You are right
________________________________ De: Siegfried Jackstien <siegfried.jackst...@freenet.de> Para: digitalradio@yahoogroups.com Enviado: jue,25 febrero, 2010 01:19 Asunto: AW: [digitalradio] ROS Advantage? As i know it is about 2.5khz wide … so a “normal” ssb filter would work … but do not use a “narrow” ssb filter Dg9bfc Sigi ________________________________ Von:digitalradio@ yahoogroups. com [mailto: digitalradio@ yahoogroups. com ] Im Auftrag von jose alberto nieto ros Gesendet: Dienstag, 23. Februar 2010 10:21 An: digitalradio@ yahoogroups. com Betreff: Re: [digitalradio] ROS Advantage? You must configure your receiver without any king filter. ROS filter the signal better than the transceiver. Please: DONT APPLY FILTERS TO YOUR TRANSCEIVERS. ________________________________ De:Ugo <ugo.dep...@me. com> Para: " digitalradio@ yahoogroups. com " < digitalradio@ yahoogroups. com > CC: " digitalradio@ yahoogroups. com " < digitalradio@ yahoogroups. com > Enviado: mar,23 febrero, 2010 07:40 Asunto: Re: [digitalradio] ROS Advantage? Hi All. Just a question, and please, be patient if I'm asking this... I'm a SWL and I decoded ros in last days, but HOW MUCH is large its bandwidth ? In other words, which is the minimun value of bandwidth enough to receive/decode ros ? Best regards and thanks in advance for any reply. 73 de Ugo - SWL 1281/VE (sent with iPhone) Il giorno 22/feb/2010, alle ore 22.33, KH6TY <kh...@comcast. net> ha scritto: >Hi Jose, > >Of course we start that way (using a SSB filter), but then a Pactor station >will come on, cover the upper fourth of the ROS signal, and decoding becomes >garbage until it leaves. With a more narrow mode, the Pactor station can just >be filtered out at IF frequencies and not affect either the AGC or the >decoding of something like MFSK16 or Olivia 16-500, as long as those signals >are sufficiently away from the Pactor signal (even if they are still within >the bandwidth of a ROS signal). > >In the case of CW stations, during the contest, they just appeared in the SSB >filter bandwidth, and therefore among the ROS tones, and some of those also >stopped decoding until they left. > >Let's say a MT63-500 signal appears at 2000 Hz tone frequency (i.e. covering >from 2000 to 2500 Hz) at the same signal strength as the ROS signal. Will ROS >stop decoding? If a MT-63-1000 signal appears at 1500 Hz tone frequency, will >ROS stop decoding? If this happens and there is a more narrowband signal like >MFSK16, for instance, covering from 500 Hz to 1000 Hz, the MFSK16 signal can >coexist with the MT63 signal unless the MT63 signal has captured the AGC and >cutting the gain. If it has, then passband tuning can cut out the MT63 signal, >leaving only the MFSK16 signal undisturbed and decoding. In other words, there >is less chance for an interfering signal to partially or completely cover a >more narrow signal that there is a much wider one, unless the wider one can >still decode with half or 25% of its tones covered up. The question posed is >how well ROS can handle QRM, and that is what I tried to see. > >If ROS can withstand half of its bandwidth covered with an interfering signal >and still decode properly then I cannot explain what I saw, but decoding >definitely stopped or changed to garbage when the Pactor signal came on. >73 - Skip KH6TY > > > >jose alberto nieto ros wrote: > >Hi, > >You must not filter anything in the transceiver. You must pass all bandwith in >your receiver because filter are doing by the PC better than you transceiver. > > > > > ________________________________ >De:KH6TY <kh...