Topband: Digial mode spurious issues

[Joe Subich, W4TV]

 > 1 } Improperly adjusted sound card interface i.e. over driven and
 > drawing ALC (remember it is a digital signal)

JT65 and JT9 are single tone at a time modes and are designed to be
operated with class C amplifiers - as is common in EME operation.
ALC is not an issue but improperly adjusted sound cards (clipping),
overdriven microphone inputs (clipping in the mic preamp) and band
audio returns (grounds) are all common causes of distorted signals.

 > 2} A poorly operating SSB transceiver where the opposite sideband has
 > poor suppression. This type of transceiver will most likely QRM
 > someone even if on CW or SSB.

Poorly adjusted SSB transceivers - poor carrier suppression, bad
opposite sideband rejection - are the biggest issue.

 > 3.) He was running way way too much power. I never operate with more
 > than 30 watts {its a low power mode.. I worked VK5BC with 30w on TB
 > ........try that with CW)

JT65 and JT9 are *not* "low power modes.  They are *weak signal* modes
- there is a big difference.  The genesis of Joe Taylor's modes was
EME and meteor scatter communications where "full gallon" transmitters
are normal and signals are still weak.  Nobody with an understanding of
the history of JT4, JT6, JT9, JT65, FSK441, etc. would ever call them
"low power" modes or suggest EME and MS operators run 30 watts or less.

73,

    ... Joe, W4TV


On 1/1/2014 9:39 PM, Jim wrote:
> Tom and all, T he signal you describe is indeed a JT65 signal and you
> can either use JT65HF OR WSJT-X to decode it but might I submit that
> the problem was with:
>
>
> 1 } Improperly adjusted sound card interface i.e. over driven and
> drawing ALC (remember it is a digital signal)
>
>
> 2} A poorly operating SSB transceiver where the opposite sideband has
> poor suppression. This type of transceiver will most likely QRM
> someone even if on CW or SSB.
>
>
> 3.) He was running way way too much power. I never operate with more
> than 30 watts {its a low power mode.. I worked VK5BC with 30w on TB
> ........try that with CW)
>
>
> As a general rule all stations operating digital use USB now on all
> bands but the program does not care which sideband you use the
> transceiver sets that
>
>
> Remember that the signal that enters the transceiver is digital and
> as such will splatter if the signal input draws any appreciable ALC
>
>
> I agree that if a particular signal was being heard on 33 he had a
> problem of some type. If you find him again I would be willing to
> make first contact ... I understand what signals should sound like
> and look like on the display. I only suggest this because this mode
> is kinda unique and uses (for the most part) canned messages.
>
>
> Now to why digital is where it is in the band.. although we have been
> here before....it is not by chance that digital is at that spot in
> the band. They want to have QSOs with DX stations too and there are a
> lot of countries that don't allow operation down the bottom of the
> band but they do allow operation 1930-1950. Besides IF someone misses
> these few KHz we have a major problem with the way we are operating.
> Next I can and have operated CW directly among a whole wack of JT65
> they didn,t know the difference and neither did I and if I can do it
> with the TINITUS others can do it.
>
>
>
>
> By the way operating digital is not about being an elite operator as
> someone suggested in one of the local chat rooms, its about doing
> something different and forging new ground.. or as James T. Kirk
> called it .. "Going where no one has gone before"
>
>
> Jim
>
> Long Live Seal Team VI
>
> http://www.qsl.net/wa3mej/index.htm ----- Original Message -----
> From: topband-request at contesting.com To: topband at contesting.com Sent:
> Wednesday, January 1, 2014 12:00:12 PM Subject: Topband Digest, Vol
> 133, Issue 1
>
> Send Topband mailing list submissions to topband at contesting.com
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>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Topband digest..."
>
>
> Today's Topics:
>
> 1. Re: Digial mode spurious issues (Mike Greenway) 2. Re: Digial mode
> spurious issues (Joe Subich, W4TV) 3. Re: Digial mode spurious issues
> (Mike Waters) 4. Re: Digital mode spurious issues (Tom W8JI)
>
>
> ----------------------------------------------------------------------
>
>  Message: 1 Date: Tue, 31 Dec 2013 17:10:27 -0500 From: "Mike
> Greenway" <K4PI at BELLSOUTH.NET> To: <topband at contesting.com> Subject:
> Re: Topband: Digial mode spurious issues Message-ID:
> <52A7C61BC0414D61A4DD6EB286A01A81 at SHACK> Content-Type: text/plain;
> charset="utf-8"
>
> I don?t am still puzzled why the digital modes decided to use the
> 1837 to 1839 area with the size of the 160 M band. I know the SSB
> guys use a lot of the 1840-1900 area but 1900 to 2000 is usable isn?t
> it? I rarely hear much up there and 3 or 4 khz up there would never
> be missed. Probably not an answer but it has seemed strange to me
> since they started operating in that area. Some of their signals are
> bone crushing and wide. 73 Mike K4PI
>
> From: topband-request at contesting.com Sent: Tuesday, December 31, 2013
> 12:00 PM To: topband at contesting.com Subject: Topband Digest, Vol 132,
> Issue 30
>
> Send Topband mailing list submissions to topband at contesting.com
>
> To subscribe or unsubscribe via the World Wide Web, visit
> http://lists.contesting.com/mailman/listinfo/topband or, via email,
> send a message with subject or body 'help' to
> topband-request at contesting.com
>
> You can reach the person managing the list at
> topband-owner at contesting.com
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Topband digest..."
>
>
> Today's Topics:
>
> 1. Digital mode spurious issues (Tom W8JI) 2. Re: Digital mode
> spurious issues (Mike Waters) 3. Re: Digital mode spurious issues
> (Jim Brown) 4. Re: Digital mode spurious issues (Richard (Rick)
> Karlquist) 5. Re: Digital mode spurious issues (Joe Subich, W4TV) 6.
