Re: [digitalradio] ROS Advantage?
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 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
Re: [digitalradio] ROS Advantage?
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
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:*
Re: [digitalradio] ROS Advantage?
I would have to agree with Andy's observation that the 1 baud mode is as good as using JT65a With the advantage of being able to send more text in one transmission. It is a very slow throughput though. Very 73, Glenn (WB2LMV) From: Howard Brown k...@yahoo.com To: digitalradio@yahoogroups.com Sent: Mon, February 22, 2010 9:55:11 AM Subject: Re: [digitalradio] ROS Advantage? 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
Re: [digitalradio] ROS Advantage?
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
Re: [digitalradio] ROS Advantage?
KH6TY wrote: 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. As with many other digital modes, I've been using it with AGC switched off. Dave (G0DJA)
Re: [digitalradio] ROS Advantage?
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
Re: [digitalradio] ROS Advantage?
That is good, Dave, except for receivers that distort heavily when the AGC is disabled. If you just use manual gain control, and reduce the gain for strong signals, the effect is the same, only manual. You will lose the weak station because you have reduced the gain and the sensitivity. The only way to still copy your weak station and get rid of the strong one is to filter at IF frequencies, which is what fixed filters or passband tuning does. IF DSP will do it also these days, but it needs to be at IF frequencies and not audio frequencies if you are going to prevent AGC capture by an unwanted stronger signal. 14.101 is adjacent to Pactor activity and if you monitor it long enough, you will see the Pactor station stop decoding of ROS. However, most of the automatic Pactor activity we hear is in the US, so the problem may not be as big on the other side of the big pond. 73 - Skip KH6TY Dave Ackrill wrote: KH6TY wrote: 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. As with many other digital modes, I've been using it with AGC switched off. Dave (G0DJA)
Re: [digitalradio] ROS Advantage?
Please, give a frequency alternative to 14.101 De: KH6TY kh...@comcast.net Para: digitalradio@yahoogroups.com Enviado: lun,22 febrero, 2010 22:39 Asunto: Re: [digitalradio] ROS Advantage? That is good, Dave, except for receivers that distort heavily when the AGC is disabled. If you just use manual gain control, and reduce the gain for strong signals, the effect is the same, only manual. You will lose the weak station because you have reduced the gain and the sensitivity. The only way to still copy your weak station and get rid of the strong one is to filter at IF frequencies, which is what fixed filters or passband tuning does. IF DSP will do it also these days, but it needs to be at IF frequencies and not audio frequencies if you are going to prevent AGC capture by an unwanted stronger signal. 14.101 is adjacent to Pactor activity and if you monitor it long enough, you will see the Pactor station stop decoding of ROS. However, most of the automatic Pactor activity we hear is in the US, so the problem may not be as big on the other side of the big pond. 73 - Skip KH6TY Dave Ackrill wrote: KH6TY wrote: 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. As with many other digital modes, I've been using it with AGC switched off. Dave (G0DJA)
Re: [digitalradio] ROS Advantage?
Glenn L. Roeser wrote: I would have to agree with Andy's observation that the 1 baud mode is as good as using JT65a With the advantage of being able to send more text in one transmission. It is a very slow throughput though. Very 73, Glenn (WB2LMV) You have to be the patient sort, maybe a WSPR QSO fan, to use ROS 1 baud. It does, however, allow you to nip down, get a pint and get back before the other person has finished calling CQ though. :-) Yet to receive an email confirmation for 1 baud as yet. Has anyone received one from me for 1 baud yet? I've see full email addresses for at least one station, IW1GJJ, tonight. Dave (G0DJA)
Re: [digitalradio] ROS Advantage?
