Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-df03.r1000.mx.aol.com (Internet Inbound) with ESMTP id 5E026380000CB; Wed, 11 Jul 2012 18:10:06 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Sp55t-0003AF-Dp for rs_out_1@blacksheep.org; Wed, 11 Jul 2012 23:09:13 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Sp55s-0003A6-MT for rsgb_lf_group@blacksheep.org; Wed, 11 Jul 2012 23:09:12 +0100 Received: from nm22-vm2.bullet.mail.ird.yahoo.com ([212.82.109.252]) by relay1.thorcom.net with smtp (Exim 4.77) (envelope-from ) id 1Sp55q-0005nQ-9R for rsgb_lf_group@blacksheep.org; Wed, 11 Jul 2012 23:09:11 +0100 Received: from [77.238.189.232] by nm22.bullet.mail.ird.yahoo.com with NNFMP; 11 Jul 2012 22:09:09 -0000 Received: from [212.82.108.135] by tm13.bullet.mail.ird.yahoo.com with NNFMP; 11 Jul 2012 22:09:09 -0000 Received: from [127.0.0.1] by omp1040.mail.ird.yahoo.com with NNFMP; 11 Jul 2012 22:09:09 -0000 X-DKIM-Result: Domain=yahoo.co.uk Result=Good and Known Domain X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 251778.59625.bm@omp1040.mail.ird.yahoo.com Received: (qmail 76614 invoked by uid 60001); 11 Jul 2012 22:09:09 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.co.uk; s=s1024; t=1342044549; bh=HBeX9tfxsgzq94ioVeFOTUjWR/HpOqq3THp4JzIAX3A=; h=X-YMail-OSG:Received:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=eSCKGul2/Xqc94nPEPb7zJH/FyUXqTyrXxQv3Ifi9SUsoZ35Y3ipjoGiSCIOGtKfkNEIixAx5+lsUuhuHpTSMQ5biQQKXvH6rZgX/K6BD9hZzecMcqbU1+CSRNHnczSH4tBl9gtX+w0QkSjFAOZWNK+iOqT083FXtjuxata9ezQ= 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=1Ky47WOJnchVqh2SlOqhnG5D1F11APTSkF0aMX8u03PWw8mZmP/tYUHBggkEP+n7xY3LOVuGmbBwoCHVhksLHQqgmcmAQoUtuH2A9DhRpwHiTXf2d4ZMsFd6EQ6O+QIxHeC+nMb8owmOlPHBVWeonzSjwnf6mg1Ad6TVNQiyWSA=; X-YMail-OSG: a35k5SQVM1n5kgbY22urWDdpVB_vKltARlwP57AIvejxUCt YAVbtgcSiu6slhNXI61Kdf0Huzq40dp8ErQPIzouCByIpr6VhezVOikcasIJ y48R0x6Oojnc7UcH9yxjfVzzY2co5_oc.2ZtIpNkKiiTVoWwpubdvxe_QMgc xKaebkVHizTcqrWuNr8Pt6VWCJ4ATtJN4kJ96I1a_fUYRCfOqQ9aWzzL4Rif w9QOmCPwcL1BUv6YxoioGQgninfKLZYtbLqmFPrLuiEfVlFA1XupmMbuCswe _YHJimFG_ABwBaZvHOdYasUMF_k0IB9YrAFY2F4qwli4qHEIUf.rSyk0Aqnk L4XR9GlInXkmwrshgGZgfgJWgXYBl1HKEHOe6aaQQQ7uf5gjnRqwqBsDSWHl ZEH_MiMTxY1R.kDwr.n2h0AGuFm9srS8.sx_Tx5hQfq6n5wtgax3GANYUOZL 3C.akYbGZrFFVfOlLun.RzC7LhlQv3E_pmpJZxefMLcV8 Received: from [86.161.255.208] by web171606.mail.ir2.yahoo.com via HTTP; Wed, 11 Jul 2012 23:09:08 BST X-Mailer: YahooMailWebService/0.8.120.356233 References: , <4FFC3518.1030405@xs4all.nl>, <4FFD5313.6103.333D978@mike.dennison.ntlworld.com> Message-ID: <1342044548.74534.YahooMailNeo@web171606.mail.ir2.yahoo.com> Date: Wed, 11 Jul 2012 23:09:08 +0100 (BST) From: M0FMT To: "rsgb_lf_group@blacksheep.org" In-Reply-To: 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 SDR; doing your best to drag them kicking and screaming into the future. I don't get the resistance..... the QEX (ARRL) files are available to all (unlike other national outfits) on DSP, a technology which has been with us for a decade or two! But easier to implement these days. [...] 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 [212.82.109.252 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: b707651713bcd4ad9db4bb0f5d794041 Subject: Re: LF: OPERA Question Content-Type: multipart/alternative; boundary="1386533404-1931456640-1342044548=:74534" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=CASHCASHCASH,HTML_20_30, 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: 0:2:474478112:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d306.2 ; domain : yahoo.co.uk DKIM : fail x-aol-sid: 3039ac1d40d74ffdf9be5257 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --1386533404-1931456640-1342044548=:74534 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable =0A=0AHi Graham=0A=0ASDR; doing your best to drag them kicking and screamin= g into the future. I don't get the resistance..... the QEX (ARRL) files are= available to all (unlike other national outfits) on DSP, a technology whic= h has been with us for a decade or two! But easier to implement these days.