[digitalradio] Re: 70cm -2M-6M-10M fan dipole ?
Andy, Will you be cutting the 2m/70cm portions for FM or the SSB portion? Those two might get tricky as 70cm is a harmonic of 2m. It of course can potentially be advantageous if using one antenna (or radiator) for both so long as you can live with the way it radiates. Radiation lobes for 2m will not generally be pointing the same direction as 70cm. People quite often build vertical J-poles as a dual band antenna, and while the vast majority load just fine on both it is absolutely not true that they radiate efficiently on both. On 70cm they radiate both up 45 deg down 45 deg- leaving the horizon virtually uncovered. Which is not to say one can't use it for a given repeater on 70cm but it won't be efficient no matter how you slice it. (Fong J-pole is an exception to this rule since it has a phasing section which corrects this- if you want a truly omnidirectional this is an easy inexpensive way to get those two bands in a vertical) A fan dipole built as a sloper this may or may not work for you and is likely to be somewhat if only slightly directional, but 70cm might be iffy. Horizontal likely should be no problem at all (though more directional again), so long as it worked out resonant for both bands. It is all in making the radiation go somewhere useful. I have not calculated nor experimented with this on the SSB portions yet; though a rough guesstimate suggests they should line up close enough. Simply leaving separate wires for each 2m 70cm will likely leave the 70cm section doing little unless you install traps on the 2m wires- assuming the 2m portion remains close to being resonant on both 2m 70cm. At least this is my recollection from an experiment some years ago- I recall I could never get the 70cm element to do much no matter how I oriented it. Wire is cheap, so have fun playing with it! By the way, you'll find the interactivity (the multiple wires trying to detune each other) reduced quite a bit if you can manage to keep the wires far enough apart. Spreading them out in different directions to some degree can help a lot- if that is an option at your QTH. These are all quite short which should help. Stu AF6IT --- In digitalradio@yahoogroups.com, obrienaj k3uka...@... wrote: I am planning another HF installation soon and may have a 33ft mast begging for some extra creative thing to hang off it . I do not do 70cm -2M-6M much and think I should , just to be able to get out when there are bands openings. Nothing with DX in mind, just something omni-directional would do (or ANY direction) I was thinking about a fan-type dipole , one feed line going to dipoles for 70cm - 2M - 6M and maybe 10M. Most likely not fully horizontal , more of a sloper. Any thoughts on something like this? Quite a wide range of frequencies. Andy K3UK
[digitalradio] Re: directly modulate computer /thus eliminating transceiver audio input
If only more software authours would provide their audio drive in stereo I/Q form it would make direct upconversion a real doddle. If the signals were generated at baseband, even poor I/Q balance would not be too serious, as the image then lies on top of the wanted signal. For narrow band modes, say no more than a couple of hundred Hz wide, a simple two opamp allpass network can be used to generate quadrature signals. 40dB isolation can be managed without too much effort. http://www.g4jnt.com/IQConverters.htm This is the soluition I use for generating linear 137 and 500kHz RF. http://www.g4jnt.com/LFUpconv.pdf Andy G4JNT --- In digitalradio@yahoogroups.com, obrienaj k3uka...@... wrote: I am developing a 'modem' to directly modulate computer generated modes to RF thus eliminating the requirement of using a transceiver audio input Welcome to the group, tell us more. Andy K3UK
Re: [digitalradio] ROS HF Path Simulations wide vs. narrow
