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 x13IVPR9028185 for ; Sun, 3 Feb 2019 19:31:31 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1gqMTm-0003Bm-PQ for rs_out_1@blacksheep.org; Sun, 03 Feb 2019 18:26:54 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1gqMTg-0003Bd-Hh for rsgb_lf_group@blacksheep.org; Sun, 03 Feb 2019 18:26:48 +0000 Received: from sonic311-14.consmr.mail.bf2.yahoo.com ([74.6.131.124]) by relay1.thorcom.net with esmtp (Exim 4.91) (envelope-from ) id 1gqMTe-0005gA-5P for rsgb_lf_group@blacksheep.org; Sun, 03 Feb 2019 18:26:47 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=aol.com; s=a2048; t=1549218401; bh=isz3RBNB2uBRTzDRdg1TS/wjF9d31MUqhZbiz1N2Wds=; h=Date:From:To:In-Reply-To:References:Subject:From:Subject; b=N72ISMyxfjgIEKCBp7PoQ7UClNMdHgSzL9IuwY8h4nvtec7U1Yza8JFCUPA5N0f3nO+5YYElvDyPktMv7gj84XqWnMuEGHfPwHwhlqYDctvlZBpVQ/NBMPM6sxBLBdE/jopbzjSs4S8bkhaUhBqYayu+zBLkiE/PQpIjDYPZLoOZbwB1R977wtDjh1fQXnHBfbl+cHDYOCavY7EiV+h7hgxRA+zO1owhSJxLHBZtTSqbvrdpFLSqLo/JSS8BnOGSrbF+l2YN2SD1c1KYlSRQUW+VxvJHIDIEio0weiFpoIUGdYmNXT/dJ9PnWrkUYUSXqO3LcVEsbaEGpT6Wcc+yqQ== X-YMail-OSG: pt40q1IVM1lPoAphMMAihTyehL96DSFjH7x9JvluCHv.aGuY8QMqvlY7gqRL4uc aDlTj5v2hn3GIdclhhyFpdEmfSSaQWwnw9hltF2EgJK0SBNh6XmVzaERv4sNl4RbgLgk_YIG36_E 4ingMKIsDovu3jOeDtxBFtuAkXbtPVVHMoPBDiDtCu0SWI9EbvuQUwXC8gnBN4kzOA2f1fcbOi_7 Mw5yqWYOGPuxpDT6FnbyF.7r_dBzP7fAPahoWbLQSj5MxqoKzJawXEm_vN.GrUFC0T.FRYpSZElo 7I0tKCNpUjEQmtlUPmytD2q_XFIPwid52jo6mNHLBBPZBwUStVRrDLIzU8Aoo6e7E6tFUPM5ymPQ G8AmQ14Tyqwax9O_00ncTBz4wBPqsiFD5AcDQXqpMk1pMxhcDbtcdNA2G.bNhjo6ZUC6m_tsvIuf L8escJpKcwpDjARSQEeKgdvdIxnEJYijAat6jqdoUzJ27GRfChDA0u52upG9dGuQkOOIiB1DAEXq cvdNplq.3eEP24Yz2BWEtXJg3I5s8iDRrNK3JZkSuPOWIj1tX0lu2hc16bfZXvVIrwVLmqzTHTMq M3PB2Q4O0Bz.QOG6tAcZKEXSwk_HVqdwwKIPRjgm99ABfgH54mUlAsxdnJLmCcwH4z4U3ghoSvk_ Z7Q4Q_elQbpqAaRAAnYMxWSg6ZX2xNxCool7jVY2cy1gG8PybxXIm3GSFECTPId5kxfTxYLvebip udTdU7IVK390NA7lehOZZPa2NBk_Ct5PFF9TtGTveHAP_ZXsN0bfCFln1xIXOP4gEqw.0kTOX6Of t9XkKWpzaNLMnCAeo_4ba17px.TdLgfOGQs2Ve7IfFfhH4.w1zhEOVK0ciQkmiHYl0l95.eiulnm vZt.wwv_JeyhM626Olm5qmtRP54GdF0Ifc752cYj4Rb1mCwm5YuvYaRdD8uL0lcgz.IphyOjRszb 0trJm2vRnISgnIhkd8zn4dHNhW8elTIFQdUnR8zCfZsqRTRK.ryVbqO6x766qHGPXo5bn3uTLIZt 6XcBVGprym6TpKL0ADUq4q46T Received: from sonic.gate.mail.ne1.yahoo.com by sonic311.consmr.mail.bf2.yahoo.com with HTTP; Sun, 3 Feb 2019 18:26:41 +0000 Date: Sun, 3 Feb 2019 18:26:40 +0000 (UTC) From: Markus Vester To: rsgb_lf_group@blacksheep.org Message-ID: <725032616.2252903.1549218400562@mail.yahoo.com> In-Reply-To: <1688162151.2205988.1549206383504@mail.yahoo.com> References: <1853806007.1845781.1549111581841.ref@mail.yahoo.com> <1853806007.1845781.1549111581841@mail.yahoo.com> <1688162151.2205988.1549206383504@mail.yahoo.com> MIME-Version: 1.0 X-Mailer: WebService/1.1.13027 aolwebmail Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; Touch; rv:11.0) like Gecko 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 the administrator of that system for details. Content preview: Here's a short summary of my recent experiments and conclusions. LEA-6T hardware: At around 27 €, this LEA-6T module is perhaps one of the cheapest solutione with two timing outputs - see http://www.eevblog.com/forum/projects/ebay-u-blox-lea-6t-gps-module-teardow [...] 