Yuri Blanarovich wrote:

What artifacts does latency in a DSP implementation cause?

I'm thinking of eg a "DSP rcvr" OOH and an "analog receiver" OTOH, both
tuned to WWV, and the noticeable delay of the DSP audio from the analog
audio. You know, ti-tick ti-tick instead of tick-tick-tick, and "blurred"
voice announcements.


Seems that it is starting to play role in QSK and contesting. Latest TenTec
Orion seems to be having problem with QSK above 40 wpm.

The other effect is some loss of inteligibility on weak signals. My friend
OK2RZ who started to use TS870 immediately complained about the inteligibility
as compared to straight analog RX. Audio sounded mushy to him, more difficult
to copy weak signals in the noise. To me it was a surprise, but he is appliance
operator with good ears and when he compared two types of rigs, he pointed out
to mushiness of 870 (esp. weak) signals.

We are considering this in the design of Dream Radio One, where heavy computer,
DSP and analog hybrid is coming to play.

Looks like DSP is here to stay, has some advantages, but will need some fine
tuning (no problem, digital stuff, right?).

Yuri, www.K3BU.us
www.computeradio.us

The "mushiness" sounds like the ADC or DSP data paths aren't deep
enough, so the weak signal is getting lost in quantization noise.
That's unfortunate, so make sure that your "dream radio" has plenty of
"footroom".

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com