[digitalradio] SS definitions
I'll preface this by saying that I'm not trying to defend or crucify ROS. But when we are dealing with definitions the FCC, it's very important we be clear accurate on our definitions. KH6TY wrote: By definition, it is SS if the pattern is independently generated from the data. One test, but not the only test The original intent of FHSS was to make third-party decoding impossible without knowledge of the code that generated the tones or carriers. True, emphasis on original intent. There are many, many SS implementations usages that are not done to prevent third party decoding. It's actually a very good way to share spectrum with dissimilar usages. And nearly all FHSS can be easily decoded independent of knowing the code now unless the data itself is highly encrypted. FCC rules disallow encryption because we are required to police the bands ourselves. As long as there is not a pattern to the frequencies generated, that is independent of the data, one of the necessary and sufficient conditions to qualify as FHSS is missing. This is overly simplistic. I have first hand experience with FCC dealings with regard to code generators used for randomization of amateur digital signals. All that is required is to make available upon demand the code sequence. You don't have to offer a decoder, nor do OO's have to be able to monitor it, etc. Just make the code sequence available upon request. However, in the case of ROS, the repeated pattern is not there, so, until the regulations are changed, ROS is illegal FHSS, even though the spreading is limited and capable of third-party monitoring. Sorry, this is overly simplistic. Many US legal codec/modems do not meet this test. ROS may or may not be legal, but it's not your repeated test definition that makes it so. The most legit issue that technically makes it SS is that a single data bit is sliced into smaller bits when sent. IE: the code rate is much greater than the data rate. (which directly correlates with spreading factor as well). That is a result of a historical attempt to prevent encryption, but this can probably be changed through the petition process with public comment. Until then, hams in the US have no choice but to abide by the regulations as written. First hand experience: It does not take petition with public comment. Just professional dialog with the FCC, and a willingness to provide details on the encoding sequence if requested. In the author's own words, three necessary and sufficient elements make it SS, and a search of the literature says the same: 1. The signal occupies a bandwidth much in excess of the minimum bandwidth necessary to send the information. 2. Spreading is accomplished by means of a spreading signal, often called a code signal, which is independent of the data. 3. At the receiver, despreading (recovering the original data) is accomplished by the correlation of the received spread signal with a synchronized replica of the spreading signal used to spread the information. This is close to, but not exactly the ITU (and thus US Federal) definition of SS. But I agree with you, ROS by the author's description met the legal definition of SS. But the real question is, should it be treated the same as traditional SS which normally uses a much larger (100x or more) spreading factor and thus would negatively impact an entire HF amateur allocation. The operative phase here is independent of the data. So how bout randomizers used to maximize average power? (used reduce crest factor). Viterbi encoders? It is just unfortunate that the FCC regulations, as currently written, do not allow ROS on HF and that they really need to be updated. Note that SS is already permittted above 222 MHz, where there is plenty of space to use for spreading that does not exist on HF. In fact, the encryption aspect is not even mentioned, except in other parts of the regulations disallowing encryption. The regulations were obviously written to prevent extremely wide SS signals from interfering with other users. Since ROS is no wider than a phone signal, there is no reason the regulations should not be modified to allow it (perhaps with other necessary limitations), but until then, and right now, ROS is illegal below 222 Mhz. It is that simple! Compare the repeated pattern of MFSK64 to the random pattern of ROS as data is applied. Invalid test. Do the same with P3 with compression turned on. I understand what you are trying to do, and agree with some points. But also see a very simplistic approach to SS tests that will ultimately do us a dis-service. Have fun, Alan km4ba
Re: [digitalradio] SS definitions
