Pete - one other thing I need to mention if you haven't noticed
already....The noise floor will be different with each of the three sampling
rates (48, 96, 192). This doesn't change the signal to noise ratio will
change the display. The lower the sampling rate the lower the noise floor.
Also, be aware that the Flex 5000 has a transmit spur approximately 2.4 KHz
down from the fundamental freq. If you are calling a station up 2 KHz or so
and are running an amplifier you will most definitely put out a signal,
thanks to the spur, that people can hear. Flex is very aware of this but
they have NOT, repeat NOT fixed this. One of their software gurus did write
a MANUAL software routine in PowerSDR to address this hardware issue and it
does reduce the spur significantly but the procedure is a manual procedure
and is only effective on one band at a time. If you change bands, you have
to run the manual routine again. It is cumbersome.
After being "busted" twice on two different bands because of this I no
longer run my Flex 5000 on HF for transmitting. It has a very good receiver
and the calibrated dBm scale is great to use for signal comparison and love
it for that, but just be aware of the xmit spur.
I can give you more specific details if desire.
73 Joel W5ZN
-----Original Message-----
From: Joel Harrison [mailto:w5zn@arrl.org]
Sent: Sunday, October 18, 2009 9:24 PM
To: 'Pete Parisetti'; 'topband@contesting.com'
Subject: RE: Topband: noise floor
Pete - my average noise floor, when measured using the same rig with a 250
Hz bandwidth and a sampling rate of 48 KHz is:
-128 dBm on 8 circle Vertical Array
-125 dBm on Beverages
-105 dBm on my inverted vee
-100 dBm and on shunt fed tower
73 Joel W5ZN
-----Original Message-----
From: Pete Parisetti [mailto:hb9dsu@gmail.com]
Sent: Sunday, October 18, 2009 9:30 AM
To: topband@contesting.com
Subject: Topband: noise floor
Hello everybody from a newcomer to the list.
I have a question. I would like to understand if my suburban location is
significantly more noisy than others or not. To do so, it is handy to have
the noise floor measured in dBm - something I can do with my SDR 5000a. The
value is around -82 dBm in conditions which I would call "bad" and around
-90 when "good", measured with the TX antenna (inverted L, 17m vertical/23
horizontal).
Would anybody else with the same rig (or similar) share their numbers?
Thank you very much in advance and 73.
Pete
___________________________
Pete Parisetti MM0TWX - HB9DSU
for music, ham radio and more
visit http://www.hb9dsu.com
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