Re: [Discuss-gnuradio] xlating filter will introduce phase shift
Hi Tom, the xlating filter work fine, the phase shift is cause by another factor. Thanks for your reply. On Sun, Aug 14, 2011 at 4:17 AM, Tom Rondeau wrote: > On Fri, Aug 12, 2011 at 3:50 AM, Page Jack wrote: > > I use xlating filter to down convert signal. after I down convert signal > it > > I decode it. > > however the data decoded is still the signal in 0 frequency before down > > convert. > > I check the xlating filter code it will change the signal phase to avoid > > aliasing, yeah > > it avoid aliasing but it is not the data I want how can I recover the > data's > > phase after > > xlating filter? > > > > Regards! > > Those filters are implemented as FIRs, which means they will have > linear phase in the passband and constant (and known) group delay. > > In general, though, you will never know the phase of the incoming > signal received over the air. If you have a signal where you require > the phase, you'll have to figure out a way to recover it, anyways. > > Tom > ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Configuring the slave for MIMO cable
That makes perfect sense now, thanks. Now that there are 2 channels I have 2 outputs which I can't directly feed into my demodulator/decoder. Is there a way in GRC to combine the 2 streams in order to only have 1 demod/decoder with the hopes of observing the array gain from the 2nd USRP at my output? Josh Blum-3 wrote: > > > > > Use exactly one source block w/ 2 channels. That way, uhd performs the > time-alignment of the streams. > > Example of the device addressing for multiple mboards: > http://www.ettus.com/uhd_docs/manual/html/usrp2.html#multiple-device-configuration > > -josh > > ___ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > -- View this message in context: http://old.nabble.com/Configuring-the-slave-for-MIMO-cable-tp32235863p32266765.html Sent from the GnuRadio mailing list archive at Nabble.com. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Configuring the slave for MIMO cable
On 08/15/2011 12:07 PM, wes.rumble wrote: > > I see what you meant Josh, thanks for your help. One more quick question, as > simple as it seems I still have to make sure. In the flowgraph in GRC I > will need 2 UHD sources right? One with the default ref source and one with Use exactly one source block w/ 2 channels. That way, uhd performs the time-alignment of the streams. Example of the device addressing for multiple mboards: http://www.ettus.com/uhd_docs/manual/html/usrp2.html#multiple-device-configuration -josh ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Configuring the slave for MIMO cable
I see what you meant Josh, thanks for your help. One more quick question, as simple as it seems I still have to make sure. In the flowgraph in GRC I will need 2 UHD sources right? One with the default ref source and one with the MIMO cable as its source. Assuming that's correct, is there a way I can add the 2 streams in order to decode the incoming data, (in my case streaming video)? -- View this message in context: http://old.nabble.com/Configuring-the-slave-for-MIMO-cable-tp32235863p32266652.html Sent from the GnuRadio mailing list archive at Nabble.com. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] The format of I/Q sample
Hi, Marcus, Thanks a lot! We will look into the UHD source code. Best regards, Yooxi Marcus D. Leech wrote: > >> Hi, Marcus, >> >> Thanks a lot for your quick reply! >> Then start from where, the integers become floating point numbers? >> I'd like to see how they are converted. >> >> Thanks, >> Yooxi >> > They are never floating-point numbers inside the FPGA or on the host > interface. For UHD, they get scaled and converted >inside the appropriate files. I can't tell you which specific file, > but the UHD source code is available, and I'm sure Josh >could tell you where the conversion between host-transport-format and > gnuradio-format happens with UHD/gr-uhd. > > -- > Marcus Leech > Principal Investigator > Shirleys Bay Radio Astronomy Consortium > http://www.sbrac.org > > > > ___ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > -- View this message in context: http://old.nabble.com/The-format-of-I-Q-sample-tp32262153p32266153.html Sent from the GnuRadio mailing list archive at Nabble.com. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] The format of I/Q sample
Hi, Marcus, Thanks a lot for your quick reply! Then start from where, the integers become floating point numbers? I'd like to see how they are converted. Thanks, Yooxi They are never floating-point numbers inside the FPGA or on the host interface. For UHD, they get scaled and converted inside the appropriate files. I can't tell you which specific file, but the UHD source code is available, and I'm sure Josh could tell you where the conversion between host-transport-format and gnuradio-format happens with UHD/gr-uhd. -- Marcus Leech Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] The format of I/Q sample