Alan, though we may disagree as to the amount or nature of FHSS in ROS, the bottom line is that the FCC engineers, as well as the ARRL engineers, reviewed both the documentation and the signal footprint, and have concluded it is FHSS. While their opinion might be changed through dialog, that is unlikely at this point, so the most sure approach is just to agree it is FHSS and petition for a variance with necessary limitations. It is highly unlikely that the FCC will reverse their decision, especially since the author, whom the FCC expected to tell the truth, wrote a 9-page paper claiming it was FHSS, titles, INTRODUCTION TO ROS: THE SPREAD SPECTRUM. To try to re-characterize it as something else in order to get approval puts the credibility of the author in serious doubt, especially after the fiasco over the posting of an FCC announcement that it was legal that the FCC claims they did not make. Admit it is FHSS, but petition for a variance or modification of the rules to allow it on the basis that it is not harmful to other modes, and that will probably be granted. It is too late, and too much dirty water has passed under the bridge, to even imagine that any other way can be successful. I think we have beat this horse to death at this point and should move on to another topic. 73 - Skip KH6TY Alan Barrow wrote: I'll preface this by saying that I'm not trying to defend or crucify ROS. But when we are dealing with definitions the FCC, it's very important we be clear accurate on our definitions. KH6TY wrote: By definition, it is SS if the pattern is independently generated from the data. One test, but not the only test The original intent of FHSS was to make third-party decoding impossible without knowledge of the code that generated the tones or carriers. True, emphasis on original intent. There are many, many SS implementations usages that are not done to prevent third party decoding. It's actually a very good way to share spectrum with dissimilar usages. And nearly all FHSS can be easily decoded independent of knowing the code now unless the data itself is highly encrypted. FCC rules disallow encryption because we are required to police the bands ourselves. As long as there is not a pattern to the frequencies generated, that is independent of the data, one of the necessary and sufficient conditions to qualify as FHSS is missing. This is overly simplistic. I have first hand experience with FCC dealings with regard to code generators used for randomization of amateur digital signals. All that is required is to make available upon demand the code sequence. You don't have to offer a decoder, nor do OO's have to be able to monitor it, etc. Just make the code sequence available upon request. However, in the case of ROS, the repeated pattern is not there, so, until the regulations are changed, ROS is illegal FHSS, even though the spreading is limited and capable of third-party monitoring. Sorry, this is overly simplistic. Many US legal codec/modems do not meet this test. ROS may or may not be legal, but it's not your repeated test definition that makes it so. The most legit issue that technically makes it SS is that a single data bit is sliced into smaller bits when sent. IE: the code rate is much greater than the data rate. (which directly correlates with spreading factor as well). That is a result of a historical attempt to prevent encryption, but this can probably be changed through the petition process with public comment. Until then, hams in the US have no choice but to abide by the regulations as written. First hand experience: It does not take petition with public comment. Just professional dialog with the FCC, and a willingness to provide details on the encoding sequence if requested. In the author's own words, three necessary and sufficient elements make it SS, and a search of the literature says the same: 1. The signal occupies a bandwidth much in excess of the minimum bandwidth necessary to send the information. 2. Spreading is accomplished by means of a spreading signal, often called a code signal, which is independent of the data. 3. At the receiver, despreading (recovering the original data) is accomplished by the correlation of the received spread signal with a synchronized replica of the spreading signal used to spread the information. This is close to, but not exactly the ITU (and thus US Federal) definition of SS. But I agree with you, ROS by the author's description met the legal definition of SS. But the real question is, should it be treated the same as traditional SS which normally uses a much larger (100x or more) spreading factor and thus would negatively impact an entire HF amateur allocation. The operative phase here is independent of the data. So how bout randomizers used to maximize average power? (used reduce crest factor). Viterbi encoders? It is just unfortunate that the FCC regulations, as currently written,
Re: [digitalradio] SS definitions
