Re: [Flexradio] A question on Frequency stability vs. Temperature
At 05:17 PM 1/1/2006, [EMAIL PROTECTED] wrote: Actually, you need to synthesize TWO signals in the passband, because errors in the A/D sample clock can't be calibrated out with a single marker. Jim, Well, I have to ask why two markers are needed or can you give a reference text I could study to see why? Warning, KISS please as I can follow y=mx+b but after that I'm lost. A change in the DDS frequency (or the reference) shifts the entire RF band around by the same amount (that is, if you're tuned to 14.100 and the DDS is (erroneously) at 14.101, then everything will be the same 1 kHz off, marker and desired signal). Let's call that an additive frequency error For a conventional receiver, additive errors are the only kind you'll see. A change in the sampling clock changes the scale factor into the filtering. A 10 kHz signal coming into the A/D and being sampled at 40 kHz has 4 samples per cycle. If the sampling clock is 50 kHz, you'll have 5 samples/cycle, which, if you're expecting 40 kHz sampling rate, would correspond to 8kHz. Likewise, a 5 kHz signal would be digitized at 10 samples/cycle instead of 8, so it would look like 4 kHz. Here, the error is multiplicative (that is, the received signal appears to be at a frequency which is the real frequency multiplied by a constant;4/5 in this example) In a system where you run data in and out at the same sample rate, small sample rate changes might not be noticeable (since the errors would counteract each other..). However, if you are depending on the sample rate to be accurate: as in a digital demodulator, or in a self calibration system, you need to deal with it. Errors in the sampling rate are kind of like having the marker spacing being wrong, i.e. the markers are every 26 kHz instead of every 25 kHz. So, you can put in two tones (fa and fb) a kilohertz or so apart and measure them. What shows up in the sampled output is two signals (f1 and f2): f1 = k1*(fa+k2) f2 = k1*(fb+k2) where k2 is the error in the DDS frequency and k1 is the sampling rate error (actual rate/expected rate). You know fa and fb (because you put them in) and you measure f1 and f2, and solve for k1 and k2. It's actually pretty easy. [ f1= k1*fa + k1*k2; f2 =k1*fb + k1*k2 f1-f2 = k1*(fa-fb) k1 = (f1-f2)/(fa-fb) Say your radio's DDS is tuned to 14.100 MHz. You put in a tone at 14.101 and a tone at 14.102 (i.e. at 1000 and 2000 Hz relative to the DDS). You measure the two tones in the audio stream and one tone shows up at 900 Hz and the other shows up at 2100Hz (that would be the frequencies where they appear in the fft, assuming the sample rate is correct). The tones SHOULD be 1000 Hz apart, but they're not, they're 1200 Hz apart, which means that the sampling clock is running slow by 20%. (k1 = 1.2 in the example above) Now, apply that correction.. and the tones appear at 750 and 1750 (the proper 1 kHz apart), but are now both low by 250 Hz, which implies that the DDS frequency is high by 250 Hz. Since two are needed then generate markers spaced every 25 KHz and just move the markers around so they aren't sitting on the center frequency. Looks like with just a little more thought on the hardware we can push it off the end of the bench and let the softheads do the trench work. Golly, product out the door next week. 73, Larry K2LT James Lux, P.E. Spacecraft Radio Frequency Subsystems Group Flight Communications Systems Section Jet Propulsion Laboratory, Mail Stop 161-213 4800 Oak Grove Drive Pasadena CA 91109 tel: (818)354-2075 fax: (818)393-6875
Re: [Flexradio] A question on Frequency stability vs. Temperature
At 06:25 PM 1/1/2006, Tom Clark, W3IWI wrote: KD5NWA wrote: The project being discussed for the Xylo is; 1. Thermal isolation with a accurate heater to reduce the drift. 2. Use the Xylo to connect to a GPS and have a accurate 1 pps clock 3. Use the 1 pps clock to measure the DDS 200MHz clock, integrate multiple reading to make for finer resolution. 4. Use the 1 pps clock to measure the A/D clock, take multiple readings also. 5. Feed the results to the PC who will proceed to correct the internal math so there is no drift. Let me suggest a different approach at step 3. Connect the DDS reference to a long counter (more than one second) -- it can be straight binary, and 32 bits is overkill. Use the 1PPS to strobe the counter into a register without stopping the counter (i.e. like lap timing with a stop watch). Then make your corrections based on accumulated phase, which can then be averaged over many seconds. 