I strongly disagree. Yes CW needs rise and fall times. But there is no
need for DSP filters to get A perfect CW signal. You can calculate the
signal without buffers or you can simply use a lookup table.
(The lookup table method is often used in small AVR chips for generating
PSK31. There is no DSP power in those simple microcontrollers)
Regards,
Erwin
On 24-11-2010 15:35, Edward H Russell wrote:
No problem if you're transmitting a continuous sine wave. But CW is a series
of pulses that need shaping by the DSP. The rise and fall have lots of other
harmonic components.
-----Original Message-----
From: [email protected] [mailto:flexedge-boun...@flex-
radio.biz] On Behalf Of Erwin van den Bosch (PA7N)
Sent: Wednesday, November 24, 2010 9:31 AM
To: [email protected]
Subject: Re: [FlexEdge] CW transmit Flex 1500 and latency
Tim, I think you don't understand my post. Please read again or tell me
why you need a DSP buffer to create a sinus wave? CW is nothing more then
a sinus wave. No DSP filtering needed to be able to output a sinus wave.
Regards,
Erwin.
On 24-11-2010 13:55, Tim Ellison wrote:
You can't have a zero size DSP buffer. DSP is the "heart" of the radio
and does other things in addition to determining filter characteristics.
I recommend waiting for CW, Part II
-Tim
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Erwin van den
Bosch (PA7N)
Sent: Wednesday, November 24, 2010 3:34 AM
To: [email protected]
Subject: [FlexEdge] CW transmit Flex 1500 and latency
Just a thought:
When I install 2.0.16 all DSP buffer sizes are 2048. For SSB and Digi
modes I can understand that because the filtering is better with A large
buffer size instead of A small buffer size.
But when transmitting CW I think the DSP transmit buffer (not the
USB/audio buffer) can be zero because you don't need filtering on the CW
carrier. Just generate a nice sinewave (via calculation or a simple lookup
table). By doing this without DSP buffers the latency may be a little less
when transmitting CW.
Regards,
Erwin
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posting topics related to SDR software development and experimentalist who are
using beta versions of the software.