> Re: Digital mode spurious issues (Charlie Cunningham) 7. Re: Digital
> mode spurious issues (Jim Brown) 8. Re: [CQ-Contest] Stew Perry
> Streaming Audio (Herb Schoenbohm) 9. Re: Digital mode spurious issues
> (Grant Saviers) 10. Re: Digital mode spurious issues (W2RU - Bud
> Hippisley) 11. Re: Digital mode spurious issues (Mike Waters) 12. Re:
> Digital mode spurious issues (Charlie Cunningham) 13. Re: Digital
> mode spurious issues (JC N4IS) 14. Re: Digital mode spurious issues
> (Mike Waters) 15. Re: Digital mode spurious issues (Tom W8JI) 16. Re:
> Digital mode spurious issues (Charlie Cunningham) 17. Re: Digital
> mode spurious issues (Steven Raas) 18. Re: Digital mode spurious
> issues (Mike Waters) 19. Re: Stew Perry Streaming Audio (Shoppa,
> Tim) 20. CA/OR/AZ activity during Stew Perry - anecdotal data (Barry
> N1EU) 21. Re: Digital mode spurious issues (Tom W8JI)
>
>
> ----------------------------------------------------------------------
>
>  Message: 1 Date: Mon, 30 Dec 2013 12:11:49 -0500 From: "Tom W8JI"
> <w8ji at w8ji.com> To: "Topband" <topband at contesting.com> Subject:
> Topband: Digital mode spurious issues Message-ID:
> <AB0B5258E3B345428ADE0FAFD65179C0 at MAIN> Content-Type: text/plain;
> format=flowed; charset="iso-8859-1"; reply-type=response
>
> I have not been on the air for a year or so, but decided to get back
> on. I was listening to a DX station around 1833 when a digimode
> station up roughly around 1837 came on with a LSB "spurious" signal
> on 1833. His signal was a series of slowly changing stepped tones. I
> don't know what mode that was. His unwanted sideband suppression was
> about 40 dB, but that was not nearly enough. He was 15 dB out of
> noise with his unwanted sideband.
>
> Does anyone know of a universal software to decode signals? Since the
> FCC does not require a CW ID, I think that is the only way to
> identify stations.
>
> I assume:
>
> 1.) Operators are unlikely to accept they have a problem if they are
> getting good reports on the intentional signal
>
> 2.) Some rigs just should not be used for digimodes (this was a
> sideband suppression issue)
>
> 3.) Those who unwisely placed digimode subbands next to popular weak
> signal areas, especially when sideband selection produces a supurious
> that falls in weak signal areas, are unlikely to rethink the poor
> placement or poor advice on selecting sidebands
>
> 4.) With a little work to convince them, most digital ops with radio
> problems would avoid operating
>
> 73 Tom
>
>
>
> ------------------------------
>
> Message: 2 Date: Mon, 30 Dec 2013 12:30:34 -0600 From: Mike Waters
> <mikewate at gmail.com> To: Tom W8JI <w8ji at w8ji.com> Cc: Topband
> <topband at contesting.com> Subject: Re: Topband: Digital mode spurious
> issues Message-ID:
> <CA+FxYXj7jeqKdTtR1BWSWZU-ZjsC0h79YN8HhjDfJKs+xLzQPA at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Tom,
>
> I believe the mode that operates at 1873-1838 is JT65, and WSJT is
> needed to decode it. I never tried it. It was developed by K1JT for
> weak-signal and EME work.
> http://www.physics.princeton.edu/pulsar/K1JT/wsjt.html
>
> A common scenario with digital modes is that the audio into the mic
> input is too high, causing unwanted spurs.
>
> 73, Mike www.w0btu.com
>
>
> On Mon, Dec 30, 2013 at 11:11 AM, Tom W8JI <w8ji at w8ji.com> wrote:
>
>> ... a digimode station up roughly around 1837 came on with a LSB
>> "spurious" signal on 1833. His signal was a series of slowly
>> changing stepped tones. I don't know what mode that was. His
>> unwanted sideband suppression was about 40 dB, but that was not
>> nearly enough. He was 15 dB out of noise with his unwanted
>> sideband.
>>
>> Does anyone know of a universal software to decode signals? Since
>> the FCC does not require a CW ID, I think that is the only way to
>> identify stations. ...
>>
>
>
> ------------------------------
>
> Message: 3 Date: Mon, 30 Dec 2013 14:17:57 -0800 From: Jim Brown
> <jim at audiosystemsgroup.com> To: topband at contesting.com Subject: Re:
> Topband: Digital mode spurious issues Message-ID:
> <52C1F115.6050304 at audiosystemsgroup.com> Content-Type: text/plain;
> charset=ISO-8859-1; format=flowed
>
> You're both right -- it is either JT65 or JT9. WSJT software, based
> on protocols developed by K1JT, will decode both modes. Another
> software package called JT65-HF will decode only JT65.
>
> And yes, the trash Tom was hearing was either overdriven audio or a
> crummy radio or both. Some of the newer hams using these modes are
> also using pretty crummy radios -- all-banders in the $900 price
> range. OTOH, most are running flea power -- 20W is QRO for this
> crowd.
>
> I've done a fair amount of JT65, mostly on 6M and 160M, using my K3.
> I've also used other K1JT modes designed for meteor scatter (FSK441)
> and ionospheric scatter (SCAT). JT9 is Joe's latest and greatest
> protocol, requiring a fraction of the bandwidth of JT65.
>
> 73, Jim K9YC
>
> On 12/30/2013 10:30 AM, Mike Waters wrote:
>> I believe the mode that operates at 1873-1838 is JT65, and WSJT is
>> needed to decode it. I never tried it. It was developed by K1JT for
>> weak-signal and EME work.
>> http://www.physics.princeton.edu/pulsar/K1JT/wsjt.html
>>
>> A common scenario with digital modes is that the audio into the mic
>> input is too high, causing unwanted spurs.
>
>
>
> ------------------------------
>
> Message: 4 Date: Mon, 30 Dec 2013 14:59:13 -0800 From: "Richard
> (Rick) Karlquist" <richard at karlquist.com> To: topband at contesting.com
> Subject: Re: Topband: Digital mode spurious issues Message-ID:
> <52C1FAC1.2000809 at karlquist.com> Content-Type: text/plain;
> charset=ISO-8859-1; format=flowed
>
> The simplest technical solution would be for the digital mode users
> to put the radio in LSB mode. This puts unwanted sideband QRM away
> from the DX CW window. Does the Joe Taylor software have a provision
> for this?
>
> Rick N6RK
>
>
> ------------------------------
>
> Message: 5 Date: Mon, 30 Dec 2013 18:05:12 -0500 From: "Joe Subich,
> W4TV" <lists at subich.com> To: topband at contesting.com Subject: Re:
> Topband: Digital mode spurious issues Message-ID:
> <52C1FC28.60806 at subich.com> Content-Type: text/plain;
> charset=ISO-8859-1; format=flowed
>
>
>> Does the Joe Taylor software have a provision for this?
>
> No, Joe Taylor's protocols are not capable of operating in LSB.
>
> 73,
>
> ... Joe, W4TV
>
>
> On 12/30/2013 5:59 PM, Richard (Rick) Karlquist wrote:
>> The simplest technical solution would be for the digital mode users
>> to put the radio in LSB mode. This puts unwanted sideband QRM away
>> from the DX CW window. Does the Joe Taylor software have a
>> provision for this?
>>
>> Rick N6RK _________________ Topband Reflector Archives -
>> http://www.contesting.com/_topband
>>
>
>
> ------------------------------
>
> Message: 6 Date: Mon, 30 Dec 2013 18:13:47 -0500 From: "Charlie
> Cunningham" <charlie-cunningham at nc.rr.com> To: "'Joe Subich, W4TV'"
> <lists at subich.com>, <topband at contesting.com> Subject: Re: Topband:
> Digital mode spurious issues Message-ID:
> <!&!AAAAAAAAAAAYAAAAAAAAAF0xXac1rOhFkn7GlcEWNIjCgAAAEAAAABg31XzAMKNCvuYjy/t7uksBAAAAAA==@nc.rr.com>
>
>  Content-Type: text/plain; charset="us-ascii"
>
> I would think that IMD products in a high-level PA that is
> over-driven beyond good linearity limits could add some junk in the
> "undesired sideband"? FWIW
>
> Charlie, K4OTV
>
> -----Original Message----- From: Topband
> [mailto:topband-bounces at contesting.com] On Behalf Of Joe Subich,
> W4TV Sent: Monday, December 30, 2013 6:05 PM To:
> topband at contesting.com Subject: Re: Topband: Digital mode spurious
> issues
>
>
>> Does the Joe Taylor software have a provision for this?
>
> No, Joe Taylor's protocols are not capable of operating in LSB.
>
> 73,
>
> ... Joe, W4TV
>
>
> On 12/30/2013 5:59 PM, Richard (Rick) Karlquist wrote:
>> The simplest technical solution would be for the digital mode users
>> to put the radio in LSB mode. This puts unwanted sideband QRM away
>> from the DX CW window. Does the Joe Taylor software have a
>> provision for this?
>>
>> Rick N6RK _________________ Topband Reflector Archives -
>> http://www.contesting.com/_topband
>>
> _________________ Topband Reflector Archives -
> http://www.contesting.com/_topband
>
>
>
> ------------------------------
>
> Message: 7 Date: Mon, 30 Dec 2013 15:51:38 -0800 From: Jim Brown
> <jim at audiosystemsgroup.com> To: topband at contesting.com Subject: Re:
> Topband: Digital mode spurious issues Message-ID:
> <52C2070A.40705 at audiosystemsgroup.com> Content-Type: text/plain;
> charset=ISO-8859-1; format=flowed
>
> On 12/30/2013 3:13 PM, Charlie Cunningham wrote:
>> I would think that IMD products in a high-level PA that is
>> over-driven beyond good linearity limits could add some junk in the
>> "undesired sideband"? FWIW
>
> Yes. Indeed, any IMD would do that. K6XX is an Elecraft engineer who
> worked on their KPA500, among other things, and looked at a lot of
> competing power amps in preparation for doing so. Bob recently did
> an excellent tutorial presentation to a meeting of the Northern
> California Contest Club about the root causes of sideband trash, the
> general properties of various amplifier types, and how to minimize
> the trash.
>
> In general:
>
> Distortion products increase when the antenna is poorly matched to
> the amplifier That's true whether it's a tuned tube amp or a fixed
> tuned solid state amp -- in other words, the tube amp must be
> carefully tuned, and the solid state amp should be used with a tuner
> if the antenna is not an ideal match.
>
> Distortion products increase as power supply voltage decreases. In
> other words, a rig designed to run on 13.8 volts will be much cleaner
> at 13.8 volts than at 12V.
>
> Most solid state output stages are cleaner at half power than at
> full power. That means that a rig will be cleaner driving a power amp
> at 50W than at 100 W.
>
> Using AGC between the power amp and the rig to set output level is a
> recipe for sideband trash.
>
> A properly tuned hollow state power amp is typically 8-10 dB cleaner
> than the best solid state amps.
>
> Fast rise time of the keying waveform is the major cause of clicks
> W8JI and others long ago identified this as the cause of the
> FT1000-series rigs awful clicks, and fixed them. The rise time of
> some rigs (notably the IC7600) is adjustable, and only the slowest
> rise time is acceptable. The K3 uses an optimally shaped keying
> waveform (which designer N6KR calls "sigmoidal") to minimize clicks,
> and it is not user adjustable.
>
> Most ICOM rigs have overshoot that also causes clicks.
>
> Something I learned from N6KR a few days ago is that the very low
> level of sideband trash from a K3 is the result of two design
> elements. First, the synthesizer is very clean.. Second, they run it
> through the TX crystal filter, which gets rid of trash more distant
> from the carrier.
>
> 73, Jim K9YC
>
>
> ------------------------------
>
> Message: 8 Date: Mon, 30 Dec 2013 20:39:45 -0400 From: Herb
> Schoenbohm <herbs at vitelcom.net> To: topband at contesting.com Subject:
> Re: Topband: [CQ-Contest] Stew Perry Streaming Audio Message-ID:
> <52C21251.6010200 at vitelcom.net> Content-Type: text/plain;
> charset=ISO-8859-1; format=flowed
>
> This is just not possible anymore and there are so many situations
> like Greg experiences where the only hope to hear anything is by
> employing new technology. Also the 100KM rule, if there is such a
> rule, is intriguing because a remote RX in the BVI (a different DXCC
> country) would really be nice now that I have a new ham a few blocks
> away running a CQ machine during the contest in the DX window for the
> duration of the contest. Problems such as this along with high urban
> QRN are much more common and solution will be found. To arbitrarily
> block new innovations and technology to solve some of these issues is
> to me not going in the right direction. I think a better approach
> would be to allow for different categories creating incentives for
> inovations, rather than just outright ban them.
>
>
> Herb Schoenbohm, KV4FZ
>
>
>
>
> On 12/28/2013 4:19 PM, Greg - ZL3IX wrote:
>> "enjoy the contest the way we did back when Stew Perry was around"
>
>
>
> ------------------------------
>
> Message: 9 Date: Mon, 30 Dec 2013 17:12:10 -0800 From: Grant Saviers
> <grants2 at pacbell.net> To: Tom W8JI <w8ji at w8ji.com>, Topband
> <topband at contesting.com> Subject: Re: Topband: Digital mode spurious
> issues Message-ID: <52C219EA.6040106 at pacbell.net> Content-Type:
> text/plain; charset=ISO-8859-1; format=flowed
>
> The SignaLink supported software page has a nice summary of software
> decoders see http://www.tigertronics.com/sl_soft.htm
>
> If "universal" means automatic selection of the correct decoding
> mode, that would be a challenge!
>
> Grant KZ1W
>
> On 12/30/2013 9:11 AM, Tom W8JI wrote:
>> I have not been on the air for a year or so, but decided to get
>> back on. I was listening to a DX station around 1833 when a
>> digimode station up roughly around 1837 came on with a LSB
>> "spurious" signal on 1833. His signal was a series of slowly
>> changing stepped tones. I don't know what mode that was. His
>> unwanted sideband suppression was about 40 dB, but that was not
>> nearly enough. He was 15 dB out of noise with his unwanted
>> sideband.
>>
>> Does anyone know of a universal software to decode signals? Since
>> the FCC does not require a CW ID, I think that is the only way to
>> identify stations.
>>
>> I assume:
>>
>> 1.) Operators are unlikely to accept they have a problem if they
>> are getting good reports on the intentional signal
>>
>> 2.) Some rigs just should not be used for digimodes (this was a
>> sideband suppression issue)
>>
>> 3.) Those who unwisely placed digimode subbands next to popular
>> weak signal areas, especially when sideband selection produces a
>> supurious that falls in weak signal areas, are unlikely to rethink
>> the poor placement or poor advice on selecting sidebands
>>
>> 4.) With a little work to convince them, most digital ops with
>> radio problems would avoid operating
>>
>> 73 Tom _________________ Topband Reflector Archives -
>> http://www.contesting.com/_topband
>>
>
>
>
> ------------------------------
>
> Message: 10 Date: Mon, 30 Dec 2013 20:32:37 -0500 From: W2RU - Bud
> Hippisley <W2RU at frontiernet.net> To: jim at audiosystemsgroup.com Cc:
> topband at contesting.com Subject: Re: Topband: Digital mode spurious
> issues Message-ID:
> <656317B8-1858-42F1-9FFD-23DDE17534A6 at frontiernet.net> Content-Type:
> text/plain; charset=us-ascii
>
> This is a little off-topic relative to the Subject line, but
> extremely relevant to enjoyable Topband operating:
>
> On Dec 30, 2013, at 6:51 38PM, Jim Brown <jim at audiosystemsgroup.com>
> wrote:
>
>> Fast rise time of the keying waveform is the major cause of clicks.
>> W8JI and others long ago identified this as the cause of the
>> FT1000-series rigs awful clicks, and fixed them. The rise time of
>> some rigs (notably the IC7600) is adjustable, and only the slowest
>> rise time is acceptable.
>
> Add the venerable Kenwood TS-950SDX to the list of rigs with
> user-adjustable rise/fall times. And -- as Jim notes -- only the
> slowest rise time is fully acceptable, despite the pains Kenwood took
> to carefully "shape" those RF waveforms during their "on" and "off"
> transition periods.
>
> In the case of the 950SDX, the user can select nominal rise/fall
> times labeled 2, 4, 6, or 8 milliseconds (ms) from one of the
> configuration menus accessible via the front panel MENU options. A
> few years back, in extensive tests on a daytime 80-m band with an
> equally fanatical friend listening critically, we determined that
> -only- the 8-ms setting was "clean" with respect to click generation.
> Probably the 6-ms setting would be marginally "OK" if the transmitted
> signal were not loud anywhere, but since my usual objective when
> chasing DX on 160 is to be as loud as I can, 6 ms is not really an
> acceptable solution for maintaining good relations with my close-in
> Topband "neighbors" here on the east coast of North America. Once we
> ran those tests, I set the TS-950SDX menu choice to 8 ms, and I've
> not changed it since.
>
> Bud, W2RU
>
>
>
>
> ------------------------------
>
> Message: 11 Date: Mon, 30 Dec 2013 20:12:33 -0600 From: Mike Waters
> <mikewate at gmail.com> To: topband <topband at contesting.com> Subject:
> Re: Topband: Digital mode spurious issues Message-ID:
> <CA+FxYXiRKZnGLMKGdN1aTsFzBFkrGdY03znWG59EtadKSmF+jQ at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> You are right. There is no universal software that can do that. But I
> used to code software, and I'm convinced that the status quo in
> amateur digital software can be greatly improved. See
> http://www.eham.net/ehamforum/smf/index.php?topic=80740.0 .
>
> If anyone wants to take up where we left off on that eHam thread,
> then let's take the discussion there.
>
> 73, Mike www.w0btu.com
>
> On Mon, Dec 30, 2013 at 7:12 PM, Grant Saviers <grants2 at pacbell.net>
> wrote:
>
>>
>> If "universal" means automatic selection of the correct decoding
>> mode, that would be a challenge!
>>
>
>
> ------------------------------
>
> Message: 12 Date: Mon, 30 Dec 2013 21:34:26 -0500 From: "Charlie
> Cunningham" <charlie-cunningham at nc.rr.com> To:
> <jim at audiosystemsgroup.com>, <topband at contesting.com> Subject: Re:
> Topband: Digital mode spurious issues Message-ID:
> <!&!AAAAAAAAAAAYAAAAAAAAAF0xXac1rOhFkn7GlcEWNIjCgAAAEAAAAJjC6JAJz/RMjAuEvO+ytjsBAAAAAA==@nc.rr.com>
>
>  Content-Type: text/plain; charset="us-ascii"
>
> Hi, Jim
>
> Well as one who has been an RF and radio engineer and designer for
> 40+ years, I have to agree with most all of your points. Great deal
> of truth in there, but so many guys don't appreciate all those things
> and their inclination is "crank it to the right" and "the "louder you
> shout, the further you get"! And they are looking for large meter
> excursions. To appreciate the tendency to overdrive transmitters and
> amplifiers. One need only listen to the the prevalence of awful key
> clicks and SSB splatter in contests!
>
> (And "real men" use vacuum tubes to develop "real power"! :-) )
>
> 73, Charie, K4OTV
>
> -----Original Message----- From: Topband
> [mailto:topband-bounces at contesting.com] On Behalf Of Jim Brown Sent:
> Monday, December 30, 2013 6:52 PM To: topband at contesting.com Subject:
> Re: Topband: Digital mode spurious issues
>
> On 12/30/2013 3:13 PM, Charlie Cunningham wrote:
>> I would think that IMD products in a high-level PA that is
>> over-driven beyond good linearity limits could add some junk in the
>> "undesired sideband"? FWIW
>
> Yes. Indeed, any IMD would do that. K6XX is an Elecraft engineer who
> worked on their KPA500, among other things, and looked at a lot of
> competing power amps in preparation for doing so. Bob recently did
> an excellent tutorial presentation to a meeting of the Northern
> California Contest Club about the root causes of sideband trash, the
> general properties of various amplifier types, and how to minimize
> the trash.
>
> In general:
>
> Distortion products increase when the antenna is poorly matched to
> the amplifier That's true whether it's a tuned tube amp or a fixed
> tuned solid state amp -- in other words, the tube amp must be
> carefully tuned, and the solid state amp should be used with a tuner
> if the antenna is not an ideal match.
>
> Distortion products increase as power supply voltage decreases. In
> other words, a rig designed to run on 13.8 volts will be much cleaner
> at 13.8 volts than at 12V.
>
> Most solid state output stages are cleaner at half power than at
> full power. That means that a rig will be cleaner driving a power amp
> at 50W than at 100 W.
>
> Using AGC between the power amp and the rig to set output level is a
> recipe for sideband trash.
>
> A properly tuned hollow state power amp is typically 8-10 dB cleaner
> than the best solid state amps.
>
> Fast rise time of the keying waveform is the major cause of clicks
> W8JI and others long ago identified this as the cause of the
> FT1000-series rigs awful clicks, and fixed them. The rise time of
> some rigs (notably the IC7600) is adjustable, and only the slowest
> rise time is acceptable. The K3 uses an optimally shaped keying
> waveform (which designer N6KR calls "sigmoidal") to minimize clicks,
> and it is not user adjustable.
>
> Most ICOM rigs have overshoot that also causes clicks.
>
> Something I learned from N6KR a few days ago is that the very low
> level of sideband trash from a K3 is the result of two design
> elements. First, the synthesizer is very clean.. Second, they run it
> through the TX crystal filter, which gets rid of trash more distant
> from the carrier.
>
> 73, Jim K9YC _________________ Topband Reflector Archives -
> http://www.contesting.com/_topband
>
>
>
> ------------------------------
>
> Message: 13 Date: Mon, 30 Dec 2013 21:50:47 -0500 From: "JC N4IS"
> <n4is at comcast.net> To: "'Mike Waters'" <mikewate at gmail.com>, "'Tom
> W8JI'" <w8ji at w8ji.com> Cc: 'Topband' <topband at contesting.com>
> Subject: Re: Topband: Digital mode spurious issues Message-ID:
> <005801cf05d3$1bd5f9c0$5381ed40$@comcast.net> Content-Type:
> text/plain; charset="us-ascii"
>
> Tom, Mike is right, the issue with audio overload is complex for most
> of new radios, most of them have A/D just at the MIC input, if the
> A/D overloads the RF chain is compromised. These radios have no
> actual filters, everything is digital, like the IC7600. An analog
> radio is BW limited by the SSB crystal filter but SDR don't, when the
> A/D overloads, there are spoors everywhere several KHz far from the
> carrier; enough to trash the entire band.
>
> Using a SDR water fall it is easy to see the signal transitions and
> associate the trash with the main signal. I've seen several spoors
> every 10 KHz almost 100KHz up and down 1838. This is a growing
> problem.
>
> 73, JC N4IS
>
>
>
> -----Original Message----- From: Topband
> [mailto:topband-bounces at contesting.com] On Behalf Of Mike Waters
> Sent: Monday, December 30, 2013 1:31 PM To: Tom W8JI Cc: Topband
> Subject: Re: Topband: Digital mode spurious issues
>
> Tom,
>
> I believe the mode that operates at 1873-1838 is JT65, and WSJT is
> needed to decode it. I never tried it. It was developed by K1JT for
> weak-signal and EME work.
> http://www.physics.princeton.edu/pulsar/K1JT/wsjt.html
>
> A common scenario with digital modes is that the audio into the mic
> input is too high, causing unwanted spurs.
>
> 73, Mike www.w0btu.com
>
>
> On Mon, Dec 30, 2013 at 11:11 AM, Tom W8JI <w8ji at w8ji.com> wrote:
>
>> ... a digimode station up roughly around 1837 came on with a LSB
>> "spurious" signal on 1833. His signal was a series of slowly
>> changing stepped tones. I don't know what mode that was. His
>> unwanted sideband suppression was about 40 dB, but that was not
>> nearly enough. He was 15 dB out of noise with his unwanted
>> sideband.
>>
>> Does anyone know of a universal software to decode signals? Since
>> the FCC does not require a CW ID, I think that is the only way to
>> identify stations. ...
>>
> _________________ Topband Reflector Archives -
> http://www.contesting.com/_topband
>
>
>
> ------------------------------
>
> Message: 14 Date: Mon, 30 Dec 2013 21:17:28 -0600 From: Mike Waters
> <mikewate at gmail.com> To: topband <topband at contesting.com> Subject:
> Re: Topband: Digital mode spurious issues Message-ID:
> <CA+FxYXikYNQqzEAf+rHdJkNG1ztop1_V3UbBiTauLsRzpMqQ_g at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Bingo! The waterfall display was a wonderful invention, wasn't it?
> And I don't even use SDR. (Yet.)
>
> When I used to operate PSK31, I adjusted the audio levels with my
> own signal displayed on the waterfall, and so it was easy to see when
> the input from the sound card was too high. The spurs from AF
> overload are very easy to see on the waterfall.
>
> 73, Mike www.w0btu.com
>
> On Mon, Dec 30, 2013 at 8:50 PM, JC N4IS <n4is at comcast.net> wrote:
>
>>
>> Using a SDR water fall it is easy to see the signal transitions
>> and associate the trash with the main signal. I've seen several
>> spoors every 10 KHz almost 100KHz up and down 1838. This is a
>> growing problem.
>>
>
>
> ------------------------------
>
> Message: 15 Date: Mon, 30 Dec 2013 22:55:46 -0500 From: "Tom W8JI"
> <w8ji at w8ji.com> To: <topband at contesting.com> Subject: Re: Topband:
> Digital mode spurious issues Message-ID:
> <11A6F15D3D9F452F83930E7A3EBDA10F at MAIN> Content-Type: text/plain;
> format=flowed; charset="iso-8859-1"; reply-type=original
>
> Thanks everyone for the suggestions. I'm going to have to install
> some software to identify some of the signals.
>
>
>> I would think that IMD products in a high-level PA that is
>> over-driven beyond good linearity limits could add some junk in the
>> "undesired sideband"? FWIW
>>
>
> IMD **requires** two or more signals at once, and does not appear
> anything like sideband leakage. This was a single shifting tone, and
> the lower frequency signal went the opposite way but the same amount
> as the main signal with shifts. That is classic for inadequate
> sideband suppression.
>
> There are multiple problems with using SSB to transmit audio tones
> and "thinking" it is a pure digi mode.
>
> 1.) things like this do not show on almost all digi waterfalls
> because they are out of passband of the other fellows receiver.
>
> 2.) SSB carrier, noise, and opposite sideband suppression is limited
> by the radio quality
>
> 3.) output purity is also limited by audio input purity, which
> includes audio line issues
>
> 4.) most digi operators do not have the low noise antennas most DXers
> have, and cannot hear some fairly strong signals. They are often on
> digimodes because of that!
>
> 5.) radios have terrible SSB transmitter performance compared to even
> fair receivers, so the transmitters often set the adjacent channel
> interference levels
>
> Placing digimodes near weak signal areas is not very wise frequency
> planning, but there is nothing anyone can do about it.
>
>
>
> ------------------------------
>
> Message: 16 Date: Mon, 30 Dec 2013 23:28:41 -0500 From: "Charlie
> Cunningham" <charlie-cunningham at nc.rr.com> To: "'Tom W8JI'"
> <w8ji at w8ji.com>, <topband at contesting.com> Subject: Re: Topband:
> Digital mode spurious issues Message-ID:
> <!&!AAAAAAAAAAAYAAAAAAAAAF0xXac1rOhFkn7GlcEWNIjCgAAAEAAAABORbRe1dtFDk174Pca2TsABAAAAAA==@nc.rr.com>
>
>  Content-Type: text/plain; charset="us-ascii"
>
> Well, I certainly have to agree, Tom, if the signal on the desired
> sideband is just a single shifting tone. Might get messier if an
> sudio stage or A/D is driven into limiting and producing harmonic
> distortion at audio, I guess.
>
> 73, Charlie, K4OTV
>
> -----Original Message----- From: Topband
> [mailto:topband-bounces at contesting.com] On Behalf Of Tom W8JI Sent:
> Monday, December 30, 2013 10:56 PM To: topband at contesting.com
> Subject: Re: Topband: Digital mode spurious issues
>
> Thanks everyone for the suggestions. I'm going to have to install
> some software to identify some of the signals.
>
>
>> I would think that IMD products in a high-level PA that is
>> over-driven beyond good linearity limits could add some junk in the
>> "undesired sideband"? FWIW
>>
>
> IMD **requires** two or more signals at once, and does not appear
> anything like sideband leakage. This was a single shifting tone, and
> the lower frequency signal went the opposite way but the same amount
> as the main signal with shifts. That is classic for inadequate
> sideband suppression.
>
> There are multiple problems with using SSB to transmit audio tones
> and "thinking" it is a pure digi mode.
>
> 1.) things like this do not show on almost all digi waterfalls
> because they are out of passband of the other fellows receiver.
>
> 2.) SSB carrier, noise, and opposite sideband suppression is limited
> by the radio quality
>
> 3.) output purity is also limited by audio input purity, which
> includes audio line issues
>
> 4.) most digi operators do not have the low noise antennas most DXers
> have, and cannot hear some fairly strong signals. They are often on
> digimodes because of that!
>
> 5.) radios have terrible SSB transmitter performance compared to even
> fair receivers, so the transmitters often set the adjacent channel
> interference levels
>
> Placing digimodes near weak signal areas is not very wise frequency
> planning, but there is nothing anyone can do about it.
>
> _________________ Topband Reflector Archives -
> http://www.contesting.com/_topband
>
>
>
> ------------------------------
>
> Message: 17 Date: Mon, 30 Dec 2013 23:29:09 -0500 From: Steven Raas
> <sjraas at gmail.com> To: Tom W8JI <w8ji at w8ji.com> Cc:
> "topband at contesting.com" <topband at contesting.com> Subject: Re:
> Topband: Digital mode spurious issues Message-ID:
> <CABOEzZoFoWUPJ9zD3b4t1yDjwjLaBKui8dnU1L+1eYB=0woMYw at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Tom,
>
> I would have to agree. Let me also add my personal experiences on
> 160m JT65, were good, however, at the latter stages of me being QRV
> on the band, I was very politely spoken to, and delightfully educated
> on such matters by Les, KL7J , whom really gave me some great insight
> on a then and still new band to me, for this I am ever grateful. We
> tried to contact on many occasions a few years back on 160M JT-65,
> however the latter attempts were lower in the band , 1807 ish or so
> if I recall. I was one of the many daily 160M ops for quite some
> time, but after learning, & progressing, if I was QRV on 160 at the
> moment, I would take it ( digital ops ) down the band. I will also
> admit, that I was lured with the possibility ( at those times ) of my
> 1st trans-oceanic 160m QSO using JT65 ( or any mode ) , with my
> experiences now, I would say that waiting for prop, and running 4 or
> 5 cw q's was much easier for those 1st trans-oceanic q's. Not to
> mention that the long deep fades that I had ( with very very limited
> antennas which are frequently common with 160 digi mode ops ) would
> not be very beneficial for JT65 ' long haul / high qsb qso's, however
> this is not always the case. I can even say that to this day, I had
> yet to work any DX on 160m JT-65, cw now, is a different story
> thankfully :) There is also WSPR activity in that area of the band if
> I recall ( that may have changed ) amongst a few others. I think that
> progress could be made in getting the digi ops to qsy, perhaps to the
> lower end of the band, I'll be honest tho, I think that the hardest
> part would be getting the word out to the masses, however when
> presented with facts, and honest concern with the forsight of keeping
> the band active and everyone happy, my guess is that few would
> gripe.. but the masses just want to make qso's like the rest of us,
> and would in time oblige. I digress..have a great new year everyone &
> enjoy !
>
> -Steve Raas N2JDQ
>
>
> On Mon, Dec 30, 2013 at 10:55 PM, Tom W8JI <w8ji at w8ji.com> wrote:
>
>> Thanks everyone for the suggestions. I'm going to have to install
>> some software to identify some of the signals.
>>
>>
>>
>> I would think that IMD products in a high-level PA that is
>> over-driven
>>> beyond good linearity limits could add some junk in the
>>> "undesired sideband"? FWIW
>>>
>>>
>> IMD **requires** two or more signals at once, and does not appear
>> anything like sideband leakage. This was a single shifting tone,
>> and the lower frequency signal went the opposite way but the same
>> amount as the main signal with shifts. That is classic for
>> inadequate sideband suppression.
>>
>> There are multiple problems with using SSB to transmit audio tones
>> and "thinking" it is a pure digi mode.
>>
>> 1.) things like this do not show on almost all digi waterfalls
>> because they are out of passband of the other fellows receiver.
>>
>> 2.) SSB carrier, noise, and opposite sideband suppression is
>> limited by the radio quality
>>
>> 3.) output purity is also limited by audio input purity, which
>> includes audio line issues
>>
>> 4.) most digi operators do not have the low noise antennas most
>> DXers have, and cannot hear some fairly strong signals. They are
>> often on digimodes because of that!
>>
>> 5.) radios have terrible SSB transmitter performance compared to
>> even fair receivers, so the transmitters often set the adjacent
>> channel interference levels
>>
>> Placing digimodes near weak signal areas is not very wise
>> frequency planning, but there is nothing anyone can do about it.
>> _________________ Topband Reflector Archives -
>> http://www.contesting.com/_topband
>>
>
>
> ------------------------------
>
> Message: 18 Date: Mon, 30 Dec 2013 22:48:18 -0600 From: Mike Waters
> <mikewate at gmail.com> To: topband <topband at contesting.com> Subject:
> Re: Topband: Digital mode spurious issues Message-ID:
> <CA+FxYXjOemiJtEBo+HJsWjeeNBZvc8YVEwx8tgEQhoCJ-8Mfcg at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Maybe not.
>
> I got a private e-mail earlier (which I haven't had time to respond
> to yet) that stated "To see who is QRV on 160M WSPR at any given
> time, check at http://wsprnet.org/drupal/wsprnet/activity Scroll down
> to 160M and the stations are listed (those followed by an R are just
> receiving)."
>
> 73, Mike www.w0btu.com
>
> On Mon, Dec 30, 2013 at 9:55 PM, Tom W8JI <w8ji at w8ji.com> wrote:
>
>> Thanks everyone for the suggestions. I'm going to have to install
>> some software to identify some of the signals.
>>
>
>
> ------------------------------
>
> Message: 19 Date: Tue, 31 Dec 2013 13:49:06 +0000 From: "Shoppa, Tim"
> <tshoppa at wmata.com> Cc: "topband at contesting.com"
> <topband at contesting.com> Subject: Re: Topband: Stew Perry Streaming
> Audio Message-ID:
> <303A17BD5F8FA34DA45EEC245271AC0B949D647F at JGEX2K10MBX2.wmata.local>
> Content-Type: text/plain; charset="us-ascii"
>
> I always set these software-based goals before the test, but funny
> how they get delayed in the face of driving kids around to
> acitivities and stringing up antennas in the trees, and then when the
> sun goes down and the contest starts swinging, all those pie in the
> sky virtual dreams evaporate in the face of real QSO's to be made
> :-)
>
> I had a lot of fun in the Stew Perry and felt my new west-facing
> pennant was an improvement for stations in the deeper west and on
> west coast. I'm sure I didn't hear some low power California stations
> that tried to call me.
>
> Tim N3QE ________________________________________ From: Shoppa, Tim
> Sent: Saturday, December 28, 2013 9:58 AM Cc: topband at contesting.com
> Subject: RE: Topband: Stew Perry Streaming Audio
>
> Streaming audio live during the contest doesn't seem particularly
> useful to me.
>
> But recordings made available post-contest over the web, those might
> be interesting to others. I'm going to see if I can set that up at my
> (much more modest) shack. I would love to hear what my signal sounds
> like on West Coast or in EU.
>
> Tim N3QE
>
> ________________________________________ From: Topband
> [topband-bounces at contesting.com] on behalf of Tree [tree at kkn.net]
> Sent: Saturday, December 28, 2013 9:39 AM To: Eric NO3M Cc: Stan
> Stockton; topband at contesting.com; cq-contest at contesting.com; Clive
> GM3POI Subject: Re: Topband: Stew Perry Streaming Audio
>
> Perhaps a different approach is to make it available to people who
> are interested in hearing it. There are probably some people who are
> not able to operate the contest and would appreciate the opportunity
> to hear what it sounds like. Also - Eric is a top notch operator and
> being able to listen to how he uses two radios might be educational
> for some.
>
> I really doubt there is going to be abuse of this - despite what our
> imaginations come up with. I know K5ZD and others have done this for
> other major contests.
>
> Tree N6TR
>
>
> On Sat, Dec 28, 2013 at 3:39 AM, Eric NO3M <no3m at no3m.net> wrote:
>
>> Since there seems to be too much concern over this, though no ill
>> intent was intended, audio will not be broadcast.
>>
>> GL / 73 Eric NO3M
>>
>> On 12/28/2013 06:23 AM, Stan Stockton wrote:
>>
>>> Eric,
>>>
>>> You made it clear what you were doing, and I am quite sure Clive
>>> understood. I think the logic behind his question has to do with
>>> whether it is within the spirit of the contest - especially this
>>> one. Let's say, as a result of the announcement or advertisement
>>> , 15 DX stations and 25 USA stations who are not even going to
>>> send in their log called you, just for fun and the novelty of it,
>>> so they could listen to their own signal at your end via
>>> Internet.
>>>
>>> What if some have enough QRM or QRN that they could only copy
>>> whether you came back to them by listening via internet? Fair to
>>> your competitors?
>>>
>>> It is cool, but I've always had a problem with this, regardless
>>> of what contest.
>>>
>>> 73...Stan, K5GO
>>>
>>> Sent from my iPad
>>>
>> _________________ Topband Reflector Archives -
>> http://www.contesting.com/_topband
>>
> _________________ Topband Reflector Archives -
> http://www.contesting.com/_topband
>
>
> ------------------------------
>
> Message: 20 Date: Tue, 31 Dec 2013 09:21:38 -0500 From: Barry N1EU
> <barry.n1eu at gmail.com> To: topBand List <topband at contesting.com>
> Subject: Topband: CA/OR/AZ activity during Stew Perry - anecdotal
> data Message-ID:
> <CAFmfzDsZyK07vxthFnRs141HN_9Q6uo8HpGSOQfHAUaO86pGmw at mail.gmail.com>
> Content-Type: text/plain; charset=UTF-8
>
> I thought I'd share some data points from my Stew Perry log. Even
> though propagation to the west coast seemed good from upstate NY, I
> had the impression of less activity than expected from California so
> I looked closer at my log. What I found was 13 q's from California
> and 14 q's each from neighboring Oregon and Arizona (each with 1/7 of
> the ham population of CA). Perhaps the ham population in California
> is disproportionately urban/suburban with less topband activity,
> Californians disproportionately go QRP in SP or ???
>
> 73 & Happy New Year, Barry N1EU
>
>
> ------------------------------
>
> Message: 21 Date: Tue, 31 Dec 2013 10:13:29 -0500 From: "Tom W8JI"
> <w8ji at w8ji.com> To: "Charlie Cunningham"
> <charlie-cunningham at nc.rr.com>, <topband at contesting.com> Subject: Re:
> Topband: Digital mode spurious issues Message-ID:
> <952FFD43F713459C9780E88B677DE50E at MAIN> Content-Type: text/plain;
> format=flowed; charset="iso-8859-1"; reply-type=original
>
>> Well, I certainly have to agree, Tom, if the signal on the desired
>> sideband is just a single shifting tone. Might get messier if an
>> sudio stage or A/D is driven into limiting and producing harmonic
>> distortion at audio, I guess.
>>
>
> The entire thing for digital modes was poorly planned. I'm surprised
> no one objected to the frequency choices (of Europe), because they
> are technically always going to be a long term problem. The frequency
> range really could not have been more poorly planned for future
> long-term band use.
>
> Any digital mode piped into the SSB transmitter system, like it or
> not, is really SSB modulated. It has all the noise, carrier, and
> opposite sideband suppression issues, as well as sensitivity to
> levels. If they transmit 1835-40 using USB on the radio, the opposite
> sideband falls in the 1832 and upward range. IMD can be anywhere, if
> it is a multiple tone at the same time mode. Harmonic distortion is
> upward from the carrier on USB.
