[digitalradio] Re: Sound card question
Vojtech and Patrick thanks you for the reply. I effectively didn't realize synchronization was so critical too. Interesting. Just a comment/question to both, since you are both developers of widely used programs (and I take this opportunity to thank you both for that), I discovered the THOR mode as release by Dave in Fldigi and I have to say based on the preliminary test that I have done (and echoed by tests done by Rein developer of the PSKmail system), that I am very impressed by the performance I get. It is also an ifsk mode like DominoEx but for some reason performs much better at least as implemented in fldigi. Not sure if it is the permanent FEC but is seems quite robust in my tests between VK and ZL. Have you had any comments or request for implementation in your software or is it just too new, or not different enough? 73s, John VK2ETA (And for Patrick, Ex FK8DV. Merci)
Re: [digitalradio] Re: Sound card question
Hello John, As far as I know, there are no public specifications or description of THOR modes. 73 Patrick - Original Message - From: vk2eta [EMAIL PROTECTED] To: digitalradio@yahoogroups.com Sent: Saturday, October 11, 2008 12:01 PM Subject: [digitalradio] Re: Sound card question Vojtech and Patrick thanks you for the reply. I effectively didn't realize synchronization was so critical too. Interesting. Just a comment/question to both, since you are both developers of widely used programs (and I take this opportunity to thank you both for that), I discovered the THOR mode as release by Dave in Fldigi and I have to say based on the preliminary test that I have done (and echoed by tests done by Rein developer of the PSKmail system), that I am very impressed by the performance I get. It is also an ifsk mode like DominoEx but for some reason performs much better at least as implemented in fldigi. Not sure if it is the permanent FEC but is seems quite robust in my tests between VK and ZL. Have you had any comments or request for implementation in your software or is it just too new, or not different enough? 73s, John VK2ETA (And for Patrick, Ex FK8DV. Merci) Announce your digital presence via our Interactive Sked Page at http://www.obriensweb.com/sked 30M digital activity at http://www.projectsandparts.com/30m Recommended software : DM780, Multipsk, FLDIGI, Winwarbler ,MMVARI. Yahoo! Groups Links
Re: [digitalradio] Re: Sound card question
Patrick, John, This is all we have published at the moment. More will be released at a later date. We are busy with the launch of NBEMS and have no time right now to write detailed specifications. http://w1hkj.com/FldigiHelp/Thor.html 73, Skip KH6TY NBEMS Development Team - Original Message - From: Patrick Lindecker To: digitalradio@yahoogroups.com Sent: Saturday, October 11, 2008 9:25 AM Subject: Re: [digitalradio] Re: Sound card question Hello John, As far as I know, there are no public specifications or description of THOR modes. 73 Patrick - Original Message - From: vk2eta [EMAIL PROTECTED] To: digitalradio@yahoogroups.com Sent: Saturday, October 11, 2008 12:01 PM Subject: [digitalradio] Re: Sound card question Vojtech and Patrick thanks you for the reply. I effectively didn't realize synchronization was so critical too. Interesting. Just a comment/question to both, since you are both developers of widely used programs (and I take this opportunity to thank you both for that), I discovered the THOR mode as release by Dave in Fldigi and I have to say based on the preliminary test that I have done (and echoed by tests done by Rein developer of the PSKmail system), that I am very impressed by the performance I get. It is also an ifsk mode like DominoEx but for some reason performs much better at least as implemented in fldigi. Not sure if it is the permanent FEC but is seems quite robust in my tests between VK and ZL. Have you had any comments or request for implementation in your software or is it just too new, or not different enough? 73s, John VK2ETA (And for Patrick, Ex FK8DV. Merci) Announce your digital presence via our Interactive Sked Page at http://www.obriensweb.com/sked 30M digital activity at http://www.projectsandparts.com/30m Recommended software : DM780, Multipsk, FLDIGI, Winwarbler ,MMVARI. Yahoo! Groups Links Internal Virus Database is out of date. Checked by AVG - http://www.avg.com Version: 8.0.138 / Virus Database: 270.6.6/1626 - Release Date: 8/21/2008 6:54 PM
