Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by klubnl.pl (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id wAQEhBAx003960 for ; Mon, 26 Nov 2018 15:43:17 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1gRI2I-0001Hu-V5 for rs_out_1@blacksheep.org; Mon, 26 Nov 2018 14:38:54 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1gRI2I-0001Hl-A4 for rsgb_lf_group@blacksheep.org; Mon, 26 Nov 2018 14:38:54 +0000 Received: from mail-ed1-x529.google.com ([2a00:1450:4864:20::529]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91_59-0488984) (envelope-from ) id 1gRI2F-00029C-7X for rsgb_lf_group@blacksheep.org; Mon, 26 Nov 2018 14:38:53 +0000 Received: by mail-ed1-x529.google.com with SMTP id d39so15998499edb.12 for ; Mon, 26 Nov 2018 06:38:50 -0800 (PST) X-DKIM-Result: Domain=gmail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=WotyH/9Eh2O8H+0Qmn0dtUaNa610TCb43WE+WMoHgtA=; b=X7cZbBnG5p33tUBv3FM4NzGLslhR2CssDHui44f59f9c1/lcLgWv7G3A244X1UKXY9 cLPUzfjv/aRlS7f37WDZZO7GI3jaHlCsLQxJiS8w5ZlXvzPpNiIa2zrMPrksrrcJ/1QY vXfnW6VtYGPfMHkml1e3zhBix8Y5C1QWN9iVymSVNmvtMi0E4wkY7sS6h+YXQ2ZP34uu 85wgB0ymHlN5x8h5yMhNP3cU5HqCidazii0st2LDHmwZSXGLNH+p5l3uDkGkljvwckkM keZU2lHfyyvMAlVWbAol7syxf8PII+zSTwL++13UReaWg9YwTGaxGhPmrK1GNOIRn1et ZlSQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=WotyH/9Eh2O8H+0Qmn0dtUaNa610TCb43WE+WMoHgtA=; b=ZKsxhXgVK8x3PijPzvsqMHR1eAOQ2ViFRPUkwY/WC4jIm+n9t5YyNxsF5kvQjkfnI1 n/sDVxhsZSCQikR+cmsBc/7N4s+/KdqgNrxEoJieHbddDIxd8x6EYQPUfGwD7iuyHZdt VGViDDrt5g24Pu6ciHWrvwWbc/6pmQFDvI7fCdQquSTMHBm2cXAfpG4rTqzaA73u20ml 2fPE52m+biXO4Ipzb91MxXRSzQK8E6I7MsfBQrRsyeoM6aPIbvxQFwzm2YVjPboFxedt 4TogvofjKMvD9ekRVQNRJeYD6IjrVg7lennpgig1YKqnj6MsRxsOgyiyN2KvcPKw/xzw +d+Q== X-Gm-Message-State: AGRZ1gJaSoBUmjFKr1KeVwtOgPJ0NyTozzic9XGwyZLe5Pv9QsNb2G3n kRRRbJ1Nlae6brr1UDex8WPAF/VKjSbtTzN+R4XX6A== X-Google-Smtp-Source: AJdET5dq37DCo0oYa9pqmH3nEEY7WodrWOMnOXs2hxV8bG3lJ3XDbWxbiIge3BkcP7Mekc5DMZK2tHtBdojejAWbLgY= X-Received: by 2002:a17:906:c7c9:: with SMTP id dc9-v6mr20073742ejb.232.1543243129072; Mon, 26 Nov 2018 06:38:49 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Andy Talbot Date: Mon, 26 Nov 2018 14:38:37 +0000 Message-ID: To: "rsgb_lf_group@blacksheep.org" , EladSDR@groups.io, rsgb_lf_group X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see @@CONTACT_ADDRESS@@ for details. Content preview: Now this test IS impressive : FDM-DUO set to 50.04MHz USB (again, a multiple of 1875Hz) ADF4351 Fract-N PLL synth generating 50.041MHz. Being a PLL synthesizer this frequency is EXACT based on the reference in. Driven from the same master ref used for the DUO, so accuracy of the referenc [...] 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 [2a00:1450:4864:20:0:0:0:529 listed in] [list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (andy.g4jnt[at]gmail.com) 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 7ee575a0a6578bbbbe5ea7af32688fd5 Subject: Re: LF: FDM-DUO Useable for Coherent Comms !!!!!!!! Content-Type: multipart/alternative; boundary="00000000000082ae76057b924a80" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: ** X-Spam-Status: No, hits=2.1 required=5.0 tests=HTML_30_40,HTML_MESSAGE, PLING_PLING 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 --00000000000082ae76057b924a80 Content-Type: text/plain; charset="UTF-8" Now this test IS impressive : FDM-DUO set to 50.04MHz USB (again, a multiple of 1875Hz) ADF4351 Fract-N PLL synth generating 50.041MHz. Being a PLL synthesizer this frequency is EXACT based on the reference in. Driven from the same master ref used for