tht i suppose would be pretty tedious because then i will probably have to study all the C++ implementations of the demod blocks. Can anyone please suggest any solution. I jus want that the data from a file be read and demodulated in the same fashion as it is done when it reads direct samples from the USRP. Thanks for all the help in advance Pratik Hetamsaria Send free SMS to your Friends on Mobile from your Yahoo! Messenger. Download Now! http://messenger.yahoo.com/download.php___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Simultaneous transmission and reception
David Scaperoth [EMAIL PROTECTED] wrote: On 7/3/07, pratik hetamsaria [EMAIL PROTECTED] wrote: Hi Everyone I am currently trying to make a USRP transceiver run, which is based on TDMA approach. As a warning, the USRP and GNU Radio are going to give you some trouble when it comes to TDMA (at least for smaller time slots). However, in the near future the mblocks and inband signalling on the USRP will allow you to precisely timestamp the data that is coming in from the ADC...so if you can stand to wait (or help out with the work), it might be in your best interest. Elaborating on it, it should be a system which works in receive mode for sometime, writes the data in a file and in the next slot transmits the data which has been written in the file. Reading from the previous archives, I figured out that switching between the modes can be done by setting the set_auto_tr(True). The switching works lovely when writing reading and is done into and from different files. But as soon as the same file is used, problem starts. I have been working on tx_voice.py and rx_voice.py. I start the receiver first so that it writes onto the file. After few seconds, i start the transmitter and then after every 5 seconds I make the transmit mode go to sleep for another 5 seconds. When you say you make the transmit mode go to sleep, how do you stop sending data from the file? -- I just use the time.sleep function for making the transmit mode go into the sleep mode. I have assumed that it doesnt transmit during that time because then the receiver gets active and starts receiving packets. Reading from archives, i figured out that the USRP transmits whenever it has some data to transmit and then gets into the receiving mode. Please correct me if i am wrong. But, the problem is that it works fine for some time but after that the transmit mode stops and the receiver keeps on receiving more packets and then we dont get into the transmit mode. How fast are you transmitting / receiving (sampling rate)? What kind of CPU are you using? Writing to a file continuously is a pretty ominous task for a computer if the sampling rate is say 1MHz. If you did this for 5 seconds, the computer may be just simply lagging behind. (Does anyone know how fast it is possible to write to a harddrive?). Are you getting 0u0u on the screen while its running? The bitrate is 5 and samples per symbol is 5 for transmit and receiver sides. The interpolation rate is 512 and the corresponding decimation rate is 256. I am using a Pentium 4 3.0 GHz processor .I am not getting any underbuffer in my case while i am transmitting. What i get is that the transmitter simply stops after transmitting a few packets. Another thing to keep in mind is that the ADC is continuously sending data across the USB. When you begin to transmit, the data sent to the USB is just garbage (noise), so in the end you have to be constantly throwing data away when you are transmitting. This will all change when the mblocks are finished. Wahoo! -Please explain what do yo mean by data sent to the USB is just noise ,so u'll have to be constantly throwing data away . The transmit mode stops even though the number of packets written to file are more than read. Maybe this could be a problem of buffering or something because if i keep the transmission in repeat mode then the transmit mode doesnt stop. However In my case, i dont want the transmission in repetition mode. I only want to transmit whatever i have received. I have also ensured that the rates of receiveing and transmission are the same. hope this helped some Even if the TDMA approach doesnt work, then my work can also be done even if i use FDMA i.e I would just like that the data received be first demodulated and remodulated and transmitted over a differnt frequency. The only thing is that i need a function of a relay. But, I am not sure whether with the rates i am transmitting and receiving this could be done. Also, i have tried making the USRP as the source and the sink by using the commands self.u = usrp.source_c(0,decim) self. dst = usrp.sink_c (0, options.interp) and making the connection as fg.connect(self.u,self.dst) I have tried viewing the signals on the scope by using self.scope from usrp_oscope.py . I just tried testing it by viewing signals sent from usrp_siggen.py at a frequency of 910Mhz and retransmitted at a frequency of 950MHz. However, the signals look very different if i just run the usrp_oscope(original version when i just receive the signal and display it on the oscope) and in the other case(where i retransmit it at a different frequency). So, could somebody please point out if i am doing any mistake over here. I have just a feeling that whatever i am doing is pretty simple to do but maybe i am doing some mistake sumwhere..:) Thanks for your
[Discuss-gnuradio] Simultaneous transmission and reception
Hi Everyone I am currently trying to make a USRP transceiver run, which is based on TDMA approach.Elaborating on it, it should be a system which works in receive mode for sometime, writes the data in a file and in the next slot transmits the data which has been written in the file. Reading from the previous archives, I figured out that switching between the modes can be done by setting the set_auto_tr(True). The switching works lovely when writing reading and is done into and from different files. But as soon as the same file is used, problem starts. I have been working on tx_voice.py and rx_voice.py. I start the receiver first so that it writes onto the file. After few seconds, i start the transmitter and then after every 5 seconds I make the transmit mode go to sleep for another 5 seconds. But, the problem is that it works fine for some time but after that the transmit mode stops and the receiver keeps on receiving more packets and then we dont get into the transmit mode. The transmit mode stops even though the number of packets written to file are more than read. Maybe this could be a problem of buffering or something because if i keep the transmission in repeat mode then the transmit mode doesnt stop. However In my case, i dont want the transmission in repetition mode. I only want to transmit whatever i have received. I have also ensured that the rates of receiveing and transmission are the same. Could anybody please help me out with the situation.I just want to retransmit the data received from USRP. Thanks for all the help in advance Pratik Hetamsaria - Heres a new way to find what you're looking for - Yahoo! Answers ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] embed fix sequence in payload part