Re: [digitalradio] Re: Sound card question
Patrick, John, The link on the Thor web page, http://w1hkj.com/FldigiHelp/Thor.html, provides some additional technical specifications for Thor: http://w1hkj.com/FldigiHelp/Modes/THORdesc.htm To answer John's question, Thor uses full time FEC. 73, Skip KH6TY NBEMS Development Team - Original Message - From: Patrick Lindecker To: digitalradio@yahoogroups.com Sent: Saturday, October 11, 2008 9:25 AM Subject: Re: [digitalradio] Re: Sound card question Hello John, As far as I know, there are no public specifications or description of THOR modes. 73 Patrick - Original Message - From: vk2eta [EMAIL PROTECTED] To: digitalradio@yahoogroups.com Sent: Saturday, October 11, 2008 12:01 PM Subject: [digitalradio] Re: Sound card question Vojtech and Patrick thanks you for the reply. I effectively didn't realize synchronization was so critical too. Interesting. Just a comment/question to both, since you are both developers of widely used programs (and I take this opportunity to thank you both for that), I discovered the THOR mode as release by Dave in Fldigi and I have to say based on the preliminary test that I have done (and echoed by tests done by Rein developer of the PSKmail system), that I am very impressed by the performance I get. It is also an ifsk mode like DominoEx but for some reason performs much better at least as implemented in fldigi. Not sure if it is the permanent FEC but is seems quite robust in my tests between VK and ZL. Have you had any comments or request for implementation in your software or is it just too new, or not different enough? 73s, John VK2ETA (And for Patrick, Ex FK8DV. Merci) Announce your digital presence via our Interactive Sked Page at http://www.obriensweb.com/sked 30M digital activity at http://www.projectsandparts.com/30m Recommended software : DM780, Multipsk, FLDIGI, Winwarbler ,MMVARI. Yahoo! Groups Links Internal Virus Database is out of date. Checked by AVG - http://www.avg.com Version: 8.0.138 / Virus Database: 270.6.6/1626 - Release Date: 8/21/2008 6:54 PM
Re: [digitalradio] Re: Sound card question
There is a basic outline of THOR at: http://www.w1hkj.com/FldigiHelp/Modes/THORdesc.htm Perhaps someone can help us understand the difference between THOR and DEX/FEC (Domino EX with FEC). Aren't they very much the same concept, or is there a design difference? 73, Rick, KV9U Patrick Lindecker wrote: Hello John, As far as I know, there are no public specifications or description of THOR modes. 73 Patrick
Re: [digitalradio] Re: Sound card question
Hello Skip, TKS for the information. I read the specifications. It seems to be a DominoEX with a MFSK16 interleaver (in the FEC DominoEx, in accord with Murray Greenman, I had reduced it as it seemed to me that the delay was a bit long). Do you confirm that it is the only difference? If so, due to the longer interleaver, the Thor mode must be a bit more robust than DominoEx Fec but with a longer delay. 73 Patrick - Original Message - From: kh6ty To: digitalradio@yahoogroups.com Sent: Saturday, October 11, 2008 4:07 PM Subject: Re: [digitalradio] Re: Sound card question Patrick, John, The link on the Thor web page, http://w1hkj.com/FldigiHelp/Thor.html, provides some additional technical specifications for Thor: http://w1hkj.com/FldigiHelp/Modes/THORdesc.htm To answer John's question, Thor uses full time FEC. 73, Skip KH6TY NBEMS Development Team - Original Message - From: Patrick Lindecker To: digitalradio@yahoogroups.com Sent: Saturday, October 11, 2008 9:25 AM Subject: Re: [digitalradio] Re: Sound card question Hello John, As far as I know, there are no public specifications or description of THOR modes. 