--- On Wed, 10/3/10, KH6TY kh...@comcast.net wrote: Alan, though we may disagree as to the amount or nature of FHSS in ROS, the bottom line is that the FCC engineers, as well as the ARRL engineers, reviewed both the documentation and the signal footprint, and have concluded it is FHSS. Who are these FCC Engineers ? All we've has is a response from someone that may be assumed to be an office clerk who simply quoted back the words in Part 97. 73 Trevor M5AKA
Re: [digitalradio] SS definitions
Engineers that work for the FCC, of course. Their names are not ordinarily revealed and the mouthpiece of the FCC is a customer service agent (and for some amateur matters, the ARRL, who relays information from the FCC offices). This structure should be fairly obvious to anyone with experience in business. Trevor, Ask Toyota for the names of the engineers investigating the unexpected acceleration and I doubt that you will get an answer! Ask the President who is responsible for reports from the White House and you will only find out through a legal action. I am sure these walls are set up to protect employees from frivolous attacks. However, there is a Freedom of Information Act that can be invoked through legal action to obtain some internal documents of the government, but they are generally not offered to the public without a court order, for obvious reasons. The FCC customer service agent is the person who relays decisions to the public, and that agent probably does not make the decisions personally or without consultation. This is analogous to the Press Secretary of the White House. If you want to verify the originator of a decision, you have a right to do so through the appropriate legal process. The FCC's customer service agent has relayed a FCC decision to reaffirm that ROS is indeed FHSS and that, under current rules, as docemented in Part 97, SS is only allowed above 222 MHz. That is generally the way it works on this side of the pond, and we have no choice but to abide by the system or petition for change. 73 - Skip KH6TY Trevor . wrote: --- On Wed, 10/3/10, KH6TY kh...@comcast.net mailto:kh6ty%40comcast.net wrote: Alan, though we may disagree as to the amount or nature of FHSS in ROS, the bottom line is that the FCC engineers, as well as the ARRL engineers, reviewed both the documentation and the signal footprint, and have concluded it is FHSS. Who are these FCC Engineers ? All we've has is a response from someone that may be assumed to be an office clerk who simply quoted back the words in Part 97. 73 Trevor M5AKA
Re: [digitalradio] SS definitions
Trevor, I might add that it is often the practice in this country for a higher court just to either reaffirm or remand a lower court decision, instead of issuing a differing decision itself. I am sure that the FCC, as a government body, also adheres to this practice. That is why the original decision of the FCC, as originally related by the customer service agent, simply reaffirms the original finding. The official word from the FCC, through one of their spokesmen, is that ROS is spread spectrum and that will stand until modified by the petition process. 73 - Skip KH6TY Trevor . wrote: --- On Wed, 10/3/10, KH6TY kh...@comcast.net mailto:kh6ty%40comcast.net wrote: Alan, though we may disagree as to the amount or nature of FHSS in ROS, the bottom line is that the FCC engineers, as well as the ARRL engineers, reviewed both the documentation and the signal footprint, and have concluded it is FHSS. Who are these FCC Engineers ? All we've has is a response from someone that may be assumed to be an office clerk who simply quoted back the words in Part 97. 73 Trevor M5AKA
Re: [digitalradio] SS definitions (here are the ITU, NITA, and Fed Std)
KH6TY wrote: Alan, though we may disagree as to the amount or nature of FHSS in ROS, Actually, I think we agree, just for different reasons. I really don't care about ROS. But do care about dangerous precedents. :-) the bottom line is that the FCC engineers, as well as the ARRL engineers, reviewed both the documentation and the signal footprint, and have concluded it is FHSS. I think we all agree it's a micro form of FHSS. I'm not sure I agree the FCC engineers have ruled. If Bill Cross or similar commented, that'd be definitive. But the ARRL interpretation of the FCC dialog still is pretty ambiguous. Lot's of the author stated and each operator has to Compare it with the ruling on Pactor 3 when challenged on a similar crusade. That's clear unambiguous, it was not FDM, even though it could be construed as such on a micro scale. And that crusade had similar arguments mis-statements. While their opinion might be changed through dialog, that is unlikely at this point, so the most sure approach is just to agree it is FHSS and petition for a variance with necessary limitations. Again, I think the real area to petition is not about ROS itself. That has been so badly handled from