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Sweeping the Si570

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  • Reginald Beardsley
    Has there been any discussion about sweeping the Si570 as a means of testing the BP filters during construction? This would require an outboard LO and mixer,
    Message 1 of 11 , Jul 1 2:12 PM
      Has there been any discussion about sweeping the Si570 as a means of testing the BP filters during construction?

      This would require an outboard LO and mixer, but could be very helpful for someone building w/ minimal equipment. A fast sweep would work well w/ a suitable scope. A slow multistep mode would allow checking them w/ only a meter.

      Have Fun!
      Reg

      BTW Tony very helpfully sent me the 3 pdf files. I eventually did see the sheet1 & sheet2 links in the "expert" section afterwards.
    • Roger Critchlow
      Sweeping isn t really possible, the Si570 tuning registers only go so far with smooth tuning updates to the tuning word before you need to reprogram the rest
      Message 2 of 11 , Jul 1 4:00 PM
        Sweeping isn't really possible, the Si570 tuning registers only go so far with smooth tuning updates to the tuning word before you need to reprogram the rest of the registers.  When you reprogram all the registers it takes a moment for the PLL to resettle, and the effects of that resettling are quite visible in the spectrum display and in the raw levels at the sound card input.

        I've written linux scripts using usbsoftrock to tune an RX ensemble through a range of frequencies and record the levels seen at the sound card, mostly looking for spur energies with a dummy load connected.  You need something that can grab a few buffers of input samples from the sound card and convert them to dB full scale.

        You could do the same with an external LO, but I think a broadband noise source or a frequency marker generator connected to the antenna input would give you a good idea of the filter envelope with a lot less fuss.  Getting a filter sweep would also require temporarily reprogramming the BPF limits in the ATTiny so it wouldn't automatically switch between filters.

        It could all be done with usbsoftrock, a sound card, one kind of source or another, something to read the soundcard level, and a bit of shell programming on linux.

        -- rec --

        On Sun, Jul 1, 2012 at 3:12 PM, Reginald Beardsley <pulaskite@...> wrote:
         

        Has there been any discussion about sweeping the Si570 as a means of testing the BP filters during construction?

        This would require an outboard LO and mixer, but could be very helpful for someone building w/ minimal equipment. A fast sweep would work well w/ a suitable scope. A slow multistep mode would allow checking them w/ only a meter.

        Have Fun!
        Reg

        BTW Tony very helpfully sent me the 3 pdf files. I eventually did see the sheet1 & sheet2 links in the "expert" section afterwards.


      • Reginald Beardsley
        Smooth tuning is not an issue, sampling the spectrum would suffice for checking the BP filters.    I haven t counted the number of poles, but they re not
        Message 3 of 11 , Jul 1 5:47 PM
          Smooth tuning is not an issue, sampling the spectrum would suffice for checking the BP filters.    I haven't counted the number of poles, but they're not very many so it has to be fairly smooth.

           I didn't realize that the bandswitching logic was in the ATTiny.  Are you sure about that?   I've downloaded the source, but not looked at it yet.  I'd assumed that bandswitching was done by commands sent over USB.  I really can't see a justification for it being in the ATTiny as it makes customizing the filters for other bands clumsy.
          The thing that interests me most about the Ensemble II is how simple and adaptable it is.

          Still, I don't think it's an issue during construction if the MUXes are not installed.  Feed a signal to the filter and pick it off at the output.  Then install the MUXes.

          Right now, I'm more concerned about mixer nonlinearity.  I hadn't realized that the Si570 produced a square wave clock.  Probably should have, but I skimmed over the data sheet the first time looking for how fast it would change frequency.  Reading more carefully I see it produces a square wave. So I need to evaluate what the outputs from a mixer would be for reasonable choices of frequency.

          Personally I've got plenty of  options. I've got an HP sweeper, but haven't powered it up in 15 years, so no idea if it still works.   I  just bought a Rigol DS1102E, so I can always feed a pulse train, average and do an FFT until I have time to fix the sweeper.

          My interest in using the Si570  to test the filters is a hangover from when I was a poor grad student trying to build radios w/o access to anything but a DVM and a 5 MHz recurrent sweep scope.  I'm sure there are many in that position today.

          I still have lots to do before I start assembly.  No point in measuring the filter response until I've calculated the transfer function.  I  will almost certainly spend 20+ hours on this before I turn on the iron and solder the first part.