73 Patrick - Original Message - From: vk2eta [EMAIL PROTECTED] To: digitalradio@yahoogroups.com Sent: Saturday, October 11, 2008 12:01 PM Subject: [digitalradio] Re: Sound card question Vojtech and Patrick thanks you for the reply. I effectively didn't realize synchronization was so critical too. Interesting. Just a comment/question to both, since you are both developers of widely used programs (and I take this opportunity to thank you both for that), I discovered the THOR mode as release by Dave in Fldigi and I have to say based on the preliminary test that I have done (and echoed by tests done by Rein developer of the PSKmail system), that I am very impressed by the performance I get. It is also an ifsk mode like DominoEx but for some reason performs much better at least as implemented in fldigi. Not sure if it is the permanent FEC but is seems quite robust in my tests between VK and ZL. Have you had any comments or request for implementation in your software or is it just too new, or not different enough? 73s, John VK2ETA (And for Patrick, Ex FK8DV. Merci) Announce your digital presence via our Interactive Sked Page at http://www.obriensweb.com/sked 30M digital activity at http://www.projectsandparts.com/30m Recommended software : DM780, Multipsk, FLDIGI, Winwarbler ,MMVARI. Yahoo! Groups Links Internal Virus Database is out of date. Checked by AVG - http://www.avg.com Version: 8.0.138 / Virus Database: 270.6.6/1626 - Release Date: 8/21/2008 6:54 PM
[digitalradio] Re: Sound card question
The following is an excerpt from the web page Sights and Sounds of Digital Signals, http://www.w1hkj.com/FldigiHelp/Modes/index.htm. THOR Modes General Description THOR is a family of offset incremental multi-frequency shift keyed modes with low symbol rate, closely related to DominoEX. A single carrier of constant amplitude is stepped between 18 tone frequencies in a constant phase manner. As a result, no unwanted sidebands are generated, and no special amplifier linearity requirements are necessary. The tones change according to an offset algorithm which ensures that no sequential tones are the same or adjacent in frequency, considerably enhancing the inter-symbol interference resistance to multi-path and Doppler effects. The mode has full-time Forward Error Correction, so is extremely robust. The default speed (11 baud) was designed for NVIS conditions (80m at night), and other speeds suit weak signal LF, and high speed HF use. The use of incremental keying gives the mode complete immunity to transmitter-receiver frequency offset, drift and excellent rejection of propagation induced Doppler. Protocol These are unconnected, manually controlled message asynchronous simplex chat modes, using binary convolutional Forward Error Correction. The default calling mode is THOR11. Coding and Character Set A binary varicode with ASCII-256 user interface (same as MFSK16) is used. Lower case characters are sent faster. An ASCII-128 secondary character set extension allows a fixed (typically ID) message to be sent whenever the transmitter is idle. Modulation uses two dibit pairs, symbol synchronous, differential. The FEC system uses binary convolution to generate two dibits per varicode bit, and halves the corrected data rate compared to the equivalent DominoEX mode. Rate R=1/2, Constraint length K=7, Interleaver L=10 (40 bits). Operating Parameters Mode Symbol Rate Typing Speed1 Duty Cycle2 Bandwidth3 ITU Designation4 THOR45 3.90625 baud14 wpm 100%173 Hz 173HF1B THOR55 5.3833 baud 22 wpm 100%244 Hz 244HF1B THOR85 7.8125 baud 28 wpm 100%346 Hz 346HF1B THOR116 10.766 baud 40 wpm 100%262 Hz 262HF1B THOR16 15.625 baud 58 wpm 100%355 Hz 355HF1B THOR22 21.533 baud 78 wpm 100%524 Hz 524HF1B Notes: 1. WPM is based on an average 5 characters per word, plus word space. Values based on sending 100 paris words. 2. Transmitter average power output relative to a constant carrier of the same PEP value. 