all sides it's probably tainted. And to be clear: Amateur radio was the net loser. The real issue is around applying macro definitions (like ITU SS, traditionally broadband, wide spreading factor) to a micro (SSB, non broadband) implementation like ROS. Put another way, what would an HF optimized SS mode do that other modes do not? What would be the negative? And factor in the potential (done right) of improved interoperation with other modes, signal processing gain, etc. And potential channel sharing (concurrent users). I think we have beat this horse to death at this point and should move on to another topic. Well, that would be great, except you keep refering to the must have idle tones like my grand-dad's rtty test. Again, I don't really care about ROS. This dialog is about the idea of using carrier patterns at idle or steady zero's/ones (like ancient RTTY) as a test for SS. That's just not it. We *are* allowed to encode data in a pseudo-random pattern, as long as the other SS tests are not triggered. Instead of concocting our own definitions, let's refer to the standards. ITU, which is referenced by NTIA, which is referenced by Fed Std, which is also reference by some FCC commercial definitions. It's the closest we have and is attached below. What's still not 100% is whether a SSB signal with a fixed dial frequency (and implied fixed carrier frequency) would be considered SS just because the audio sent changed in a SS fashion. It's back to is FSK AFSK the same mode, or just happen to look the same. Which is becoming tiresome, and makes me think reminisce about the traditional anti new mode (PSK, Pactor, ALE, whatever) crusades. :-) Remember, PSK was going to ruin the world as well. So was SSB in it's day! Have fun, Alan km4ba Here are the ITU definitions. Note the spreading factor definitions, etc: *Term* : spread spectrum (SS) system *Definition* : System in which the average energy of the transmitted signal is spread over a bandwidth which is much wider than the information bandwidth (the bandwidth of the transmitted signal is wider than the information bandwidth by at least a factor of two for double sideband AM and typically a factor of four or greater for narrow-band FM, and 100 to 1 for a linear SS system). *Term* : Direct sequence (DS) spread spectrum *Definition* : signal structuring technique utilizing a digital code spreading sequence having a chip rate 1/Tsin much higher than the information signal bit rate 1/Ts. Each information bit of the digital signal is transmitted as a pseudo-random sequence of chips, which produces a broad noise-like spectrum with a bandwidth (distance between first nulls) of 2 Bsin ? 2/Tsin. The receiver correlates the RF input signal with a local copy of the spreading sequence to recover the narrow-band data information at a rate 1/Ts. ***Term* : Frequency-hopping (FH) spread spectrum *Definition* : signal structuring technique employing automatic switching of the transmitted frequency. Selection of the frequency to be transmitted is typically made in a pseudo-random manner from a set of frequencies covering a band wider than the information bandwidth. The intended receiver frequency-hops in synchronization with the transmitter in order to retrieve the desired information. Here's the NTIA redbook definitions, which is also reference in Fed-Std 1037c: Spread Spectrum: A signal structuring technique that employs direct sequence, frequency hopping or a hybrid of these, which can be used for multiple access and/or multiple functions. This technique decreases the potential interference to other receivers while achieving privacy and increasing the immunity of spread spectrum receivers to noise and interference. Spread spectrum generally makes use of a
RE: [digitalradio] SS definitions
8P9RY comments below From: digitalradio@yahoogroups.com [mailto:digitalra...@yahoogroups.com] On Behalf Of Trevor . Sent: Wednesday, March 10, 2010 3:21 PM To: digitalradio@yahoogroups.com Subject: Re: [digitalradio] SS definitions --- On Wed, 10/3/10, KH6TY kh...@comcast.net mailto:kh6ty%40comcast.net wrote: Alan, though we may disagree as to the amount or nature of FHSS in ROS, the bottom line is that the FCC engineers, as well as the ARRL engineers, reviewed both the documentation and the signal footprint, and have concluded it is FHSS. Who are these FCC Engineers ? All we've has is a response from someone that may be assumed to be an office clerk who simply quoted back the words in Part 97. What a convenient assumption. Have you spoken with the agent in question, assessed her technical skills, and inquired as to what effort went into the response she conveyed? 73, Dave, 8P9RY
Re: [digitalradio] SS definitions (here are the ITU, NITA, and Fed Std)
