Re: [Discuss-gnuradio] Resistance? Capacitance? Inductance?
On Tue, Feb 26, 2013 at 04:10:55PM -0600, Joel Mayer wrote: Dear GNU Radio aficionado's- Whatever happened to resistance, capacitance, and inductance? When I joined this thread I was hoping you would once in a while talk about ways of using the software in the computer to modify the resonant circuit in the hardware radio by making adjustments to the resistors, capacitors, and inductors. Oh, one of my favourite topics :) I'll have to point out that I'm completely biased here: When I started playing around with radio, the thingy between antenna and the computer was a total black box, just producing the bits and bytes I needed. In fact, that's what got me attracted to the SDR world, because I could already program, but those Smith charts... but that's not the point. First, I'll give you a practical answer: This mailing list is about GNU Radio, which is in a sense very hardware-independent. So there you go. But it's also very important to understand that Software Radio is not about modelling hardware. Using software allows the use of DSP, which means we can do stuff like linear-phase filters etc. (good luck tuning your R/C/I to do that), and we can create transceivers for digitally modulated signals very easily, which is really awkward in discrete hardware (although analog modulations are also easily coded). So, perhaps I just misunderstood your question. But despite not knowing how you would modify an inductor through software, this wouldn't help in building a transceiver that, upon sensing a change in the radio environment, would reconfigure itself and change the waveform used-- which is one goal of GNU Radio. Of course, this comes with some abstraction, which means that changing the resonant circuit of my USRP is nothing more than a library call to set_center_frequency() or whatever it's called. MB -- Karlsruhe Institute of Technology (KIT) Communications Engineering Lab (CEL) Dipl.-Ing. Martin Braun Research Associate Kaiserstraße 12 Building 05.01 76131 Karlsruhe Phone: +49 721 608-43790 Fax: +49 721 608-46071 www.cel.kit.edu KIT -- University of the State of Baden-Württemberg and National Laboratory of the Helmholtz Association pgpG31DzLG2VC.pgp Description: PGP signature ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Resistance? Capacitance? Inductance?
Timothy L. Vance Chief Engineer, Expeditionary Electronic Warfare Naval Surface Warfare Center, Crane Building 3330N, 300 Hwy 361 Crane, IN 47522 Office: 812-854-5499 Cell: 812-296-1192 Email: timothy.va...@navy.mil SIPR:timothy.va...@navy.smil.mil ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Resistance? Capacitance? Inductance?
On Tue, Feb 26, 2013 at 5:10 PM, Joel Mayer joelm_armill...@msn.com wrote: ** Dear GNU Radio aficionado's- Whatever happened to resistance, capacitance, and inductance? When I joined this thread I was hoping you would once in a while talk about ways of using the software in the computer to modify the resonant circuit in the hardware radio by making adjustments to the resistors, capacitors, and inductors. Am I just dreaming? Am I on the wrong page? Is there any hope? Resistance? As in uprising? Ah a DSP counter revolution!! :-) Are you referring to the stuff in the black (err... white) box known as the USRP? ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio -- M. Ranganathan ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Resistance? Capacitance? Inductance?
