Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-md01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 925D0380000EA; Thu, 12 Jul 2012 06:36:45 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1SpGjr-0004oI-Hk for rs_out_1@blacksheep.org; Thu, 12 Jul 2012 11:35:15 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1SpGjq-0004o9-7n for rsgb_lf_group@blacksheep.org; Thu, 12 Jul 2012 11:35:14 +0100 Received: from nm19-vm0.bullet.mail.ird.yahoo.com ([77.238.189.92]) by relay1.thorcom.net with smtp (Exim 4.77) (envelope-from ) id 1SpGjn-0000zk-K3 for rsgb_lf_group@blacksheep.org; Thu, 12 Jul 2012 11:35:13 +0100 Received: from [77.238.189.49] by nm19.bullet.mail.ird.yahoo.com with NNFMP; 12 Jul 2012 10:35:10 -0000 Received: from [212.82.108.118] by tm2.bullet.mail.ird.yahoo.com with NNFMP; 12 Jul 2012 10:35:10 -0000 Received: from [127.0.0.1] by omp1027.mail.ird.yahoo.com with NNFMP; 12 Jul 2012 10:35:10 -0000 X-DKIM-Result: Domain=yahoo.co.uk Result=Good and Known Domain X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 784172.8098.bm@omp1027.mail.ird.yahoo.com Received: (qmail 27473 invoked by uid 60001); 12 Jul 2012 10:35:10 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.co.uk; s=s1024; t=1342089310; bh=BcnvHFYANgUj5CLa76w/5X1tdqIyGxFaRq46/iCOyR4=; h=X-YMail-OSG:Received:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=ZnD1xGBCfrOTm72NRbDtdvgbMcpgyf2EPCkuNJzdTjzacabzEInTJtZe3LzUpbg2uo9Vu3NbFMWy9JinVxSum/P4AF777IyRBMpzrtqmyJUrc/JzjsbozGlH0VoFdKKBsA+13lv7KVubGB3YcNDomPIZN8f4aMtD0z7zJQBNPXA= DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.co.uk; h=X-YMail-OSG:Received:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=ZhYQ6Qqosn/M/IFVTIQOtvZTP3NpciCwNxtpJOzknUg6Jmgm6K5fWlGcRaKEJ9QKyEs18v0JmRGIjGawn9jYLT9+jXgn5SkA+ppbz4a9h8prSIkZeXDwbl4tHUsP7aTOXDT4G77Tmz6jxcFdorJcjSko6s4O1HYdUpUBqQAlLH4=; X-YMail-OSG: UZ6uOvUVM1nVxVzE7tTTcaN9c4_Pb0Srefemxv1c6_GvKor GRBpbIYUE9EAHuGQJ15DJFRxLLcJ9PP27ENE20GjIjkebUIZW9Xr31pM7L7X l_qQLpUbsxPtIPsf_1Xm34rRpBH1rlSPnATH79HxnNI8c0JK4iUmp.FT7C_k QbJ8V_X6DKUUveHIeQAW7G.R0r3D8sBg1NBycbKrAzSjIDw3f4tH7rViExiw EhtdDF.pl6jr0GEDPKSx3X9jYc8z0Kt1tmD5eNdDlH_2fiELFGGdG1vpjPZm 6dYwOcK7fYiqWUluQHO98adlkE9_h_175l53_dQhCwHHsl_c1o.zmRb9dHkv Jklvsv7cZIn4WnH6V8aqHrNAmziedrwuRiO8izujXPl0RxB.GZQa_.snZ2Vt kkGbtkxq2YSGz9g3A3cpkSosixPjM2PU8FZtgJVDOW9jTvGwXoaoKnmAtwoB ilhb1OJEo09TY02gPMSDea1Ubaw9KylrVxWr9ZVV7IQ-- Received: from [86.162.70.13] by web171604.mail.ir2.yahoo.com via HTTP; Thu, 12 Jul 2012 11:35:10 BST X-Mailer: YahooMailWebService/0.8.120.356233 References: , <4FFC3518.1030405@xs4all.nl>, <4FFD5313.6103.333D978@mike.dennison.ntlworld.com> <1342044548.74534.YahooMailNeo@web171606.mail.ir2.yahoo.com> <97A4971B4EDA4297832CD2C85C342CEB@AGB> Message-ID: <1342089310.18206.YahooMailNeo@web171604.mail.ir2.yahoo.com> Date: Thu, 12 Jul 2012 11:35:10 +0100 (BST) From: M0FMT To: "rsgb_lf_group@blacksheep.org" In-Reply-To: <97A4971B4EDA4297832CD2C85C342CEB@AGB> MIME-Version: 1.0 X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Hi Graham I am as bad not keen on WSPR but this Opera mode has court my attention primarily because IMHO it suits the LF type TX gear in common with CW, QRSS and FSK. And it has proved to be very effective. I have used my RX filters down to 200Hz and found by experiment that it was best to leave the IF at 2.4+/-kHz for best results. Didn't know exactly why it should be better but felt must be a function of the DSP software. So thanks for the conformation. I think there is a limit to listening through a narrow CW filter I have used 50Hz but the keying sound is very "soft" and even at moderate speeds in my experience becomes less easy to copy....... speaking as a 5WPMer. [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [77.238.189.92 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (m0fmt[at]yahoo.co.uk) 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 FSL_FREEMAIL_2 FSL_FREEMAIL_2 0.0 FSL_FREEMAIL_1 FSL_FREEMAIL_1 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 3f12a6171cff302119f724e64afab799 Subject: Re: LF: OPERA Question Content-Type: multipart/alternative; boundary="435439028-1098923883-1342089310=:18206" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.8 required=5.0 tests=CASHCASHCASH,HTML_30_40, HTML_MESSAGE,TO_ADDRESS_EQ_REAL autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:503195136:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d025.2 ; domain : yahoo.co.uk DKIM : fail x-aol-sid: 3039ac1d60554ffea8bd60fc X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --435439028-1098923883-1342089310=:18206 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Hi Graham=0AI am as bad not keen on WSPR but this Opera mode has court my= =A0attention=A0primarily because IMHO it suits the=A0LF type TX gear in com= mon with CW, QRSS and FSK. And it has proved to be very effective. I have u= sed my RX filters=A0down to 200Hz and=A0found by experiment that it was bes= t to leave the IF at 2.4+/-kHz for best results. Didn't know exactly why it= should be better but felt=A0must be a=A0function of the DSP software.=A0= =A0So thanks for the conformation.=0AI think there is a limit to listening = through a narrow CW filter=A0 I have used 50Hz but the keying sound is very= "soft" and even at moderate speeds in my experience becomes less easy to c= opy....... speaking as a 5WPMer.=0A=0A73 es GL Pete M0FMT IO91UX=0A=0A=0A>_= _______________________________=0A> From: Graham = =0A>To: rsgb_lf_group@blacksheep.org =0A>Sent: Thursday, 12 July 2012, 0:43= =0A>Subject: Re: LF: OPERA Question=0A> =0A>=0A> =0A>Each to=A0 his=A0 o= wn Pete, =0A>=0A>Really=A0 its=A0 only=A0 slowly that=A0 the=A0 amount =0Ao= f=A0 work and=A0 technical=A0 input that's=A0 =0Aneeded=A0=A0to=A0 produce= =A0 one of these numeric=A0 =0Abased=A0=A0data=A0 modes is=A0 becoming=A0 a= pparent , odd=A0 =0Aas you=A0 say some of the=A0 fire fights=A0 over=A0 mod= e V mode , =0Acpu loading=A0 etc=A0 =0A>=0A>A simple=A0 question=A0 over= =A0 filter=A0 bandwidth =0Areveals=A0=A0 yet=A0 another=A0 layer of=A0 math= s=A0 and=A0 =0Aintrigue, based=A0round=A0 the=A0 definition=A0 =0Aof=A0=A0t= he=A0 word 'filter'=A0 weather=A0 you are=A0 =0Areferring to a=A0 analogue= =A0 device=A0 or =0Aa=A0=A0computational=A0 routine=A0 that's=A0 deployed= =A0 =0Ato=A0 provide a=A0 best=A0 fit=A0 of the=A0 recovered=A0 =0A'pulse' = ... reminds=A0 me=A0 of=A0 a episode of the=A0 =0AAvengers=A0 , every time= =A0 you open a=A0 door=A0 the=A0 =0Aroom=A0 has changed=A0 , in this=A0 cas= e the=A0 words=A0 =0Ahave=A0 different=A0 meanings . . . same thing=A0 with= the=A0 spread =0Aspectrum knees=A0 up ,=A0 spreading=A0 routines=A0 applie= d=A0 =0Ato=A0 data=A0 , nothing=A0 to=A0 do=A0 with=A0 radio=A0 =0Abandwidt= h .. =0A>=0A>In simplicity , the=A0 answer from Jose=A0 was=A0 'Do=A0 =0An= othing=A0 to the=A0 signal , leave=A0 all=A0 filtering=A0 to the =0Asoftwar= e'=A0=A0=A0 selecting=A0 a=A0 narrow=A0 filter=A0 =0Aadds=A0=A0 phase shift= , time delay=A0 and=A0 additional=A0 noise =0A....... so=A0 direct=A0 conv= ersion=A0 SDR=A0 is the=A0 =0Aoptimum=A0 Rx=A0 system ! =0A>=0A>The=A0 main= =A0 thing=A0 is=A0 'we'=A0 have=A0 some=A0 =0Apretty robust=A0 data=A0 mode= s to=A0 play=A0 with=A0 on =0Ahere=A0 , activity is=A0 increasing=A0 by the= =A0 day=A0 and=A0 =0Aits=A0 only=A0=A0 July=A0 ! =A0 =0A>=0A>73 - G .. = =0A>=0A>=0A> =0A>From: M0FMT =0A>Sent: Wednesday, July 11, 2012 11:09 PM = =0A>To: rsgb_lf_group@blacksheep.org =0A>Subject: Re: LF: OPERA Question = =0A>=0A> =0A> =0A>Hi Graham =0A>=0A>SDR; doing your best to drag them kick= ing and screaming into the future. I =0Adon't get the resistance..... the Q= EX (ARRL) files are available to all (unlike other national outfits) on DSP= , a technology =0Awhich has been with us for a decade or two! But easier to= implement these =0Adays.=0A> =0A>73 es GL Pete M0FMT IO91UX=0A>=0A>=0A>>__= ______________________________=0A>>From: Graham = =0A>>To: rsgb_lf_group@blacksheep.org =0A>>Cc: james.moritz@btopenworld.com= =0A>>Sent: Wednesday, 11 July 2012, 16:51=0A>>Subject: Re: LF: OPERA Que= stion=0A>>=0A>>''At first glance it appears =0A crazy''=0A>>=0A>>Mike,=0A>= >=0A>>Welcome to the crazy world of=A0 JR=A0 =0A !=0A>>=0A>>The=A0 basic= =A0 explanation is the=A0 narrow filters=A0 =0A increase the=A0 noise powe= r in a limited=A0 bandwidth , ringing=A0 =0A due to the=A0 Q , similar to= =A0 CW , narrow filters tend to=A0 =0A round=A0 the=A0 CW signal=0A>>=0A>>= The DSP=A0 engine=A0 is=A0 =0A better equipped to=A0 differentiate between= =A0 carrier and noise =0A and=A0 has a=A0 much=A0 greater=A0 dynamic=A0 ra= nge , so=A0 =0A optimum results=A0 are obtained , when the=A0 signal is=A0= =0A presented=A0 to the=A0 interface, as close to to the=A0 original =0A = as=A0 possible , the=A0 DSP filter profiles are=A0 tailored to the =0A mo= de/speed in use=0A>>=0A>>This can be=A0 noticed=A0 with the=A0 =0A new=A0 = generation of=A0 SDR=A0 support software , where=A0 =0A audio/voice recove= ry=A0 can be=A0 superior to conventional hardware =0A based systems=0A>>= =0A>>With hardware filtering , there=A0 are=A0 =0A transit=A0 (group) dela= ys which=A0 can alter the=A0 amplitude / =0A time=A0 , either=A0 from=A0 o= n/off=A0 keying=A0 or=A0 with =0A FSK, this can=A0 be=A0 observed when=A0 = sending=A0 wide=A0 =0A band=A0 FSK , although=A0 the=A0 audio level=A0 rem= ains=A0 =0A constant and=A0 'phase continuous'=A0 , its possible=A0 some t= imes =0A to=A0 see a=A0 'am modulation'=A0 envelope=A0 on the=A0 =0A carr= ier=A0 =A0 ... $$$$=A0 can solve this=A0 problem , but=A0 =0A for=A0 most= =A0 Ham=A0 kit its=A0 something=A0 that =0A 'happens'=0A>>=0A>>Physical=A0= constraints , if=A0 there=A0 is=A0 =0A a=A0 very large=A0 carrier in the= =A0 pass band=A0 and=A0 =0A this=A0 is pushing=A0 the=A0 hardware into=A0 = non-linearity / =0A A/D=A0 to over=A0 range=A0 , giving=A0 quantising=A0 e= rrors, =0A then=A0 , yes=A0 filtering would help , but=A0 its more=A0 =0A = likely=A0 its the=A0 analogue=A0 path=A0 that's=A0 causing =0A intermod p= roducts .....reducing=A0 the=A0 rf/if gain will=A0 provide =0A the=A0 solu= tion=0A>>=0A>>I think that's=A0 about the=A0 picture , =0A if=A0 Jim's=A0 = about , im sure=A0 he=A0 will fill in the=A0 =0A gaps=0A>>=0A>>73 =0A -G.= .=0A>>=0A>>=0A>>=0A>>=0A>>-------------------------------------------------= -=0A>>From: =0A "Mike Dennison" =0A>>Sent: =0A= Wednesday, July 11, 2012 10:18 AM=0A>>To: ;= =0A>>Subject: =0A Re: LF:=A0 OPERA=A0 Q= uestion=0A>>=0A>>>> Narrow=A0 IF =0A filters=A0 are=A0 not=A0 desirable=A0= and=A0 reduce =0A the=0A>>>> performance of the=A0 demodulator=A0 , bette= r=A0 =0A simply=A0 use=A0 SSB=A0 filter=0A>>>> GL ..73 -G..=0A>>> =0A>>> G= raham,=0A>>> =0A>>> Why is that the case? What does the =0A considerable e= xtra bandwidth=0A>>> achieve? Is the SSB bandwidth optimal, or =0A would i= t be even better=0A>>> with 10kHz bandwidth, or 100kHz?. Why is 3kHz =0A b= etter than perhaps=0A>>> 1kHz or 2kHz?=0A>>> =0A>>> At first glance it =0A = appears crazy to let in all sorts of adjacent=0A>>> channel QRM (the =0A = bandwidth is more than ten times the size of the=0A>>> entire Opera window)= =0A when using a mode that occupies a fraction of=0A>>> 1Hz.=0A>>> =0A>>>= Is =0A it simply that the 1.7kHz Tx tone is high enough for the SSB=0A>>>= filter to =0A kill its harmonics, and on receive it is difficult to get a= =0A>>> 1.7kHz =0A tone out of a CW filter, even with passband shifting.=0A= >>> =0A>>> Am I =0A missing something?=0A>>> =0A>>> 73 de Mike, G3XDV=0A>>= > =0A g3xdv.blogspot.co.uk=0A>>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=0A>>> =0A>>> =0A>>> =0A>>=0A>>=0A>>=0A>> =0A>=0A> --435439028-1098923883-1342089310=:18206 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
Hi Graham
I am as bad not keen on WSPR = but this Opera mode has court my attention primarily because IMHO= it suits the LF type TX gear in common with CW, QRSS and FSK. And it = has proved to be very effective. I have used my RX filters down to 200= Hz and found by experiment that it was best to leave the IF at 2.4+/-k= Hz for best results. Didn't know exactly why it should be better but felt&n= bsp;must be a function of the DSP software.  So thanks for t= he conformation.
I think there is a limit to listeni= ng through a narrow CW filter  I have used 50Hz but the keying sound i= s very "soft" and even at moderate speeds in my experience becomes less eas= y to copy....... speaking as a 5WPMer.
 
73 es GL Pete M0FMT IO91UX
<= blockquote style=3D"padding-left: 5px; margin-top: 5px; margin-left: 5px; b= order-left-color: rgb(16, 16, 255); border-left-width: 2px; border-left-sty= le: solid;">
From: Graham <g8fzk@g8fzk.fsnet.co.uk>
= To: rsgb_lf_group@blacksheep.= org
Sent: Thursday, 1= 2 July 2012, 0:43
Subject:= Re: LF: OPERA=20 Question

=0A=0A =0A =0A
=0A
Each = to  his  own Pete,
=0A
 
=0A
Really  = its  only  slowly that  the  amount =0Aof  work an= d  technical  input that's  =0Aneeded  to  pr= oduce  one of these numeric  =0Abased  data  modes= is  becoming  apparent , odd  =0Aas you  say some of t= he  fire fights  over  mode V mode , =0Acpu loading  et= c 
=0A
 
=0A
A simple  question  ove= r  filter  bandwidth =0Areveals   yet  another&nbs= p; layer of  maths  and  =0Aintrigue, based round = the  definition  =0Aof  the  word 'filter'  = weather  you are  =0Areferring to a  analogue  device&n= bsp; or =0Aa  computational  routine  that's  depl= oyed  =0Ato  provide a  best  fit  of the  re= covered  =0A'pulse' ... reminds  me  of  a episode of t= he  =0AAvengers  , every time  you open a  door  t= he  =0Aroom  has changed  , in this  case the  wor= ds  =0Ahave  different  meanings . . . same thing  with= the  spread =0Aspectrum knees  up ,  spreading  routin= es  applied  =0Ato  data  , nothing  to  do&n= bsp; with  radio  =0Abandwidth ..
=0A
 
=0AIn simplicity , the  answer from Jose  was  'Do  =0A= nothing  to the  signal , leave  all  filtering  t= o the =0Asoftware'    selecting  a  narrow  f= ilter  =0Aadds   phase shift , time delay  and  ad= ditional  noise =0A....... so  direct  conversion  SDR&= nbsp; is the  =0Aoptimum  Rx  system !
=0A
 =0A
The  main  thing  is  'we'  have = some  =0Apretty robust  data  modes to  play  wit= h  on =0Ahere  , activity is  increasing  by the  = day  and  =0Aits  only   July  !   =0A
 
=0A
73 - G ..
=0A
 
=0A
=0A

=0A
= =0A
From: M0FMT
=0A
Sent: Wednesday, July 11, 2012 11:09 PM
=0A=0A
Subject: Re: LF: OPERA Question
=0A

=0A
=0A
=0A
=0A
Hi Graham<= /div>=0A
 
=0A
SDR; doing your best to drag them kicking = and screaming into the future. I =0Adon't get the resistance..... the QEX (= ARRL) files are available to all (unlike other national outfits) on DSP, a technology =0Awhich has been wi= th us for a decade or two! But easier to implement these =0Adays.
= =0A
73 es GL Pete M0FMT IO91UX
=0A
=0A
=0A
=0A
<= span style=3D"font-weight: bold;">From: Graham <g8fzk@g8fzk.fsnet.co.uk>
To: rsgb_lf_group@blacksheep.org =0A
Cc: =0A james.moritz@btopenworl= d.com
Sent: Wednesday,= 11 July 2012, =0A 16:51
Subject:= Re: LF: OPERA =0A Question

''At first glan= ce it appears =0A crazy''

Mike,

Welcome to the crazy world o= f  JR  =0A !

The  basic  explanation is the&nbs= p; narrow filters  =0A increase the  noise power in a limited&nb= sp; bandwidth , ringing  =0A due to the  Q , similar to  CW= , narrow filters tend to  =0A round  the  CW signal
The DSP  engine  is  =0A better equipped to  differen= tiate between  carrier and noise =0A and  has a  much = greater  dynamic  range , so  =0A optimum results  ar= e obtained , when the  signal is  =0A presented  to the&nbs= p; interface, as close to to the  original =0A as  possible , th= e  DSP filter profiles are  tailored to the =0A mode/speed in us= e

This can be  noticed  with the  =0A new  gene= ration of  SDR  support software , where  =0A audio/voice r= ecovery  can be  superior to conventional hardware =0A based sys= tems

With hardware filtering , there  are  =0A transit&nb= sp; (group) delays which  can alter the  amplitude / =0A time&nb= sp; , either  from  on/off  keying  or  with =0A = FSK, this can  be  observed when  sending  wide  = =0A band  FSK , although  the  audio level  remains&nb= sp; =0A constant and  'phase continuous'  , its possible  s= ome times =0A to  see a  'am modulation'  envelope  on= the  =0A carrier    ... $$$$  can solve this  pr= oblem , but  =0A for  most  Ham  kit its  somethi= ng  that =0A 'happens'

Physical  constraints , if  t= here  is  =0A a  very large  carrier in the  pass= band  and  =0A this  is pushing  the  hardware i= nto  non-linearity / =0A A/D  to over  range  , giving=   quantising  errors, =0A then  , yes  filtering would= help , but  its more  =0A likely  its the  analogue&n= bsp; path  that's  causing =0A intermod products .....reducing&n= bsp; the  rf/if gain will  provide =0A the  solution
I think that's  about the  picture , =0A if  Jim's  a= bout , im sure  he  will fill in the  =0A gaps

73 = =0A -G..




----------------------------------------------= ----
From: =0A "Mike Dennison" <mike.dennison@ntlworld.com>
Sent: =0A Wednesday,= July 11, 2012 10:18 AM
To: <rsgb_lf_group@blacksheep.org>; =0A <rsgb_lf_group@yahoogroups= .co.uk>
Subject: =0A Re: LF:  OPERA  Question

&= gt;> Narrow  IF =0A filters  are  not  desirable&nb= sp; and  reduce =0A the
>> performance of the  demodula= tor  , better  =0A simply  use  SSB  filter
&g= t;> GL ..73 -G..
> =0A
> Graham,
>
> Why is t= hat the case? What does the =0A considerable extra bandwidth
> achie= ve? Is the SSB bandwidth optimal, or =0A would it be even better
> w= ith 10kHz bandwidth, or 100kHz?. Why is 3kHz =0A better than perhaps
&g= t; 1kHz or 2kHz?
>
> At first glance it =0A appears crazy to = let in all sorts of adjacent
> channel QRM (the =0A bandwidth is mor= e than ten times the size of the
> entire Opera window) =0A when usi= ng a mode that occupies a fraction of
> 1Hz.
>
> Is =0A = it simply that the 1.7kHz Tx tone is high enough for the SSB
> filte= r to =0A kill its harmonics, and on receive it is difficult to get a
&g= t; 1.7kHz =0A tone out of a CW filter, even with passband shifting.
>= ;
> Am I =0A missing something?
>
> 73 de Mike, G3XDV<= br>> =0A g3xdv.blogspot.co.uk
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D
>
>
> =0A



=
=0A


<= /body> --435439028-1098923883-1342089310=:18206--