hi.. i am presently working on tx_voice.py and rx_voice.py for transmission of audio files. I am interested in finding out the BER . Now, the problem is that a few packets are dropped so i need to keep track of a packet sequence number. I am trying to embed a packet sequence number so that during the time of demodulation i know exactly which bits i should compare. I have looked into the code of packet_utils.py located at python2.4/site-packages/gnuradio and try to embed the sequence number over there in the payload part. What i have understood is that the preamble and access codes are dropped during the time of reception. So, i thought it would be easier to embed it in the payload part. Please correct me if i am wrong. But when i try adding any sequence then during the time of reception, i receive the errors as i have mentioned. I have seen that there is an option of padding the payload with zeros. So, after i add a sequence number, the length of the payload still remains the same as it was before adding the sequence number (the number of bits padded have changed).So, i dont know what really has changed which causes this error. What i have added is just one line in the make_packet function of packet_utils.py def make_packet(payload, samples_per_symbol, bits_per_symbol, access_code=default_access_code, pad_for_usrp=True): (packed_access_code, padded) = conv_1_0_string_to_packed_binary_string(access_code) (packed_preamble, ignore) = conv_1_0_string_to_packed_binary_string(preamble) payload = packed_preamble + payload %LINE ADDED payload_with_crc = gru.gen_and_append_crc32(payload) pkt = ''.join((packed_access_code, make_header(L), whiten(payload_with_crc), '\x55')) if pad_for_usrp: pkt = pkt + (_npadding_bytes(len(pkt), samples_per_symbol, bits_per_symbol) * '\x55') return pkt I have not changed anything at the receiving end. Please tell me if i need to do change anything during reception. I have printed the msg length from the pkt.py code at python2.4/site-packages/gnuradio/blksimpl For comparison of BER i am taking the payload part as reference i.e. i am writing the payload part onto a file and during the time of reception also, i am doing the same. Please tell if there is a better way of doing BER. thanks for your help Pratik Hetamsaria Tom Rondeau [EMAIL PROTECTED] wrote: pratik hetamsaria wrote: hi.. i am trying to embed a fixed sequence which i want to recover during demodulation. I have read from the previous archives that it would be easier to embed it in the payload part.However, as soon as i add anything in the payload part, and try to receive using rx_voice, i get an error saying terminate called after throwing an instance of 'std::runtime_error' what(): msg length is not a multiple of d_itemsize Aborted (core dumped) What I have understood is that the msg length changes as soon as I add something to the payload.If I dont do anything and just run rx_voice.py then the msg length comes to be 1687/1720 I have tried getting the msg length after adding different sequences. If i change the code as: payload = payload + preamble, the msg length changes to 1719 Otherwise, If i change as: payload = payload + default_access_code the msg length changes to 1751 where default_access_code and preamble are given in packet_utils.py. I have not been able to find out the value of d_itemsize or what should be its value so that the code runs. I would be very grateful for any help. Thanking you, Pratik Hetamsaria Pratik, I'm not entirely sure what you're trying to do. Which example code are you using? And also, what's the purpose of what you are trying to do? That might help us set you in the right direction. Please list the code where you are making the change to add your fixed sequence. Tom - Heres a new way to find what you're looking for - Yahoo! Answers ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] error using rx_voice.py
I am working on tx_voice.py and rx_voice.py and I am trying to embed a fixed sequence in the payload part of my packet. However, when i try to receive the data using rx_voice, i get an error saying terminate called after throwing an instance of 'std::runtime_error' what(): msg length is not a multiple of d_itemsize Aborted (core dumped) I have added only one line in make_packet in packet_utils.py and it looks like this:(just the important lines as i thought) def make_packet(payload, samples_per_symbol, bits_per_symbol, access_code=default_access_code, pad_for_usrp=True): (packed_access_code, padded) = conv_1_0_string_to_packed_binary_string(access_code) (packed_preamble, ignore) = conv_1_0_string_to_packed_binary_string(preamble) payload = packed_preamble + payload payload_with_crc = gru.gen_and_append_crc32(payload) pkt = ''.join((packed_access_code, make_header(L), whiten(payload_with_crc), '\x55')) if pad_for_usrp: pkt = pkt + (_npadding_bytes(len(pkt), samples_per_symbol, bits_per_symbol) * '\x55') return pkt Can anyone please explain how to remove this error. I want to add fixed sequence so that it helps in calculation of BER. Thanks, Pratik Hetamsaria - Heres a new way to find what you're looking for - Yahoo! Answers ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Transceiver function of USRP
hi.. i are trying to implement a transceiver function in gnu radio.what i want is that the usrp be in the transmitting mode for say a specified no. of packets and then it switches onto the receiving mode for another specified no. of packets. i have already seen usrp_nbfm_ptt.py which does exactly the same thing but it is event driven. i am not able to understand how does this switching exactly take place in that and how does by just making one flow graph we are able to switch. i have tried making it go automatically by using the start(),stop() and wait() functions of the flow graph but have not managed to do it. Maybe what i am trying is the wrong approach,so can anybody please explain how to do the above thing. i jus want that the event driven thing in usrp_nbfm_ptt.py switch automatically based on any criteria, be it no. of packets, time etc. thanks pratik hetamsaria - Looking for people who are YOUR TYPE? Find them here!___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