On Wed, Feb 27, 2013 at 3:04 AM, Martin Braun (CEL) martin.br...@kit.edu wrote: On Tue, Feb 26, 2013 at 04:10:55PM -0600, Joel Mayer wrote: Dear GNU Radio aficionado's- Whatever happened to resistance, capacitance, and inductance? When I joined this thread I was hoping you would once in a while talk about ways of using the software in the computer to modify the resonant circuit in the hardware radio by making adjustments to the resistors, capacitors, and inductors. Oh, one of my favourite topics :) I'll have to point out that I'm completely biased here: When I started playing around with radio, the thingy between antenna and the computer was a total black box, just producing the bits and bytes I needed. In fact, that's what got me attracted to the SDR world, because I could already program, but those Smith charts... but that's not the point. First, I'll give you a practical answer: This mailing list is about GNU Radio, which is in a sense very hardware-independent. So there you go. But it's also very important to understand that Software Radio is not about modelling hardware. Using software allows the use of DSP, which means we can do stuff like linear-phase filters etc. (good luck tuning your R/C/I to do that), and we can create transceivers for digitally modulated signals very easily, which is really awkward in discrete hardware (although analog modulations are also easily coded). So, perhaps I just misunderstood your question. But despite not knowing how you would modify an inductor through software, this wouldn't help in building a transceiver that, upon sensing a change in the radio environment, would reconfigure itself and change the waveform used-- which is one goal of GNU Radio. Of course, this comes with some abstraction, which means that changing the resonant circuit of my USRP is nothing more than a library call to set_center_frequency() or whatever it's called. MB On the other hand, one of the major areas of work that we are still pursuing lies in the RF front end. We have wideband systems. Ettus has produced a number of daughterboards that cover multiple GHz of spectrum, which is fantastic. But through that, we suffer a bit on the amplifiers and filters needed for some kinds of communications tasks. What Ettus has done is produced very good IP3s, NFs, gains, etc over these large bandwidths, but that doesn't exactly compare to having a filter and amplifier specific to a small bandwidth for something like cellular communications. Or even, for that matter, antennas for various waveforms. Even today's wideband RFICs tend to have a lot of tweakable/tunable parameters to meet specific needs of different areas of spectrum. Are there software solutions that could be used to automatically adjust these parameters? Or an RLC matching circuit? Some of this, I know, requires advances in the materials and components to make any sense, in other cases the feedback loop could be a bit long to make any significant impact. But it's fun to think about. Goes back to my dissertation days, actually :) Tom ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Resistance? Capacitance? Inductance?
On 27/02/13 10:08 AM, Tom Rondeau wrote: On the other hand, one of the major areas of work that we are still pursuing lies in the RF front end. We have wideband systems. Ettus has produced a number of daughterboards that cover multiple GHz of spectrum, which is fantastic. But through that, we suffer a bit on the amplifiers and filters needed for some kinds of communications tasks. What Ettus has done is produced very good IP3s, NFs, gains, etc over these large bandwidths, but that doesn't exactly compare to having a filter and amplifier specific to a small bandwidth for something like cellular communications. Or even, for that matter, antennas for various waveforms. Even today's wideband RFICs tend to have a lot of tweakable/tunable parameters to meet specific needs of different areas of spectrum. Are there software solutions that could be used to automatically adjust these parameters? Or an RLC matching circuit? Some of this, I know, requires advances in the materials and components to make any sense, in other cases the feedback loop could be a bit long to make any significant impact. But it's fun to think about. Goes back to my dissertation days, actually :) Tom In some sense, what we're talking about here is the difference between Software *Controlled* Radio, and Software *Defined* Radio. A chain of DSP blocks applies a series of mathematical transforms to a digitized signal, in similar ways to the way a series of R/L/C/Gain components do to an analog signal. One can think of the R/L/C approach as performing rough *approximations* to a transform that is defined in strict mathematical terms. The DSP approach, in general, is able to achieve a higher fidelity of those transforms with a higher degree of flexibility and reconfigurability than could possibly be achieved with analog hardware. Although, at some considerable cost--a simple FM demodulator chip is $0.35 in bulk, whereas the amount of compute-gear you require to do the same thing is considerably more costly. But DSP/SDR doesn't require that you break out the soldering iron and parts bin every time you want to tweak/repurpose things. Now, having said that, the notion of having some kind of tracking filtering isn't a bad idea, the problem comes down to implementation, and the cost trade-offs involved. Considering things like daughter cards covering 30Mhz to 4.4Ghz, exactly how many cuts across that bandwidth do you make, and how much are people willing to pay for additional dynamic range implied by band-limiting at the RF end of things? The technology is mostly there -- GaAsFET RF switches, LTCC filter modules, saw filters, dielectric filters, etc, are all out there. But almost any hard decision made by the manufacturer in such things is likely to be wrong in enough cases that perhaps all of that should be done externally to a daughtercard, with provision for a generic switching interface (like the existing GPIOs on many Ettus daughtercards). In an ideal world, you wouldn't need much front-end filtering. Your gain stages would be uber-linear up to ridiculous input powers, and you'd have a 24-bit ADC sampling at several Gsps. We aren't anywhere near there yet. -- 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] Resistance? Capacitance? Inductance?