Thanks for the testing Tony. We observe Doppler shifts of as much as 100 Hz and Doppler spreads around 50 Hz or greater. On SSB phone, a S3 signal will not be intelligible and you can hear the voice pitch go down in a fluttering manner. ROS definitely produces nothing but garbage when SSB phone is not understandable, but Contestia will keep on printing perfectly. That is just one more reason that there are better modes than ROS we can use, are of much less bandwidth, and equal of better sensitivity. As someone pointed out, spread spectrum is basically used for encryption and has no advantage in disturbed environments. BTW, it is interesting to note the huge impact of Pawel Jalocha has on the use of digital on the ham bands. His SLOPSK development was the basis for G3PLX's PSK31, and now, Olivia is the highest performing digital mode. It is as if he were the father of all we are working with today! I wish I knew more about his background. 73, Skip KH6TY On 7/21/2010 12:15 AM, Tony wrote: On 7/20/2010 3:54 PM, KH6TY wrote: Our on-air tests show that ROS 16 baud, 2200 Hz wide spread spectrum was very poor on UHF under Doppler spreading. Can you confirm this with flutter tests like Jaak has done. Skip, My path tests show that ROS is less tolerant to Doppler spread than Olivia or one of it's variants so I'd have to agree with your on-air evaluation. Throughput starts to fail as the Doppler spread is increased beyond 20Hz (two channels 2ms delay) and I suspect you could be experiencing frequency dispersions beyond that range. I haven't been able to find any propagation data that shows how much Doppler spread is likely take place on VHF/UHF. Wish I knew that answer to that. Tony -K2MO Tony, Our on-air tests show that ROS 16 baud, 2200 Hz wide spread spectrum was very poor on UHF under Doppler spreading. Can you confirm this with flutter tests like Jaak has done on http://contestia.blogspot.com/p/pathsim_09.html http://contestia.blogspot.com/p/pathsim_09.html ? 73, Skip KH6TY On 7/19/2010 9:42 PM, Tony wrote: All, With all the attention ROS has been getting lately, I thought it would be interesting to see how the narrow mode compared to the wide version under the controlled environment of the HF path simulator. After a few hours of testing, it seems there's little difference between the two. The simulator indicated that they both had the same sensitivity (-15db) and essentially the same poor channel performance characteristics (see throughput samples below). In no case did one mode outperform the other to the point where it would make any real difference; both have the essentially the same wpm rate as well. These tests are not conclusive, but they do suggest that there may not be any real advantage in using the wide mode vs narrow under most circumstances. Of course, the simulator can only emulate the basic characteristics of the real HF channel so it would be interesting to hear from those who have compared the two on-air. Tony -K2MO CCIR-520-2 POOR CHANNEL SIMULATIONS: -11DB SNR ROS 2250 / 16 baud the quick brown fox jumps over the lazy dog the quick brown fox jumps over the lazlµog Lghe quick brown fox jumps over the lazy dog the quccirown fox jumps over the lazy dog the quick brown fox jumps over the lazy dog Âe quick brown fox jumps over the lazy dog the quick brown fealoeumps ovahe lazEh/i ROS 500 / 16 baud the quick brown fox jumps over the lazy dog the quick brown fox jumps over the lazy dog the quick breFn fox juo3s over tes lazy dog the quæe t ´uls r?umps over the lazy dog the quick brown fox jumps over the lazy dog the quick brown f Á jumps over the lazy dog the quick brown fox jumps over the lazy dogQo __ Information from ESET NOD32 Antivirus, version of virus signature database 5293 (20100719) __ The message was checked by ESET NOD32 Antivirus. http://www.eset.com http://www.eset.com http://www.obriensweb.com/digispotter.html Chat, Skeds, and Spots all in one (resize to suit) Facebook= http://www.facebook.com/pages/digitalradio/123270301037522 Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: digitalradio-dig...@yahoogroups.com digitalradio-fullfeatu...@yahoogroups.com * To unsubscribe from this group, send an email to: digitalradio-unsubscr...@yahoogroups.com * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [digitalradio] Hey ..Good luck! e--5
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Re: [digitalradio] 70cm -2M-6M-10M fan dipole ?