          The only reason I bought a kit is the obstacle of learning to use a PCB design package.  I can't just sit w/ perfboard and a schematic the way I used to do.  Unfortunately, not just because of the lack of thru hole parts.  I built a RS-232 level shifter recently and was mortified at how badly it looked.  I used to be able to extemporize w/ a soldering iron, but 15 years of neglect have made me very clumsy :-(

          Have Fun!
          Reg


          --- On Sun, 7/1/12, Roger Critchlow <rec@...> wrote:

          From: Roger Critchlow <rec@...>
          Subject: Re: [softrock40] Sweeping the Si570
          To: softrock40@yahoogroups.com
          Date: Sunday, July 1, 2012, 6:00 PM

           

          Sweeping isn't really possible, the Si570 tuning registers only go so far with smooth tuning updates to the tuning word before you need to reprogram the rest of the registers.  When you reprogram all the registers it takes a moment for the PLL to resettle, and the effects of that resettling are quite visible in the spectrum display and in the raw levels at the sound card input.


          I've written linux scripts using usbsoftrock to tune an RX ensemble through a range of frequencies and record the levels seen at the sound card, mostly looking for spur energies with a dummy load connected.  You need something that can grab a few buffers of input samples from the sound card and convert them to dB full scale.

          You could do the same with an external LO, but I think a broadband noise source or a frequency marker generator connected to the antenna input would give you a good idea of the filter envelope with a lot less fuss.  Getting a filter sweep would also require temporarily reprogramming the BPF limits in the ATTiny so it wouldn't automatically switch between filters.

          It could all be done with usbsoftrock, a sound card, one kind of source or another, something to read the soundcard level, and a bit of shell programming on linux.

          -- rec --

          On Sun, Jul 1, 2012 at 3:12 PM, Reginald Beardsley <pulaskite@...> wrote:
           

          Has there been any discussion about sweeping the Si570 as a means of testing the BP filters during construction?

          This would require an outboard LO and mixer, but could be very helpful for someone building w/ minimal equipment. A fast sweep would work well w/ a suitable scope. A slow multistep mode would allow checking them w/ only a meter.

          Have Fun!
          Reg

          BTW Tony very helpfully sent me the 3 pdf files. I eventually did see the sheet1 & sheet2 links in the "expert" section afterwards.


        • EB4APL
          Hi Reginald, My comments are below. ... The ATTiny is the only device connected to the USB, it provides communication with the SDR program, decodes the
          Message 4 of 11 , Jul 1 6:52 PM
            Hi Reginald,

            My comments are  below.


            El 02/07/2012 2:47, Reginald Beardsley wrote:
             

            Smooth tuning is not an issue, sampling the spectrum would suffice for checking the BP filters.    I haven't counted the number of poles, but they're not very many so it has to be fairly smooth.

             I didn't realize that the bandswitching logic was in the ATTiny.  Are you sure about that?   I've downloaded the source, but not looked at it yet.  I'd assumed that bandswitching was done by commands sent over USB.  I really can't see a justification for it being in the ATTiny as it makes customizing the filters for other bands clumsy.

            The ATTiny is the only device connected to the USB, it provides communication with the SDR program, decodes the frequency change commands, applies calibration and commands the Si570.  And last, it commands the filters.  The filter changeover frequencies can be configured using CFGSR and the ATTiny  changes them automatically when your SDR program sends the frequency change commands.  Very clever.

            The thing that interests me most about the Ensemble II is how simple and adaptable it is.

            Still, I don't think it's an issue during construction if the MUXes are not installed.  Feed a signal to the filter and pick it off at the output.  Then install the MUXes.

            Right now, I'm more concerned about mixer nonlinearity.  I hadn't realized that the Si570 produced a square wave clock.  Probably should have, but I skimmed over the data sheet the first time looking for how fast it would change frequency.  Reading more carefully I see it produces a square wave. So I need to evaluate what the outputs from a mixer would be for reasonable choices of frequency.

            The mixer used in the Softrock series is a set of on-off switches configured as a quadrature sampling detector, also called a Tayloe detector.  They are different from classical mixers and I understand that they are very linear but I'm sure others can respond better with facts and figures.  They have their limitations at high frequencies so the VHF ensemble uses a conventional diode mixer for the first conversion.  And they also convert from even harmonics of the LO frequency, hence the low pas filters bank.

            73 de Ignacio, EB4APL


            Personally I've got plenty of  options. I've got an HP sweeper, but haven't powered it up in 15 years, so no idea if it still works.   I  just bought a Rigol DS1102E, so I can always feed a pulse train, average and do an FFT until I have time to fix the sweeper.

            My interest in using the Si570  to test the filters is a hangover from when I was a poor grad student trying to build radios w/o access to anything but a DVM and a 5 MHz recurrent sweep scope.  I'm sure there are many in that position today.

            I still have lots to do before I start assembly.  No point in measuring the filter response until I've calculated the transfer function.  I  will almost certainly spend 20+ hours on this before I turn on the iron and solder the first part.