73, Tom Doesn't even need to be a long counter. you know approximately what the MSBs are going to be, all you're interested in is the LSBs. (i.e. whether there were 200,000,001 counts last second, or 199,999,999). Figure out your worst case variation, and that's how long the counter needs to be. Of course, in a modern FPGA, you're probably not short of counter stages, but you still have to pump all those bits back to the CPU, and most of them are superfluous. The other thing to watch out for is the type of counter. It needs to be synchronous, so that when you latch it, you aren't capturing it in mid ripple carry. Sometimes, it's easier to set up some fixed dividers with relatively prime divisors and just latch the single bit of output from each divider, so you aren't as concerned about the state of ALL the flipflops in the divider. non power of 2 Ripple counter/dividers have jitter on their MSB output bit, so you might not gain much here, but for small divisors, you can use things like Johnson counters. You can also clock a short PN generator and latch the state of the shift register (it's sometimes easier to make a synchronous PN generator than a synchronous counter). Jim, W6RMK
Re: [Flexradio] Software taming the wandering oscillator - a thought
At 08:36 PM 1/1/2006, Eric Ellison wrote: Bill I am reposting this, since I never saw any comments or answer. There must be some 'time nut' familiar enough with the SDR to postulate an answer to the question of WHERE and HOW do we get a signal to reference back in external hardware/software. And what the implications are for getting to our accuracy objective. Since this is a high level sig probably with adequate fan out it would really be better than trying to buffer the LO so we can count it. This is a real challenge to do cleanly, which is why I went to the insert a marker near the signal of interest and measure it approach. It requires no mods to the SDR1000. Jim
Re: [Flexradio] A question on Frequency stability vs. Temperature
Jim, Thank you for an excellent explanation of the two markers required. I'll be back with the next question after I digest the information. What I need is an accurate measure of frequency in the AM broadcast band, 500 to 1700 KHz, so I would think 1-10^7 is good enough for me. It needs to be mobile, I can run it from my vehicle so the power requirement is trivial. I can monitor GPS on the move, need it for navigation anyways. Looks like my requirement has minimal intrusion into the SDR1000 box. Just need the digital data and control for the marker freqs to the PC. USB type link should work. Stuff the signals into the QRP BNC. The second requirement for the weak signal/microwave crowd use would be to get a lower phase noise source into the SDR1000. Perhaps this would also be a good time to move to the new AD9950 series DDS as those specs seem to be a major improvement. Lots to ponder. Again, Thanks for your lesson. 73, Larry K2LT From: Jim Lux [EMAIL PROTECTED] Date: 2006/01/02 Mon PM 02:45:09 WET
[Flexradio] Compiling the SDR code...
I've picked up Visual Studio .net (ver. 2003) and would like to start playing with the SDR code. I have never used the Visual Studio IDE (and it's been at least 10 years since I last programmed in C), but I figure - why let ignorance get in the way of having fun?Anyway...I've just tried building the Preview 9 code using Visual Studio and I'm getting some errors. Specifically, I'm seeing errors such as: Type or namespace name 'DirectX' does not exist in the class or namespace 'Microsoft' Type or namespace 'Device' could not be found (etc.) Type or namespace 'VertexBuffer' could not be found (etc.) Type or namespace 'Custom Vertex' could not be found (etc.) Type or namespace 'Vector2' could not be found (etc.) Type or namespace 'JoyStickState' could not be found (etc.) There are also some other errors (or warnings?) stating that Microsoft.DirectX, Microsoft.DirectX.Direct3D,(and similar) not found.And finally, there are a number of files it cannot find, such as CATStructs.xml, DttSP.dll, etc.However, these last files are in my "playpen" folder with the other SDR source code, but for some reason Visual Studio is not seeing them - how do I tell it where to look, or where should I place these files?And regarding the other errors - what should I do to remove them?(Also - could someone explain to me the difference between "Build Solution" and "Build Deployment"?)Thanks for any help or insights anyone can provide!Best regards,- Jeff, WA6AHL
Re: [Flexradio] Compiling the SDR code...