3. This is the Necessary Bandwidth as defined by the ITU. 4. A summary of the ITU Designation system can be found at http://en.wikipedia.org/wiki/Types_of_radio_emissions 5. Double spaced mode. 6. Default and normal calling mode. Implementation details are contained in the GPL software source code for fldigi which can be downloaded from the following site: http://www.w1hkj.com/fldigi-distro/fldigi-3.03.tar.gz This is a tar zipped format that will be familiar to all Unix, Linux, Free BSD and OS X developers. Windows developers can unzip this type of archive using one of several archive managers including PKZIP. Fldigi is open source source software that is licensed under the General Public License, http://www.gnu.org/copyleft/gpl.html. You are free to use the source intact, to modify, to improve and even to incorporate into a commercial product. You must however abide by the the license under which it has been developed and published. To date one other amateur product has used fldigi source with great success, DM-780, by Simon Brown. DominoEX-FEC and THOR differ in two ways: The FEC table structures in DominoEX-FEC have been manipulated in a way that prevents the transmission of control codes. THOR uses the same FEC table as MFSK and can transmit the full ASCII character set. The interleave used in THOR is longer than used in DominoEX-FEC, and it will have a slower throughput but greater immunity againts multi-path. Fldigi can encode and decode both DominoEX-FEC and THOR. 73, Dave, W1HKJ
[digitalradio] Re: Sound card question
Hi John. 1. I noticed that although most PSK31 signals I receive are showing the two phase positions as displayed on the scope at 180 degrees, some are consistently at less angle than that, typically down to about 135 degrees. When I say consistently I mean it is obviously not just a momentary shift due to propagation as one can see with DX or QRMed signals. Is this related to the difference in calibration between the sound cards? Yes 2. In the case of PSK31 how much does mis-calibration really affects the reception? Does it result in a simple an increase percentage of mis-decoded characters when propagation/QRM creates unwanted phase shifts? In case of PSK31 it depends on the implementation of the decoder algorithm. Uncalibrated clock will cause phase shift to be different from 180 grades, which adds some uncertainity to decoded bit value. But uncalibrated clock will also negatively influence decoder ability to bit synchronize. I remember optimizing PocketDigi PSK31 decoder for best SNR. One of my optimizations was decreasing speed of PSK31 decoder clock synchronization. One does not want a single noise spike to have much influence. I was very surprised, when I found that my decoder did not work at all when the sound card clock was 1% off. 3. Which modes are the most / least sensitive to sound cards calibration differences? My guest is that in the least category we should find the psk and ifsk (e.g. Domino) modes and in the most sensitive category MFSK modes. Is that a correct assesment? Least sensitive will be CW and RTTY, which are asynchronous modes. Narrow spaced multitone modes (MFSK, Olivia, Contestia, Throb, Domino) will have problems if the tone scale is stretched or shrinked against the decoder bins caused by sound card clock error. Also the same applies here as at 2). Ability to bit synchronize if the sound card clock is off depends on the implementation of the decoder algorithm and is usually a compromise between SNR ability, time to synchronize and sensitivity to clock difference between modulator and demodulator. 73, Vojtech OK1IAK
Re: [digitalradio] Re: Sound card question
Hello John, As said by Vojtech the big problem is the synchronization. As there is no specific synchro signal, you must synchronize of the signal itself (using some non-linear function). The synchronization is primarily done for the theoritical modulation speed with the hypothesis of a pefect sound card speed. If there is a difference in sound card speed, the synchro must make up for the difference. If this one is too much important (let's say 1 %), it is difficult (or let's say not possible) to synchronize. A bad synchronisation means some noise in the moment when one need to do the bit estimation, and hence some noise on the phasemeter. The more sensitive modes are the modes with a lot of carriers as MT63 (because the relative difference between carriers become weaker and weaker and finally you can mix two carriers). The degradation of the decoding versus the difference with the nominal sound card speed varies from one mode to another. It is a slow function in PSK31 but a quick function in Olivia. As said by Votjech, CW and RTTY as not so sensitive because there is no synchronization done (they are asynchronous modes), but reversely the minimum S/N cannot be so good as a synchronous mode (as PSK31 for example). 