            The only reason I bought a kit is the obstacle of learning to use a PCB design package.  I can't just sit w/ perfboard and a schematic the way I used to do.  Unfortunately, not just because of the lack of thru hole parts.  I built a RS-232 level shifter recently and was mortified at how badly it looked.  I used to be able to extemporize w/ a soldering iron, but 15 years of neglect have made me very clumsy :-(


            Have Fun!
            Reg


          • g8voip
            Hi Reg, Nothing clumsy about the ABPF switching control being within the AVR controller. It is a very elegent solution as it relies solely on the Si570
            Message 5 of 11 , Jul 1 11:08 PM
              Hi Reg,

              Nothing clumsy about the ABPF switching control being within the AVR controller.

              It is a very elegent solution as it relies solely on the Si570 frequency commands received from the SDR program via USB, so is totally independent of the SDR program being used.

              Before this, the original version of the AVR firmware was unable to control the filter switching so the SoftRock v9.0 started off with manual plug in filters like the v6.3 RXTX, followed then by the switched filter module, filters being selected with jumpers through to the first full electronic control.

              Its all been a logical progression to where we are now.

              Using the CFGSR utility you can customise the filter crossover points to cater for none standard filters or indeed make use of it in other ways. I have a set up with three SoftRock v9.0 receivers fitted with VHF converters for 6m, 4m and 2m and have the crossover points set to use the logic outputs to select the converter based on the frequency being tuned to. Very flexible.

              The point regarding smooth tuning etc, without using it, the output of the Si570 is inhibited for something like 200mS if my memory serves my right. This creates a large jump in any spectrum display so it would prevent meaningful continuous sweep results. Smooth tuning within the +/- 3000 ppm range reduces the inhibited time to 20mS. Once you go outside the +/- 3000 ppm range you get the longer inhibit as all the registers need to be rewritten.

              73, Bob G8VOI


              --- In softrock40@yahoogroups.com, Reginald Beardsley <pulaskite@...> wrote:
              >
              > Smooth tuning is not an issue, sampling the spectrum would suffice for checking the BP filters.    I haven't counted the number of poles, but they're not very many so it has to be fairly smooth.
              >
              >  I didn't realize that the bandswitching logic was in the ATTiny.  Are you sure about that?   I've downloaded the source, but not looked at it yet.  I'd assumed that bandswitching was done by commands sent over USB.  I really can't see a justification for it being in the ATTiny as it makes customizing the filters for other bands clumsy.
              > The thing that interests me most about the Ensemble II is how simple and adaptable it is.
              >
              > Still, I don't think it's an issue during construction if the MUXes are not installed.  Feed a signal to the filter and pick it off at the output.  Then install the MUXes.
              >
              > Right now, I'm more concerned about mixer nonlinearity.  I hadn't realized that the Si570 produced a square wave clock.  Probably should have, but I skimmed over the data sheet the first time looking for how fast it would change frequency.  Reading more carefully I see it produces a square wave. So I need to evaluate what the outputs from a mixer would be for reasonable choices of frequency.
              >
              > Personally I've got plenty of  options. I've got an HP sweeper, but haven't powered it up in 15 years, so no idea if it still works.   I  just bought a Rigol DS1102E, so I can always feed a pulse train, average and do an FFT until I have time to fix the sweeper.
              >
              > My interest in using the Si570  to test the filters is a hangover from when I was a poor grad student trying to build radios w/o access to anything but a DVM and a 5 MHz recurrent sweep scope.  I'm sure there are many in that position today.
              >
              > I still have lots to do before I start assembly.  No point in measuring the filter response
              > until I've calculated the transfer function.  I  will almost certainly
              > spend 20+ hours on this before I turn on the iron and solder the first
              > part.
              >
              > The only reason I bought a kit is the obstacle of learning to use a
              > PCB design package.  I can't just sit w/ perfboard and a schematic the
              > way I used to do.  Unfortunately, not just because of the lack of thru
              > hole parts.  I built a RS-232 level shifter recently and was mortified
              > at how badly it looked.  I used to be able to extemporize w/ a
              > soldering iron, but 15 years of neglect have made me very clumsy :-(
              >
              > Have Fun!
              > Reg
              >
              >
              > --- On Sun, 7/1/12, Roger Critchlow <rec@...> wrote:
              >
              > From: Roger Critchlow <rec@...>
              > Subject: Re: [softrock40] Sweeping the Si570
              > To: softrock40@yahoogroups.com
              > Date: Sunday, July 1, 2012, 6:00 PM
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              > Sweeping isn't really possible, the Si570 tuning registers only go so far with smooth tuning updates to the tuning word before you need to reprogram the rest of the registers.  When you reprogram all the registers it takes a moment for the PLL to resettle, and the effects of that resettling are quite visible in the spectrum display and in the raw levels at the sound card input.
              >
              > I've written linux scripts using usbsoftrock to tune an RX ensemble through a range of frequencies and record the levels seen at the sound card, mostly looking for spur energies with a dummy load connected.  You need something that can grab a few buffers of input samples from the sound card and convert them to dB full scale.
              >
              > You could do the same with an external LO, but I think a broadband noise source or a frequency marker generator connected to the antenna input would give you a good idea of the filter envelope with a lot less fuss.  Getting a filter sweep would also require temporarily reprogramming the BPF limits in the ATTiny so it wouldn't automatically switch between filters.
              >
              > It could all be done with usbsoftrock, a sound card, one kind of source or another, something to read the soundcard level, and a bit of shell programming on linux.
              > -- rec --
              >
              > On Sun, Jul 1, 2012 at 3:12 PM, Reginald Beardsley <pulaskite@...> wrote:
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              > Has there been any discussion about sweeping the Si570 as a means of testing the BP filters during construction?
              >
              >
              >
              > This would require an outboard LO and mixer, but could be very helpful for someone building w/ minimal equipment. A fast sweep would work well w/ a suitable scope. A slow multistep mode would allow checking them w/ only a meter.
              >
              >
              >
              >
              > Have Fun!
              >
              > Reg
              >
              >
              >
              > BTW Tony very helpfully sent me the 3 pdf files. I eventually did see the sheet1 & sheet2 links in the "expert" section afterwards.
              >
            • ae9rb
              ... I just finished writing code for the Si570 so this is fresher in my memory. The spec says in the section describing large frequency changes: The process
              Message 6 of 11 , Jul 2 12:50 AM
                --- In softrock40@yahoogroups.com, "g8voip" <g8voi.reeves59@...> wrote:
                > The point regarding smooth tuning etc, without using it, the output of the Si570 is inhibited for something like 200mS if my memory serves my right. This creates a large jump in any spectrum display so it would prevent meaningful continuous sweep results. Smooth tuning within the +/- 3000 ppm range reduces the inhibited time to 20mS. Once you go outside the +/- 3000 ppm range you get the longer inhibit as all the registers need to be rewritten.