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 [74.6.131.124 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 (markusvester[at]aol.com) 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: f9f85a03ab18710b130c40acc03380f0 Subject: LF: Generating EbNaut from u-blox GPS timepulse Content-Type: multipart/alternative; boundary="----=_Part_2252902_26065457.1549218400560" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: ** X-Spam-Status: No, hits=2.7 required=5.0 tests=FORGED_MUA_MOZILLA, HTML_MESSAGE 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 ------=_Part_2252902_26065457.1549218400560 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Here's a short summary of my recent experiments and conclusions. LEA-6T hardware: At around 27 =E2=82=AC, this LEA-6T module is perhaps one of the cheapest s= olutione with two timing outputs - see http://www.eevblog.com/forum/projects/ebay-u-blox-lea-6t-gps-module-teardow= n-and-initial-test/Although the LEA series has been superseded by NEO-7 and= -8 with GLONASS and Galileo capabilities, but these tend to be much more e= xpensive. My unit arrived within about a week, and started up fine through the includ= ed USB adapter board. Unfortunately my device did not remember settings aft= er powerdown, which turned out to be due to a missing flash eeprom chip, an= d also (believe it or not) a faulty solder joint on backup-battery charging= resistor. In fact all the solder joints looked as if they had been hand so= ldered in a Chinese garage factory but that's fine with me. =C2=A0 Then I connected the timepulse outputs through 470 ohm protection resistors= and separate coax cables. With 3.3 Vpp behind the resistor we get ~ 1 mW a= vailable power. However connecting the little ublox module barefoot to the = antenna produced good carrier traces and successful EbNaut decodes at the D= L0AO MF-Grabber, 48 km from here. For PA switching, I later employed a simp= le VOX circuit fed by TP2 output signal. The frequency can be set at any integer Hz from 1 to 24 MHz. The stepsize i= s fine for LF and MF but perhaps inconvenient at VLF where we would rather = avoitd integer Hz frequencies. But it may be possible to create small and p= recise sub-Hz offsets by regularly advancing phase, using the user-delay fi= eld. Note that at higher HF frequencies, a noticable degradation of GPS sen= sitivity occured presumably due to interference to the on-board ceramic ant= enna. EbNaut generation: The idea for ebnaut is to generate PSK by using ublox commands to change po= larity of timepulse, minimizing hardware and doing away with audio mixers o= r external phase switches. I started by monitoring the 40-byte TP5 commands= in in the binary message display. Then based on the specificaton on the u-= blox website, https://www.u-blox.com/sites/default/files/products/documents/u-blox6_Recei= verDescrProtSpec_%28GPS.G6-SW-10018%29_Public.pdf (chapters 23 and 31.24.3), I wrote a small Basic executable setubx.exe whic= h reads a template and=C2=A0patches the frequency, flag and checksum fields= . The output can be redirected to the virtual com-port of the USB device (e= .g. >com6). Note that any changes are not executed immediately but only at the start th= e next second. If a command has been issued as early as 1 to 0.1 s before, = the output inversion happens about 50 ms after the tick (implying a negligi= ble 0.05 s extra symbol delay). The advantage is that no subsecond timing i= s required for the issuing of commands, enabling the use of simple DOS time= out or sleep functions. On the other hand, the maximum signalling speed is = thus limited to 1 second per symbol. As mentioned before, I have created a directory for Windows scripts and a f= ew screenshots, and also this email: http://df6nm.bplaced.net/LF/u-blox_ebnaut/ To prepare an EbNaut transmission, you'd go through the following steps: - download and unpack ebnaut_ublox.zip=20 - use Paul's ebnaut-tx.exe and "write lines" to produce a pskln_xxx.txt out= put file, - edit the file with notepad to replace "1" by "call 1" (same for 0) and sa= ve as a .bat file, - right-click and edit frequency and delay functions in 1.bat and 0.bat=C2= =A0=C2=A0=20 - edit the send_ebnaut...bat according to your desired transmit schedule. BTW I did struggle with strange peculiarities in batch scripting... We need= to wait until the second before the next of 3-second-multiple, but why thi= s cryptic notation: @set /a waittime=3D2-(3%time:~6,2%%%3) - set /a is for arithmetic calculations for a variable, - %time:~6,2% provides two digits for the seconds in a minute, - %% is an expansion of the % modulo operator which is required in a batch = script,=C2=A0=C2=A0=20 - 3%time:~6,2% expands xx to 3xx, only to avoid 08 being interpreted as an = invalid octal number.=20 Spectral purity: Originally I had hoped for relatively low jitter, as little as 21 ns from t= he 48 MHz clock. But it turned out that on most output frequencies the jitt= er is really much larger, leading to relatively strong 1 kHz spaced spuriou= s sidelines. It looks as if frequencies were internally generated on a rela= tively coarse raster, and then the phase is being pulled in periodically ea= ch millisecond. But some preferred frequencies are much cleaner than others= , specifically =C2=A0- integer divisors of 48 MHz (well-known and easy to understand),=20 =C2=A0- but also all multiples of 366.2155 Hz. This raster happens to be 48= 000.34 kHz/2^17, so I speculate that this may be a "DDS"-like architecture,= clocked by my particular 48 MHz crystal, and outputting the msb of an over= flowing 17-bit-counter. When the output frequency is set slightly above one of these sweet spots, t= he level of 1 kHz sidelines gradually increases. But going only 1 Hz below = the spot produces a sharp detoriation to the worst levels. For example: =C2=A0137330 Hz -15 dB, 137331 Hz -54 dB, =C2=A0137536 Hz =3D 48 MHz/349: -54 dB, =C2=A0475710 Hz -5 dB(!), 475712 Hz -47 dB. When sweeping through frequencies, a "sawtooth-like" dependence of spurious= levels can be observed (screenshot lea-6t_sweep_474-480.5kHz.png).=20 Hope this may be useful=E2=80=A6 Best 73, Markus (DF6NM) ------=_Part_2252902_26065457.1549218400560 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Here's a short summary of my recent experiments and conc= lusions.

