Re: [digitalradio] Re: An observation on Olivia
Multipath (ISI) or doppler can create such a mess... I have seen the same on 40 already Jose, CO2JA -- Original Message -- From: "jhaynesatalumni" <[EMAIL PROTECTED]> Reply-To: digitalradio@yahoogroups.com Date: Fri, 02 Feb 2007 17:32:28 - >--- In digitalradio@yahoogroups.com, "expeditionradio" ><[EMAIL PROTECTED]> wrote: > >> Are you tuned so that the phase scope is centered? >> What software are you using, and how do you have the threshold >> (squelch) set, and the allowable frequency drift? >> >> Bonnie VR2/KQ6XA >> Hong Kong, etc. >> >The software is W1HKJ's fldigi. Guess I could have rebooted into >Windows to try something else, but then I was getting perfect copy >on one of the stations. Yes, they were both correctly tuned in >and the squelch was turned off. I'm guessing there was some kind >of ionospheric activity affecting one signal path and not the other. >So I'm curious what kind of path activity can make such a mess of >Olivia. > > > __ __ __ __ Correo enviado por ElectroMAIL. Facultad Eléctrica. CUJAE Dominio: electrica.cujae.edu.cu
Re: [digitalradio] Re: An observation on Olivia
Multipath (ISI) or doppler can create such a mess... I have seen the same on 40 already Jose, CO2JA -- Original Message -- From: "jhaynesatalumni" <[EMAIL PROTECTED]> Reply-To: digitalradio@yahoogroups.com Date: Fri, 02 Feb 2007 17:32:28 - >--- In digitalradio@yahoogroups.com, "expeditionradio" ><[EMAIL PROTECTED]> wrote: > >> Are you tuned so that the phase scope is centered? >> What software are you using, and how do you have the threshold >> (squelch) set, and the allowable frequency drift? >> >> Bonnie VR2/KQ6XA >> Hong Kong, etc. >> >The software is W1HKJ's fldigi. Guess I could have rebooted into >Windows to try something else, but then I was getting perfect copy >on one of the stations. Yes, they were both correctly tuned in >and the squelch was turned off. I'm guessing there was some kind >of ionospheric activity affecting one signal path and not the other. >So I'm curious what kind of path activity can make such a mess of >Olivia. > > > __ __ __ __ Correo enviado por ElectroMAIL. Facultad Eléctrica. CUJAE Dominio: electrica.cujae.edu.cu __ __ __ __ Correo enviado por ElectroMAIL. Facultad Eléctrica. CUJAE Dominio: electrica.cujae.edu.cu
Re: [digitalradio] PSK Modes
-- Original Message -- From: KV9U <[EMAIL PROTECTED]> Reply-To: digitalradio@yahoogroups.com Date: Mon, 22 Jan 2007 14:47:12 -0600 >Some of us did try Chip modes when Nino first came out with them, but >they did not seem to perform as well as existing modes. So we coincide...it is a pity...but using the ionosphere, you have to play by its rules. >I really implore to our treasured programmers to see if they can come up >with some modes that can compete with Pactor modes. Especially some ARQ >modes that can work on MS OS. > >We know from Pactor 2, that a raised cosine shaped pulse is likely a >very good basic waveform. That is for saving bandwidth, mostly. It might allow better decoding, as well. >Then for the most robust mode, a two tone >DBPSK modulation is used and as the conditions improve, the modulation >changes to DQPSK and then with further improvements to 8-DPSK and even >16-DPSK for maximum throughput when conditions are very good. This is >what enables Pactor 2 to send about 700 bits per second at the peak >speed and do it in only a 500 Hz wide span. The steepest loss of performance in PSK constellations occurs from QPSK onwards as the distances between the constellation points diminish. It is well treated in "Communications Systems" by Carlson et al. >We know this can be done at the higher speeds under good conditions with >sound card modes since SCAMP was even faster than P2, although a much >wider signal. The problem with SCAMP was that it had no fallback position. So, fallback is important on HF. >Pactor 3 is runs an occupied bandwidth of about 2.4 kHz, but raw speed >is over 2700 bps. Instead of 2 tones, P3 uses up to 18, separated by 120 >Hz and modulated at 100 baud DBPSK or DQPSK. > >SCS has some fairly detailed data on Pactor 3 at: > >http://www.scs-ptc.com/download/PACTOR-III-Protocol.pdf > >I wish someone could explain why we can not have a sound card mode that >is roughly the same as Pactor 2 at least. Even if there was no ARQ at first. I don't know if the least complex of it all is ARQ...most likely, the rest is harder