= =0A=0A73 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 Question=0A> =0A>''At first glance it = appears crazy''=0A>=0A>Mike,=0A>=0A>Welcome to the crazy world of=A0 JR=A0 = !=0A>=0A>The=A0 basic=A0 explanation is the=A0 narrow filters=A0 increase t= he=A0 noise power in a limited=A0 bandwidth , ringing=A0 due to the=A0 Q ,= similar to=A0 CW , narrow filters tend to=A0 round=A0 the=A0 CW signal=0A>= =0A>The DSP=A0 engine=A0 is=A0 better equipped to=A0 differentiate between= =A0 carrier and noise and=A0 has a=A0 much=A0 greater=A0 dynamic=A0 range ,= so=A0 optimum results=A0 are obtained , when the=A0 signal is=A0 presented= =A0 to the=A0 interface, as close to to the=A0 original as=A0 possible , th= e=A0 DSP filter profiles are=A0 tailored to the mode/speed in use=0A>=0A>Th= is can be=A0 noticed=A0 with the=A0 new=A0 generation of=A0 SDR=A0 support= software , where=A0 audio/voice recovery=A0 can be=A0 superior to conventi= onal hardware based systems=0A>=0A>With hardware filtering , there=A0 are= =A0 transit=A0 (group) delays which=A0 can alter the=A0 amplitude / time=A0= , either=A0 from=A0 on/off=A0 keying=A0 or=A0 with FSK, this can=A0 be=A0 = observed when=A0 sending=A0 wide=A0 band=A0 FSK , although=A0 the=A0 audio = level=A0 remains=A0 constant and=A0 'phase continuous'=A0 , its possible=A0= some times to=A0 see a=A0 'am modulation'=A0 envelope=A0 on the=A0 carrier= =A0 =A0 ... $$$$=A0 can solve this=A0 problem , but=A0 for=A0 most=A0 Ham= =A0 kit its=A0 something=A0 that 'happens'=0A>=0A>Physical=A0 constraints ,= if=A0 there=A0 is=A0 a=A0 very large=A0 carrier in the=A0 pass band=A0 and= =A0 this=A0 is pushing=A0 the=A0 hardware into=A0 non-linearity / A/D=A0 to= over=A0 range=A0 , giving=A0 quantising=A0 errors, then=A0 , yes=A0 filte= ring would help , but=A0 its more=A0 likely=A0 its the=A0 analogue=A0 path= =A0 that's=A0 causing intermod products .....reducing=A0 the=A0 rf/if gain = will=A0 provide the=A0 solution=0A>=0A>I think that's=A0 about the=A0 pictu= re , if=A0 Jim's=A0 about , im sure=A0 he=A0 will fill in the=A0 gaps=0A>= =0A>73 -G..=0A>=0A>=0A>=0A>=0A>--------------------------------------------= ------=0A>From: "Mike Dennison" =0A>Sent: Wedne= sday, July 11, 2012 10:18 AM=0A>To: ; =0A>Subject: Re: LF:=A0 OPERA=A0 Question=0A>=0A>= >> Narrow=A0 IF filters=A0 are=A0 not=A0 desirable=A0 and=A0 reduce the= =0A>>> performance of the=A0 demodulator=A0 , better=A0 simply=A0 use=A0 SS= B=A0 filter=0A>>> GL ..73 -G..=0A>> =0A>> Graham,=0A>> =0A>> Why is that th= e case? What does the considerable extra bandwidth=0A>> achieve? Is the SSB= bandwidth optimal, or would it be even better=0A>> with 10kHz bandwidth, o= r 100kHz?. Why is 3kHz better than perhaps=0A>> 1kHz or 2kHz?=0A>> =0A>> At= first glance it appears crazy to let in all sorts of adjacent=0A>> channel= QRM (the bandwidth is more than ten times the size of the=0A>> entire Oper= a window) when using a mode that occupies a fraction of=0A>> 1Hz.=0A>> =0A>= > Is it simply that the 1.7kHz Tx tone is high enough for the SSB=0A>> filt= er to kill its harmonics, and on receive it is difficult to get a=0A>> 1.7k= Hz tone out of a CW filter, even with passband shifting.=0A>> =0A>> Am I mi= ssing something?=0A>> =0A>> 73 de Mike, G3XDV=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> --1386533404-1931456640-1342044548=:74534 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
<= /div>
Hi Graham
 