On Wed, Feb 27, 2013 at 11:38 AM, Marcus D. Leech mle...@ripnet.com wrote: On 27/02/13 10:08 AM, Tom Rondeau wrote: On the other hand, one of the major areas of work that we are still pursuing lies in the RF front end. We have wideband systems. Ettus has produced a number of daughterboards that cover multiple GHz of spectrum, which is fantastic. But through that, we suffer a bit on the amplifiers and filters needed for some kinds of communications tasks. What Ettus has done is produced very good IP3s, NFs, gains, etc over these large bandwidths, but that doesn't exactly compare to having a filter and amplifier specific to a small bandwidth for something like cellular communications. Or even, for that matter, antennas for various waveforms. Even today's wideband RFICs tend to have a lot of tweakable/tunable parameters to meet specific needs of different areas of spectrum. Are there software solutions that could be used to automatically adjust these parameters? Or an RLC matching circuit? Some of this, I know, requires advances in the materials and components to make any sense, in other cases the feedback loop could be a bit long to make any significant impact. But it's fun to think about. Goes back to my dissertation days, actually :) Tom In some sense, what we're talking about here is the difference between Software *Controlled* Radio, and Software *Defined* Radio. A chain of DSP blocks applies a series of mathematical transforms to a digitized signal, in similar ways to the way a series of R/L/C/Gain components do to an analog signal. One can think of the R/L/C approach as performing rough *approximations* to a transform that is defined in strict mathematical terms. The DSP approach, in general, is able to achieve a higher fidelity of those transforms with a higher degree of flexibility and reconfigurability than could possibly be achieved with analog hardware. Although, at some considerable cost--a simple FM demodulator chip is $0.35 in bulk, whereas the amount of compute-gear you require to do the same thing is considerably more costly. But DSP/SDR doesn't require that you break out the soldering iron and parts bin every time you want to tweak/repurpose things. Now, having said that, the notion of having some kind of tracking filtering isn't a bad idea, the problem comes down to implementation, and the cost trade-offs involved. Considering things like daughter cards covering 30Mhz to 4.4Ghz, exactly how many cuts across that bandwidth do you make, and how much are people willing to pay for additional dynamic range implied by band-limiting at the RF end of things? The technology is mostly there -- GaAsFET RF switches, LTCC filter modules, saw filters, dielectric filters, etc, are all out there. But almost any hard decision made by the manufacturer in such things is likely to be wrong in enough cases that perhaps all of that should be done externally to a daughtercard, with provision for a generic switching interface (like the existing GPIOs on many Ettus daughtercards). Well said. In an ideal world, you wouldn't need much front-end filtering. Your gain stages would be uber-linear up to ridiculous input powers, and you'd have a 24-bit ADC sampling at several Gsps. We aren't anywhere near there yet. Yeah that's a hard one to swallow. The near-far problem in some bands makes even what you're considering here problematic. ~140 dB dynamic range does sound pretty good for most things, though :) There are other proposed solutions out there that take this concept even farther but require much greater investment in hardware cost (we're talking multiple ADCs, DSP units, etc.). But we're still going to need front end filtering and amplifiers for a while longer. Oh, and let's still not forget the antenna, though there are decent solutions for narrowband signals over large bandwidths (that is, good performance over a large bandwidth with varying group delays along the way, so you can only get away with narrowband signals or clever correction algorithms). Tom -- 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] Resistance? Capacitance? Inductance?