the DUO, so accuracy of the reference is irrelevant. Phase shift on the 1kHz tone out of the DUO, using a vectorscope on the internal soundcard : ZERO.ZERO degrees phase shift in 8 minutes of monitoring The vectorscope is showing as one unmoving pixel that blinks occasionally That certainly does look seriously coherent to me ! Now need to work out how to check NCO rounding errors in the Tx path with its higher sampling rate. Andy www.g4jnt.com On Mon, 26 Nov 2018 at 13:54, Andy Talbot wrote: > After tests the other day looking at the few milliHz error observable > using the FDM-DUO locked to an external reference, I decided to make sure > it was purely an NCO rounding error and nothing else hapening inside the > radio > > Assuming a 32 Bit NCO clocked at 122.88MHz, we need to know the lowest > common frequency that is both a multiple of the tuning step and also a > binary submultiple of the clock. this, and all its multiples, can be > generated exactly with no NCO tuning error. > > For the DUO receiver this frequency is 1875Hz, being Fc/65536 and an > integral number of Hz. > Therefore, any RF tuning point (LO frequency) that is a multiple of > 1875Hz should exhibit no NCO offset error. > > The only frequency in the 137kHz band that meets this criteria is > 136.875kHz so the radio was set to this in USB mode. (1875Hz * 73) > My DDS low frequency signal generator was set to generate at 137.975kHz so > a 1kHz tone resulted. Using the DUO's internal soundcard, the G3PLX > vectorscope software was used to measure the phase of the 1kHz output > against a reference NCO of 1kHz derived from samples arriving from the > soundcard. Since the soundcard samples at 48kHz which is an integer > multiple of 1kHz there will be no rounding errors. Radio and sources were > locked to the same reference (*) so its accuracy didn't enter into the > equation. > > The only potential error in frequency is my DDS source that, due to its > internal maths / rounding, was generating this RF 2.17uHz high (that 's > 2.17micro-Hertz) > > The vectorscope showed a dot on the screen and a phase readout of this > position to a resolution of 0.1 degree. After 48 minutes of > monitoring, the observed phase of the 1kHz tone had shifted from 131.9deg > to 130.0deg, ie -1.9 degrees in 2880 seconds. This equates to a frequency > error of 1.9/360/2880 = 1.8uHz > Which equal to the error of the DDS RF source allowing for the 0.1deg > phase readout resolution > > So, it looks as if the EXACT frequency of the FDM-DUO's local oscillator > when set to any particular frequency ought to be calculable: > > Work out the nearest integer N value programmed into the NCO for the 1Hz > frequency specified, then calculate backwards using that N to get the > actual frequency generated. Multiples of 1875Hz will be exact > > Glad that's sorted ! > > (*) initially, as I was running out of BNC sockets on my Shack master > reference splitter (driven from an old GPSDO) I initially ran the RF > source from another GPSDO. Almost immediately a slight phase wander of the > 137kHz signal was seen. This calculated as being a frequency difference > in the order of 10^-9 (1 PPB) between the two references. Which is > exactly the sort of short term error one would expect to see in simple > GPSDOs) A rearrangememt of 10MHz master feeds and all was sorted for the > test. > > Andy > www.g4jnt.com > > --00000000000082ae76057b924a80 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Now this test IS impressive :
FDM-DUO set to 50.04MHz USB=C2=A0 =C2=A0(again, a multiple= of 1875Hz)

