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 (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