On Wed, Feb 27, 2013 at 11:52 AM, Tom Rondeau t...@trondeau.com wrote: On Wed, Feb 27, 2013 at 11:38 AM, Marcus D. Leech mle...@ripnet.com wrote: On 27/02/13 10:08 AM, Tom Rondeau wrote: On the other hand, one of the major areas of work that we are still pursuing lies in the RF front end. We have wideband systems. Ettus has produced a number of daughterboards that cover multiple GHz of spectrum, which is fantastic. But through that, we suffer a bit on the amplifiers and filters needed for some kinds of communications tasks. What Ettus has done is produced very good IP3s, NFs, gains, etc over these large bandwidths, but that doesn't exactly compare to having a filter and amplifier specific to a small bandwidth for something like cellular communications. Or even, for that matter, antennas for various waveforms. Even today's wideband RFICs tend to have a lot of tweakable/tunable parameters to meet specific needs of different areas of spectrum. Are there software solutions that could be used to automatically adjust these parameters? Or an RLC matching circuit? Some of this, I know, requires advances in the materials and components to make any sense, in other cases the feedback loop could be a bit long to make any significant impact. But it's fun to think about. Goes back to my dissertation days, actually :) Tom In some sense, what we're talking about here is the difference between Software *Controlled* Radio, and Software *Defined* Radio. A chain of DSP blocks applies a series of mathematical transforms to a digitized signal, in similar ways to the way a series of R/L/C/Gain components do to an analog signal. One can think of the R/L/C approach as performing rough *approximations* to a transform that is defined in strict mathematical terms. The DSP approach, in general, is able to achieve a higher fidelity of those transforms with a higher degree of flexibility and reconfigurability than could possibly be achieved with analog hardware. Although, at some considerable cost--a simple FM demodulator chip is $0.35 in bulk, whereas the amount of compute-gear you require to do the same thing is considerably more costly. But DSP/SDR doesn't require that you break out the soldering iron and parts bin every time you want to tweak/repurpose things. Now, having said that, the notion of having some kind of tracking filtering isn't a bad idea, the problem comes down to implementation, and the cost trade-offs involved. Considering things like daughter cards covering 30Mhz to 4.4Ghz, exactly how many cuts across that bandwidth do you make, and how much are people willing to pay for additional dynamic range implied by band-limiting at the RF end of things? The technology is mostly there -- GaAsFET RF switches, LTCC filter modules, saw filters, dielectric filters, etc, are all out there. But almost any hard decision made by the manufacturer in such things is likely to be wrong in enough cases that perhaps all of that should be done externally to a daughtercard, with provision for a generic switching interface (like the existing GPIOs on many Ettus daughtercards). Well said. In an ideal world, you wouldn't need much front-end filtering. Your gain stages would be uber-linear up to ridiculous input powers, and you'd have a 24-bit ADC sampling at several Gsps. We aren't anywhere near there yet. Yeah that's a hard one to swallow. The near-far problem in some bands makes even what you're considering here problematic. ~140 dB dynamic range does sound pretty good for most things, though :) There are other proposed solutions out there that take this concept even farther but require much greater investment in hardware cost (we're talking multiple ADCs, DSP units, etc.). But we're still going to need front end filtering and amplifiers for a while longer. Oh, and let's still not forget the antenna, though there are decent solutions for narrowband signals over large bandwidths (that is, good performance over a large bandwidth with varying group delays along the way, so you can only get away with narrowband signals or clever correction algorithms). Tom -- Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org For those interested, this DARPA project was pointed out to me: https://www.fbo.gov/index?s=opportunitymode=formid=7c438631d57659b7b9f932df6d3da484tab=core_cview=1 Here's a brief write-up that summarizes the effort (apologies for the in-your-face ad at the top): http://www.militaryaerospace.com/articles/2012/08/darpa-rf-fpga.html Tom ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Resistance? Capacitance? Inductance?
On 27/02/13 05:45 PM, Tom Rondeau wrote: For those interested, this DARPA project was pointed out to me: https://www.fbo.gov/index?s=opportunitymode=formid=7c438631d57659b7b9f932df6d3da484tab=core_cview=1 Here's a brief write-up that summarizes the effort (apologies for the in-your-face ad at the top): http://www.militaryaerospace.com/articles/2012/08/darpa-rf-fpga.html Tom Some of the commercial broadish-band tuner chips already have some of this with switchable 3rd-order filter networks on-chip (or partially on-chip). The E4000, R820T, TDA18272, and others have some of this, targetted at the DVB-T/ATSC markets. -- 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] Resistance? Capacitance? Inductance?
http://staff.washington.edu/jon/gr-mrfm/ USRP and GNU Radio controlling micromechanical oscillators for Magnetic Resonance Force Microscopy (MRFM). Does that count? -John On Tue, Feb 26, 2013 at 2:10 PM, Joel Mayer joelm_armill...@msn.com wrote: ** Dear GNU Radio aficionado's- Whatever happened to resistance, capacitance, and inductance? When I joined this thread I was hoping you would once in a while talk about ways of using the software in the computer to modify the resonant circuit in the hardware radio by making adjustments to the resistors, capacitors, and inductors. Am I just dreaming? Am I on the wrong page? Is there any hope? ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio