DSP vs. non-DSP portable transceivers
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DSP vs. non-DSP portable transceivers
 
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At the Dayton (yeah, OK, Xenia) Hamvention, just before giving a demo of the KX2, a bystander asked me, “Why would you need DSP in a portable transceiver?” He went on to mention a few currently available rigs he was considering that didn’t have DSP, including one very new one [an “upgraded” legacy model]. I’ll leave the entire list to the reader’s imagination.
There are two basic reasons to use DSP: 1. As the core of the transceiver’s architecture, to reduce size and weight and increase flexibility 2. To provide a number of important features that have typically been seen only in desktop radios Explaining #1 is always a bit of a challenge since it dives into theory. Here’s the short version: The receiver in both the KX2 and KX3 uses a high-level quadrature mixer that down-converts the RF signal to baseband (0 kHz) or to a low I.F. (8 kHz). The resulting I and Q signals are fed to a pair of high-performance audio A-to-D converters, and all demodulation is then handled in DSP code. This configuration has immense versatility, reduces component count, and provides very consistent unit-to-unit performance in parameters such as selectivity. To explain #2, I prefer to just dive into the demo. There's a long list of functions that directly benefit those who operate portable, as well as anyone trying to maximize their communications capabilities. Here are the DSP functions that I try to include in demos (given enough time), along with their benefits for the operator: * Multiple Modes The KX2 and KX3 both support SSB, CW, AM, FM, and several data modes, without the need for supplementary hardware. All demodulation is handled by the DSP. And if we add a new mode in the future, it will be available to all KX-line radio owners free of charge with a simple firmware upgrade. * Bandwidth Control The DSP bandwidth can be adjusted from 50 Hz to 4000 Hz (5000 Hz in AM mode). The passband can also be shifted. Rigs without DSP are limited to the passband of their analog filters (including crystal filters). * Stereo Audio Effects and Dual Receive Both rigs demodulate two independent audio channels, allowing for simulated stereo, which reduces listening fatigue. Stereo is also used when DUAL RX is enabled; this allows the operator to listen to one signal in the left ear (VFO A) and another in the right (VFO B). This is essential for use with DX stations operating split, and greatly facilitates hunt ’n’ pounce contest operation where one receiver is parked on a station to be worked, while the other is used to locate the next one. * Adjustable AGC The KX2/KX3 include user-configurable AGC. Threshold, attack, decay, and hold time can all be adjusted. These are parameters that would require dozens of components in a non-DSP design. There’s also a short-duration pulse detector (AGC PLS). When this is turned on--the default--the DSP will seamlessly remove such pulses before they can pin your S-meter and cause a long RX recovery delay. (Rob Sherwood complemented us on this feature, which he found was missing on even high-end desktop transceivers. So, for in-house purposes, we call it “Sherwood mode” :) * Noise Blanking Many non-DSP radios lack noise blanking, or have simple blanking circuitry that can be easily overloaded. The KX-line DSP implements very effective blanking that can take out narrow pulses even at very low settings, and greatly attenuate irregular, high-duty cycle noise sources typical of light dimmers, electric fences, and wideband radar. Blanking can make the difference between a good QSO and not even hearing the other station. * Noise Reduction We often have to deal with stochastic (“white”) noise on the bands. Our DSP-based NR can be adjusted over a wide range to improve intelligibility, especially of speech signals. * Audio Peaking Filter (APF) CW operators often have to copy signals right at or even below the noise floor. At times like this, our APF can dramatically improve copy without adding significant ringing. APF uses a special filter shape for this purpose, with a 30-Hz-wide peak and broad, low-delay skirts. * Text Decode/Encode DSP allows the KX2/KX3 to demodulate and display CW, RTTY, and PSK31/63 signals directly on the LCD (or in the case of the KX3, as several lines of text on the PX3 panadapter). These modes are also directly supported for transmit purposes, using a keyer paddle (a keyboard can also be used, in conjunction with KX2/3 Utility and a notebook computer). * Receive and Transmit EQ 8-band EQ is provided to allow the operator to tailor both receive and transmit audio to meet special hearing requirements, optimize for use with particular microphones, etc. * CWT (CW/data tuning [auto-spot] and mini-spectral display) The DSP sends the MCU information about how far off the nearest signal is from the user’s selected sidetone or mark tone frequency. We use this to enable quick, one-tap auto-spotting of signals, as well as to drive a 10-segment bar graph that shows the signal’s position in the filter passband. * AF Limiter Some operators prefer to turn off AGC and control gain manually. This eliminates the “signal flattening” effect of AGC, instead emphasizing the amplitude dynamics among multiple signals. When AGC is off, DSP provides an adjustable-threshold AF limiter to protect your ears when very strong signals appear (AF LIM menu entry). * Special Transmit Features The KX2/KX3 include very effective adjustable speech compression, variable-threshold VOX and anti-VOX, and transmit noise gating. All three can be used to improve effectiveness of speech modes in noisy outdoor conditions. There’s also a two-message digital voice recorder that takes advantage of the DSP’s large flash memory. DVR message play can save your voice when you need to repeatedly call other stations. This is especially likely when running QRP and/or using compromise field antennas. * * * I’m pretty sure that the bystander in question walked away with a KX2, post-demo :) 73, Wayne N6KR ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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And that my friends, tells you everything you need to know about the K4.
Buck, k4ia Honor Roll 8BDXCC EasyWayHamBooks.com On 5/22/2018 11:55 AM, Wayne Burdick wrote: > At the Dayton (yeah, OK, Xenia) Hamvention, just before giving a demo of the KX2, a bystander asked me, “Why would you need DSP in a portable transceiver?” He went on to mention a few currently available rigs he was considering that didn’t have DSP, including one very new one [an “upgraded” legacy model]. I’ll leave the entire list to the reader’s imagination. > > There are two basic reasons to use DSP: > > 1. As the core of the transceiver’s architecture, to reduce size and weight and increase flexibility > > 2. To provide a number of important features that have typically been seen only in desktop radios > > Explaining #1 is always a bit of a challenge since it dives into theory. Here’s the short version: The receiver in both the KX2 and KX3 uses a high-level quadrature mixer that down-converts the RF signal to baseband (0 kHz) or to a low I.F. (8 kHz). The resulting I and Q signals are fed to a pair of high-performance audio A-to-D converters, and all demodulation is then handled in DSP code. This configuration has immense versatility, reduces component count, and provides very consistent unit-to-unit performance in parameters such as selectivity. > > To explain #2, I prefer to just dive into the demo. There's a long list of functions that directly benefit those who operate portable, as well as anyone trying to maximize their communications capabilities. > > Here are the DSP functions that I try to include in demos (given enough time), along with their benefits for the operator: > > * Multiple Modes > > The KX2 and KX3 both support SSB, CW, AM, FM, and several data modes, without the need for supplementary hardware. All demodulation is handled by the DSP. And if we add a new mode in the future, it will be available to all KX-line radio owners free of charge with a simple firmware upgrade. > > * Bandwidth Control > > The DSP bandwidth can be adjusted from 50 Hz to 4000 Hz (5000 Hz in AM mode). The passband can also be shifted. Rigs without DSP are limited to the passband of their analog filters (including crystal filters). > > * Stereo Audio Effects and Dual Receive > > Both rigs demodulate two independent audio channels, allowing for simulated stereo, which reduces listening fatigue. > > Stereo is also used when DUAL RX is enabled; this allows the operator to listen to one signal in the left ear (VFO A) and another in the right (VFO B). This is essential for use with DX stations operating split, and greatly facilitates hunt ’n’ pounce contest operation where one receiver is parked on a station to be worked, while the other is used to locate the next one. > > * Adjustable AGC > > The KX2/KX3 include user-configurable AGC. Threshold, attack, decay, and hold time can all be adjusted. These are parameters that would require dozens of components in a non-DSP design. There’s also a short-duration pulse detector (AGC PLS). When this is turned on--the default--the DSP will seamlessly remove such pulses before they can pin your S-meter and cause a long RX recovery delay. (Rob Sherwood complemented us on this feature, which he found was missing on even high-end desktop transceivers. So, for in-house purposes, we call it “Sherwood mode” :) > > * Noise Blanking > > Many non-DSP radios lack noise blanking, or have simple blanking circuitry that can be easily overloaded. The KX-line DSP implements very effective blanking that can take out narrow pulses even at very low settings, and greatly attenuate irregular, high-duty cycle noise sources typical of light dimmers, electric fences, and wideband radar. Blanking can make the difference between a good QSO and not even hearing the other station. > > * Noise Reduction > > We often have to deal with stochastic (“white”) noise on the bands. Our DSP-based NR can be adjusted over a wide range to improve intelligibility, especially of speech signals. > > * Audio Peaking Filter (APF) > > CW operators often have to copy signals right at or even below the noise floor. At times like this, our APF can dramatically improve copy without adding significant ringing. APF uses a special filter shape for this purpose, with a 30-Hz-wide peak and broad, low-delay skirts. > > * Text Decode/Encode > > DSP allows the KX2/KX3 to demodulate and display CW, RTTY, and PSK31/63 signals directly on the LCD (or in the case of the KX3, as several lines of text on the PX3 panadapter). These modes are also directly supported for transmit purposes, using a keyer paddle (a keyboard can also be used, in conjunction with KX2/3 Utility and a notebook computer). > > * Receive and Transmit EQ > > 8-band EQ is provided to allow the operator to tailor both receive and transmit audio to meet special hearing requirements, optimize for use with particular microphones, etc. > > * CWT (CW/data tuning [auto-spot] and mini-spectral display) > > The DSP sends the MCU information about how far off the nearest signal is from the user’s selected sidetone or mark tone frequency. We use this to enable quick, one-tap auto-spotting of signals, as well as to drive a 10-segment bar graph that shows the signal’s position in the filter passband. > > * AF Limiter > > Some operators prefer to turn off AGC and control gain manually. This eliminates the “signal flattening” effect of AGC, instead emphasizing the amplitude dynamics among multiple signals. When AGC is off, DSP provides an adjustable-threshold AF limiter to protect your ears when very strong signals appear (AF LIM menu entry). > > * Special Transmit Features > > The KX2/KX3 include very effective adjustable speech compression, variable-threshold VOX and anti-VOX, and transmit noise gating. All three can be used to improve effectiveness of speech modes in noisy outdoor conditions. > > There’s also a two-message digital voice recorder that takes advantage of the DSP’s large flash memory. DVR message play can save your voice when you need to repeatedly call other stations. This is especially likely when running QRP and/or using compromise field antennas. > > * * * > > I’m pretty sure that the bystander in question walked away with a KX2, post-demo :) > > 73, > Wayne > N6KR > > > > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: DSP vs. non-DSP portable transceivers
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Hi Buck,
I’m not entirely sure how to parse your response to my posting. But I can cover several possible interpretations by pointing out that the K3S has all of the same DSP features as the KX2/KX3, and then some. The K3S also has the advantages of a superhet, with narrow crystal filters in the 1st IF protecting the ADCs. The P3 panadapter, meanwhile, is actually a direct-sampling SDR, with its own DSP. It taps off the 1st IF, which is protected by the K3’s marrow RF band-pass filters. The P3’s noise floor is extremely low because it is also preceded by the K3’s preamp, LNA, and low-loss mixer. 73, Wayne N6KR ---- http://www.elecraft.com > On May 22, 2018, at 11:09 AM, Buck <[hidden email]> wrote: > > And that my friends, tells you everything you need to know about the K4. > > Buck, k4ia > Honor Roll > 8BDXCC > EasyWayHamBooks.com > >> On 5/22/2018 11:55 AM, Wayne Burdick wrote: >> At the Dayton (yeah, OK, Xenia) Hamvention, just before giving a demo of the KX2, a bystander asked me, “Why would you need DSP in a portable transceiver?” He went on to mention a few currently available rigs he was considering that didn’t have DSP, including one very new one [an “upgraded” legacy model]. I’ll leave the entire list to the reader’s imagination. >> There are two basic reasons to use DSP: >> 1. As the core of the transceiver’s architecture, to reduce size and weight and increase flexibility >> 2. To provide a number of important features that have typically been seen only in desktop radios >> Explaining #1 is always a bit of a challenge since it dives into theory. Here’s the short version: The receiver in both the KX2 and KX3 uses a high-level quadrature mixer that down-converts the RF signal to baseband (0 kHz) or to a low I.F. (8 kHz). The resulting I and Q signals are fed to a pair of high-performance audio A-to-D converters, and all demodulation is then handled in DSP code. This configuration has immense versatility, reduces component count, and provides very consistent unit-to-unit performance in parameters such as selectivity. >> To explain #2, I prefer to just dive into the demo. There's a long list of functions that directly benefit those who operate portable, as well as anyone trying to maximize their communications capabilities. >> Here are the DSP functions that I try to include in demos (given enough time), along with their benefits for the operator: >> * Multiple Modes >> The KX2 and KX3 both support SSB, CW, AM, FM, and several data modes, without the need for supplementary hardware. All demodulation is handled by the DSP. And if we add a new mode in the future, it will be available to all KX-line radio owners free of charge with a simple firmware upgrade. >> * Bandwidth Control >> The DSP bandwidth can be adjusted from 50 Hz to 4000 Hz (5000 Hz in AM mode). The passband can also be shifted. Rigs