Andy, You first have to decide if you will use horizontal or vertical polarization - vertical polarization mostly for working the repeaters on 2M and 70CM, or horizontal polarization for working SSB stations. Omnidirectionality is easy with vertical polarization but much more difficult with horizontal polarization. If you will be working repeaters, you do not need much antenna gain, but for SSB, you need much more gain. The other question is the feedline. What transceiver are you using? Does it have separate antenna outputs for 2M and 70 CM? For example, on the IC-706MKIIG, the 2M and 70 CM antenna outputs are combined, so you can use a diplexer to send the RF to the two antennas from a single feedline. The 6M output is combined with the HF output, so that requires a separate feedline. You probably want horizontal polarization for 6M, and an aluminum dipole would be self-supporting. If you use two at 90 degrees and switch feedlines with a switch, you have omnidirectional coverage on 6M. On 2m and 70 CM horizontal polarization, I use bi-directional skeleton slots for each band, which gives me enough gain for DX, mount two at 90 degrees to each other and just switch feedlines for omnidirectional coverage. If all you are interested in is working repeaters, then a dipole for 6M and commercial 5/8 wavelength verticals for FM on 2M and 70CM will work with one feedline if diplexers are available to split 6M and 2m/70CM. Again, much depends on the antenna outputs of the transceiver, whether you should use a single feedline or two feedlines. 73, Skip KH6TY On 7/20/2010 8:58 PM, obrienaj wrote: I am planning another HF installation soon and may have a 33ft mast begging for some extra creative thing to hang off it . I do not do 70cm -2M-6M much and think I should , just to be able to get out when there are bands openings. Nothing with DX in mind, just something omni-directional would do (or ANY direction) I was thinking about a fan-type dipole , one feed line going to dipoles for 70cm - 2M - 6M and maybe 10M. Most likely not fully horizontal , more of a sloper. Any thoughts on something like this? Quite a wide range of frequencies. Andy K3UK
AW: [digitalradio] 70cm -2M-6M-10M fan dipole ?
What about a multiband verticl fort he uppoer bands .. Stacked with some gain like the x 510 or the x 6000 Omnidirectional . 2 or 3 bands . with some gain . can be used also for local repeater or emergency work . Just an idea For 6 and 10 better use a small beam But you can start with a ladderline fed dipole for 6 and 10 Many antannas possible so I would sax . see what you have in your junk box and garage . and then make something with that parts. Greetz Dg9bfc Sigi
RE: [digitalradio] Re: ROS back bigger and better !
Hi Ted: Concur, which is why I simply created the internal email filter with the rule, scan any msg in the inbox for the word ros, and place in the Junk Mail folder for disposal along with the offers for blonds, diplomas from MIT, and enhancements. 73 Les Lester B Veenstra MØYCM K1YCM mailto:les...@veenstras.com les...@veenstras.com mailto:m0...@veenstras.com m0...@veenstras.com mailto:k1...@veenstras.com k1...@veenstras.com US Postal Address: PSC 45 Box 781 APO AE 09468 USA UK Postal Address: Dawn Cottage Norwood, Harrogate HG3 1SD, UK Telephones: Office: +44-(0)1423-846-385 Home: +44-(0)1943-880-963 Guam Cell: +1-671-788-5654 UK Cell: +44-(0)7716-298-224 US Cell: +1-240-425-7335 Jamaica: +1-876-352-7504 This e-mail and any documents attached hereto contain confidential or privileged information. The information is intended to be for use only by the individual or entity to whom they are addressed. If you are not the intended recipient or the person responsible for delivering the e-mail to the intended recipient, be aware that any disclosure, copying, distribution or use of the contents of this e-mail or any documents attached hereto is prohibited. From: digitalradio@yahoogroups.com [mailto:digitalra...@yahoogroups.com] On Behalf Of Ted Bear Sent: Tuesday, July 20, 2010 8:22 PM To: digitalradio@yahoogroups.com Subject: [digitalradio] Re: ROS back bigger and better ! Holy Moly.. When you guys going to drop the ROS subject and get back to interesting DIGITAL
Re: Re: [digitalradio] Re: Olivia vs. RTTY vs. PSK spectrum efficiency