to implement. >And how different is Pactor 3, than what the SSTV hams are using >everyday? Aren't they using OFDM with QAM? If you recall what Tom Rink >said back in 1995 on the TAPR HF SIG: That it is not adaptive as pactor is. >"As mentioned in the introduction, PACTOR-II uses a two-tone DPSK modulation >system. Due to the raised cosine pulse shaping, the maximum required >bandwidth is only around 450 Hz at minus 50 dB. ASK, which was also tested in >the >early stage, provided poorer results in weak conditions compared with a higher >DPSK modulation, as different amplitude levels are more difficult to >distinguish in noisy channels than more phase levels. >Additionally, ASK increases the Crest >Factor of the signal. For these reasons, it is not used in the final >PACTOR-II protocol. Basic information on these items can also be found in the >first part of this series." > >Although not ASK, doesn't QAM employ amplitude changes as part of the >modulation scheme? Yes. A key requirement is having the highest distance between constellation points to have an edge against the noise (or QRM). That's why, in DRM, the FAC uses 4QAM, as it allows to send the reduced but very important info it conveys. But the MSC must use 64QAM, because the amount of data to be sent does not allow otherwise in the least bandwidth. >What happens if you use a multitone DPSK? It seems to a non-engineering >person like myself, that a lot of what P2 and P3 are made up of are >really a series of PSK100 or PSK200 tones (carriers). >Isn't Q15X25 a similar modulation scheme? It even runs at 83.33 baud >rather than a minimum of 100 baud such as P2. > >Why did it not work as well as P modes? > >Or is it because it has no coding such as Reed-Solomon block coding or >Viterbi convolutional coding? Certainly...all those tricks add up, and most likely, in a non proportional way...I cannot assure it by heart, but is very likely. One of the gains of the code used in pactor modes is using convolutional encoding with Viterbi decoding. The Viterbi decoder, knowing the history of what has been sent, as the convolutionally coded stream depends on what has been sent previously, makes a soft decode of what is the most likely symbol transmitted. RS coding, after deinterleaving, on the other side, may allow to recover erors WITHOUT retransmission, which may save more "bandwidth" than what is wasted on the FEC overhead. Also, P2 and P3 avoid the edges of the channel to have the least amplitude and delay differences between carriers. That's why a "reduced" version of Q15X25 is being more succesful in holding the link. >73, > >Rick, KV9U 73, Jose, CO2JA __ __ __ __ Correo enviado por ElectroMAIL. Facultad Eléctrica. CUJAE Dominio: electrica.cujae.edu.cu
Re: [digitalradio] PSK Modes
Nino: I have not had luck with Chip...not a single QSO so far. On 40 meters local NVIS test it did not work. Maybe the 300 baud chip rate was too fast for it to work. Would it be prefarable to use it on a "close to the MUF, single ray link"?? I would like to try it on the air. How has been the actual experience with Chip modes? 73 de Jose, CO2JA -- Original Message -- From: "Nino Porcino \(IZ8BLY\)" <[EMAIL PROTECTED]> Reply-To: digitalradio@yahoogroups.com Date: Mon, 22 Jan 2007 18:18:07 +0100 >Walt/K5YFW wrote: > >> if you may be receiving 1, 2 and 3 hop signals. How does this affect BPSK >> and QPSK signals from for example PSK31/63/125? > >the 3 different signals will sum at the receiver, but, having each one a >different phase, the sum is destructive with the result that they tend to >cancel. If the paths are stable you notice a drop in the signal strength but >if paths are unstable (as it is often the case) one signal may win over the >others and the phase of the PSK decoder will wander back and forth. The >clock recovery is also problematic because of the unstability of the >reference. > >Among the possible solutions to multipath there is the spread spectrum >modulation (as in Chip64) where the symbols at the receiver aren't expected >at a precise timing, but are decoded in a "clockless" manner. In Chip64 >signal scope you can actually see the signal trace wandering left and rigth >due to path hopping or see the ghosted trace of the secondary path. > >Nino/IZ8BLY > > > __ __ __ __ Correo enviado por ElectroMAIL. Facultad Eléctrica. CUJAE Dominio: electrica.cujae.edu.cu
Re: [digitalradio] Clarification : Establishing digital calling/beacon frequencies
I have worked Olivia on 14105-14110...also MT63, not very often, indeed. Never checked below 14070 for digitalmaybe it could be interesting. On 40, I have found 2 watering holes: 7070-7075 and 7035-7038 I have used Olivia and Hell on 7073. I have worked quite a few exotic DX on 7035, and would like to keep it that way, keeping the chatter on 7070...yesterday night there were two south african stations, making it a more interesting place to look around. Jose, CO2JA -- Original Message -- From: "Danny Douglas" <[EMAIL PROTECTED]> Reply-To: digitalradio@yahoogroups.com Date: Thu, 21 Dec 2006 09:59:21 -0500 >I have used Olivia, Throb, PSK63, Hell, MFSK all successfully on the low end >just below the normal PSK freqs on 20 meters. It would seem to me the best >place on all bands, using the low end of normal PSK frqs, where people would >notice you. Early on, in each of those modes, that is about the only place I >heard anyone, or saw any spots. > >Danny Douglas N7DC >ex WN5QMX ET2US WA5UKR ET3USA >SV0WPP VS6DD N7DC/YV5 G5CTB all >DX 2-6 years each >. >QSL LOTW-buro- direct >As courtesty I upload to eQSL but if you >use that - also pls upload to LOTW >or hard card. > >moderator [EMAIL PROTECTED] > - Original Message - > From: Andrew J. O'Brien > To: digitalradio@yahoogroups.com > Sent: Wednesday, December 20, 2006 6:38 PM > Subject: [digitalradio] Clarification : Establishing digital calling/beacon > frequencies > > > Just to clarify my original point... > > I'm looking to establish a suggested calling frequency for ALL digital modes > except CW, PSK31, RTTY, SSTV , PACTOR , and ALE(data ALE). > > My suggestion is that members of this list utilize a common frequency to > call CQ and/or use attended beacon features within their digital software. > This would be for Olivia, Dominio EX, Throb, PSK63/125 , , MT63 ,Hell CHIP, > MFSK16/8, PAX/PAX2 , THROB, experimental AX25. > > The idea is simply to make it easier to find stations to work rather than > trawling the bands in 300-500 Hz ranges looking for potential signals. > > My experience suggest that even on good propagation days, say on 20M, the > amount of simultaneous QSOs in the aforementioned modes rarely exceeds 3-5 . > When it is at the 5 level, it is often 2-3 Olivia stations, maybe 1 MFSK16 > and one Hell. I will argue that MOST of the time it is less than three > simultaneous QSOs . Sometimes NO signals at all. > > Thus, the amount of interest in the "exotic digital modes " is at such a > level that we would benefit from clustering, and our use of a calling/beacon > frequency would not likely clutter up the portion of the band. > > If we established 4 beacon frequencies (80,40,30, and 20M) you could easily > monitor the bands via scan features in the radio . > > Again, the idea would be just to "meet" on the calling frequency and move > further up/down the band for extended conversation. I am NOT suggesting a > different calling frequency for each mode. > > 20 M seems like the easies band to establish a data frequency that allows > worldwide participation. The others are more complex due to varying regional > bandplans. I will read the feedback I have received so far and suggest some > frequencies to try this weekend. > __ __ __ __ Correo enviado por ElectroMAIL. Facultad El�ctrica. CUJAE Dominio: electrica.cujae.edu.cu
Re: [digitalradio] MFSK beacon
Here, if the people gets home after the band is closed to Europe, there is no chance to report anything at all. I would advice to take it easy and let a weekend pass, at least... Jose, CO2JA MSc.Jose Angel Amador Fundora Departamento de Telecomunicaciones Facultad de Ingenieria Electrica, CUJAE Calle 114 #11901 e/ 119 y 127 Marianao 19390, Ciudad de la Habana, Cuba Tel:(53 7) 266-3352 Email: [EMAIL PROTECTED] - Original Message -- From: "Alves" <[EMAIL PROTECTED]> Reply-To: digitalradio@yahoogroups.com Date: Thu, 23 Nov 2006 06:52:51 - >Well, >I'm getting out of this list, nobody seems to be interested by my >experiments. > >Ciao, F4EOB. > > > > > > > >Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org > > >Yahoo! Groups Links > > > > > __ __ __ __ Correo enviado por ElectroMAIL. Facultad El�ctrica. CUJAE Dominio: electrica.cujae.edu.cu __ XIII Convención Científica de Ingeniería y Arquitectura 28/noviembre al 1/diciembre de 2006 Cujae, Ciudad de la Habana, Cuba http://www.cujae.edu.cu/eventos/convencion
