Re: [Discuss-gnuradio] 802.11 and Bluetooth
Hi Thomas, I have put the code at http://www.cs.wisc.edu/~shravan/specsense.txt It has some small modifications to the original usrp_spectrum_sense.py. The output is a set of samples (freq, power); This is done 1 Mhz at a time in steps of 0.5 Mhz. Let me know in case you make some modifications to this and get a better output. I am just curious, are the units of log10 block output in dB ? Thanks, Shravan On 12/6/06, Thomas Schmid <[EMAIL PROTECTED]> wrote: Hi Shravan, That is really cool. Can you share with us your modifications to the script and the command line you used? I would like to try this at my home where I see like 20 APs from my neighbors and compare it to the plot of the wi-spy. Thomas > > Actually, you get a reasonable plot. Although you can only sense a > maximum of ~6 Mhz at once, doing so in steps of frequency gives a fair > idea. I made some changes to the spectrum_sense example, so as to a > fftshift and remove outer 25% of the bins. I used a frequency step of > 0.5 Mhz and also passed it through the log10 block. Attached are the > plots for entire spectrum (spec.pdf) and channel 1 (0.5m.pdf). > > Although, I am not sure what the "UNITS" are, they should give a sense > of the relative powers at different frequencies. (Would they end up > in dB as I passed it through the log10 block? I couldnt particularly > understand Eric's code i.e. what is passed to the log10 block) > > Thanks, > > Shravan ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
RE: [Discuss-gnuradio] Problem using benchmark_rx.py
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Tarun Tiwari > Sent: Thursday, December 07, 2006 12:25 AM > To: discuss-gnuradio@gnu.org > Subject: [Discuss-gnuradio] Problem using benchmark_rx.py > > Hi, > > I am trying to transmit packets using benchamark_tx.py and recieve them using benchmark_rx.py. As mentioned in README file I started first benchmark_rx.py at one > machine then started benchmark_tx.py on another machine, but I dont see any print on receiver machine. I am using following commands: > > Tx Machine: > [EMAIL PROTECTED] ~]# ./benchmark_tx.py -f 100e6 --tx-amplitude=3000 -M 2 -r 100e3 -s 1000 > > Rx Machine: > [EMAIL PROTECTED] ~]# ./benchmark_rx.py -f 100e6 > >>> gr_fir_fff: using SSE > > and I dont get any output. > > Can somebody guide me how to succesfully receive the transmitted packets? > > Thanks in advance. > > Tarun Try using the '-v' (verbose) flag on both Rx and Tx, which will give you all the information about the modulation, bit rate, etc. The most likely candidate here is that you've specified the bit rate (100 kbps, GMSK) on the transmitter but not the receiver. The receiver defaults to 500 kbps. Use the '-r 100k' on your receiver as well. Are you transmitting over the air, or connected over cable? And what daughterboards are you using? This will impact the transmit amplitude you'll need. What you've specified is a pretty good mid range for most setups. I only point this out as the next place to look once you've corrected the bit rate and it still doesn't work. Tom ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] USRP and USB full speed (1.1) transmit
I've been working on adding USB1.1 (full speed) support to the USRP software/firmware so I can use it with a TI OSK board. I've been going back and forth with Matt on some issues and we are getting out of his area of expertise. Here is summary of progress to date. After modifying the 8051 code I had the following behavior: When I compile the code for the OSK, I see two symbols transmitted, then dead air. Two symbols is 64 bytes (2 symbols x 8 sample/symbol x 4 bytes/sample), then there are 512 - 64 bytes of no signal. It feels like the 64 byte packets are read into a buffer of 512 bytes, where all the un-written bytes are zeros. It feels like somewhere in the USB chain, I send the 64 byte packet, then something reads the 64 bytes and zero pads the packet to 512 bytes. I suspect the FPGA tries to read 512 bytes from the FX2 chip, but that is only because this is the area of the code I least understand :) Matt suggested the following FPGA change, and I also chnaged a similar construct a few lines further on: http://gnuradio.utah.edu/trac/browser/gnuradio/trunk/usrp/fpga/sdr_lib/tx_buffer.v And look at line 94, you will see the test for "end of packet". write_count[8] goes high when we have put 256 elements (512 bytes) into the fifo. You would need to modify this to write_count[5] which will go high when 32 elements (64 bytes) have been put into the fifo. This results in: Well, it looks like data is coming out, but it looks like I get 64 bytes out, then there is a "hiccup" about 5 microseconds long. I am getting suspicious the OSK doesn't get the data on the USB bus fast enough. I'm still not entirely clear how the FX2 works. I am wondering if there is a way to let the buffers in the FX2 chip fill up more before the FPGA starts pulling data from the FX2. The OSK has a 192 MHz ARM9 processor. i have looked through the 8051 code for packet size dependencies and can't fins any I haven't aready tried to address. Does anyone else have any thoughts? Thanks, Philip ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