Jeff, The problem is that you need the DirectX SDK in order to compile the source. You can download this from Microsoft.com. Be warned that it is a large download (approx. 230MB). Even though we have taken a step back from the DirectX graphics, we have always had the option of using a DirectInput device (such as a joystick) as an input in the old CW form. This necessitates the SDK for compilation. Eric Wachsmann FlexRadio Systems -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jeff Anderson Sent: Monday, January 02, 2006 11:31 AM To: FlexRadio@flex-radio.biz Subject: [Flexradio] Compiling the SDR code... I've picked up Visual Studio .net (ver. 2003) and would like to start playing with the SDR code. I have never used the Visual Studio IDE (and it's been at least 10 years since I last programmed in C), but I figure - why let ignorance get in the way of having fun? Anyway...I've just tried building the Preview 9 code using Visual Studio and I'm getting some errors. Specifically, I'm seeing errors such as: Type or namespace name 'DirectX' does not exist in the class or namespace 'Microsoft' Type or namespace 'Device' could not be found (etc.) Type or namespace 'VertexBuffer' could not be found (etc.) Type or namespace 'Custom Vertex' could not be found (etc.) Type or namespace 'Vector2' could not be found (etc.) Type or namespace 'JoyStickState' could not be found (etc.) There are also some other errors (or warnings?) stating that Microsoft.DirectX, Microsoft.DirectX.Direct3D,(and similar) not found. And finally, there are a number of files it cannot find, such as CATStructs.xml, DttSP.dll, etc. However, these last files are in my playpen folder with the other SDR source code, but for some reason Visual Studio is not seeing them - how do I tell it where to look, or where should I place these files? And regarding the other errors - what should I do to remove them? (Also - could someone explain to me the difference between Build Solution and Build Deployment?) Thanks for any help or insights anyone can provide! Best regards, - Jeff, WA6AHL
Re: [Flexradio] Software taming the wandering oscillator - a thought
John et.al. Dang this is Great! It gives me a hard er.. well.. This is the way to go for three projects. Pardon my ignorance, but is the V-F Osc a pluggable part? This is the best of all worlds. Unmodified, the SDR works just as it does now. Modification kit we can move the osc chip off the board at the expense of an external board with all sorts of isolation. Software solution, put the V-F osc on the external board, count it, discipline it and send it to the radio as well as corrections the software. SMA connectors and a little glue should marry it for the guys who want Accuracy to Microwave. Looking forward to the TAPR Reflock solution! We are all just really noodling, but getting closer! If Jim Lux says we should be countin' the 200 mhz to determine the 'software correction' (as he did in a message further up) I'm with him and you. Jim: Thanks for the answer to my question of a 'full count'. And counting only to the worst case. I think you have mentioned that before but I forgot. Anyone want to sketch this into a schematic? Eric John Acermann said: I've suggested to Gerald that the right answer to the mechanical issues around the oscillator could be to build a small board with a single ended to differential buffer/converter and an SMA connector that would plug in where the oscillator now goes. That would provide a clean interface for whatever oscillator you might want to use. The other half of the equation would be to make an external board to hold the current oscillator with an SMA connection for the output. That setup would make it very easy to add thermal control, and also to tap the signal for other purposes. The oscillator interface board could well be part of the final version of the TAPR Reflock solution for the SDR-1000, but no promises yet as we're still noodling the design. 73, John
Re: [Flexradio] Software taming the wandering oscillator - a thought
Can I throw one more option in the mix to make it an even four? While Googling the other day, I came across VCTCXO that is just about pin compatible, is output compatible (PECL), voltage compatible (3.3v) has the same frequency range as the XO (max=300MHz), has the same or a little better phase noise numbers and is an order of magnitude better in stability (+/- 20 ppm). http://greenrayindustries.com/library/ZT620.pdf I asked Gerald to look at it and he replied... This is a very interesting part that I have never seen. I look all the time for good oscillators but never came across this one. To make it work, you would have to: 1) Cut all the center pins. 2) Move the jumpers on the TRX to single ended mode. 3) Bias pin 1 to Vdd/2. The precision of this reference will set the frequency since this is a voltage controlled oscillator. Now an EE, I'm not, but the modification listed in item #3 don't seem too unreasonable. It might even be a good XO option for the external board option listed below. I am inquiring about cost and hopefully will have price and availability info in the next day or two. Comments opinions? -Tim --- Tim Ellison ( [EMAIL PROTECTED] ) Integrated Technical Services ( http://www.itsco.com ) -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Eric Ellison Sent: Monday, January 02, 2006 6:25 PM To: 'John Ackermann N8UR' Cc: FlexRadio@flex-radio.biz Subject: Re: [Flexradio] Software taming the wandering oscillator - a thought John et.al. Dang this is Great! It gives me a hard er.. well.. This is the way to go for three projects. Pardon my ignorance, but is the V-F Osc a pluggable part? This is the best of all worlds. Unmodified, the SDR works just as it does now. Modification kit we can move the osc chip off the board at the expense of an external board with all sorts of isolation. Software solution, put the V-F osc on the external board, count it, discipline it and send it to the radio as well as corrections the software. SMA connectors and a little glue should marry it for the guys who want Accuracy to Microwave. Looking forward to the TAPR Reflock solution! We are all just really noodling, but getting closer! If Jim Lux says we should be countin' the 200 mhz to determine the 'software correction' (as he did in a message further up) I'm with him and you. Jim: Thanks for the answer to my question of a 'full count'. And counting only to the worst case. I think you have mentioned that before but I forgot. Anyone want to sketch this into a schematic? Eric John Acermann said: I've suggested to Gerald that the right answer to the mechanical issues around the oscillator could be to build a small board with a single ended to differential buffer/converter and an SMA connector that would plug in where the oscillator now goes. That would provide a clean interface for whatever oscillator you might want to use. The other half of the equation would be to make an external board to hold the current oscillator with an SMA connection for the output. That setup would make it very easy to add thermal control, and also to tap the signal for other purposes. The oscillator interface board could well be part of the final version of the TAPR Reflock solution for the SDR-1000, but no promises yet as we're still noodling the design. 73, John ___ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Re: [Flexradio] Compiling the SDR code...