                I just finished writing code for the Si570 so this is fresher in my memory.

                The spec says in the section describing large frequency changes: "The process of freezing and unfreezing the DCO will cause the output clock to momentarily stop and start at any arbitrary point during a clock cycle. This process can take up to 10 ms. Circuitry that is sensitive to glitches or runt pulses may have to be reset after the new frequency configuration is written."

                A change of less than 3500 ppm without altering HSDIV/N1 will only guarantee the clock is changed clean enough to not freak out things like microprocessors. It's 14 bytes plus framing over I2C to freeze, program, and unfreeze the Si570. Not changing the divider in a smooth tune only saves you a few bytes and you still must freeze or bad things happen.

                You can completely bypass the AVR logic and read/write the registers directly. Regardless if you do this or just the set freq command, the USB protocol and OS calls will start to factor in the timing.

                Reg, it's very easy to use another radio to make sure you aren't receiving 1/3rd and transmitting 2nd harmonics. So most hams already have the right tools. Also, the coils have had many years of scrutiny from thousands of builders and we don't see valid posts about filters needing adjustment. Mixing square waves on HF is like hitting the side of a barn with a (soft)rock. Wokka wokka.

                73 David AE9RB
              • Reginald Beardsley
                All, The Ensemble II is a very elegant design.  It s also extremely simple, so after an hour or two studying the schematic and reading the data sheet for the
                Message 7 of 11 , Jul 2 5:40 AM
                  All,

                  The Ensemble II is a very elegant design.  It's also extremely simple, so after an hour or two studying the schematic and reading the data sheet for the Si570, I feel confident that I understand it quite well.  Well enough to stand w/o further preparation before a room full of Phd level scientists and engineers and make a presentation on its operation to any level of detail desired.

                  I have not yet computed things like transfer functions of the filters,  gain, impedances at key points, etc.  That will take some time. I might try to learn a Spice program, but more likely I'll do things the old fashioned way and just do the math myself. I'll need a refresher at certain points, but that's why I have a library.

                  Hopefully this will make clear I am not some solder monkey assembling things I don't understand.

                  I am entirely self taught in electronics and computing despite lots of education in other areas.  I am rather out of practice in the area of electronics, but there are many areas in which that is true.

                  Since this forum is largely populated by hams, I would expect that when I wrote of sweeping the Si570 with an outboard LO and mixer to test the filters, that it would be obvious from the engineering context that these would be respectively a sine wave oscillator and a classical analog mixer (e.g. a diode ring mixer).

                  There are a lot of people here who appear to have  exaggerated notions of their knowledge and other people's ignorance.  I received a missive from one individual that informed me that Tom Hong had asked about the Bit Error Rate of the Ensemble II and that this proved that Hong had no idea what he was on about because the Ensemble is all analog and BER only applied to digital circuits.  Claude Shannon certainly would not agree.