RE: [Discuss-gnuradio] Setting Intermediate Frequency
Davide Anastasia [mailto:[EMAIL PROTECTED] wrote: >I hope there is somewhere a functions reference of the GNU Radio >Framework to read... Try this http://www.nd.edu/~jnl/sdr/docs/tutorials/9.html and this http://www.gnu.org/software/gnuradio/doc/modules.html If there's anything else, I'd love to hear about it. I'm still floundering. Jim Davies ** This email and any files transmitted with it are private and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please return it to the address it came from telling them it is not for you and then delete it from your system. This email message has been swept for computer viruses. ** The original of this email was scanned for viruses by Government Secure Intranet (GSi) virus scanning service supplied exclusively by Cable & Wireless in partnership with MessageLabs. On leaving the GSI this email was certified virus free. The MessageLabs Anti Virus Service is the first managed service to achieve the CSIA Claims Tested Mark (CCTM Certificate Number 2006/04/0007), the UK Government quality mark initiative for information security products and services. For more information about this please visit www.cctmark.gov.uk ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] PlayStation 3
My initial readings of the playstation three blurbs/"datasheets" reveals they were incomplete. In addition to gigabit ethernet, it does have USB support. Phil Covington pointed out this page: http://felter.org/wesley/files/ps3/linux-20061110-docs/LinuxKernelOverview.html and Sony is supporting the kernel development. I spoke with knowledgeable people with Yellow Dog and have been having participating in ongoing talks with IBM and Mercury and this has all produced some good results. Now if we can only get our hands on one or more of these PS3's. If you want to get a real laugh, search for PS3 using froogle and look at all of the listings in the thousands of dollars. MADNESS. Anyway, now that we have very good information, I have placed my pre-order with Yellow Dog Linux FROM Yellow Dog Linux for $100. This is a nonrefundable deposit. If you do this, it comes preloaded with YDL, running when it shows up, and the delta price between PS3 and PS3+YDL is less than them individually. Bob -- AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair "If you board the wrong train, it is no use running along the corridor in the other direction. " - Dietrich Bonhoffer ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] USRP and USB full speed (1.1) transmit
> Well, it looks like data is coming out, but it looks like I get 64 > bytes out, then there is a "hiccup" about 5 microseconds long. I am > getting suspicious the OSK doesn't get the data on the USB bus fast > enough. What is the source of the data you're transferring over the bus? If it is coming faster than USB1.1 can handle, of course you'll see "hiccups" where data is dropped. (The USB2 firmware/fpga sets a flag that the software can read when this happens -- that's what produces those "U" dribbles on the terminal sometimes.) I think there's a way to select a counter in the FPGA that just transfers an incrementing number in each outgoing USB packet. (Perhaps it's a different FPGA load instead of a settable flag in the main version.) This was used to debug similar issues between the FPGA and the FX2, and between the FX2 and the software library. Alternatively, you can decimate the source down to a very low data rate, so it won't overflow. Get the rate as low as you possibly can, for debugging. (Or, if there's a demodulator in the FPGA, you could e.g. have it tune an FM radio station, demodulate it on-chip, and transfer only the audio over the USB bus, which would be well within its available bandwidth. But I don't think anybody has coded that FPGA transform... yet.) John ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Problem using benchmark_rx.py
Thank you Tom,
I did change the bit rate for Rx and used -v mode, but its still not
working. Please see the output of program:
Transmitter:
[EMAIL PROTECTED] ~]# ./benchmark_tx.py -f 100e6 --tx-amplitude=500 -M 2 -r
100e3 -v
gr_fir_fff: using SSE
bits per symbol = 1
Gaussian filter bt = 0.35
Using TX d'board A: Basic Tx
Tx amplitude 500.0
modulation: gmsk_mod
bitrate: 100kb/s
samples/symbol:4
interp: 320
Tx Frequency:100M
...