>
> Collins got burned by this. They tried running a pure audio tone into
> the SSB transmitter of the early S line to generate CW. The FCC (back
> when they did enforcement) starting handing out pink slips left and
> right to Collins owners. Any carrier, noise, or harmonic distortion
> at all resulted in an FCC citation, so Collins had to convert
> transmitters back to a keyed carrier.
>
> Anything converted to RF in a SSB transmitter system really belongs
> off by itself, well away from other operation. It's really a
> technical issue that will always exist, because the basic RF
> generation system or idea is flawed.
>
>
>
> ------------------------------
>
> Subject: Digest Footer
>
> _______________________________________________ Topband mailing list
> Topband at contesting.com
> http://lists.contesting.com/mailman/listinfo/topband
>
>
> ------------------------------
>
> End of Topband Digest, Vol 132, Issue 30
> ****************************************
>
> ------------------------------
>
> Message: 2 Date: Tue, 31 Dec 2013 17:51:52 -0500 From: "Joe Subich,
> W4TV" <lists at subich.com> To: topband at contesting.com Subject: Re:
> Topband: Digial mode spurious issues Message-ID:
> <52C34A88.3010206 at subich.com> Content-Type: text/plain;
> charset=windows-1252; format=flowed
>
>
> On 12/31/2013 5:10 PM, Mike Greenway wrote:
>> I don?t am still puzzled why the digital modes decided to use the
>> 1837to 1839 area with the size of the 160 M band.
>
> For the same reason the SSB guys insist on using 1840-1850 ... with
> their significantly smaller band (1810-1850 in some cases) Region 1
> put digital between CW (1810-1830) and SSB (1840-1850). With what is
> left of the "DX Window" at 1830-1835 that left 1835-1840 for
> digital.
>
> It's an unavoidable fact of life that new activity will go where the
> existing activity is. Look at digital on 40 meters - it is almost all
> between 7030/7035 and 7045 because that's where the EU and JA
> stations are. 160 is no different, digital activity in EU is
> 1835-1840 so that's where everyone else will be if they want a chance
> to work EU. As much as it pains me to say it - if you want to fix the
> situation get ITU to expand the 160 meter band in Region 1 and
> convince IARU Region 1 to relocate both digital and SSB activity
> higher/into the expanded band.
>
> 73,
>
> ... Joe, W4TV
>
>
> On 12/31/2013 5:10 PM, Mike Greenway wrote:
>> I don?t am still puzzled why the digital modes decided to use the
>> 1837to 1839 area with the size of the 160 M band. I know the SSB
>> guys use a
> lot of the 1840-1900 area but 1900 to 2000 is usable isn?t it? I
> rarely hear much up there and 3 or 4 khz up there would never be
> missed. Probably not an answer but it has seemed strange to me since
> they started operating in that area. Some of their signals are bone
> crushing and wide. 73 Mike K4PI
>
>
>
> ------------------------------
>
> Message: 3 Date: Tue, 31 Dec 2013 17:29:57 -0600 From: Mike Waters
> <mikewate at gmail.com> To: Mike Greenway <K4PI at bellsouth.net>, topband
> <topband at contesting.com> Subject: Re: Topband: Digial mode spurious
> issues Message-ID:
> <CA+FxYXimxpes9qB+SafJF2JdnM1fAvtrFd0NuBKOOg3ohw9Nbg at mail.gmail.com>
> Content-Type: text/plain; charset=windows-1252
>
> Absolutely! From what I see from my QTH in SW MO, 1845 would be a
> good place for JT65 to move to. There is a ragchew group that meets
> on 1850, but seldom is there much activity below that.
>
> I seldom listen much above 1900. Maybe you're right, that would be a
> better place. But they definitely need to move up, as there's often
> DX just below them and we are just not going to get everyone to
> transmit a clean digital signal.
>
> By the way, Mike, it's easy to trim the large amount of text off the
> end of your messages with Shift-Ctrl-End and then Delete. :-) I've
> noticed others here forgetting to do that lately, too.
>
> 73, Mike www.w0btu.com
>
>
> On Tue, Dec 31, 2013 at 4:10 PM, Mike Greenway <K4PI at bellsouth.net>
> wrote:
>
>> I don?t am still puzzled why the digital modes decided to use the
>> 1837 to 1839 area with the size of the 160 M band. I know the SSB
>> guys use a lot of the 1840-1900 area but 1900 to 2000 is usable
>> isn?t it? I rarely hear much up there and 3 or 4 khz up there would
>> never be missed. Probably not an answer but it has seemed strange
>> to me since they started operating in that area. Some of their
>> signals are bone crushing and wide. 73 Mike K4PI
>>
>
>
> ------------------------------
>
> Message: 4 Date: Tue, 31 Dec 2013 19:14:13 -0500 From: "Tom W8JI"
> <w8ji at w8ji.com> To: <topband at contesting.com> Subject: Re: Topband:
> Digital mode spurious issues Message-ID:
> <18EE60A52F2A4E9182529136341FE673 at MAIN> Content-Type: text/plain;
> format=flowed; charset="iso-8859-1"; reply-type=response
>
>> AFAIK, all non-DSP rigs with synthesizers work this way. Assuming
>> you want the output frequency to be derived from the master clock
>> frequency, there is no easy way to shift an RF carrier. You can't
>> use a free running oscillator, because it won't be derived from the
>> master clock frequency. You can't switch between a mark synthesizer
>> and a space synthesizer because of transients. If you try to key
>> the programmed frequency of a BFO synthesizer, the PLL will
>> probably go out of lock momentarily, producing garbage. Also, it
>> may not be fast enough to keep up with RTTY. After considering all
>> this (as a very experienced synthesizer designer) it is hard for me
>> to blame the designers for using AFSK.
>
> It is easy to do it much better, and it would only cost pennies extra
> at the most. The signal could be generated by the normal SSB system
> and then run through a narrow IF filter. Problem solved. They could
> have done CW the same way, or in a similar fashion, with an unshaped
> off-on carrier through a narrow filter. They just didn't think to use
> the parts they already had in the radio.
>
> But that isn't this issue. This issue is they run baseband audio from
> a computer into a SSB transmitter to generate TX signals. This means
> it is really a SSB transmitter processing the tones, and they don't
> even restrict bandwidth with a narrow filter. That is really the
> entire issue. Instead of a narrow filter cleaning up stuff, it all
> goes through a SSB filter. Anyone with a computer and a little skill
> can invent a "new mode". It's just bad engineering to stick that
> stuff near weak signals, because the problem can only be fixed at the
> transmitter.
>
> 73 Tom
>
>
>
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