                  For the benefit of those not familiar w/ Shannon, he published a seminal paper in 1946 on the communication capacity of an analog channel. One of the concepts he presented is the notion of the Bit Error Rate of an analog channel as a function of bandwidth, noise level and signalling rate. The digital portion of a well designed digital communication system has a BER which is negative. It is able to correct for the BER of the analog portion. That's what makes digital communication so attractive and things like GPS and WSPR possible. It's why we have digital TV broadcasting.

                  I asked if there had been any discussion about using the Si570 to test the filters during construction. Obviously that is not the case, so I consider the topic closed. After I get done I will report what I find. It looks sufficiently promising to be worth trying it and comparing the result to my HP sweeper and impulse testing w/ the Rigol. If it turns out as I expect, I'll do a little write up w/ schematics for the LO & mixer, measured component values, theoretical transfer functions and measured results.

                  One final comment. I have for many years been active in a list devoted to reflection seismic data processing. Very often someone shows up w/ what seems like a nonsensical question. While I do not respond to such questions, others often do. There have been numerous instances where the subsequent discussion showed that the original poster simply failed to frame the question properly. This is particularly common w/ people educated in China. I suspect it's partly a native language effect and partly the educational system.

                  The best response to a fool is silence. Because all responses will produce the same result, it is the response that has the highest benefit/cost ratio. It gives the fool a chance to recognize his folly w/o conflating it w/ your own.

                  Have Fun!
                  Reg
                • Sid Boyce
                  Reg, Reg! No one is questioning your ability, skill nor knowledge. In the case of using the si570 the way you desire, obviously no one has tried it and for one
                  Message 8 of 11 , Jul 2 10:21 AM
                    Reg, Reg!
                    No one is questioning your ability, skill nor knowledge.

                    In the case of using the si570 the way you desire, obviously no one has tried it and for one that is why I never replied to it. To me it seemed feasible but I never gave it any serious thought or consideration.

                    Don't forget that the best brains and most knowledgeable people on the planet dismissed the transistor and just about every technical development that came along, even today many dismiss the SDR as capable of performing as a serious rig for contesting.

                    When Gene Amdahl was seeking funding for his mainframe project it was difficult as the advice prospective venture capitalists got from the acknowledged experts was, as he said, the kindest thing said about them was that they were not very bright and they didn't know what they were doing. They had never designed a chip yet they tasked themselves to design and build the equipment to build and test a chip more advanced than anything ever made.
                    Luckily Fujitsu came forward with the funding and the Amdahl mainframe was manufactured and took the industry by storm.
                    So --- if so many of the best brains has always got it totally wrong you shouldn't expect any greater insights  from this group devoted to building and running Tony's Softrock designs.

                    On the missive regarding reaction to Tom's questions - where could you employ someone who has superior qualifications in RF design but doesn't know how a transformer works having never done actual RF design or building nor understanding component functions inherent in RF circuits?

                    If you hired him/her, without the basics would you rate him as useful to your company?
                    I think if you hired such an individual, that individual would pretty quickly be regarded by co-workers as a square peg in a round hole and be asking serious questions about the ability of the hirer to assess job candidates.

                    BTW - it's a situation I've encountered and the manager never lasted long after that.
                    At Univac one guy asked the then European director a question in a group of other employees - "Peter, I don't mean to be facetious, but how come you have the job you have? I mean, you are not even very bright". A few months later Peter was no longer in the job.  

                    BER, FEC, Hamming, etc. have been around a long time and have been used extensively in communication networks delivering teletype (5 unit code) data over radio where path fading is a problem and monitoring is essential to ensuring the right frequency is selected to effect trouble free communication between 2 points. 

                    I have to construct and test filters for my HiQSDR and my miniVNA Pro or the HiQSDR itself can be used as a VNA which will allow me to verify and adjust those filters to match as closely as possible to the published data.

                    There are many ways to skin a cat, yours, mine and those of many others I won't name to save possible blushes from them.
                    Who knows, your methods may produce something providing more spectacular than anyone thought possible. I'm sure others would welcome and appreciate your contribution.
                    73 ... Sid.

                    On 02/07/12 13:40, Reginald Beardsley wrote:
                     

                    All,

                    The Ensemble II is a very elegant design.  It's also extremely simple, so after an hour or two studying the schematic and reading the data sheet for the Si570, I feel confident that I understand it quite well.  Well enough to stand w/o further preparation before a room full of Phd level scientists and engineers and make a presentation on its operation to any level of detail desired.

                    I have not yet computed things like transfer functions of the filters,  gain, impedances at key points, etc.  That will take some time. I might try to learn a Spice program, but more likely I'll do things the old fashioned way and just do the math myself. I'll need a refresher at certain points, but that's why I have a library.