@comcast. net> >Para: digitalradio@ yahoogroups. com >Enviado: lun,22 febrero, 2010 18:31 >Asunto: Re: [digitalradio] ROS Advantage? > > >Howard, > >After monitoring 14.101 continuously for two days, I find the following: > >1. CW signals (of narrow width, of course) during this past weekend contest >often disrupted decoding, and it looks like it was not desensitization due to >AGC capture, as the ROS signals on the waterfall did not appear any weaker. > >2. Pactor signals of 500 Hz width, outside the ROS signal, that capture the >AGC, do desensitize the receiver and cause loss of decoding, as expected. >Passband tuning takes care of that problem however. > >3. Pactor signals which have the same degree of darkness as the ROS carriers, >and occur within the upper third of the ROS signal, cause loss of decoding, >and it is not possible to fix the problem with passband tuning, as trying to >do that appears to take away enough of the ROS signal that the degree of >frequency hopping used is insufficient to overcome. Receiver is the IC-746Pro. > >4. If more than one ROS signal is present on the frequency, ROS will decode >one of them - apparently the strongest one - and the weaker one is blanked out >until the stronger one goes away and the the weaker one is decoded. > >5. Compared to Olivia 16-500, for example, the width of the ROS signal seems >to be a disadvantage as far as handling QRM is concerned. Five Olivia 16-500 >signals will fit in the same space as one ROS signal needs, so QRM, covering >the top 40% of the ROS signal, for example, would probably not disrupt any of >three Olivia signals in the bottom 60% of the ROS signal bandwidth. > >In other words, the wide bandwidth required for ROS to work is a disadvantage >because IF filtering cannot remove narrower band QRM signals that fall within >the area of the ROS signal, but IF filtering can remove the same QRM from the >passband that has been narrowed to accept only an Olivia signal. A much wider >expansion or spectrum spread might reduce the probability of decoding >disruption, but that also makes the signal wider still and more susceptible to >additional QRM. The advantage of FHSS appears to be more in favor of making it >hard to copy a traditional SS signal unless the code is available, than QRM >survival, but on crowded ham bands, it looks like a sensitive mode like Olivia >or MFSK16, because it is more narrow, and filters can be tighter, stands a >better chance of surviving QRM than the ROS signal which is exposed to more >possibilities of QRM due to its comparatively greater width. > >The mode sure is fun to use and it is too bad it does not appear to be as QRM >resistant as hoped, at least according to my observations. > >Another problem is finding a frequency space wide enough to accommodate >several ROS signals at once so there is no cross-interference. It is much >easier to find space for five Olivia or MFSK16 signals than for even two ROS >signals. > >These are only my personal observations and opinions. Others may find >differently. > >I still plan to find out if ROS can withstand the extreme Doppler shift and >flutter on UHF which just tears up even moderately strong SSB phone signals. >Olivia appears to be the best alternative mode to SSB phone we have found so >far and sometimes provides slightly better copy than SSB phone, but for very >weak signals, CW still works the best. Even though the note is very rough >sounding, as in Aurora communications, CW can still be copied by ear as it >modulates the background noise. >73 - Skip KH6TY > > > > >Howard Brown wrote: > >Aside from the legal aspect, does anyone have an opinion as to whether the >limited hopping (within the 3khz that it hops) helps the robustness of the >waveform? If it makes a tremendous difference, maybe we should all work to >get it accepted. > >Howard K5HB > > ________________________________ >From:J. Moen <j...@jwmoen.com> >To: digitalradio@ yahoogroups. com >Sent: Sun, February 21, 2010 9:13:50 PM >Subject: Re: [digitalradio] FCC Technology Jail: ROS Dead on HF for USA Hams > > >Bonnie's note describes the US/FCC regulations issues regarding ROS and SS >really well. It's the best description of the US problem I've seen on this >reflector. > >After reading what seems like hundreds of notes, I now agree that if ROS uses >FHSS techniques, as its author says it does (and none of us has seen the >code), then even though it 1) uses less 3 kHz bandwidth, 2) does not appear >to do any more harm than a SSB signal and 3) is similar to other FSK modes, it >is not legal in FCC jurisdictions. > >As Bonnie points out, ROS "doesn't hop the VFO frequency," but within the 2.5 >bandwidth, it technically is SS. This would be true if ROS used 300 Hz >bandwidth instead of 2.5 kHz, but