without DSP are limited to the passband of their analog filters (including crystal filters). >> * Stereo Audio Effects and Dual Receive >> Both rigs demodulate two independent audio channels, allowing for simulated stereo, which reduces listening fatigue. >> Stereo is also used when DUAL RX is enabled; this allows the operator to listen to one signal in the left ear (VFO A) and another in the right (VFO B). This is essential for use with DX stations operating split, and greatly facilitates hunt ’n’ pounce contest operation where one receiver is parked on a station to be worked, while the other is used to locate the next one. >> * Adjustable AGC >> The KX2/KX3 include user-configurable AGC. Threshold, attack, decay, and hold time can all be adjusted. These are parameters that would require dozens of components in a non-DSP design. There’s also a short-duration pulse detector (AGC PLS). When this is turned on--the default--the DSP will seamlessly remove such pulses before they can pin your S-meter and cause a long RX recovery delay. (Rob Sherwood complemented us on this feature, which he found was missing on even high-end desktop transceivers. So, for in-house purposes, we call it “Sherwood mode” :) >> * Noise Blanking >> Many non-DSP radios lack noise blanking, or have simple blanking circuitry that can be easily overloaded. The KX-line DSP implements very effective blanking that can take out narrow pulses even at very low settings, and greatly attenuate irregular, high-duty cycle noise sources typical of light dimmers, electric fences, and wideband radar. Blanking can make the difference between a good QSO and not even hearing the other station. >> * Noise Reduction >> We often have to deal with stochastic (“white”) noise on the bands. Our DSP-based NR can be adjusted over a wide range to improve intelligibility, especially of speech signals. >> * Audio Peaking Filter (APF) >> CW operators often have to copy signals right at or even below the noise floor. At times like this, our APF can dramatically improve copy without adding significant ringing. APF uses a special filter shape for this purpose, with a 30-Hz-wide peak and broad, low-delay skirts. >> * Text Decode/Encode >> DSP allows the KX2/KX3 to demodulate and display CW, RTTY, and PSK31/63 signals directly on the LCD (or in the case of the KX3, as several lines of text on the PX3 panadapter). These modes are also directly supported for transmit purposes, using a keyer paddle (a keyboard can also be used, in conjunction with KX2/3 Utility and a notebook computer). >> * Receive and Transmit EQ >> 8-band EQ is provided to allow the operator to tailor both receive and transmit audio to meet special hearing requirements, optimize for use with particular microphones, etc. >> * CWT (CW/data tuning [auto-spot] and mini-spectral display) >> The DSP sends the MCU information about how far off the nearest signal is from the user’s selected sidetone or mark tone frequency. We use this to enable quick, one-tap auto-spotting of signals, as well as to drive a 10-segment bar graph that shows the signal’s position in the filter passband. >> * AF Limiter >> Some operators prefer to turn off AGC and control gain manually. This eliminates the “signal flattening” effect of AGC, instead emphasizing the amplitude dynamics among multiple signals. When AGC is off, DSP provides an adjustable-threshold AF limiter to protect your ears when very strong signals appear (AF LIM menu entry). >> * Special Transmit Features >> The KX2/KX3 include very effective adjustable speech compression, variable-threshold VOX and anti-VOX, and transmit noise gating. All three can be used to improve effectiveness of speech modes in noisy outdoor conditions. >> There’s also a two-message digital voice recorder that takes advantage of the DSP’s large flash memory. DVR message play can save your voice when you need to repeatedly call other stations. This is especially likely when running QRP and/or using compromise field antennas. >> * * * >> I’m pretty sure that the bystander in question walked away with a KX2, post-demo :) >> 73, >> Wayne >> N6KR >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: DSP vs. non-DSP portable transceivers
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If I was Eric and Wayne, I'd name the next base transceiver the K5, just