Thanks, Eric, that was it. By the way - where is the text stored for the "banner" that appears on the top bar of the application (the one that says, at the moment, "...1.4.5 Preview 9"? I'd like to change it to something unique so that, when I'm running the app, I know which version I'm running. Thanks again, - Jeff -Original Message-From: FlexRadio - Eric [mailto:[EMAIL PROTECTED]Sent: Monday, January 02, 2006 11:17 AMTo: 'Jeff Anderson'; FlexRadio@flex-radio.bizSubject: RE: [Flexradio] Compiling the SDR code... Jeff, The problem is that you need the DirectX SDK in order to compile the source. You can download this from Microsoft.com. Be warned that it is a large download (approx. 230MB). Even though we have taken a step back from the DirectX graphics, we have always had the option of using a DirectInput device (such as a joystick) as an input in the old CW form. This necessitates the SDK for compilation. Eric Wachsmann FlexRadio Systems -Original Message-From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jeff AndersonSent: Monday, January 02, 2006 11:31 AMTo: FlexRadio@flex-radio.bizSubject: [Flexradio] Compiling the SDR code... I've picked up Visual Studio .net (ver. 2003) and would like to start playing with the SDR code. I have never used the Visual Studio IDE (and it's been at least 10 years since I last programmed in C), but I figure - why let ignorance get in the way of having fun? Anyway...I've just tried building the Preview 9 code using Visual Studio and I'm getting some errors. Specifically, I'm seeing errors such as: Type or namespace name 'DirectX' does not exist in the class or namespace 'Microsoft' Type or namespace 'Device' could not be found (etc.) Type or namespace 'VertexBuffer' could not be found (etc.) Type or namespace 'Custom Vertex' could not be found (etc.) Type or namespace 'Vector2' could not be found (etc.) Type or namespace 'JoyStickState' could not be found (etc.) There are also some other errors (or warnings?) stating that Microsoft.DirectX, Microsoft.DirectX.Direct3D,(and similar) not found. And finally, there are a number of files it cannot find, such as CATStructs.xml, DttSP.dll, etc. However, these last files are in my "playpen" folder with the other SDR source code, but for some reason Visual Studio is not seeing them - how do I tell it where to look, or where should I place these files? And regarding the other errors - what should I do to remove them? (Also - could someone explain to me the difference between "Build Solution" and "Build Deployment"?) Thanks for any help or insights anyone can provide! Best regards, - Jeff, WA6AHL
Re: [Flexradio] Software taming the wandering oscillator - a thought
Eric Ellison said the following on 01/02/2006 06:25 PM: This is the way to go for three projects. Pardon my ignorance, but is the V-F Osc a pluggable part? This is the best of all worlds. Unmodified, the Yes, it's a can oscillator with 4 pins. It basically has the same footprint as a 14 pin (I think) DIP package, but with only four pins, one at each corner. John
Re: [Flexradio] Compiling the SDR code...