                    Hopefully this will make clear I am not some solder monkey assembling things I don't understand.

                    I am entirely self taught in electronics and computing despite lots of education in other areas.  I am rather out of practice in the area of electronics, but there are many areas in which that is true.

                    Since this forum is largely populated by hams, I would expect that when I wrote of sweeping the Si570 with an outboard LO and mixer to test the filters, that it would be obvious from the engineering context that these would be respectively a sine wave oscillator and a classical analog mixer (e.g. a diode ring mixer).

                    There are a lot of people here who appear to have  exaggerated notions of their knowledge and other people's ignorance.  I received a missive from one individual that informed me that Tom Hong had asked about the Bit Error Rate of the Ensemble II and that this proved that Hong had no idea what he was on about because the Ensemble is all analog and BER only applied to digital circuits.  Claude Shannon certainly would not agree.

                    For the benefit of those not familiar w/ Shannon, he published a seminal paper in 1946 on the communication capacity of an analog channel. One of the concepts he presented is the notion of the Bit Error Rate of an analog channel as a function of bandwidth, noise level and signalling rate. The digital portion of a well designed digital communication system has a BER which is negative. It is able to correct for the BER of the analog portion. That's what makes digital communication so attractive and things like GPS and WSPR possible. It's why we have digital TV broadcasting.

                    I asked if there had been any discussion about using the Si570 to test the filters during construction. Obviously that is not the case, so I consider the topic closed. After I get done I will report what I find. It looks sufficiently promising to be worth trying it and comparing the result to my HP sweeper and impulse testing w/ the Rigol. If it turns out as I expect, I'll do a little write up w/ schematics for the LO & mixer, measured component values, theoretical transfer functions and measured results.

                    One final comment. I have for many years been active in a list devoted to reflection seismic data processing. Very often someone shows up w/ what seems like a nonsensical question. While I do not respond to such questions, others often do. There have been numerous instances where the subsequent discussion showed that the original poster simply failed to frame the question properly. This is particularly common w/ people educated in China. I suspect it's partly a native language effect and partly the educational system.

                    The best response to a fool is silence. Because all responses will produce the same result, it is the response that has the highest benefit/cost ratio. It gives the fool a chance to recognize his folly w/o conflating it w/ your own.

                    Have Fun!
                    Reg



                    -- 
                    Sid Boyce ... Hamradio License G3VBV, Licensed Private Pilot
                    Emeritus IBM/Amdahl Mainframes and Sun/Fujitsu Servers Tech Support
                    Senior Staff Specialist, Cricket Coach
                    Microsoft Windows Free Zone - Linux used for all Computing Tasks
                    
                  • Jasmine Strong
                    It seems like, for sweep generation purposes, a highpass filter (a simple LC with a rolloff at a few kHz) and a clock gating circuit could be added after the
                    Message 9 of 11 , Jul 2 11:31 AM

                      It seems like, for sweep generation purposes, a highpass filter (a simple LC with a rolloff at a few kHz) and a clock gating circuit could be added after the Si570, so that the chirp produced during a "large step" tuning change could be suppressed.  You'd gate the output off, retune, and then gate it back on after a time sufficient to ensure the output was stable.  the highpass filter would suppress the DC component.

                      -J.

                      On Jul 2, 2012, at 10:21 AM, Sid Boyce wrote:

                       

                      Reg, Reg!
                      No one is questioning your ability, skill nor knowledge.

                      In the case of using the si570 the way you desire, obviously no one has tried it and for one that is why I never replied to it. To me it seemed feasible but I never gave it any serious thought or consideration.

                      Don't forget that the best brains and most knowledgeable people on the planet dismissed the transistor and just about every technical development that came along, even today many dismiss the SDR as capable of performing as a serious rig for contesting.

                      When Gene Amdahl was seeking funding for his mainframe project it was difficult as the advice prospective venture capitalists got from the acknowledged experts was, as he said, the kindest thing said about them was that they were not very bright and they didn't know what they were doing. They had never designed a chip yet they tasked themselves to design and build the equipment to build and test a chip more advanced than anything ever made.
                      Luckily Fujitsu came forward with the funding and the Amdahl mainframe was manufactured and took the industry by storm.
                      So --- if so many of the best brains has always got it totally wrong you shouldn't expect any greater insights  from this group devoted to building and running Tony's Softrock designs.

                      On the missive regarding reaction to Tom's questions - where could you employ someone who has superior qualifications in RF design but doesn't know how a transformer works having never done actual RF design or building nor understanding component functions inherent in RF circuits?

                      If you hired him/her, without the basics would you rate him as useful to your company?
                      I think if you hired such an individual, that individual would pretty quickly be regarded by co-workers as a square peg in a round hole and be asking serious questions about the ability of the hirer to assess job candidates.

