Thanks for the info Gerald. I ran the same test using my 5000A with an
external 26 dB preamp on 6M. Same settings as below. PowerSDR 2.0.8
showed a 2.9 dB improvement in noise floor compared with v2.0.16 (same
as the 3000). However, the 2.0.8 numbers weren't believable since they
indicated a noise figure of 0.7 dB. However, the 3.6 dB NF indicated by
v2.0.16 is in the right ballpark when you do the math for a 26 dB, 0.5
dB NF preamp in front of the 5000A on 6M. I'll do more testing when I
get a chance to put the 5000A on the bench, but for now it looks like
the v2.0.16 numbers are more realistic.
What's strange is that I've done this noise floor measurement before
with v2.0.8 and earlier and always showed a noise figure around 3.5 -
4.0 dB (with the ext. preamp and a 50 ohm antenna termination). Now
that the 5000A has upgraded firmware (done at the factory for the V/U
upgrade), when I run with v2.0.8 I get different results from before.
Any idea what might be causing this?
73,
Clay W7CE
On 11/12/2010 3:15 PM, Gerald Youngblood wrote:
2.0.16 sounds more like the correct noise figure for the FLEX-3000.
Gerald
Gerald Youngblood, K5SDR
President and CEO
FlexRadio Systems(TM)
13091 Pond Springs Road, #250
Austin, TX 78729
Phone: 512-535-4713 Ext. 202
Email: [email protected] <mailto:[email protected]>
Web: www.flexradio.com <http://www.flex-radio.com/>
Tune In Excitement (TM)
PowerSDR(TM) is a trademark of FlexRadio Systems
On Fri, Nov 12, 2010 at 4:59 PM, Clay W7CE <[email protected]
<mailto:[email protected]>> wrote:
I tried the comparison again, this time in a more controlled
manner. I connected a 50 ohm termination to the antenna input of
the 3000. In CW mode with a BW of 500Hz (50.192600 MHz), PowerSDR
2.0.8 shows the noise floor to be -142.5 dBM, which corresponds to
a noise figure of 4.5 dB. PowerSDR 2.0.16 shows the noise floor
to be -139.6 dBm, which corresponds to a noise figure of 7.4 dBm,
which is 2.9 dB worse. Both measurements were taken with RX1
meter set to "Sig Avg", and in the Setup Dialog, "Show Decimal"
was checked, the meter Average Time was set to 10000 ms, and
Digital Refresh was set to 1000 ms. Shorter averaging times give
similar values, but the digital meter display fluctuates around
the center value. The preamp was set to Pre2 for both versions.
I hope the additional data helps.
73,
Clay W7CE
On 11/12/2010 2:03 PM, Clay W7CE wrote:
Gerald,
I tried what you suggested and reset the database for both
2.0.8 and 2.0.16. PowerSDR 2.0.16 still shows the noise
floor, as measured by RX1 Meter in "Sig Avg" mode, to be 3 dB
higher than 2.0.8. Using SpecJT, both versions show the same
average noise power when AF and AGC-T are set to 50 and 60,
respectively. It appears that something has changed in the
way the S-Meter reading is calculated. Rough calculations
based on RX noise figure and current sky temperature, lead me
to believe that the 2.0.8 reading is more accurate.
I'm getting ready to hook up my 5000A, which I just got back
with the V/U upgrade, and will see if it behaves similarly.
I'll also try the 1500 later.
73,
Clay W7CE
On 11/12/2010 6:11 AM, Gerald Youngblood wrote:
Clay,
Try starting with a clean database on both versions. This
is probably calibration data in the database and not an
actual change in the noise floor.
Gerald
Gerald Youngblood, K5SDR
President and CEO
FlexRadio Systems(TM)
13091 Pond Springs Road, #250
Austin, TX 78729
Phone: 512-535-4713 Ext. 202
Email: [email protected] <mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>
Web: www.flexradio.com <http://www.flexradio.com>
<http://www.flex-radio.com/>
Tune In Excitement (TM)
PowerSDR(TM) is a trademark of FlexRadio Systems
On Fri, Nov 12, 2010 at 1:39 AM, Clay W7CE
<[email protected] <mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>> wrote:
I just installed 2.0.16 on a Win7 Ultimate 64-bit machine
(upgrading from 2.0.8). Initially, I'm running it with
a Flex
3000, and it upgraded the firmware in the 3000 to
2.0.4.1. The
FlexRadio Firewire driver stayed the same at
3.5.2.8028. After
initial manual setup, I checked the local noise floor
on 6M with
the antenna pointed in what is typically my quietest
direction and
with the antenna elevated 40 degrees (to minimize the
effects of
any man-made QRN). The noise floor seemed high, so I
shutdown
2.0.16 and started 2.0.8. It seems to work with the
firmware
upgrade, so I went to the same frequency and the
indicated noise
floor is 3 dB lower (better). Several iterations of
switching
versions yielded the same results. As far as I can
tell, the two
versions are configured identically. Both versions of the
software are set to USB, 2.7k BW with the NB and SR
off. Also the
RX1 Meter is set to "Sig Avg" in both cases, and they
both have
AGC-T set to 69 and Pre2 selected. I've also noticed
that the
noise displayed in the panadapter seems to have a
larger range of
min and max peaks on 2.0.16 compared with 2.0.8.
Why do the two versions show a different noise floor
when used
with the same receiver and antenna? Also, if there is
a reason
for the difference, which is more accurate?
Tomorrow I should get a chance to try 2.0.16 with a
Flex 5000A and
a 1500. It will be interesting to see if there are
differences in
the indicated noise floor on those two receivers when I
switch
PowerSDR versions.
73,
Clay W7CE
_______________________________________________
Flexedge mailing list
[email protected] <mailto:[email protected]>
<mailto:[email protected]
<mailto:[email protected]>>
http://mail.flex-radio.biz/mailman/listinfo/flexedge_flex-radio.biz
This is the FlexRadio Systems e-mail Reflector called
FlexEdge.
It is used for posting topics related to SDR software
development
and experimentalist who are using beta versions of the
software.
_______________________________________________
Flexedge mailing list
[email protected] <mailto:[email protected]>
http://mail.flex-radio.biz/mailman/listinfo/flexedge_flex-radio.biz
This is the FlexRadio Systems e-mail Reflector called
FlexEdge. It is used for posting topics related to SDR
software development and experimentalist who are using beta
versions of the software.
_______________________________________________
Flexedge mailing list
[email protected] <mailto:[email protected]>
http://mail.flex-radio.biz/mailman/listinfo/flexedge_flex-radio.biz
This is the FlexRadio Systems e-mail Reflector called FlexEdge.
It is used for posting topics related to SDR software development
and experimentalist who are using beta versions of the software.
_______________________________________________
Flexedge mailing list
[email protected]
http://mail.flex-radio.biz/mailman/listinfo/flexedge_flex-radio.biz
This is the FlexRadio Systems e-mail Reflector called FlexEdge. It is used for
posting topics related to SDR software development and experimentalist who are
using beta versions of the software.