hopped about using FHSS within the 300 Hz >bandwidth. So I have to agree the FCC regs are not well written in this case. > >Regarding the corollary issue of US/FCC regulations focused on content instead >of bandwidth, I'm not competent to comment. > > Jim - K6JM > >----- Original Message ----- >>From:expeditionradio >>To:digitalradio@ yahoogroups. com >>Sent:Sunday, February 21, 2010 5:09 PM >>Subject:[digitalradio] FCC Technology Jail: ROS Dead on HF for USA Hams >> >> >>Given the fact that ROS Modem has been advertised as Frequency Hopping Spread >>Spectrum (FHSS), it may be quite difficult for USA amateur radio operators to >>obtain a positive interpretation of rules by FCC to allow use of ROS on HF >>without some type of experimental license or waiver. Otherwise, hams will >>need an amendment of FCC rules to use it in USA. >> >>Sadly, this may lead to the early death of ROS among USA hams. >> >>If ROS Modem had simply provided the technical specifications of the >>emission, and not called it "Spread Spectrum", there would have been a chance >>for it to be easily adopted by Ham Radio operators in USA. >> >>But, the ROS modem designer is rightfully proud of the design, and he lives >>in a country that is not bound by FCC rules, and probably had little or no >>knowledge of how his advertising might prevent thousands of hams from using >>it in USA. >> >>But, as they say, "You cannot un-ring a bell, once it has been rung". >> >>ROS signal can be viewed as a type of FSK, similar to various other types of >>n-ary-FSK presently in widespread use by USA hams. The specific algorithms >>for signal process and format could simply have been documented without >>calling it Frequency Hopping Spread Spectrum (FHSS). Since it is a narrowband >>signal (using the FCC and ITU definitions of narrowband emission = less than >>3kHz) within the width of an SSB passband, it does not fit the traditional >>FHSS description as a conventional wideband technique. >> >>It probably would not have been viewed as FHSS under the spirit and intention >>of the FCC rules. It doesn't hop the VFO frequency. It simply FSKs according >>to a programmable algorithm, and it meets the infamous 1kHz shift 300 baud >>rule. >>http://www.arrl. org/FandES/ field/regulation s/news/part97/ d-305.html# >>307f3 >> >>This is a typical example of how outdated the present FCC rules are, keeping >>USA hams in "TECHNOLOGY JAIL" while the rest of the world's hams move forward >>with digital technology. It should come as no surprise that most of the new >>ham radio digital modes are not being developed in USA! >> >>But, for a moment, let's put aside the issue of current FCC "prohibition" >>against Spread Spectrum and/or Frequency Hopping Spread Spectrum, and how it >>relates to ROS mode. Let's look at "bandwidth". >> >>There is the other issue of "bandwidth" that some misguided USA hams have >>brought up here and in other forums related to ROS. Some superstitious hams >>seem to erroneously think that there is an over-reaching "bandwidth limit" in >>the FCC rules for data/text modes on HF that might indicate what part of the >>ham band to operate it or not operate it. >> >>FACT: >>"There is currently no finite bandwidth limit on HF data/text emission in USA >>ham bands, except for the sub-band and band edges." >> >>FACT: >>"FCC data/text HF rules are still mainly based on "content" of the emission, >>not bandwidth." >> >>New SDR radios have the potential to transmit and receive wider bandwidths >>than the traditional 3kHz SSB passband. We will see a lot more development in >>this area of technology in the future, and a lot more gray areas of 20th >>century FCC rules that inhibit innovation and progress for ham radio HF >>digital technology in the 21st century. >> >>Several years ago, there was a proposal to FCC to provide regulation by >>bandwidth rather than content. However, it failed to be adopted, and ARRL's >>petition to limit bandwidth was withdrawn >>http://www.arrl. org/news/ stories/2007/ 04/27/101/ ?nc=1 >> >>Thus, USA hams will continue to be in Technology Jail without access to many >>new modes in the foreseeable future :( >> >>Best Wishes, >>Bonnie Crystal KQ6XA >