Jeff, The best way to modify the main title is in design mode of console.cs. Make sure to compile first so as no to lose custom controls (see note about bug in IDE in the readme.txt in the PowerSDR root folder). Once that is done, simply double click on the console.cs file in the solution explorer and it will open (slowly) in design mode. Click once on the representation of the console and then modify the Text property to change the title. Alternatively, you can simply add a line in the constructor (towards the end) that says something like the following: this.Text = [insert text here]; Eric Wachsmann FlexRadio Systems -Original Message- From: Jeff Anderson [mailto:[EMAIL PROTECTED] Sent: Monday, January 02, 2006 6:02 PM To: FlexRadio - Eric; FlexRadio@flex-radio.biz Subject: RE: [Flexradio] Compiling the SDR code... Thanks, Eric, that was it. By the way - where is the text stored for the banner that appears on the top bar of the application (the one that says, at the moment, ...1.4.5 Preview 9? I'd like to change it to something unique so that, when I'm running the app, I know which version I'm running. Thanks again, - Jeff -Original Message- From: FlexRadio - Eric [mailto:[EMAIL PROTECTED] Sent: Monday, January 02, 2006 11:17 AM To: 'Jeff Anderson'; FlexRadio@flex-radio.biz Subject: RE: [Flexradio] Compiling the SDR code... Jeff, The problem is that you need the DirectX SDK in order to compile the source. You can download this from Microsoft.com. Be warned that it is a large download (approx. 230MB). Even though we have taken a step back from the DirectX graphics, we have always had the option of using a DirectInput device (such as a joystick) as an input in the old CW form. This necessitates the SDK for compilation. Eric Wachsmann FlexRadio Systems -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jeff Anderson Sent: Monday, January 02, 2006 11:31 AM To: FlexRadio@flex-radio.biz Subject: [Flexradio] Compiling the SDR code... I've picked up Visual Studio .net (ver. 2003) and would like to start playing with the SDR code. I have never used the Visual Studio IDE (and it's been at least 10 years since I last programmed in C), but I figure - why let ignorance get in the way of having fun? Anyway...I've just tried building the Preview 9 code using Visual Studio and I'm getting some errors. Specifically, I'm seeing errors such as: Type or namespace name 'DirectX' does not exist in the class or namespace 'Microsoft' Type or namespace 'Device' could not be found (etc.) Type or namespace 'VertexBuffer' could not be found (etc.) Type or namespace 'Custom Vertex' could not be found (etc.) Type or namespace 'Vector2' could not be found (etc.) Type or namespace 'JoyStickState' could not be found (etc.) There are also some other errors (or warnings?) stating that Microsoft.DirectX, Microsoft.DirectX.Direct3D,(and similar) not found. And finally, there are a number of files it cannot find, such as CATStructs.xml, DttSP.dll, etc. However, these last files are in my playpen folder with the other SDR source code, but for some reason Visual Studio is not seeing them - how do I tell it where to look, or where should I place these files? And regarding the other errors - what should I do to remove them? (Also - could someone explain to me the difference between Build Solution and Build Deployment?) Thanks for any help or insights anyone can provide! Best regards, - Jeff, WA6AHL
[Flexradio] SDR-1000 + DEMI 144-28HP + N6CA Sequencer + NCS-3240 + Heil ProSet
Well, I have my new SDR-1000 set up with all of the above. The N6CA sequencer works fine, Pin 7 XVTR PTT works fine, and SDR-1000 PTT works fine. I can even hear the background TX leakage from the SDR-1000+DEMI combo in the IC-746PRO on 2m. But - no TX audio. I use the NCS 3240 Multi-Switcher + Heil ProSet with my IC-746PRO and it's good. Other than quintuple-checking my Mic wiring, which I've already done twice, does anyone have any suggestions on how to make this thing talk? Tnx 73, Dan KB5MY/6 DM13nc
Re: [Flexradio] SDR-1000 + DEMI 144-28HP + N6CA Sequencer + NCS-3240 +Heil ProSet
Dan, What sound card are you using? If you have the Delta-44, open the Delta Control panel. When you talk into the mic (no PTT) you should see signal in channel 3 IN. If not, audio is not getting to the sound card. -Tim --- Tim Ellison ( [EMAIL PROTECTED] ) Integrated Technical Services ( http://www.itsco.com ) -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dan Hammill Sent: Monday, January 02, 2006 9:42 PM To: FlexRadio@flex-radio.biz Subject: [Flexradio] SDR-1000 + DEMI 144-28HP + N6CA Sequencer + NCS-3240 +Heil ProSet Well, I have my new SDR-1000 set up with all of the above. The N6CA sequencer works fine, Pin 7 XVTR PTT works fine, and SDR-1000 PTT works fine. I can even hear the background TX leakage from the SDR-1000+DEMI combo in the IC-746PRO on 2m. But - no TX audio. I use the NCS 3240 Multi-Switcher + Heil ProSet with my IC-746PRO and it's good. Other than quintuple-checking my Mic wiring, which I've already done twice, does anyone have any suggestions on how to make this thing talk? Tnx 73, Dan KB5MY/6 DM13nc ___ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Re: [Flexradio] Software taming the wandering oscillator - a thought