73 Patrick - Original Message - From: vk2eta [EMAIL PROTECTED] To: digitalradio@yahoogroups.com Sent: Friday, October 10, 2008 3:48 AM Subject: [digitalradio] Re: Sound card question While we are on this interesting subject of sound card calibration I have a question in regards to the effect of the calibration itself on the capability of properly decoding the signals.So two questions: 1. I noticed that although most PSK31 signals I receive are showing the two phase positions as displayed on the scope at 180 degrees, some are consistently at less angle than that, typically down to about 135 degrees. When I say consistently I mean it is obviously not just a momentary shift due to propagation as one can see with DX or QRMed signals. Is this related to the difference in calibration between the sound cards? 2. In the case of PSK31 how much does mis-calibration really affects the reception? Does it result in a simple an increase percentage of mis-decoded characters when propagation/QRM creates unwanted phase shifts? 2. Which modes are the most / least sensitive to sound cards calibration differences? My guest is that in the least category we should find the psk and ifsk (e.g. Domino) modes and in the most sensitive category MFSK modes. Is that a correct assesment? Thanks, John (VK2ETA) Announce your digital presence via our Interactive Sked Page at http://www.obriensweb.com/sked 30M digital activity at http://www.projectsandparts.com/30m Recommended software : DM780, Multipsk, FLDIGI, Winwarbler ,MMVARI. Yahoo! Groups Links
Re: [digitalradio] Re: Sound card question
Hello Paul, Multipsk - will it store/save the correction between applications? No you must calibrate each application with the true sound card speed. If I have a choice between a 16 bit external soundblaster and a 24 bit external sound blaster, which should I use at what setting for best I don't think you could see any difference for decoding. If the level is good, 8, 16 or 24 bits will give the same results (theoriticaly there is a difference (due to the quantification noise), but the difference is on 1/10 or 1/100 dB order). However, if you plan to work with SdR (and hence work with weak signals), it could be interesting to have a 24 bits sound card (perhaps some SdR programs can work with 24 bits, but I'm not sure). 73 Patrick - Original Message - From: Paul [EMAIL PROTECTED] To: digitalradio@yahoogroups.com Sent: Thursday, October 09, 2008 7:39 AM Subject: [digitalradio] Re: Sound card question If I run one of the calibration routines - what MixW supplies or Multipsk - will it store/save the correction between applications? That is, is it a one time fix? Or does each application/mode have a correction field that I must adjust - then it saves it for recall like a preference? I mostly use WinWarbler, MixW, Multipsk, PSKDeluxe, and if I get a Pentium IV class machine, DM780. I also use CWGet as backup on when working CW. If I have a choice between a 16 bit external soundblaster and a 24 bit external sound blaster, which should I use at what setting for best results? Back when I just plugged into the internal sound card - simple, no choices. Now I've got options. Thank you and 73, Paul PS: I apologize if I asked this a few weeks ago. I haven't had access to my computer since then and the mind wanders. Announce your digital presence via our Interactive Sked Page at http://www.obriensweb.com/sked 30M digital activity at http://www.projectsandparts.com/30m Recommended software : DM780, Multipsk, FLDIGI, Winwarbler ,MMVARI. Yahoo! Groups Links
