Vojtech .... I think you will find that SS could make monitoring the bands more difficult as SS rings bells of the cryptographic sort in odd places .. and as these bell ringers are still trying to decode enigma and ultra intercepts from ww2 ... meetings in forests and the like ring any bells ? (tnx)... perhaps it would be too much to handle ... On the other hand .. yes your right multi channel occupancy and sub noise level communications are quite possible .. but hams with such ability .. why, can hear the clanging of the bells from here ! ... I think psk31 and mfsk suffered a similar cold reception from this side of the pond , but that was more of an embarrassment that hams had better station's with more bells and whistles(piccolo?) G ..
--- In [email protected], "Vojtech" <bubn...@...> wrote: > > I did not follow the whole conversation. Anyway, spread spectrum has > following benefits as far as I am known: > > It allows more stations to use the spectrum. The trick is in spreading the > signal by a sequence, which appears to be random. Many stations transmitting > spread spectrum signals at various time and frequency offsets will all > together resemble white noise. On the contrary, many conventional narrow band > signals will approach white noise much slower. There is a classic article > from Costas (of the PSK Costa's loop decoder algorithm) explaining why even > DSB has theoretical benefits over SSB because it spreads the signal to higher > bandwidth, which makes the total interference look more like white noise. > > The spreading in frequency makes the signal less sensitive to narrow band > carriers, it makes it difficult to jam a signal by a single or couple of > carriers. > > The other benefit is critical to military use. It is difficult to detect and > if one does not know the spreading sequence, it is impossible to decode. > > Spread spectrum somehow contradicts the HAM radio philosophy. Spread spectrum > to be useful mandates the software itself to identify and lock to the signal. > It is impossible identify weak SS signal from white noise by ears. The > operator will just enumerate the channels and the machine will do the rest. > Higher amount of SS stations at the same frequency will increase background > noise, so it will create an interference to let's say a CW operator. > Therefore one would need to dedicate SS channels, otherwise there would be > plenty of complaints from CW operators. > > I don't see a real benefit in running SS signal in just 2.5kHz SSB bandwidth. > Olivia or MFSK will do better because they use the whole spectrum for itself, > while SS on purpose leaves all the orthogonal spreading sequences to be used > by other stations. For the same bandwidth, SS is designed to share frequency, > classic multitone signals for best coding gain. That is a whole world of > difference. > > SS would be very beneficial for beacon network, where all beacons share the > same channel. This is what the GPS satellite network does indeed. > > SS may be used for single channel world wide chatting mode. One will be able > to decode many signals at once with powerful computer. > > 73, Vojtech OK1IAK >