because. On 5/22/2018 11:26 AM, Wayne Burdick wrote: > Hi Buck, > > I’m not entirely sure how to parse your response to my posting. But I can cover several possible interpretations by pointing out that the K3S has all of the same DSP features as the KX2/KX3, and then some. The K3S also has the advantages of a superhet, with narrow crystal filters in the 1st IF protecting the ADCs. > > The P3 panadapter, meanwhile, is actually a direct-sampling SDR, with its own DSP. It taps off the 1st IF, which is protected by the K3’s marrow RF band-pass filters. The P3’s noise floor is extremely low because it is also preceded by the K3’s preamp, LNA, and low-loss mixer. > > 73, > Wayne > N6KR ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: DSP vs. non-DSP portable transceivers
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In reply to this post by wayne burdick
On 5/22/2018 11:26 AM, Wayne Burdick wrote:
> The P3 panadapter, meanwhile, is actually a direct-sampling SDR, with its own DSP. It taps off the 1st IF, which is protected by the K3’s marrow RF band-pass filters. The P3’s noise floor is extremely low because it is also preceded by the K3’s preamp, LNA, and low-loss mixer. Yes. AND in the hands of a knowledgeable engineer/technician, a near lab-quality test instrument, with a display that can easily be calibrated to the signal level at the antenna input. I've used it to measure occupied bandwidth of transmitted signals to precision of a few Hz, and the SVGA board, with it's separate, higher res FFT, improves that to one Hz. I own two other dedicated spectrum analyzers -- an HP 8657A and a Rigol. They are not capable of these measurements, because they lack the frequency resolution (by a factor of about 500:1). Many other modern SDRs also have this capability when used with suitable software. 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
P3 SVGA - measuring occupied bandwidth
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On 22/05/18 19:57, Jim Brown wrote:
> Yes. AND in the hands of a knowledgeable engineer/technician, a near > lab-quality test instrument, with a display that can easily be > calibrated to the signal level at the antenna input. I've used it to > measure occupied bandwidth of transmitted signals to precision of a few > Hz, and the SVGA board, with it's separate, higher res FFT, improves > that to one Hz. Jim - in this context, are you using the definition of "occupied bandwidth" as in ITU RR 1.153, i.e. 99% mean power? If so, how do you do that with the P3 SVGA? 73, Richard G4DYA ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: P3 SVGA - measuring occupied bandwidth
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On 2018-05-23 3:54 AM, Richard Lamont wrote: > > Jim - in this context, are you using the definition of "occupied > bandwidth" as in ITU RR 1.153, i.e. 99% mean power? If so, how do you > do that with the P3 SVGA? Whilst it's not completely accurate, it is very easy to approximate the "occupied bandwidth" of reasonably strong signals using the P3. Set average to maximum and look at the points 20 dB down on either side. This will over estimate the bandwidth of a signal depending on the peak to average ratio of the given modulation (e.g., level of clipping of an SSB signal) but still provides a useful first order approximation. The greater difficulty is in measuring the occupied bandwidth of very narrow modes (e.g. JT65, JT9, FT8, RTTY or even CW) due to the 2 KHz minimum span of the P3 ... a 500 Hz span would be better for measuring narrow modes. 73, ... Joe, W4TV On 2018-05-23 3:54 AM, Richard Lamont wrote: > On 22/05/18 19:57, Jim Brown wrote: > >> Yes. AND in the hands of a knowledgeable engineer/technician, a near >> lab-quality test instrument, with a display that can easily be >> calibrated to the signal level at the antenna input. I've used it to >> measure occupied bandwidth of transmitted signals to precision of a few >> Hz, and the SVGA board, with it's separate, higher res FFT, improves >> that to one Hz. > > Jim - in this context, are you using the definition of "occupied > bandwidth" as in ITU RR 1.153, i.e. 99% mean power? If so, how do you do > that with the P3 SVGA? > > 73, > > Richard G4DYA > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by wayne burdick
To put it mildly, with progress in computing, the implementation in DSP is
easier, smaller, cheaper and mostly better. Programming is expensive. Same with tube and SS amplifiers. Most likely, hardware-wise SS is easier, cheaper and mostly better. Initial design and programming are expensive. Average age of ham radios is around 65 (QST). Old "truths" die slowly. Ignacy, NO9E -- Sent from: http://elecraft.365791.n2.nabble.com/ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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"Good, Fast, Cheap ... choose two."