LEA-6T hardware:
At a= round 27 =E2=82=AC, this LEA-6T module is perhaps one of the cheapest solut= ione with two timing outputs - see
http://www.eevblog.com= /forum/projects/ebay-u-blox-lea-6t-gps-module-teardown-and-initial-test/
Although the LEA series has been superseded by NEO-7 and -= 8 with GLONASS and Galileo capabilities, but these tend to be much more exp= ensive.

My unit arrived within about a= week, and started up fine through the included USB adapter board. Unfortun= ately my device did not remember settings after powerdown, which turned out= to be due to a missing flash eeprom chip, and also (believe it or not) a f= aulty solder joint on backup-battery charging resistor. In fact all the sol= der joints looked as if they had been hand soldered in a Chinese garage fac= tory but that's fine with me.
 
Th= en I connected the timepulse outputs through 470 ohm protection resistors a= nd separate coax cables. With 3.3 Vpp behind the resistor we get ~ 1 mW ava= ilable power. However connecting the little ublox module barefoot to the an= tenna produced good carrier traces and successful EbNaut decodes at the DL0= AO MF-Grabber, 48 km from here. For PA switching, I later employed a simple= VOX circuit fed by TP2 output signal.

The frequency can be set at any integer Hz from 1 to 24 MHz. The stepsize= is fine for LF and MF but perhaps inconvenient at VLF where we would rathe= r avoitd integer Hz frequencies. But it may be possible to create small and= precise sub-Hz offsets by regularly advancing phase, using the user-delay = field. Note that at higher HF frequencies, a noticable degradation of GPS s= ensitivity occured presumably due to interference to the on-board ceramic a= ntenna.

EbNaut generation:

The idea for ebnaut is to generate PSK by using= ublox commands to change polarity of timepulse, minimizing hardware and do= ing away with audio mixers or external phase switches. I started by monitor= ing the 40-byte TP5 commands in in the binary message display. Then based o= n the specificaton on the u-blox website,
https://www.u-b= lox.com/sites/default/files/products/documents/u-blox6_ReceiverDescrProtSpe= c_%28GPS.G6-SW-10018%29_Public.pdf
(chapters 23 and 31.24= .3), I wrote a small Basic executable setubx.exe which reads a template and=  patches the frequency, flag and checksum fields. The output can be re= directed to the virtual com-port of the USB device (e.g. >com6).

Note that any changes are not executed immed= iately but only at the start the next second. If a command has been issued = as early as 1 to 0.1 s before, the output inversion happens about 50 ms aft= er the tick (implying a negligible 0.05 s extra symbol delay). The advantag= e is that no subsecond timing is required for the issuing of commands, enab= ling the use of simple DOS timeout or sleep functions. On the other hand, t= he maximum signalling speed is thus limited to 1 second per symbol.

As mentioned before, I have created a direct= ory for Windows scripts and a few screenshots, and also this email:
http://df6nm.bplaced.net/LF/u-blox_ebnaut/
To prepare an EbNaut transmission, you'd go through the fo= llowing steps:
- download and unpack ebnaut_ublox.zip - use Paul's ebnaut-tx.exe and "write lines" to produce a p= skln_xxx.txt output file,
- edit the file with notepad to= replace "1" by "call 1" (same for 0) and save as a .bat file,
- right-click and edit frequency and delay functions in 1.bat and 0.b= at  
- edit the send_ebnaut...bat according to= your desired transmit schedule.

BTW = I did struggle with strange peculiarities in batch scripting... We need to = wait until the second before the next of 3-second-multiple, but why this cr= yptic notation:
@set /a waittime=3D2-(3%time:~6,2%%%3)- set /a is for arithmetic calculations for a variable,
- %time:~6,2% provides two digits for the seconds in a minut= e,
- %% is an expansion of the % modulo operator which is= required in a batch script,  
- 3%time:~6,2% = expands xx to 3xx, only to avoid 08 being interpreted as an invalid octal n= umber.

Spectral purity:

Originally I had hoped for relatively low jitter,= as little as 21 ns from the 48 MHz clock. But it turned out that on most o= utput frequencies the jitter is really much larger, leading to relatively s= trong 1 kHz spaced spurious sidelines. It looks as if frequencies were inte= rnally generated on a relatively coarse raster, and then the phase is being= pulled in periodically each millisecond. But some preferred frequencies ar= e much cleaner than others, specifically
 - integer = divisors of 48 MHz (well-known and easy to understand),
=  - but also all multiples of 366.2155 Hz. This raster happens to be 48= 000.34 kHz/2^17, so I speculate that this may be a "DDS"-like architecture,= clocked by my particular 48 MHz crystal, and outputting the msb of an over= flowing 17-bit-counter.

When the outp= ut frequency is set slightly above one of these sweet spots, the level of 1= kHz sidelines gradually increases. But going only 1 Hz below the spot prod= uces a sharp detoriation to the worst levels. For example:
 137330 Hz -15 dB, 137331 Hz -54 dB,
 137536 = Hz =3D 48 MHz/349: -54 dB,
 475710 Hz -5 dB(!), 4757= 12 Hz -47 dB.

When sweeping through fr= equencies, a "sawtooth-like" dependence of spurious levels can be observed = (screenshot lea-6t_sweep_474-480.5kHz.png).

Hope this may be useful=E2=80=A6

Best 73,
Markus (DF6NM)


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