Fred, Thanks for the first hand feedback on Greenray. Better to know now than later. -Tim --- Tim Ellison ( [EMAIL PROTECTED] ) Integrated Technical Services ( http://www.itsco.com ) -Original Message- From: Fred Brandeberry [mailto:[EMAIL PROTECTED] Sent: Tuesday, January 03, 2006 12:26 AM To: Tim Ellison Subject: Re: [Flexradio] Software taming the wandering oscillator - a thought Hi Gang, Just a comment to the discussion, I have dealt with Greenray several times in the past. Don't know how they are now, but some years ago they were rather loose with their specifications, hardware tended to be okay but old in design. I found it best to look very closely at how they did their measurements, and or be willing to pay for an example to test. In each case I was able to deal with unanticipated problems without an awful lot of work... But they existed nontheless... definitely not plug and play. 73, Fred - Original Message - From: Tim Ellison [EMAIL PROTECTED] To: Eric Ellison [EMAIL PROTECTED]; John Ackermann N8UR [EMAIL PROTECTED] Cc: FlexRadio@flex-radio.biz Sent: Monday, January 02, 2006 4:46 PM Subject: Re: [Flexradio] Software taming the wandering oscillator - a thought Can I throw one more option in the mix to make it an even four? While Googling the other day, I came across VCTCXO that is just about pin compatible, is output compatible (PECL), voltage compatible (3.3v) has the same frequency range as the XO (max=300MHz), has the same or a little better phase noise numbers and is an order of magnitude better in stability (+/- 20 ppm). http://greenrayindustries.com/library/ZT620.pdf I asked Gerald to look at it and he replied... This is a very interesting part that I have never seen. I look all the time for good oscillators but never came across this one. To make it work, you would have to: 1) Cut all the center pins. 2) Move the jumpers on the TRX to single ended mode. 3) Bias pin 1 to Vdd/2. The precision of this reference will set the frequency since this is a voltage controlled oscillator. Now an EE, I'm not, but the modification listed in item #3 don't seem too unreasonable. It might even be a good XO option for the external board option listed below. I am inquiring about cost and hopefully will have price and availability info in the next day or two. Comments opinions? -Tim --- Tim Ellison ( [EMAIL PROTECTED] ) Integrated Technical Services ( http://www.itsco.com ) -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Eric Ellison Sent: Monday, January 02, 2006 6:25 PM To: 'John Ackermann N8UR' Cc: FlexRadio@flex-radio.biz Subject: Re: [Flexradio] Software taming the wandering oscillator - a thought John et.al. Dang this is Great! It gives me a hard er.. well.. This is the way to go for three projects. Pardon my ignorance, but is the V-F Osc a pluggable part? This is the best of all worlds. Unmodified, the SDR works just as it does now. Modification kit we can move the osc chip off the board at the expense of an external board with all sorts of isolation. Software solution, put the V-F osc on the external board, count it, discipline it and send it to the radio as well as corrections the software. SMA connectors and a little glue should marry it for the guys who want Accuracy to Microwave. Looking forward to the TAPR Reflock solution! We are all just really noodling, but getting closer! If Jim Lux says we should be countin' the 200 mhz to determine the 'software correction' (as he did in a message further up) I'm with him and you. Jim: Thanks for the answer to my question of a 'full count'. And counting only to the worst case. I think you have mentioned that before but I forgot. Anyone want to sketch this into a schematic? Eric John Acermann said: I've suggested to Gerald that the right answer to the mechanical issues around the oscillator could be to build a small board with a single ended to differential buffer/converter and an SMA connector that would plug in where the oscillator now goes. That would provide a clean interface for whatever oscillator you might want to use. The other half of the equation would be to make an external board to hold the current oscillator with an SMA connection for the output. That setup would make it very easy to add thermal control, and also to tap the signal for other purposes. The oscillator interface board could well be part of the final version of the TAPR Reflock solution for the SDR-1000, but no promises yet as we're still noodling the design. 73, John ___ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio mailing list FlexRadio@flex-radio.biz