73, Fred ["Skip"] K6DGW Sparks NV DM09dn Washoe County On 5/23/2018 7:32 AM, Ignacy wrote: > To put it mildly, with progress in computing, the implementation in DSP is > easier, smaller, cheaper and mostly better. Programming is expensive. > > Same with tube and SS amplifiers. Most likely, hardware-wise SS is easier, > cheaper and mostly better. Initial design and programming are expensive. > > Average age of ham radios is around 65 (QST). Old "truths" die slowly. > > Ignacy, NO9E > > > > -- > Sent from: http://elecraft.365791.n2.nabble.com/ > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: P3 SVGA - measuring occupied bandwidth
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In reply to this post by Richard Lamont
On 5/23/2018 12:54 AM, Richard Lamont wrote:
> Jim - in this context, are you using the definition of "occupied > bandwidth" as in ITU RR 1.153, i.e. 99% mean power? If so, how do you do > that with the P3 SVGA? For CW, I transmit a long series of dits, put the P3 in peak mode, and accumulate peaks. When the display stops changing, I freeze it, use the cursor to manually log enough points to define the curve on both sides of the carrier, starting at -20dB carrier and every 5 dB until the data falls off screen. I then save the screen to a file. I've done essentially the same thing with RTTY and PSK. For SSB, my test signal is bandwidth limited Pink Noise. Pink Noise is widely used as an audio test signal because both spectral balance and dynamics are a good first approximation of speech. Pink Noise is defined as equal power per percentage bandwidth, whereas white noise is equal voltage per Hz. Pink noise can be though of as white noise with a 3dB per octave rolloff. That's not easy to generate -- an RC rolloff is 6 dB/octave. And this important comment. NC0B uses White Noise as a source. This is VERY BAD practice, because it puts nearly all of the modulation above the voice spectrum, and greatly de-emphasizes speech. I've corrected him on this three times, first as long as five years ago, yet he continues to do it wrong. The importance of this is that GOOD audio processing is designed for the spectrum and dynamics of speech, so any audio test signal should approximate speech as closely as possible. Rob is a great engineer and does ham radio a great service with his testing, but he fails to even attempt to understand the difference between RF and audio. As to my credentials to say this -- I spent 40 years in pro audio, with much of my work directed to sound systems for both speech intelligibility and music. For 20 years, I've been a member of the AES Standards Committee, and of Working Groups on Speech Intellibility. About ten years ago, I was elected a Fellow of the AES. 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
Re: P3 SVGA - measuring occupied bandwidth
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In reply to this post by Joe Subich, W4TV-4
On 5/23/2018 6:47 AM, Joe Subich, W4TV wrote:
> The greater difficulty is in measuring the occupied bandwidth of very > narrow modes (e.g. JT65, JT9, FT8, RTTY or even CW) due to the 2 KHz > minimum span of the P3 ... a 500 Hz span would be better for measuring > narrow modes. Not so difficult at all, using the methods I outlined in a previous post. I have successfully used it on RTTY, CW, PSK31 an a steady carrier. Most of that data is summarized in this Power Point pdf. Most of these data are from the SVGA. http://k9yc.com/P3_Spectrum_Measurements.pdf Note -- TXEQ in my K3s are set maximum rolloff of the 50, 100, and 200 Hz octave bands and some rolloff of the 400 Hz band. This accounts for the difference in the shape of the top of the curve between my K3s and other rigs tested. 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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