                      BTW - it's a situation I've encountered and the manager never lasted long after that.
                      At Univac one guy asked the then European director a question in a group of other employees - "Peter, I don't mean to be facetious, but how come you have the job you have? I mean, you are not even very bright". A few months later Peter was no longer in the job.  

                      BER, FEC, Hamming, etc. have been around a long time and have been used extensively in communication networks delivering teletype (5 unit code) data over radio where path fading is a problem and monitoring is essential to ensuring the right frequency is selected to effect trouble free communication between 2 points. 

                      I have to construct and test filters for my HiQSDR and my miniVNA Pro or the HiQSDR itself can be used as a VNA which will allow me to verify and adjust those filters to match as closely as possible to the published data.

                      There are many ways to skin a cat, yours, mine and those of many others I won't name to save possible blushes from them.
                      Who knows, your methods may produce something providing more spectacular than anyone thought possible. I'm sure others would welcome and appreciate your contribution.
                      73 ... Sid.

                      On 02/07/12 13:40, Reginald Beardsley wrote:
                       

                      All,

                      The Ensemble II is a very elegant design.  It's also extremely simple, so after an hour or two studying the schematic and reading the data sheet for the Si570, I feel confident that I understand it quite well.  Well enough to stand w/o further preparation before a room full of Phd level scientists and engineers and make a presentation on its operation to any level of detail desired.

                      I have not yet computed things like transfer functions of the filters,  gain, impedances at key points, etc.  That will take some time. I might try to learn a Spice program, but more likely I'll do things the old fashioned way and just do the math myself. I'll need a refresher at certain points, but that's why I have a library.

                      Hopefully this will make clear I am not some solder monkey assembling things I don't understand.

                      I am entirely self taught in electronics and computing despite lots of education in other areas.  I am rather out of practice in the area of electronics, but there are many areas in which that is true.

                      Since this forum is largely populated by hams, I would expect that when I wrote of sweeping the Si570 with an outboard LO and mixer to test the filters, that it would be obvious from the engineering context that these would be respectively a sine wave oscillator and a classical analog mixer (e.g. a diode ring mixer).

                      There are a lot of people here who appear to have  exaggerated notions of their knowledge and other people's ignorance.  I received a missive from one individual that informed me that Tom Hong had asked about the Bit Error Rate of the Ensemble II and that this proved that Hong had no idea what he was on about because the Ensemble is all analog and BER only applied to digital circuits.  Claude Shannon certainly would not agree.

                      For the benefit of those not familiar w/ Shannon, he published a seminal paper in 1946 on the communication capacity of an analog channel. One of the concepts he presented is the notion of the Bit Error Rate of an analog channel as a function of bandwidth, noise level and signalling rate. The digital portion of a well designed digital communication system has a BER which is negative. It is able to correct for the BER of the analog portion. That's what makes digital communication so attractive and things like GPS and WSPR possible. It's why we have digital TV broadcasting.

                      I asked if there had been any discussion about using the Si570 to test the filters during construction. Obviously that is not the case, so I consider the topic closed. After I get done I will report what I find. It looks sufficiently promising to be worth trying it and comparing the result to my HP sweeper and impulse testing w/ the Rigol. If it turns out as I expect, I'll do a little write up w/ schematics for the LO & mixer, measured component values, theoretical transfer functions and measured results.

                      One final comment. I have for many years been active in a list devoted to reflection seismic data processing. Very often someone shows up w/ what seems like a nonsensical question. While I do not respond to such questions, others often do. There have been numerous instances where the subsequent discussion showed that the original poster simply failed to frame the question properly. This is particularly common w/ people educated in China. I suspect it's partly a native language effect and partly the educational system.

                      The best response to a fool is silence. Because all responses will produce the same result, it is the response that has the highest benefit/cost ratio. It gives the fool a chance to recognize his folly w/o conflating it w/ your own.

                      Have Fun!
                      Reg



                      -- 
                      Sid Boyce ... Hamradio License G3VBV, Licensed Private Pilot
                      Emeritus IBM/Amdahl Mainframes and Sun/Fujitsu Servers Tech Support
                      Senior Staff Specialist, Cricket Coach
                      Microsoft Windows Free Zone - Linux used for all Computing Tasks
                      


                    • Graeme Jury
                      Hi Mike, I m afraid I don t have good news for you as I have a Dell Inspiron E1505 lap top with the Sigmatel sound card. It has exactly the same problem as you
                      Message 10 of 11 , Jul 2 3:05 PM
                        Hi Mike,

                        I'm afraid I don't have good news for you as I have a Dell Inspiron
                        E1505 lap top with the Sigmatel sound card. It has exactly the same
                        problem as you and after you have spent as many hours as I have messing
                        around with it you will find the pases shift is not consistent and can
                        go from plus 20 deg to minus 20 deg and other values as well. I found
                        that switching the card repeatedly from stereo to mono would eventually
                        lead to it coming up in phase and it was not too bad when it was going
                        right. At 96 khz I would have been satisfied with it.