.
Receiver:
[EMAIL PROTECTED] ~]# ./benchmark_rx.py -f 100e6 -r 100e3 -v
gr_fir_fff: using SSE
bits per symbol = 1
M&M clock recovery omega = 4.00
M&M clock recovery gain mu = 0.05
M&M clock recovery mu = 0.50
M&M clock recovery omega rel. limit = 0.005000
frequency error = 0.00
Using RX d'board A: Basic Rx
Rx gain: 10
modulation: gmsk_demod
bitrate: 100kb/s
samples/symbol:4
decim: 160
Rx Frequency:100M
I am connecting the the two boards using cables using -32dB RF attenuator on
each port of daughterboards.
I am using Basic Tx and Basic Rx Boards.
Please advise me, if I need to do some changes in benchmark_rx.py program.
And meanwhile, can you tell me do we need to call any function between
fg.start()# start flow graph
fg.wait() # wait for it to finish
To debug the program, I tried printing something inside rx_callback
subroutine, but I think rx_callback is not being called anywhere in the
program, thats why I am not able to see any printed output on screen. Am I
right? I tried this one:
def rx_callback(ok, payload):
global n_rcvd, n_right
(pktno,) = struct.unpack('!H', payload[0:2])
n_rcvd += 1
if ok:
n_right += 1
print "Hello Tarun\n"
print "ok = %5s pktno = %4d n_rcvd = %4d n_right = %4d" % (
ok, pktno, n_rcvd, n_right)
but no result
Please advise me.
Thank you again.
Regards,
Tarun
On 12/7/06, Tom Rondeau <[EMAIL PROTECTED]> wrote:
> From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of
Tarun
Tiwari
> Sent: Thursday, December 07, 2006 12:25 AM
> To: discuss-gnuradio@gnu.org
> Subject: [Discuss-gnuradio] Problem using benchmark_rx.py
>
> Hi,
>
> I am trying to transmit packets using benchamark_tx.py and recieve them
using benchmark_rx.py. As mentioned in README file I started first
benchmark_rx.py at one
> machine then started benchmark_tx.py on another machine, but I dont see
any print on receiver machine. I am using following commands:
>
> Tx Machine:
> [EMAIL PROTECTED] ~]# ./benchmark_tx.py -f 100e6 --tx-amplitude=3000 -M 2 -r
100e3 -s 1000
>
> Rx Machine:
> [EMAIL PROTECTED] ~]# ./benchmark_rx.py -f 100e6
> >>> gr_fir_fff: using SSE
>
> and I dont get any output.
>
> Can somebody guide me how to succesfully receive the transmitted
packets?
>
> Thanks in advance.
>
> Tarun
Try using the '-v' (verbose) flag on both Rx and Tx, which will give you
all
the information about the modulation, bit rate, etc. The most likely
candidate here is that you've specified the bit rate (100 kbps, GMSK) on
the
transmitter but not the receiver. The receiver defaults to 500 kbps. Use
the
'-r 100k' on your receiver as well.
Are you transmitting over the air, or connected over cable? And what
daughterboards are you using? This will impact the transmit amplitude
you'll
need. What you've specified is a pretty good mid range for most setups. I
only point this out as the next place to look once you've corrected the
bit
rate and it still doesn't work.
Tom
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[Discuss-gnuradio] What antenna for WWV/WWVB?