Hi, Marcus, Thanks a lot for your quick reply! Then start from where, the integers become floating point numbers? I'd like to see how they are converted. Thanks, Yooxi Marcus D. Leech wrote: > > On 08/15/2011 01:22 PM, xi yang wrote: >> Hi, Tom, >> >> Thanks a lot for your prompt reply! >> Do you mean on the Transmitting side? >> I want to know how 32-bit floating point number is converted to 16bits >> or from 16bits to 32bits. >> Where can I find the file that performs this conversion? >> >> We are actually working on the Receiving side. >> Before we move I/Q samples from rx_buffer to USB, we want to do FFT >> and deliver the FFT results instead of the raw I/Q samples to the host. >> For my FPGA FFT module, I use 32bits floating point numbers as input. >> So I want to know how the I/Q samples are represented by 16bits so >> that I can convert them to 32bits. >> In 32bits representation, bits 0 through 22 form the mantissa, bits 23 >> through 30 form the exponent, and bit 31 is the sign bit. >> In 16bits, do we simply cut 16bits of the mantissa? >> Then bits 0 through 6 form the mantissa, bits7 through 14 form the >> exponent,and bit 15 is the sign bit. Is that right? >> It's better if we can have a look at the conversion file. >> Thanks, >> Yooxi >> > The host interface uses 16-bit integers for I and Q. They're only > represented as floating-point numbers within a Gnu Radio flow-graph. > > Internally in the FPGA, everything is integers, starting with 12-bit > integers from the ADC (on the USRP1), then through the CIC decimators >and DDC, they become larger, but what is finally injected into the > host is 16-bit (integer) I and 16-bit (integer) Q. >Standard twos-complement representation for the integers, I don't > happen to recall off the top of my head whether they're "big endian" >or "little endian". > > > > > > > -- > Marcus Leech > Principal Investigator > Shirleys Bay Radio Astronomy Consortium > http://www.sbrac.org > > > > ___ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > -- View this message in context: http://old.nabble.com/The-format-of-I-Q-sample-tp32262153p32266070.html Sent from the GnuRadio mailing list archive at Nabble.com. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] The format of I/Q sample
On 08/15/2011 01:22 PM, xi yang wrote: Hi, Tom, Thanks a lot for your prompt reply! Do you mean on the Transmitting side? I want to know how 32-bit floating point number is converted to 16bits or from 16bits to 32bits. Where can I find the file that performs this conversion? We are actually working on the Receiving side. Before we move I/Q samples from rx_buffer to USB, we want to do FFT and deliver the FFT results instead of the raw I/Q samples to the host. For my FPGA FFT module, I use 32bits floating point numbers as input. So I want to know how the I/Q samples are represented by 16bits so that I can convert them to 32bits. In 32bits representation, bits 0 through 22 form the mantissa, bits 23 through 30 form the exponent, and bit 31 is the sign bit. In 16bits, do we simply cut 16bits of the mantissa? Then bits 0 through 6 form the mantissa, bits7 through 14 form the exponent,and bit 15 is the sign bit. Is that right? It's better if we can have a look at the conversion file. Thanks, Yooxi The host interface uses 16-bit integers for I and Q. They're only represented as floating-point numbers within a Gnu Radio flow-graph. Internally in the FPGA, everything is integers, starting with 12-bit integers from the ADC (on the USRP1), then through the CIC decimators and DDC, they become larger, but what is finally injected into the host is 16-bit (integer) I and 16-bit (integer) Q. Standard twos-complement representation for the integers, I don't happen to recall off the top of my head whether they're "big endian" or "little endian". -- Marcus Leech Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] The format of I/Q sample
