You must configure your receiver so that no filters are used (other than standard SBB ) . ROS filters the signal better than the transceiver.
Please: DONT APPLY FILTERS TO YOUR TRANSCEIVERS. Jose Alberto Nieto Ros (edit by K3UK) ________________________________ De: Ugo <[email protected]> Para: "[email protected]" <[email protected]> CC: "[email protected]" <[email protected]> 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 <[email protected]> >>>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 >>
