[Elecraft] K3 - Revolutionary Noise Reduction

[Scott Manthe]

12:01am 4/1/09.  Bravo, my friend!!

73,
Scott, N9AA

Tony Fegan VE3QF wrote:
>          K3 - Revolutionary Noise Reduction
>
>      It was announced today, by Professor Morsig at the Institute of 
> Ljubljana, that the K3 has been chosen to test a revolutionary new 
> approach to combating receiver noise and improving HF reception.
>      The basic principal behind this approach is the shifting in 
> frequency of noise by a few mHz (that's milli-hertz) away from the tuned 
> frequency. This in effect produces a hole in the noise spectrum where 
> weaker signals may be detected. The residual noise is directly 
> proportional to the bandwidth of the hole. Therefore, for wider signals, 
> such as SSB, a modified approach is required. The hole is moved 
> progressively over the required signals bandwidth and the signal is 
> sampled at each step and integrated to reproduce the original wideband 
> signal.
>      A second feature associated with this algorithm deals with 
> variations in propagation. We all know that propagation is largely 
> dependent on the solar flux. Propagation is changed due to the effects 
> of the solar wind. A little known fact is that the remnants of the solar 
> wind that reach the receive antenna modulates the noise. When the noise 
> is detected this modulation can be interpreted to give information about 
> the condition of the D, E and F layers. This can be used to produce a 
> real-time table of MUF and critical frequencies for each layer. At night 
> some kind of remote sensing with suitable location corrections has to be 
> used.
>      The third and more revolutionary feature, which depends heavily on 
> the previous features, involves the generation and use of virtual 
> transceivers or individual ionosphere layer repeaters. As an example we 
> will assume a distant CW signal is transmitted on 21.110Mhz and the MUF 
> is around 15.000Mhz. The signal will not be refracted to our receiving 
> station and most of it is lost in space. If we transmit a heterodyning 
> carrier pulse on 14.110MHz, which is below the MUF, then it will mix 
> with the transmitted signal and produce a weak signal pulse at 7.000MHz 
> which is reflected back to the receiving station. There is a time delay 
> between the sending of the pulse and receiving the return pulse. The 
> transmitted pulse length is made less than this delay so that the 
> 7.000MHz return pulse may be received between transmit pulses. This 
> process is repeated and the received signals integrated to reconstitute 
> the original signal sent.
>      There are some operating problems to be worked out with the 
> transmission of multiple heterodyning carriers. Thus only a few K3's are 
> expected be loaded with the new firmware until these problems are 
> resolved (spread spectrum has been suggested).
>      New menu items may be added to include these features in a future 
> K3 DSP firmware update. MUF OFF/AUTO and 1-10 will vary the effect of 
> received signals using simulated MUF values. This can improve signals on 
> all bands. Unfortunately this enhancement is not reciprocal and only 
> works on receive. Thus K3 to K3 contacts should have a distinct 
> advantage. The algorithms used are not open source as these features are 
> expected to have a huge affect on the whole radio communications 
> industry. It is still in the early beta-test stages.
>
>      The above is a rough summary of the original unwinese language 
> document submitted by Professor G. E. T. Morsig who is the 1st Associate 
> Professor of Radio at the Institute of Ljubljana. He will be very 
> interested in your assessment of this system and may be contacted via 
> F(zero)OL (qrz.com).
>
>      My apologies if I have made a minor slip or two in the translation. 
> Unwinese is not an easy language to translate.
>
>      Please do not contact Elecraft for this firmware until there is an 
> official statement!
>
> 73 and Enjoy
>      Tony Fegan VE3QF (anxiously awaiting further developments!)
>