[TenTec] Flex-Radio compared to Pegasus

Duane - N9DG n9dg at yahoo.com
Tue Jun 7 21:31:49 EDT 2005

--- designer <designer at quickdata.com> wrote:

> I did search the archives but found nothing current about
> the Pegasus 
> compared to Flex-Radio SDR-1000. Now that the Pegasus has
> been 
> discontinued, is SDR-1000 the only "living" game in town
> for SDR?

Actually the Pegasus shares much more in common with the more
traditional radios out there than the ideal concept of "SDR".
Yes it has updateable firmware but it is a "tradition radio"
first and SDR second. Its SDR aspects are confined to its
inner workings that you as a user have little or no direct
access to. So in reality other than being 100% computer
*controlled* it only *minimally* embodies the wide range of
concepts for SDR. I'm saying this as an owner of several
Pegasus radios that I *do* like very much. I operate them as
a collective group under several simultaneous sessions of
N4PY software that is providing me some key usability
features that the new crop of $10K+ radios still can't match.
But I also am realist in terms of what they can ultimately
do,...or not.

The SDR-1000 is *much* closer to the ideal implementation of
the SDR promise. It allows users to work with its inner
workings of its DSP code if you're so inclined or capable to
do so. Yes I have one of those too. I like it a lot and find
it to be a much better RX in terms of filtering, dynamic
range, and audio fidelity (the Pegasus is only second to it
for audio fidelity). Its promise is still all in the future
and has an active and growing user community with a core of
dedicated programmers shepherding its software to accommodate
some *very* exciting new ideas for how we will work and
interact with our radios in the future. These guys are *not*
just trying to emulate a traditional radio in software, yes
it will be able to, *and* it will be able to do so much more.
So the real fun with the SDR-1000 is just begining.
> As used Pegasus's appear for sale from time to time. Has
> there been 
> any comparison between the Pegasus's RX and TX and that of
> Flex-Radio?

Here are some of the key comparisons that I can think of at
the moment:

1. IF filter passband shape factor - The SDR-1000 wins this
contest by far, as you may have noticed the narrower filters
in the Pegasus are rather broad at their 60 dB points. The
SDR-1000 will do a 25 Hz, yes 25 Hz filter with very steep
skirts; it is truly something to behold. The Corsairs, and
Omni VI I have which have narrow filters in both IF's can't
match it at all.

2. Close in dynamic range - the SDR - 1000 is much better, it
is amazing how you can slice a weak CW signal out from
between two stronger signals at +/- 100 Hz away. The Pegs
shape factor simply doesn't allow it. 

3. LO phase noise - SDR-1000 is much better, the Pegasus is
rather mediocre. 

4. Latency of signals through the radio. - The Pegasus has
essentially no latency, the SDR-1000 currently has
significant latency, though has improved from what it was. It
stil might be tough to really get good high speed QSK
performance out of it because of it. I run 3.2GHz processor
and the latency is significant. I have not transmitted with
CW yet so I can't elaborate on keying turn around in detail
but have been listening to the same signal on two radios at
one time and can easily observe the latency. 

5. Audio fidelity - The SDR-1000 wins handily here. I
attribute that to the fact that it uses a low distortion
sound card (or at least you better plan on it) and the fact
that it is essentially a direct conversion RX. Until the
SDR-1000 arrived here the Pegasus was the best in this shack
by a sizable margin as compared to IC-706, IC-765, IC-820H,
Corsair, Delta, or even a recently acquired Omni VI (no
option upgrades). 

6. Plug it in a go - Not so with the SDR-1000, there is
plenty to setup and configure. However it is not difficult at
all if you are comfortable with PC hardware and software
setup, if not you will do some head scratching. The
installers for the PowerSDR software are very well thought
out and work very well. Its defaults are very sensible and
practical and get you steered into the right direction. They
also allow for multiple versions to all be installed at the
same time on the same machine so you can easily go back to
previous version with re-installing anything. It is fun to go
back to older versions every now and then just to see how it
has progressed. 

7. Band scope - The Pegasus with N4PY software can
effectively let you see a large part of the band, but it is
not real-time. The SDR-1000's panadapter is near real-time
but is currently confined to just 20kHz; this is largely a
function of the sound card and the software as currently
written. The current software only uses 48kHz sampling, this
limitation is changing in the not too distant future. 

8. Open-ended-ness - The Pegasus can do a lot of tricks with
its RISC-like command structure (look and what both N4PY and
Callsign Software have done for that radio). It is however
really rather limited in the grand scheme of things mostly
due the fact the signal processing itself is contained wholly
within the radio at all times. It is also constrained by a
57K serial connection, The SDR-1000 does not have these
restrictions at all since the DSP and control work is all
done in the host PC. 

9. The biggest hardware related performance faults I can find
with the SDR-1000 is that it can be prone to out of band
signals, for example on 160 I have plenty of AM broadcast
bleed through. Have not tried really pin down the exact cause
and in fairness to the SDR-1000 I've been running it in a
rather exposed lash-up fashion. The other fault that I see
from time to time is spurs that I assume are from the DDS,
they are especially pronounced on 6M but are pretty much
non-existent on the lower bands. 


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