Hi, Tom, Thanks a lot for your prompt reply! Do you mean on the Transmitting side? I want to know how 32-bit floating point number is converted to 16bits or from 16bits to 32bits. Where can I find the file that performs this conversion? We are actually working on the Receiving side. Before we move I/Q samples from rx_buffer to USB, we want to do FFT and deliver the FFT results instead of the raw I/Q samples to the host. For my FPGA FFT module, I use 32bits floating point numbers as input. So I want to know how the I/Q samples are represented by 16bits so that I can convert them to 32bits. In 32bits representation, bits 0 through 22 form the mantissa, bits 23 through 30 form the exponent, and bit 31 is the sign bit. In 16bits, do we simply cut 16bits of the mantissa? Then bits 0 through 6 form the mantissa, bits7 through 14 form the exponent,and bit 15 is the sign bit. Is that right? It's better if we can have a look at the conversion file. Thanks, Yooxi 2011/8/15 Tom Rondeau > On Mon, Aug 15, 2011 at 12:48 AM, xi yang wrote: > > Hi, all > > > > I want to use fpga to do FFT before the data are transmitted to usb. > > > > In FFT module, I used float point numbers to be its input. According to > the > > IEEE Floating-Point Standard, a float point number is represented by 32 > bits > > (bits 0 through 22 form the mantissa, bits 23 through 30 form the > exponent, > > and bit 31 is the sign bit). However, in GNU Radio, the UHD drive sends > > 16bits I, and 16bits Q. > > > > Are I and Q float point numbers? How do the 16bits represent a float > number? > > Any suggestion about the I/Q's format is appreciated! > > > > Thanks, > > Yooxi > > The interface to the USRP is defined to take floating point numbers. > It will perform the conversion to the 16-bit shorts that are sent over > the wire for you. Also remember that the output of the FFT is a > vector, so you'll want to use the gr_vector_to_stream block to convert > it back to a stream of floating point samples. > > Tom > ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] benchmark OFDM Question
Hello Tom, Thank you so much Tom for your quick response.. yes i have found the code scripts in gnurdio-examples/python/ofdm. Please help me to implment this in GRC. i dont know how to use this code to make simulation blocks in SDR.. where i have to put this code to make simulation ? i am looking forward to hearfrom you. Thanks for ur help... Thanks and Regards, Waqas. waqa...@hotmail.com waqasme wrote: > > Thank you so much Tom for your quick response.. yes i have found the code > scripts in gnurdio-examples/python/ofdm. > But iam not sure how to implement this code to make simulation in GNU > radio. could you please explain in bit detail how to use this code to make > the tranmission and reception blocks in GNU Radio. I will really > appriciate if you kindly guide me how to make this simulation work. Thanks > for your help and for your valuable information. looking forward to hear > from you. > > Regards, > > Waqas. > waqa...@hotmail.com > On Sat, Aug 13, 2011 at 11:38 AM, waqasme wrote: >> Hi Everyone/Smith, >> I am doin my M.Sc. project on OFDM Implementation in GNU RADIO (SDR) via >> USRP. >> I am quite new to GNU Radio i dont know much about its functions. I am >> looking for benchmark_ofdm.py file that i can use to implement the design >> n >> GNU radio and later on transmit and recieve via USRP. >> I will be very greatful to you if anyone of you send me the file or tell >> me >> where i can get all this info and how to implement (procedure). >> Thanks in advance... >> Waqas. > > In the source code, you can find these scripts in > gnurdio-examples/python/ofdm. > > Tom > > ___ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > -- View this message in context: http://old.nabble.com/benchmark-OFDM-Question-tp31765422p32265421.html Sent from the GnuRadio mailing list archive at Nabble.com. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] tx/rx vs rx2
hi, i have 2 rfx 1800 and am using one of the tx/rx connections for the only antenna i have. what is the difference between the tx/rx and the rx2 connection? i understand it's a very basic question though would appreciate an answer. thanks in advance, walter ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] The format of I/Q sample
On Mon, Aug 15, 2011 at 12:48 AM, xi yang wrote: > Hi, all > > I want to use fpga to do FFT before the data are transmitted to usb. > > In FFT module, I used float point numbers to be its input. According to the > IEEE Floating-Point Standard, a float point number is represented by 32 bits > (bits 0 through 22 form the mantissa, bits 23 through 30 form the exponent, > and bit 31 is the sign bit). However, in GNU Radio, the UHD drive sends > 16bits I, and 16bits Q. > > Are I and Q float point numbers? How do the 16bits represent a float number? > Any suggestion about the I/Q's format is appreciated! > > Thanks, > Yooxi The interface to the USRP is defined to take floating point numbers. It will perform the conversion to the 16-bit shorts that are sent over the wire for you. Also remember that the output of the FFT is a vector, so you'll want to use the gr_vector_to_stream block to convert it back to a stream of floating point samples. Tom ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