[digitalradio] Re: Sound card question
While we are on this interesting subject of sound card calibration I have a question in regards to the effect of the calibration itself on the capability of properly decoding the signals.So two questions: 1. I noticed that although most PSK31 signals I receive are showing the two phase positions as displayed on the scope at 180 degrees, some are consistently at less angle than that, typically down to about 135 degrees. When I say consistently I mean it is obviously not just a momentary shift due to propagation as one can see with DX or QRMed signals. Is this related to the difference in calibration between the sound cards? 2. In the case of PSK31 how much does mis-calibration really affects the reception? Does it result in a simple an increase percentage of mis-decoded characters when propagation/QRM creates unwanted phase shifts? 2. Which modes are the most / least sensitive to sound cards calibration differences? My guest is that in the least category we should find the psk and ifsk (e.g. Domino) modes and in the most sensitive category MFSK modes. Is that a correct assesment? Thanks, John (VK2ETA)
[digitalradio] Re: Sound card question
If I run one of the calibration routines - what MixW supplies or Multipsk - will it store/save the correction between applications? That is, is it a one time fix? Or does each application/mode have a correction field that I must adjust - then it saves it for recall like a preference? I mostly use WinWarbler, MixW, Multipsk, PSKDeluxe, and if I get a Pentium IV class machine, DM780. I also use CWGet as backup on when working CW. If I have a choice between a 16 bit external soundblaster and a 24 bit external sound blaster, which should I use at what setting for best results? Back when I just plugged into the internal sound card - simple, no choices. Now I've got options. Thank you and 73, Paul PS: I apologize if I asked this a few weeks ago. I haven't had access to my computer since then and the mind wanders.
[digitalradio] Re: Sound card question
Thanks, Simon! It makes sense that if the native speed is 48K, any other speed would require some type of conversion. One more question, if I can impose on your good nature! What impact, if any, does the error in sampling rate have on any TX/RX offset? During the Tara Rumble I noticed that almost every station that responded to my CQ, came back a bit lower in frequency than mine. One station I responded to even told me I was off- frequency. I don't believe my IC-746 has any offset, and my RIT/XIT was off. Does that large error rate of 6984 ppm create an offset, and can I determine how great it is? Tnx es 73 Dave KB3MOW --- In digitalradio@yahoogroups.com, Simon Brown \(KNS\) [EMAIL PROTECTED] wrote: It means that the drivers are better - the internal clock runs at 48kHz, other rates are created by either the driver or (very often) Windows. Windows XP does not do a good job of this, VISTA however is excellent at converting the sample rates. Simon Brown, HB9DRV www.ham-radio-deluxe.com - Original Message - From: Dave 'Doc' Corio [EMAIL PROTECTED] I've calibrated my sound card (Diamond PCI) two ways, using MMSSTV at 48000 Hz, and MMTTY at 11025 Hz. Here are the results of the calibration: MMSSTV 195 PPM 48009.37 MMTTY 6984 PPM 11102
Re: [digitalradio] Re: Sound card question
A significant difference between TX and RX can result in an offset. During my holidays in Oct / Nov I will add full soundcard calibration for all modes in DM780. Simon Brown, HB9DRV www.ham-radio-deluxe.com - Original Message - From: Dave [EMAIL PROTECTED] What impact, if any, does the error in sampling rate have on any TX/RX offset? During the Tara Rumble I noticed that almost every station that responded to my CQ, came back a bit lower in frequency than mine. One station I responded to even told me I was off- frequency. I don't believe my IC-746 has any offset, and my RIT/XIT was off. Does that large error rate of 6984 ppm create an offset, and can I determine how great it is?