Jose, I will be using 432.090 MHz because that is definitely legal for US hams. I will be testing the effect of severe Doppler-induced fading and flutter. We badly need a mode for 432 MHz that has good sensitivity and can survive fast Doppler shifts, and I hope a FHSS mode like ROS is going to do it. Will have a result around the last week of next month. The hflink published ALE frequencies might be a good alternative for others around the world, since ALE users should not notice the FHSS ROS activity (according to the ROS documentation) and their soundings are infrequent and of short duration, so they should cause minimal interference to ROS activities. They are also already in the area for wide bandwidth signals, I think. On 20m, those frequencies appear to be 14100.5, 14109.0, and 14.112.0. See http://hflink.com/channels/. Keep in mind there are NO frequencies completely free of QRM except on VHF and UHF, but some can be found on HF that have less opportunity for interference than others, so the ALE frequencies might be a good place to try. Of course, ALE users MUST, by US law, be sure the frequency is clear before transmitting, and the same applies to ROS users. We all have to share frequencies, since no frequencies are owned by anyone, but are used on a first-come, first-served basis. 73 - Skip KH6TY jose alberto nieto ros wrote: Please, give a frequency alternative to 14.101 *De:* KH6TY kh...@comcast.net *Para:* digitalradio@yahoogroups.com *Enviado:* lun,22 febrero, 2010 22:39 *Asunto:* Re: [digitalradio] ROS Advantage? That is good, Dave, except for receivers that distort heavily when the AGC is disabled. If you just use manual gain control, and reduce the gain for strong signals, the effect is the same, only manual. You will lose the weak station because you have reduced the gain and the sensitivity. The only way to still copy your weak station and get rid of the strong one is to filter at IF frequencies, which is what fixed filters or passband tuning does. IF DSP will do it also these days, but it needs to be at IF frequencies and not audio frequencies if you are going to prevent AGC capture by an unwanted stronger signal. 14.101 is adjacent to Pactor activity and if you monitor it long enough, you will see the Pactor station stop decoding of ROS. However, most of the automatic Pactor activity we hear is in the US, so the problem may not be as big on the other side of the big pond. 73 - Skip KH6TY Dave Ackrill wrote: KH6TY wrote: 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. As with many other digital modes, I've been using it with AGC switched off. Dave (G0DJA)
Re: [digitalradio] ROS Advantage?
That is true, narrow band interference cause a minimal interference to ROS, and at the same form, ROS cause minimal interference to narrow band modes. The problem is if you join two wide modes at the same frequency. De: KH6TY kh...@comcast.net Para: digitalradio@yahoogroups.com Enviado: lun,22 febrero, 2010 23:23 Asunto: Re: [digitalradio] ROS Advantage? The hflink published ALE frequencies might be a good alternative for others around the world, since ALE users should not notice the FHSS ROS activity (according to the ROS documentation) and their soundings are infrequent and of short duration, so they should cause minimal interference to ROS activities.
Re: [digitalradio] ROS Advantage?
I agree with Andy - try 14.109 USB next. ALE is wideband, but of short duration. It is worth a try, I think. 73 - Skip KH6TY jose alberto nieto ros wrote: That is true, narrow band interference cause a minimal interference to ROS, and at the same form, ROS cause minimal interference to narrow band modes. The problem is if you join two wide modes at the same frequency. *De:* KH6TY kh...@comcast.net *Para:* digitalradio@yahoogroups.com *Enviado:* lun,22 febrero, 2010 23:23 *Asunto:* Re: [digitalradio] ROS Advantage? The hflink published ALE frequencies might be a good alternative for others around the world, since ALE users should not notice the FHSS ROS activity (according to the ROS documentation) and their soundings are infrequent and of short duration, so they should cause minimal interference to ROS activities.
Re: [digitalradio] ROS Advantage?