What is the minimum antenna(s) I would need to pull in WWV (5/10/15Mhz) and WWVB at 60KHz with my USRP with the Basic RX daughtercard? I was wanting to look at decoding the BCD time code. How about if I wanted to get my local airports ATIS at 126Mhz? I am playing with some of the basic example code, either am_rcv.py or the hf_explorer stuff and cannot get much accept local am stations (very weakly) and I can get strong fm stations with the wfm example. I just tried the little am antenna off an old stereo right now which is not much and have even tried the kids slinky thinking to get something longer to get a 1/4 wave or something close I am not a ham radio guy obviously. Thanks! smime.p7s Description: S/MIME Cryptographic Signature ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] PlayStation 3
PS3 support is moving into the mainline kernel: http://www.linuxdevices.com/news/NS6521115697.html Philip On 12/7/06, Robert McGwier <[EMAIL PROTECTED]> wrote: My initial readings of the playstation three blurbs/"datasheets" reveals they were incomplete. In addition to gigabit ethernet, it does have USB support. Phil Covington pointed out this page: http://felter.org/wesley/files/ps3/linux-20061110-docs/LinuxKernelOverview.html and Sony is supporting the kernel development. I spoke with knowledgeable people with Yellow Dog and have been having participating in ongoing talks with IBM and Mercury and this has all produced some good results. Now if we can only get our hands on one or more of these PS3's. If you want to get a real laugh, search for PS3 using froogle and look at all of the listings in the thousands of dollars. MADNESS. Anyway, now that we have very good information, I have placed my pre-order with Yellow Dog Linux FROM Yellow Dog Linux for $100. This is a nonrefundable deposit. If you do this, it comes preloaded with YDL, running when it shows up, and the delta price between PS3 and PS3+YDL is less than them individually. Bob -- AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair "If you board the wrong train, it is no use running along the corridor in the other direction. " - Dietrich Bonhoffer ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Re: [hpsdr] PlayStation 3
Sattler, Jay wrote: What Bob? You didn't order the Y-Bio 56 core Bioinformatics Cluster?? Maybe next time : ) How do I sign up? ;-). Bob -- AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair "If you board the wrong train, it is no use running along the corridor in the other direction. " - Dietrich Bonhoffer ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] What antenna for WWV/WWVB?
On 12/7/06, Heiko Jones <[EMAIL PROTECTED]> wrote:
What is the minimum antenna(s) I would need to pull in WWV (5/10/15Mhz)
and WWVB at 60KHz with my USRP with the Basic RX daughtercard? I was
wanting to look at decoding the BCD time code.
How about if I wanted to get my local airports ATIS at 126Mhz?
Short answer: It depends.
Slightly longer version: It depends upon three main factors 1) RF
frequency 2) distance from source (signal lost based on distance), and
3) atmosphere conditions ("propagation") which is frequency dependent.
WWVB at 60KHz would normally use a loop antenna around a ferrite core,
similar to those found an AM radio. Depending on where you are (cont
US vs. Europe) a small AM loop antenna might work, or a large outside
antenna might be needed if you are in EU.
A VHF signal like 126MHz is roughly line of sight plus 5% (I think), a
1/4-wave vertical would normally work if mounted outside above a large
percentage of nearby buildings and terrain. So a 42cm (~16.5 in)
vertical antenna with a metal ground plane mounted at roof height
would likely work if you are "near" an airport.
A useful starting point is the ARRL's Technical Information Service web pages,
. A copy of the ARRL Handbook
can also be an accessible reference for many common RF related
questions written in an accessible form (compared to standard EE / RF
engineering references), so if you plan on doing a fair bit of SDR
work I would recommend getting a recent copy.
