*To:* Clay W7CE w...@curtiss.net
*Cc:* Bob McGwier rwmcgw...@gmail.com ; flexradio@flex-radio.biz
*Sent:* Tuesday, April 14, 2009 8:56 AM
*Subject:* Re: [Flexradio] PowerSDR S-Meter Power Readings
Clay,
Are you using the same antenna setting for all of the measurements? If
not, this could
The meter is calculated on a single filter with a large signal in its
path and for the rest of the time, it is assumed that noise is
negligible compared to the tones in the calibration. This assumption
appears to break down near the noise floor if your measurements are
correct. This is
-
From: Eric Wachsmann
To: Clay W7CE
Cc: Bob McGwier ; flexradio@flex-radio.biz
Sent: Tuesday, April 14, 2009 8:56 AM
Subject: Re: [Flexradio] PowerSDR S-Meter Power Readings
Clay,
Are you using the same antenna setting for all of the measurements
Subject: Re: [Flexradio] PowerSDR S-Meter Power Readings
The meter is calculated on a single filter with a large signal in its path
and for the rest of the time, it is assumed that noise is negligible
compared to the tones in the calibration. This assumption appears to
break down near the noise
Hi Bob,
It's certainly possible that I'm doing this wrong, so let me explain my
procedure and then you can tell me if I'm making a mistake. All of the
following is performed on 6M at 50.200 MHz with a 50 ohm termination
connected to antenna port 1 and the bandwidth set to 500 Hz (mode CWU).
Clay,
Are you using the same antenna setting for all of the measurements? If not,
this could account for the difference you are seeing. We offset the meter
and display values to account for the loss through the switches in the
antenna circuitry depending on the selected antenna.
Eric
Hi Eric,
Yes. All measurements were made using antenna port 1.
73,
Clay W7CE
- Original Message -
From: Eric Wachsmann
To: Clay W7CE
Cc: Bob McGwier ; flexradio@flex-radio.biz
Sent: Tuesday, April 14, 2009 8:56 AM
Subject: Re: [Flexradio] PowerSDR S-Meter Power Readings
You are not reading this correctly.
The power displayed on the meter is integrated power in the receive
filter, just as it should be. The computation is accurate to much more
than 0.1 dB irrespective of what the display is doing. But as in all
cases of such compromises, it is designed to
: [Flexradio] PowerSDR S-Meter Power Readings
You are not reading this correctly.
The power displayed on the meter is integrated power in the receive
filter, just as it should be. The computation is accurate to much more
than 0.1 dB irrespective of what the display is doing. But as in all
cases
Clay,
I think the code you are looking for is in DttSP/sdr.c in a function called
do_rx_meter. I believe it is already doing what you're wanting though (i.e.
calculating total power within the filter). This is pretty easy to verify
with a two-tone signal generator setup. In my experience, the
McGwier
Sent: Monday, April 13, 2009 2:30 PM
To: Clay W7CE
Cc: flexradio@flex-radio.biz
Subject: Re: [Flexradio] PowerSDR S-Meter Power Readings
You are not reading this correctly.
The power displayed on the meter is integrated power in the receive
filter, just as it should
On Mon, Apr 13, 2009 at 5:29 AM, Bob McGwier rwmcgw...@gmail.com wrote:
You are not reading this correctly.
The power displayed on the meter is integrated power in the receive filter,
just as it should be. The computation is accurate to much more than 0.1 dB
irrespective of what the display
Actually, it will. There is an option for this in the Setup Form - Display
Tab called Show Decimal.
Eric
On Mon, Apr 13, 2009 at 10:59 AM, Brian Lloyd brian-wb6...@lloyd.comwrote:
On Mon, Apr 13, 2009 at 5:29 AM, Bob McGwier rwmcgw...@gmail.com wrote:
You are not reading this correctly.
Since the very first C language version of the sdr, we integrated the
received power in the filter (by summing the bins of the filter and
relying on parseval's relation). This is indeed in do_rx_meter in
sdr.c The thing to be aware of is that do_rx_meter is used for all
metering in the
I've been looking through the PowerSDR code to see how the RX meter signal
strength is computed. Based on what I've observed it appears to based on
the maximum signal found within the currently selected bandwidth. So if I'm
receiving two CW signals within the current bandwidth, it will show
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