I think the key to making it really fly would be to hold some short sprint contests using PSK63 only. That way you could get a lot of guys to try it without a big commitment of time and effort. As it gains acceptance thru that and word of mouth, it could be added as an optional mode in more mainstream contests. Hold some sprints and talk it up on the email reflectors and it stands a chance... Ty K3MM Jul 20, 2010 07:10:30 PM, digitalradio@yahoogroups.com wrote: PSK63 was developed as an intended RTTY contesting mode replacement, not for conversation. PSK31 is too slow for contesting and has a preamble and a postamble that slows turnovers down, so the idea was that 100 wpm PSK63 would, overall, including faster turnovers than PSK31, be as fast as RTTY for contest exchanges, and contesters would benefit from less power needed, panoramic reception, less crowding, and faster synchronization. In the contesting world, a rapid exchange and turnover is more important than a faster typing speed. Peter Martinez designed PSK31 for ragchewing and so selected 50 wpm as fast enough for conversation for most typists. Even though Don, AA5AU, a big-time winner of RTTY contests, said he was just blown away about the possibility of PSK63 for contesting when I showed it to him, I was unable to get it implemented into WriteLog, as the author took a chicken and egg approach in which he said he would not add PSK63 to WriteLog until it became popular for contesting! Since WriteLog is so popular with contest winners, and did not support PSK63, the mode never took off, except in Europe. What might help would be for someone to convince the contest managers to do something like adding a multiplier for PSK63 contacts, or perhaps some other acceptable incentive, to make it worthwhile to use PSK63 for contests. Everybody would win, because so many PSK63 signals can fit into the space of one RTTY signal, and with panoramic displays, you get a list of callsigns to select from all presented to you, and can even highlight zones or callsign areas you need for multipliers, etc.. 73, Skip KH6TY On 7/20/2010 7:03 PM, Ralph Mowery wrote: - Original Message From: g4ilo jul...@g4ilo.com To: mailto:digitalradio%40yahoogroups.com; target=_blank class= parsedEmaildigitalradio@yahoogroups.com Sent: Tue, July 20, 2010 4:29:15 AM Subject: [digitalradio] Re: Olivia vs. RTTY vs. PSK spectrum efficiency Just because a mode is better doesn't mean that people will want to use it, though, and I guess both RTTY and PSK31 are so established now that you'll never persuade people to give them up. Julian, G4ILO While rtty can be replaced by other modes, they will not run on the 50 plus old mechanical printers and the demodulators that go with them. Just as some like to run AM on the ham bands. Not that good of a use of bandwidth, but just something to play with that many enjoy. I doubt that many hams that run the digital modes can really type very fast and depend on the micros in the programs. For the ones doing it in real time, psk31 probably has enough speed.
Re: [digitalradio] Question on bandwidth on HF
JT8 is proposed as a possible alternative to JT4. Modulation is 8-FSK at 2.857 baud. FEC uses convolutional codes with K=14, r=1/4, K=15, r=1/6, or K=16, r=1/8, depending on message length. Synchronization uses 8×8 Costas arrays at the beginning and end of a transmission, followed by two additional symbols to distinguish between 30-bit, 48-bit, and 78-bit messages. Total bandwidth is 23 Hz. At present, only the 78-bit messages have been implemented. http://www.physics.princeton.edu/pulsar/K1JT/WSJT8_User.pdf VE3BDR From: Russell Blair Sent: Wednesday, July 21, 2010 9:46 PM To: Digital Radio Subject: [digitalradio] Question on bandwidth on HF THIS IS NOT TO START A BIG THING...I was using one of the new modes today WSJT8 Beta and was informed that the bandwidth exceeded to limits on HF... My question What is the bandwidth ? Russell NC5O 1- Whoever said nothing is impossible never tried slamming a revolving door! 2- A government big enough to give you everything you want, is strong enough to take everything you have. - Gerald Ford IN GOD WE TRUST Russell Blair (NC5O) Skype-Russell.Blair Hell Field #300 DRCC #55 30m Dig-group #693 Digital Mode Club #03198 No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.851 / Virus Database: 271.1.1/3019 - Release Date: 07/21/10 02:36:00
Re: [digitalradio] Question on bandwidth on HF
It is a very NARROW mode On 7/21/10, Russell Blair russell_blai...@yahoo.com wrote: THIS IS NOT TO START A BIG THING...I was using one of the new modes today WSJT8 Beta and was informed that the bandwidth exceeded to limits on HF... My question What is the bandwidth ? Russell NC5O 1- Whoever said nothing is impossible never tried slamming a revolving door! 2- A government big enough to give you everything you want, is strong enough to take everything you have. - Gerald Ford IN GOD WE TRUST Russell Blair (NC5O) Skype-Russell.Blair Hell Field #300 DRCC #55 30m Dig-group #693 Digital Mode Club #03198 -- Sent from my mobile device
