[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: SDR-1000 (was FT-847 discontinued?)



Remembering my telephone company theory about the Nyquist theory that 
the analogue 4000 hertz voice channel had to be sampled at least twice 
that (8000 hertz) to be able to reliably reproduce it at the receiving 
end.  Petnium 4 Gigabit processors  should be able to keep up with that 
task if they are not already overworked.

73,
Jim


k0vty@juno.com wrote:

>If I recall correctly :
>Quantizing any short duration signal to digitize it must be done fast
>enough to be able to 
>re constitute the signal again
>Quantizing a CW dit requires high speed sampling .
>Higher than SSB voice.    
>I hope I am correct on this as it has been a long time ago that 
>quantizing received radar pulses was an every day event.
>Like you I am trying to grasp new ways and equipment idea's.
>
>Keep trying 
>
>Joe K0VTY
>============================
>On Thu, 15 Dec 2005 18:46:21 -0600 "John P. Toscano"
><tosca005@tc.umn.edu> writes:
>  
>
>>Dave G. wrote:
>>
>>    
>>
>>>The problem for high speed CW lies in the inherent delay with 
>>>the DSP processing algorithms. IMHO because of that delay 
>>>it's not yet a serious contest rig YMMV!!
>>>      
>>>
>>Dave (or anyone else on the list who knows):
>>
>>Is the "slow" CW speed only a function of computer-generated CW?  If 
>>so, 
>>couldn't you get around that problem by using an external keyer?  
>>The 
>>MFJ-495, for example, allows you to send CW via straight key, 
>>paddles, a 
>>PC keyboard plugged directly into it, or via a serial data stream 
>>from a 
>>computer.  It handles speeds up to 990 WPM (or so they say), which 
>>oughta be fast enough for almost anyone.  :)  (Heck, if I could 
>>reliably 
>>work CW at a "mere" 20 WPM I'd be ecstatic!)
>>
>>Or is the SDR not able to send fast CW even if it doesn't have to 
>>synthesize the CW from keyboard commands on the same PC that is 
>>supporting the digital encoding/decoding process?  It just seems odd 
>>to 
>>me that it could encode voice into an SSB or AM or FM signal, but 
>>simple 
>>"on/off" sequences of Morse code would be hard for it to do...  But 
>>I'm 
>>certainly very uneducated (at least so far) about the whole SDR DSP 
>>process, so maybe I'm way off base...
>>
>>If the problem is the delay between hitting the dit or dah side of 
>>the 
>>paddle and the time that you hear feedback from the monitor speaker, 
>>it 
>>should be possible to listen to yourself send only from the output 
>>of 
>>the keyer, and have the SDR not echo what you send back to your 
>>ears. 
>>Then, it doesn't matter if it takes an extra 300ms for your CW to 
>>finish 
>>transmitting before the person on the other end can respond.
>>
>>Or am I still missing something totally?  (These are honest 
>>questions, 
>>I'm not trying to take pot shots at anyone, I really don't know the 
>>answers to them.  Since I've been tempted to step into the SDR-1000 
>>world "one of these days", I'd really like to know more about it.)
>>
>>73 de W0JT
>>----
>>Sent via amsat-bb@amsat.org. Opinions expressed are those of the 
>>author.
>>Not an AMSAT member? Join now to support the amateur satellite 
>>program!
>>To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
>>    
>>
>----
>Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
>Not an AMSAT member? Join now to support the amateur satellite program!
>To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home