ADF4351 Fract-N PLL synth ge= nerating 50.041MHz.=C2=A0 Being a PLL synthesizer this frequency is EXACT b= ased on the reference in.=C2=A0 =C2=A0Driven from the same master ref used = for the DUO,=C2=A0 so accuracy of the reference=C2=A0 is irrelevant.=C2=A0<= /div>

Phase shift on the 1kHz tone out of the = DUO, using a vectorscope on the internal soundcard :

ZERO.ZERO degrees phase shift in 8 minutes of monitoring
=
The vectorscope is showing as one unmoving pixel that blinks occa= sionally

That certainly does look seriou= sly coherent to me !

Now need to work ou= t how to check NCO rounding errors in the Tx path with its higher sampling = rate.



On Mon, 26 Nov 2018 at 13:54, Andy Talbo= t <andy.g4jnt@gmail.com> = wrote:
= After tests the other day looking at the few milliHz error observable using= the FDM-DUO locked to an external reference, I decided to make sure it was= purely an NCO rounding error and nothing else hapening inside the radio

Assuming a 32 Bit NCO clocked at 122.88MHz= ,=C2=A0 we need to know the lowest common frequency that is both a multiple= of the tuning step and also a binary submultiple of the clock.=C2=A0 =C2= =A0this, and all its multiples,=C2=A0 can be generated exactly with no NCO = tuning error.=C2=A0 =C2=A0

For the DUO r= eceiver this frequency is 1875Hz, being Fc/65536 and an integral number of = Hz.
Therefore, any RF tuning point (LO frequency)=C2=A0 that= is a multiple of 1875Hz should exhibit no NCO offset error.

The only frequency in the 137kHz band that meets this = criteria is 136.875kHz=C2=A0 so the radio was set to this in USB mode.=C2= =A0 (1875Hz * 73)
My DDS low frequency signal generator was = set to generate at 137.975kHz so a 1kHz tone resulted.=C2=A0 =C2=A0Using th= e DUO's internal soundcard, the G3PLX vectorscope software was used to = measure the phase of the 1kHz output against a reference NCO of 1kHz derive= d from samples arriving from the soundcard.=C2=A0 Since the soundcard sampl= es at 48kHz which is an integer multiple of 1kHz there will be no rounding = errors.=C2=A0 Radio and sources were locked to the same reference (*) so it= s accuracy didn't enter into the equation.=C2=A0=C2=A0
=
The only potential error in frequency is my DDS source = that, due to its internal maths / rounding, was generating this RF 2.17uHz = high=C2=A0 (that 's 2.17micro-Hertz)

The vectorscope showed a dot on the screen and a phase readout of this pos= ition to a resolution of 0.1 degree.=C2=A0 =C2=A0 =C2=A0 After 48 minutes o= f monitoring, the observed phase of the 1kHz tone had shifted from 131.9deg= to 130.0deg, ie -1.9 degrees in 2880 seconds.=C2=A0 =C2=A0This equates to = a frequency error of 1.9/360/2880 =3D 1.8uHz
Which equal to = the error of the DDS RF source allowing for the 0.1deg phase readout resolu= tion

So, it looks as if the EXACT freque= ncy of the FDM-DUO's local oscillator when set to any particular freque= ncy ought to be calculable:

Work out the= nearest integer N value programmed into the NCO for the 1Hz frequency spec= ified, then calculate backwards using that N to get the actual frequency ge= nerated.=C2=A0 =C2=A0Multiples of 1875Hz will be exact

<= /div>
Glad that's sorted !

= (*) initially, as I was running out of BNC sockets on my Shack master refer= ence splitter (driven from an old GPSDO)=C2=A0 I initially ran the RF sourc= e from another GPSDO.=C2=A0 Almost immediately a slight phase wander of the= 137kHz signal was seen.=C2=A0 =C2=A0This calculated as being a frequency d= ifference in the order of 10^-9 (1 PPB) between the two references.=C2=A0 = =C2=A0Which is exactly the sort of short term error one would expect to see= in simple GPSDOs)=C2=A0 =C2=A0 A rearrangememt of 10MHz master feeds and a= ll was sorted for the test.

--00000000000082ae76057b924a80--