Tim,
Thanks for the quick response and info on WBIR (wide band image rejection).
It is noted. True, I was just syncing the two receivers and not using true
diversity reception with two antennas. The configuration I gave in my
example was just a simple way to demonstrate the discrepancy. It happens
with separate antennas, but not as noticeable.
Thanks!!
Bill AD6I
-----Original Message-----
From: Tim Ellison
Sent: Monday, November 29, 2010 5:12 PM
To: jens...@digilink.net ; flexradio@flex-radio.biz
Subject: RE: [Flexradio] Flex 5000A RX2 Diversity Audio Issues
See my comments below
-Tim
-----Original Message-----
From: flexradio-boun...@flex-radio.biz
[mailto:flexradio-boun...@flex-radio.biz] On Behalf Of jens...@digilink.net
Sent: Monday, November 29, 2010 7:17 PM
To: flexradio@flex-radio.biz
Subject: [Flexradio] Flex 5000A RX2 Diversity Audio Issues
When in diversity mode, I am experiencing audio volume level changes with
the changing or movement of frequency.
[Tim] What mode are you using? Synchronous or "beam steering" diversity
using the "radar screen" or just syncing the receivers to the same frequency
(stereo or dual diversity).
Here is a simple and controlled example of what is happening.
The set up is as follows:
RX 1 receiving on antenna 1 and RX2 on RX1 tap.
[Tim] Here is one problem. You are not using separate antennas so there are
no diverse signals to operate on. RX2 cannot be on the RX-1 TAP if you want
diversity RX. You have to have separate antennas
http://kc.flexradio.com/KnowledgebaseArticle50386.aspx
Both receivers (identical setup) same mode, filter, agc gain & time
constant, preamp settings and VFOs sync. Audio is set so that each
receiver is balanced right and left channels. Note: this is not one
receiver on right channel and the other on left channel.
[Tim] This sounds like you are doing stereo diversity.
As the frequency is tuned, by any method, the volume changes at times by as
much as 10db or more. The receivers appear to stay sync’d. If I adjust one
up or down 1 cycle, a one cycle beat is noted, press the sync button and
beat note goes away. What appears to be happening is that from time to
time, the audio outputs are partially out of phase. When the volume drops,
I can mute either receivers audio one at a time and have the volume
increase. (RS 1 is muted by use of SQL control and RX2 by its mute). This
audio issue is not always happening, but once it starts it is repeatable.
[Tim] This sounds like WBIR (wide band image rejection) going off in the
weeds. WBIR is not working 100% correctly in this version of PowerSDR. Bob
is working on a new and much improved version.
Is this a software problem?
[Tim] I'd say yes, it is a software problem.
Anyone experiencing the same issue?
For reference: Power SDR Beta v2.0.16 Flex 5000:1610-2789 Computer running
Win 7 -- HP Pavilion A6750F Desktop PC 2.3 GHz AMD Phenom X4 9650 Quad-Core
Processor, 8 GB RAM -- OHCI 1394 Host controller (104C) TI – Chip set
(8235) XI02200A Rev 01)
Let me know what you think!
Thanks
Bill - AD6I
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