Re: [digitalradio] Re: Sound card question
Hello Dave, It is simple. If the offset in sampling frequency is x% and the true AF frequency is f0, the displayed frequency f will be equal to f=f0*(1-x/100) Example: if the sampling offset is +1% and f0 is 1000 Hz, the frequency displayed will be equal to 1000*(1-0.01)=990 Hz 73 Patrick - Original Message - From: Dave [EMAIL PROTECTED] To: digitalradio@yahoogroups.com Sent: Tuesday, October 07, 2008 3:57 PM Subject: [digitalradio] Re: Sound card question Thanks, Simon! It makes sense that if the native speed is 48K, any other speed would require some type of conversion. One more question, if I can impose on your good nature! What impact, if any, does the error in sampling rate have on any TX/RX offset? During the Tara Rumble I noticed that almost every station that responded to my CQ, came back a bit lower in frequency than mine. One station I responded to even told me I was off- frequency. I don't believe my IC-746 has any offset, and my RIT/XIT was off. Does that large error rate of 6984 ppm create an offset, and can I determine how great it is? Tnx es 73 Dave KB3MOW --- In digitalradio@yahoogroups.com, Simon Brown \(KNS\) [EMAIL PROTECTED] wrote: It means that the drivers are better - the internal clock runs at 48kHz, other rates are created by either the driver or (very often) Windows. Windows XP does not do a good job of this, VISTA however is excellent at converting the sample rates. Simon Brown, HB9DRV www.ham-radio-deluxe.com - Original Message - From: Dave 'Doc' Corio [EMAIL PROTECTED] I've calibrated my sound card (Diamond PCI) two ways, using MMSSTV at 48000 Hz, and MMTTY at 11025 Hz. Here are the results of the calibration: MMSSTV 195 PPM 48009.37 MMTTY 6984 PPM 11102 Announce your digital presence via our Interactive Sked Page at http://www.obriensweb.com/sked 30M digital activity at http://www.projectsandparts.com/30m Recommended software : DM780, Multipsk, FLDIGI, Winwarbler ,MMVARI. Yahoo! Groups Links
Re: [digitalradio] Re: Sound card question
Thanks, Patrick! If I understand this, then, here is what I should expect: My sound card calibrates to 48009.37, which is .9998% fast I transmit with an audio frequency of 2415 Hz I am therefore actually transmitting on 2439 Hz, or .9998% higher than indicated Does that sound right? Tnx es 73 Dave KB3MOW Patrick Lindecker wrote: Hello Dave, It is simple. If the offset in sampling frequency is x% and the true AF frequency is f0, the displayed frequency f will be equal to f=f0*(1-x/100) Example: if the sampling offset is +1% and f0 is 1000 Hz, the frequency displayed will be equal to 1000*(1-0.01)=990 Hz 73 Patrick - Original Message - From: Dave [EMAIL PROTECTED] mailto:dcorio%40zitomedia.net To: digitalradio@yahoogroups.com mailto:digitalradio%40yahoogroups.com Sent: Tuesday, October 07, 2008 3:57 PM Subject: [digitalradio] Re: Sound card question Thanks, Simon! It makes sense that if the native speed is 48K, any other speed would require some type of conversion. One more question, if I can impose on your good nature! What impact, if any, does the error in sampling rate have on any TX/RX offset? During the Tara Rumble I noticed that almost every station that responded to my CQ, came back a bit lower in frequency than mine. One station I responded to even told me I was off- frequency. I don't believe my IC-746 has any offset, and my RIT/XIT was off. Does that large error rate of 6984 ppm create an offset, and can I determine how great it is? Tnx es 73 Dave KB3MOW --- In digitalradio@yahoogroups.com mailto:digitalradio%40yahoogroups.com, Simon Brown \(KNS\) [EMAIL PROTECTED] wrote: It means that the drivers are better - the internal clock runs at 48kHz, other rates are created by either the driver or (very often) Windows. Windows XP does not do a good job of this, VISTA however is excellent at converting the sample rates. Simon Brown, HB9DRV www.ham-radio-deluxe.com - Original Message - From: Dave 'Doc' Corio [EMAIL PROTECTED] I've calibrated my sound card (Diamond PCI) two ways, using MMSSTV at 48000 Hz, and MMTTY at 11025 Hz. Here are the results of the calibration: MMSSTV 195 PPM 48009.37 MMTTY 6984 PPM 11102 Announce your digital presence via our Interactive Sked Page at http://www.obriensweb.com/sked http://www.obriensweb.com/sked 30M digital activity at http://www.projectsandparts.com/30m http://www.projectsandparts.com/30m Recommended software : DM780, Multipsk, FLDIGI, Winwarbler ,MMVARI. Yahoo! Groups Links