-Michael Taylor, VE3TIX
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Re: [Discuss-gnuradio] USRP and USB full speed (1.1) transmit
On Thu, Dec 07, 2006 at 08:48:54AM -0500, Philip Balister wrote: > I've been working on adding USB1.1 (full speed) support to the USRP > software/firmware so I can use it with a TI OSK board. I've been going > back and forth with Matt on some issues and we are getting out of his > area of expertise. Here is summary of progress to date. > > After modifying the 8051 code I had the following behavior: > > When I compile the code for the OSK, I see two symbols transmitted, > then dead air. Two symbols is 64 bytes (2 symbols x 8 sample/symbol x > 4 bytes/sample), then there are 512 - 64 bytes of no signal. It feels > like the 64 byte packets are read into a buffer of 512 bytes, where > all the un-written bytes are zeros. > It feels like somewhere in the USB chain, I send the 64 byte packet, > then something reads the 64 bytes and zero pads the packet to 512 > bytes. I suspect the FPGA tries to read 512 bytes from the FX2 chip, > but that is only because this is the area of the code I least > understand :) Unless your FX2 code sets up the transfer size to 64, then this is probably what is happening. That is, the host is sending 64 bytes, but the FX2 is ignoring the real length, and is assuming that it's 512 bytes. Or see below, about the GPIF DMA program still tranfering 256 16-bit values. > Matt suggested the following FPGA change, and I also chnaged a similar > construct a few lines further on: > > http://gnuradio.utah.edu/trac/browser/gnuradio/trunk/usrp/fpga/sdr_lib/tx_buffer.v > > And look at line 94, you will see the test for "end of packet". > write_count[8] goes high when we have put 256 elements (512 bytes) into > the fifo. You would need to modify this to write_count[5] which will go > high when 32 elements (64 bytes) have been put into the fifo. > > This results in: > > Well, it looks like data is coming out, but it looks like I get 64 > bytes out, then there is a "hiccup" about 5 microseconds long. I am > getting suspicious the OSK doesn't get the data on the USB bus fast > enough. I'm still not entirely clear how the FX2 works. I am wondering > if there is a way to let the buffers in the FX2 chip fill up more > before the FPGA starts pulling data from the FX2. Remember that the GPIF is currently set up to DMA 256 16-bit values. Perhaps that part needs changing. The magic value is probably buried in the WaveData table in usrp_gpif.c Another thing you could try is to set up the GPIF in a non-flowstate mode. You'd need to use the Cypress tool to do this (or Larry Doolittle's perl (?) code. Running in full speed, you don't need to be able to burst data at 96MB/sec between the FX2 and FPGA. Philip, do you have access to a logic analyzer? It would extremely helpful for determining what's really happening between the FX2 and FPGA. Eric ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
RE: [Discuss-gnuradio] Problem using benchmark_rx.py
Tarun,
> From: Tarun Tiwari [mailto:[EMAIL PROTECTED]
>
> Thank you Tom,
>
> I did change the bit rate for Rx and used -v mode, but its still not
working. Please see the output of program:
>
> Transmitter:
> [EMAIL PROTECTED] ~]# ./benchmark_tx.py -f 100e6 --tx-amplitude=500 -M 2 -r
100e3 -v
> >>> gr_fir_fff: using SSE
> bits per symbol = 1
> Gaussian filter bt = 0.35
> Using TX d'board A: Basic Tx
> Tx amplitude 500.0
> modulation: gmsk_mod
> bitrate: 100kb/s
> samples/symbol: 4
> interp: 320
> Tx Frequency: 100M
>...
>
>.
>
>
> Receiver:
> [EMAIL PROTECTED] ~]# ./benchmark_rx.py -f 100e6 -r 100e3 -v
> >>> gr_fir_fff: using SSE
> bits per symbol = 1
> M&M clock recovery omega = 4.00
> M&M clock recovery gain mu = 0.05
> M&M clock recovery mu = 0.50
> M&M clock recovery omega rel. limit = 0.005000
> frequency error = 0.00
> Using RX d'board A: Basic Rx
> Rx gain: 10
> modulation: gmsk_demod
> bitrate: 100kb/s
> samples/symbol: 4
> decim: 160
> Rx Frequency: 100M
>
>
>
> I am connecting the the two boards using cables using -32dB RF attenuator
on each port of daughterboards.