SDR; doing your best to drag= them kicking and screaming into the future. I don't get the resistance....= . the QEX (ARRL) files are available to all (unlike other national outfits) on DSP, a technology which has been with u= s for a decade or two! But easier to implement these days.
73= es GL Pete M0FMT IO91UX
= From: Graham <g8fzk@g8f= zk.fsnet.co.uk>
To:= rsgb_lf_group@blacksheep.org
Cc:= james.moritz@btopenworld.com
Sent: Wednesday, 11 July 2012, 16:51
Subject: Re: LF: OPERA Question

''At first glance it appears crazy''

Mike,

W= elcome to the crazy world of  JR  !

The  basic  = explanation is the  narrow filters  increase the  noise powe= r in a limited  bandwidth , ringing  due to the  Q , simila= r to  CW , narrow filters tend to  round  the  CW signal

The DSP  engine  is  better equipped to = differentiate between  carrier and noise and  has a  much&n= bsp; greater  dynamic  range , so  optimum results  are= obtained , when the  signal is  presented  to the  int= erface, as close to to the  original as  possible , the  DSP= filter profiles are  tailored to the mode/speed in use

This ca= n be  noticed  with the  new  generation of  SDR&= nbsp; support software , where  audio/voice recovery  can be = ; superior to conventional hardware based systems

With hardware filt= ering , there  are  transit  (group) delays which  can = alter the  amplitude / time  , either  from  on/off&nbs= p; keying  or  with FSK, this can  be  observed when&nb= sp; sending  wide  band  FSK , although  the  audio level  remains  constant and  'phase contin= uous'  , its possible  some times to  see a  'am modula= tion'  envelope  on the  carrier    ... $$$$ = can solve this  problem , but  for  most  Ham  k= it its  something  that 'happens'

Physical  constrain= ts , if  there  is  a  very large  carrier in the&= nbsp; pass band  and  this  is pushing  the  hardw= are into  non-linearity / A/D  to over  range  , giving=   quantising  errors, then  , yes  filtering would hel= p , but  its more  likely  its the  analogue  path=   that's  causing intermod products .....reducing  the = rf/if gain will  provide the  solution

I think that's&nbs= p; about the  picture , if  Jim's  about , im sure  he  will fill in the  gaps

73 -G..


=

--------------------------------------------------
From: "Mike D= ennison" <mike.dennison@ntlworld.com>
Sent: W= ednesday, July 11, 2012 10:18 AM
To: <rsgb_lf_gr= oup@blacksheep.org>; <rsgb_lf_group@ya= hoogroups.co.uk>
Subject: Re: LF:  OPERA  Question
<= br>>> Narrow  IF filters  are  not  desirable&nb= sp; and  reduce the
>> performance of the  demodulator&= nbsp; , better  simply  use  SSB  filter
>> GL= ..73 -G..
>
> Graham,
>
> Why is that the case? = What does the considerable extra bandwidth
> achieve? Is the SSB bandwidt= h optimal, or would it be even better
> with 10kHz bandwidth, or 100k= Hz?. Why is 3kHz better than perhaps
> 1kHz or 2kHz?
>
>= At first glance it appears crazy to let in all sorts of adjacent
> c= hannel QRM (the bandwidth is more than ten times the size of the
> en= tire Opera window) when using a mode that occupies a fraction of
> 1H= z.
>
> Is it simply that the 1.7kHz Tx tone is high enough for= the SSB
> filter to kill its harmonics, and on receive it is difficu= lt to get a
> 1.7kHz tone out of a CW filter, even with passband shif= ting.
>
> Am I missing something?
>
> 73 de Mike,= G3XDV
> g3xdv.blogspot.co.uk
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D
>
>
>



=
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