KH6TY wrote: Jose, I will be using 432.090 MHz because that is definitely legal for US hams. I will be testing the effect of severe Doppler-induced fading and flutter. We badly need a mode for 432 MHz that has good sensitivity and can survive fast Doppler shifts, and I hope a FHSS mode like ROS is going to do it. Will have a result around the last week of next month. I'd be interested in those results as I hope to fix a problem on my 1296MHz antenna soon, and aircraft reflection (Doppler) is definitely a problem on many other data modes on 23cm. Now, if we could crack extreme doppler, like Aurora on VHF or rain/hail/snow scatter on 10 and 24GHz, that would be a real step forward... Dave (G0DJA)
Re: [digitalradio] ROS Advantage- mode ranking
It seems unfair, especially because of all the hard work put in to developing it, but I do not see it as any better than many other modes... nothing that says gee...this is way better . It is GOOD, and a mode to add to our bag of tricks, but not a killer app. The software interface is very nicely done, Jose should be congratulated on this. I'll place a few modes in a robustness category for us all. SUPER WEAK MODES JT65A (and family) WSPR ROS 1 Jason WEAK MODES Olivia 1000/32 ALE400 Domino MFSK16/8 Pactor III MT63 ROS 16 PSK10 PSKAM10 Contesia 500/12 DominoEX 4 FEC31 THROBx4 THOR 11 AVERAGE PSK31 PSK63 PACTOR II /I Hell RTTYM Contestia 50016 Chip 64/128 Olvia 8/500 Strong signal required RTTY PSK125-500 Standard ALE Packet 300 baud WINMOR
Re: [digitalradio] ROS Advantage- mode ranking
Andy obrien wrote: It seems unfair, especially because of all the hard work put in to developing it, but I do not see it as any better than many other modes... nothing that says gee...this is way better . It is GOOD, and a mode to add to our bag of tricks, but not a killer app. The software interface is very nicely done, Jose should be congratulated on this. I'll place a few modes in a robustness category for us all. I'm not sure things tend to boil down that way, to be honest Andy, Otherwise why so much RTTY on the bands? Even AX:25 is getting a bit long in the tooth now, but people still struggle on with it... Dave (G0DJA)
Re: [digitalradio] ROS Advantage?
One thing, 14.109 means that first tone is on 14.109.4 and last tone is on 14.111.65 According to that, wich would the best option? De: KH6TY kh...@comcast.net Para: digitalradio@yahoogroups.com Enviado: lun,22 febrero, 2010 23:46 Asunto: Re: [digitalradio] ROS Advantage? I agree with Andy - try 14.109 USB next. ALE is wideband, but of short duration. It is worth a try, I think. 73 - Skip KH6TY jose alberto nieto ros wrote: That is true, narrow band interference cause a minimal interference to ROS, and at the same form, ROS cause minimal interference to narrow band modes. The problem is if you join two wide modes at the same frequency. De: KH6TY kh...@comcast. net Para: digitalradio@ yahoogroups. com Enviado: lun,22 febrero, 2010 23:23 Asunto: Re: [digitalradio] ROS Advantage? The hflink published ALE frequencies might be a good alternative for others around the world, since ALE users should not notice the FHSS ROS activity (according to the ROS documentation) and their soundings are infrequent and of short duration, so they should cause minimal interference to ROS activities.
Re: [digitalradio] ROS Advantage?
Andy, you have used ALE. What center frequency or suppressed carrier frequency should be used to be on the ALE channel at 14.109? 73 - Skip KH6TY jose alberto nieto ros wrote: One thing, 14.109 means that first tone is on 14.109.4 and last tone is on 14.111.65 According to that, wich would the best option? *De:* KH6TY kh...@comcast.net *Para:* digitalradio@yahoogroups.com *Enviado:* lun,22 febrero, 2010 23:46 *Asunto:* Re: [digitalradio] ROS Advantage? I agree with Andy - try 14.109 USB next. ALE is wideband, but of short duration. It is worth a try, I think. 73 - Skip KH6TY jose alberto nieto ros wrote: That is true, narrow band interference cause a minimal interference to ROS, and at the same form, ROS cause minimal interference to narrow band modes. The problem is if you join two wide modes at the same frequency. *De:* KH6TY kh...@comcast. net *Para:* digitalradio@ yahoogroups. com *Enviado:* lun,22 febrero, 2010 23:23 *Asunto:* Re: [digitalradio] ROS Advantage? The hflink published ALE frequencies might be a good alternative for others around the world, since ALE users should not notice the FHSS ROS activity (according to the ROS documentation) and their soundings are infrequent and of short duration, so they should cause minimal interference to ROS activities.
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