>
> I am using Basic Tx and Basic Rx Boards.
That's what I thought. You can't transmit at 100 MHz with the Basic boards
(DAC is 128 Msps; you can really only transmit up to 44 MHz). Cut it down to
something like 20 MHz.
> Please advise me, if I need to do some changes in benchmark_rx.py program.
And meanwhile, can you tell me do we need to call any function between
>
> fg.start() # start flow graph
> fg.wait() # wait for it to finish
>
> To debug the program, I tried printing something inside rx_callback
subroutine, but I think rx_callback is not being called anywhere in the
program, thats why I am > not able to see any printed output on screen. Am I
right? I tried this one:
>
> def rx_callback(ok, payload):
> global n_rcvd, n_right
> (pktno,) = struct.unpack('!H', payload[0:2])
> n_rcvd += 1
> if ok:
> n_right += 1
> print "Hello Tarun\n"
> print "ok = %5s pktno = %4d n_rcvd = %4d n_right = %4d" % (
> ok, pktno, n_rcvd, n_right)
>
>
> but no result
> Please advise me.
The rx_callback function only gets called if a packet is seen, which means
correlating with the access code, so unless you're receiving packets, you'll
never enter this function. Hopefully the change in carrier frequency will
fix it.
Tom
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[Discuss-gnuradio] Attenuators ?
Hello everyone, I want to be able to capture RF data from one wireless card using gnuradio without any external interference. I was thinking of using an attenuator (with SMA or BNC connectors) one end of which I can connect to a wireless card and the other end to gnuradio board. I have some PCMCIA wireless cards which have the BNC-F interface. Two questions: 1. What is the minimum attenuation required so that I dont end up frying the boards? 2. I would like to have the attenuation to be "tunable". Do you know of any tunable attenuators (preferably low cost) which fit my requirements? Thanks a ton! Shravan ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Problem using benchmark_rx.py
On Thu, Dec 07, 2006 at 12:20:20PM -0700, Tarun Tiwari wrote: > Thank you Tom, > > I did change the bit rate for Rx and used -v mode, but its still not > working. Please see the output of program: Since you are using the Basic Tx, try removing the attenuator. Also, be sure to set the gains on both tx and rx to their maximum values. Eric ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Attenuators ?
On Friday 08 December 2006 08:40, Shravan Rayanchu wrote: > Hello everyone, > > I want to be able to capture RF data from one wireless card using > gnuradio without any external interference. I was thinking of using an > attenuator (with SMA or BNC connectors) one end of which I can connect > to a wireless card and the other end to gnuradio board. I have some > PCMCIA wireless cards which have the BNC-F interface. > > Two questions: > > 1. What is the minimum attenuation required so that I dont end up > frying the boards? You should be save by inserting 40db attentuation. > 2. I would like to have the attenuation to be "tunable". Do you know > of any tunable attenuators (preferably low cost) which fit my > requirements? Have a look on ebay. There are plenty of adjustable (not frequency tunable) attentuators and fixed attentuators for sale. cheerio Berndt ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] RF Energy during pkt reception (spectrum sense + bbn code)
Hello everyone, I am trying to plot the RF power spectrum obtained a during packet reception. For this, I have merged usrp_spectrum_sense.py with bbn_80211_rx.py. To make it easier to understand, I have put a figure illustrating the resultant flow graph at http://www.cs.wisc.edu/~shravan/pkt_energy.jpg usrp_c is used as a source and then there are two separate paths that the samples take. One gives us the power spectrum and the other tells us whenever a packet is received. I am basically interested in knowing the output of the power spectrum part when a packet is received on the bbn part of the flow graph i.e. I want to "plot the power spectrum for exactly those samples which result in a packet being received on the bbn part of the flow graph". The problem I am facing is how to correlate the samples i.e. how would I know which samples resulted in a packet and then plot the spectrum for those samples ...? Can I keep track of something like a global sample number which I can use .. ? The issue seems to be complicated because of how scheduling is performed .. I would appreciate it if you can throw in ideas .. Thanks for the help, Shravan ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
