> A PSK31, detectable at -10 dB on a 3 kHz BW may ideally be a +6dB signal > on a 63 Hz BW, > assuming equal noise density in the whole 3 kHz passband. Apples remain > apples, oranges > remain oranges, and you can weigh them with the same scale.
Good explaination Jose... Tony, K2MO ----- Original Message ----- From: "Jose A. Amador" <[EMAIL PROTECTED]> To: <digitalradio@yahoogroups.com> Sent: Thursday, August 21, 2008 6:56 PM Subject: Re: [digitalradio] Path Simulator Test - PSK FEC31 > > SNR in a 3 kHz BW has become a gauging standard. Even when a PSK decoder > may see a PSK31 signal some 16 dB better on a 63 Hz bandwidth. > > Even when the actual signal is much narrower and the decoder uses a > matching bandwidth, which allows a better SNR to the demodulator, it is > useful to have a standard to compare, which matches the radios in > general use nowadays. > > Stating different measuring bandwidths for different modes would obscure > the results if you want to make such a comparison. > > A PSK31, detectable at -10 dB on a 3 kHz BW may ideally be a +6dB > signal on a 63 Hz BW, assuming equal noise density in the whole 3 kHz > passband. > > Apples remain apples, oranges remain oranges, and you can weigh them > with the same scale. > > 73, > > Jose, CO2JA > > --- > > Tony wrote: > >> Mark, >> >>> If the SNR is negative, how is it that you can copy any signal? >> >> The path simulator adds Gaussian white noise to the input signal to >> simulate >> a signal-to-noise ratio through a 3KHz band pass filter. If the SNR is >> less >> than 0, it's below the noise level. >> >> The signal is still there, it's just weaker than the noise. >> >> Tony, K2MO >> >> ----- Original Message ----- >> From: "Mark Miller" <[EMAIL PROTECTED]> >> To: <digitalradio@yahoogroups.com>; <digitalradio@yahoogroups.com> >> Sent: Thursday, August 21, 2008 5:42 AM >> Subject: Re: [digitalradio] Path Simulator Test - PSK FEC31 >> >> >>> If the SNR is negative, how is it that you can copy any signal? >>> >>> 73, >>> Mark N5RFX >>> >>> At 02:36 AM 8/21/2008, Tony wrote: >>>> __________________________________________ >>>> >>>> Sensitivity Test - Direct Path >>>> (no ionospheric disturbance) >>>> >>>> Minimum SNR for error-free copy >>>> >>>> Contestia 500/32............-15db >>>> DominoEX-4 ..................-15db >>>> F >> >> >> ------------------------------------ >> >> Announce your digital presence via our Interactive Sked Page at >> http://www.obriensweb.com/sked >> >> Check our other Yahoo Groups.... >> http://groups.yahoo.com/group/dxlist/ >> http://groups.yahoo.com/group/contesting >> http://groups.yahoo.com/group/themixwgroup >> Yahoo! Groups Links >> >> >> >> > > > -- > MSc. Ing. Jose Angel Amador Fundora > Profesor Auxiliar > Departamento de Telecomunicaciones > Facultad de Ingenieria Electrica, CUJAE > Calle 114 #11901 e/ 119 y 127 > Marianao 19390, Ciudad de la Habana, Cuba > Tel: (53 7) 266-3445 > Email: amador at electrica.cujae.edu.cu > >
