Re: [digitalradio] Path Simulator Test - PSK FEC31
Mark, Why would one use a 3 kHz bandwidth for a 100 Hz wide mode? Wouldn't it be more realistic to do comparisons based on a noise bandwidth that is the same as or just slightly wider than the signal bandwidth? I don't have a choice in the matter because the band pass filter is fixed at 3KHz. I believe each mode would still behave the same when subjected to simulated ionospheric disturbances regardless of whether the bandwidth was 3KHz or just wide enough to wrap around the mode. Good question though Mark... Tony, K2MO
Re: [digitalradio] Path Simulator Test - PSK FEC31
My pleasure Mark... Tony, thanks the bandwidth is 3K for all modes that is what was throwing me. I was thinking S/N = Eb/No. I see my mistake now. I'm going to include the bandwidth in the list to avoid any confusion with the SNR figures. Thanks for bringing it to my attention. Tony, K2MO - Original Message - From: Mark Miller [EMAIL PROTECTED] To: digitalradio@yahoogroups.com Sent: Thursday, August 21, 2008 9:36 PM Subject: Re: [digitalradio] Path Simulator Test - PSK FEC31 At 04:31 PM 8/21/2008, Tony wrote: 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. Tony, thanks the bandwidth is 3K for all modes that is what was throwing me. I was thinking S/N = Eb/No. I see my mistake now. 73, Mark N5RFX
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
Re: [digitalradio] Path Simulator Test - PSK FEC31
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
Re: [digitalradio] Path Simulator Test - PSK FEC31
Why would one use a 3 kHz bandwidth for a 100 Hz wide mode? Wouldn't it be more realistic to do comparisons based on a noise bandwidth that is the same as or just slightly wider than the signal bandwidth? - ps 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
Re: [digitalradio] Path Simulator Test - PSK FEC31
At 04:31 PM 8/21/2008, Tony wrote: 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. Tony, thanks the bandwidth is 3K for all modes that is what was throwing me. I was thinking S/N = Eb/No. I see my mistake now. 73, Mark N5RFX
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