                        I tried to get Dell to look at this but they refused to let me tell them
                        they had shipped a defective product until I purchased a service
                        contract from them but I refused to pay to tell them they had a faulty
                        product. Of course normal users would never know that the card channels
                        were out of phase and inconsistently as well and the card would seem
                        fine to them.

                        As an audio card in an SDR it does the job just fine so my advice is to
                        get yourself a good card for the IQ channels. If you are going to be a
                        powerSDR-IQ user under Windows, don't mess around and just get a USB2SDR
                        card from Christos and have performance and ease of setup. The extra
                        money up front is worth it. If you are a Linux user then the sdrWidget
                        will give wonderful performance with all the controls necessary
                        integrated into the board. There are also some very good commercial
                        sound cards available and many posts have been made about them so a skim
                        back will get you the info.

                        The bottom line ... Your card is no good, you will need to buy another.

                        Sorry about that chief. 73, Graeme ZL2APV
                      • Hulen Smith
                        Reg, We in analog microwave BERT our circuits as a routine matter. We test for most of the parameters you mentioned. I appreciate your comments sir. They are
                        Message 11 of 11 , Jul 2 10:30 PM
                          Reg,
                          We in analog microwave BERT our circuits as a routine matter. We test for most of the parameters you mentioned. I appreciate your comments sir.
                          They are ALL valid. 

                          Hulen
                          K5HCS
                          GRTL
                          KM Telecomm,

                          Sent from my iPhone

                          On Jul 2, 2012, at 7:40 AM, Reginald Beardsley <pulaskite@...> wrote:

                           

                          All,

                          The Ensemble II is a very elegant design.  It's also extremely simple, so after an hour or two studying the schematic and reading the data sheet for the Si570, I feel confident that I understand it quite well.  Well enough to stand w/o further preparation before a room full of Phd level scientists and engineers and make a presentation on its operation to any level of detail desired.

                          I have not yet computed things like transfer functions of the filters,  gain, impedances at key points, etc.  That will take some time. I might try to learn a Spice program, but more likely I'll do things the old fashioned way and just do the math myself. I'll need a refresher at certain points, but that's why I have a library.

                          Hopefully this will make clear I am not some solder monkey assembling things I don't understand.

                          I am entirely self taught in electronics and computing despite lots of education in other areas.  I am rather out of practice in the area of electronics, but there are many areas in which that is true.

                          Since this forum is largely populated by hams, I would expect that when I wrote of sweeping the Si570 with an outboard LO and mixer to test the filters, that it would be obvious from the engineering context that these would be respectively a sine wave oscillator and a classical analog mixer (e.g. a diode ring mixer).

                          There are a lot of people here who appear to have  exaggerated notions of their knowledge and other people's ignorance.  I received a missive from one individual that informed me that Tom Hong had asked about the Bit Error Rate of the Ensemble II and that this proved that Hong had no idea what he was on about because the Ensemble is all analog and BER only applied to digital circuits.  Claude Shannon certainly would not agree.

                          For the benefit of those not familiar w/ Shannon, he published a seminal paper in 1946 on the communication capacity of an analog channel. One of the concepts he presented is the notion of the Bit Error Rate of an analog channel as a function of bandwidth, noise level and signalling rate. The digital portion of a well designed digital communication system has a BER which is negative. It is able to correct for the BER of the analog portion. That's what makes digital communication so attractive and things like GPS and WSPR possible. It's why we have digital TV broadcasting.

                          I asked if there had been any discussion about using the Si570 to test the filters during construction. Obviously that is not the case, so I consider the topic closed. After I get done I will report what I find. It looks sufficiently promising to be worth trying it and comparing the result to my HP sweeper and impulse testing w/ the Rigol. If it turns out as I expect, I'll do a little write up w/ schematics for the LO & mixer, measured component values, theoretical transfer functions and measured results.

                          One final comment. I have for many years been active in a list devoted to reflection seismic data processing. Very often someone shows up w/ what seems like a nonsensical question. While I do not respond to such questions, others often do. There have been numerous instances where the subsequent discussion showed that the original poster simply failed to frame the question properly. This is particularly common w/ people educated in China. I suspect it's partly a native language effect and partly the educational system.

                          The best response to a fool is silence. Because all responses will produce the same result, it is the response that has the highest benefit/cost ratio. It gives the fool a chance to recognize his folly w/o conflating it w/ your own.

                          Have Fun!
                          Reg

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