Alan, please carry on the debate with someone else. I have spent a huge amount of time on this issue, trying to help in whatever way I can, although I do not have all the answers, obviously. I need to do something other than sit in front of this computer all day! Have fun, 73 - Skip KH6TY Alan Barrow wrote: KH6TY wrote: Alan, though we may disagree as to the amount or nature of FHSS in ROS, Actually, I think we agree, just for different reasons. I really don't care about ROS. But do care about dangerous precedents. :-) the bottom line is that the FCC engineers, as well as the ARRL engineers, reviewed both the documentation and the signal footprint, and have concluded it is FHSS. I think we all agree it's a micro form of FHSS. I'm not sure I agree the FCC engineers have ruled. If Bill Cross or similar commented, that'd be definitive. But the ARRL interpretation of the FCC dialog still is pretty ambiguous. Lot's of the author stated and each operator has to Compare it with the ruling on Pactor 3 when challenged on a similar crusade. That's clear unambiguous, it was not FDM, even though it could be construed as such on a micro scale. And that crusade had similar arguments mis-statements. While their opinion might be changed through dialog, that is unlikely at this point, so the most sure approach is just to agree it is FHSS and petition for a variance with necessary limitations. Again, I think the real area to petition is not about ROS itself. That has been so badly handled from all sides it's probably tainted. And to be clear: Amateur radio was the net loser. The real issue is around applying macro definitions (like ITU SS, traditionally broadband, wide spreading factor) to a micro (SSB, non broadband) implementation like ROS. Put another way, what would an HF optimized SS mode do that other modes do not? What would be the negative? And factor in the potential (done right) of improved interoperation with other modes, signal processing gain, etc. And potential channel sharing (concurrent users). I think we have beat this horse to death at this point and should move on to another topic. Well, that would be great, except you keep refering to the must have idle tones like my grand-dad's rtty test. Again, I don't really care about ROS. This dialog is about the idea of using carrier patterns at idle or steady zero's/ones (like ancient RTTY) as a test for SS. That's just not it. We *are* allowed to encode data in a pseudo-random pattern, as long as the other SS tests are not triggered. Instead of concocting our own definitions, let's refer to the standards. ITU, which is referenced by NTIA, which is referenced by Fed Std, which is also reference by some FCC commercial definitions. It's the closest we have and is attached below. What's still not 100% is whether a SSB signal with a fixed dial frequency (and implied fixed carrier frequency) would be considered SS just because the audio sent changed in a SS fashion. It's back to is FSK AFSK the same mode, or just happen to look the same. Which is becoming tiresome, and makes me think reminisce about the traditional anti new mode (PSK, Pactor, ALE, whatever) crusades. :-) Remember, PSK was going to ruin the world as well. So was SSB in it's day! Have fun, Alan km4ba Here are the ITU definitions. Note the spreading factor definitions, etc: *Term* : spread spectrum (SS) system *Definition* : System in which the average energy of the transmitted signal is spread over a bandwidth which is much wider than the information bandwidth (the bandwidth of the transmitted signal is wider than the information bandwidth by at least a factor of two for double sideband AM and typically a factor of four or greater for narrow-band FM, and 100 to 1 for a linear SS system). *Term* : Direct sequence (DS) spread spectrum *Definition* : signal structuring technique utilizing a digital code spreading sequence having a chip rate 1/Tsin much higher than the information signal bit rate 1/Ts. Each information bit of the digital signal is transmitted as a pseudo-random sequence of chips, which produces a broad noise-like spectrum with a bandwidth (distance between first nulls) of 2 Bsin ? 2/Tsin. The receiver correlates the RF input signal with a local copy of the spreading sequence to recover the narrow-band data information at a rate 1/Ts. ***Term* : Frequency-hopping (FH) spread spectrum *Definition* : signal structuring technique employing automatic switching of the transmitted frequency. Selection of the frequency to be transmitted is typically made in a pseudo-random manner from a set of frequencies covering a band wider than the information bandwidth. The intended receiver frequency-hops in synchronization with the transmitter in order to retrieve the desired information. Here's the NTIA redbook definitions, which is also reference in Fed-Std 1037c: Spread Spectrum: A signal structuring technique that employs direct sequence, frequency