Re: [digitalradio] Re: Sound card question
Dave, My sound card calibrates to 48009.37, which is .9998% fast So the offset is +0.0195 % I transmit with an audio frequency of 2415 Hz I am therefore actually transmitting on 2439 Hz, or .9998% higher No in TX it will be the reverse of RX. The true TX frequency will be equal to : 2415*(1+0.0195/100)=2145.47 Hz Reversely, if you listen to a a 2145.47 Hz transmission, it will be appear for your program as a 2415 Hz transmission. 73 Patrick - Original Message - From: Dave 'Doc' Corio [EMAIL PROTECTED] To: digitalradio@yahoogroups.com Sent: Tuesday, October 07, 2008 11:28 PM Subject: Re: [digitalradio] Re: Sound card question Thanks, Patrick! If I understand this, then, here is what I should expect: My sound card calibrates to 48009.37, which is .9998% fast I transmit with an audio frequency of 2415 Hz I am therefore actually transmitting on 2439 Hz, or .9998% higher than indicated Does that sound right? Tnx es 73 Dave KB3MOW Patrick Lindecker wrote: Hello Dave, It is simple. If the offset in sampling frequency is x% and the true AF frequency is f0, the displayed frequency f will be equal to f=f0*(1-x/100) Example: if the sampling offset is +1% and f0 is 1000 Hz, the frequency displayed will be equal to 1000*(1-0.01)=990 Hz 73 Patrick - Original Message - From: Dave [EMAIL PROTECTED] mailto:dcorio%40zitomedia.net To: digitalradio@yahoogroups.com mailto:digitalradio%40yahoogroups.com Sent: Tuesday, October 07, 2008 3:57 PM Subject: [digitalradio] Re: Sound card question Thanks, Simon! It makes sense that if the native speed is 48K, any other speed would require some type of conversion. One more question, if I can impose on your good nature! What impact, if any, does the error in sampling rate have on any TX/RX offset? During the Tara Rumble I noticed that almost every station that responded to my CQ, came back a bit lower in frequency than mine. One station I responded to even told me I was off- frequency. I don't believe my IC-746 has any offset, and my RIT/XIT was off. Does that large error rate of 6984 ppm create an offset, and can I determine how great it is? Tnx es 73 Dave KB3MOW --- In digitalradio@yahoogroups.com mailto:digitalradio%40yahoogroups.com, Simon Brown \(KNS\) [EMAIL PROTECTED] wrote: It means that the drivers are better - the internal clock runs at 48kHz, other rates are created by either the driver or (very often) Windows. Windows XP does not do a good job of this, VISTA however is excellent at converting the sample rates. Simon Brown, HB9DRV www.ham-radio-deluxe.com - Original Message - From: Dave 'Doc' Corio [EMAIL PROTECTED] I've calibrated my sound card (Diamond PCI) two ways, using MMSSTV at 48000 Hz, and MMTTY at 11025 Hz. Here are the results of the calibration: MMSSTV 195 PPM 48009.37 MMTTY 6984 PPM 11102 Announce your digital presence via our Interactive Sked Page at http://www.obriensweb.com/sked http://www.obriensweb.com/sked 30M digital activity at http://www.projectsandparts.com/30m http://www.projectsandparts.com/30m Recommended software : DM780, Multipsk, FLDIGI, Winwarbler ,MMVARI. Yahoo! Groups Links Announce your digital presence via our Interactive Sked Page at http://www.obriensweb.com/sked 30M digital activity at http://www.projectsandparts.com/30m Recommended software : DM780, Multipsk, FLDIGI, Winwarbler ,MMVARI. Yahoo! Groups Links
