[hpsdr] ANAN200D RX1/RX2 Phase Coherent and Phase difference (2)

[Jan Simons]

Hello (may be now readable),

Have received my ANAN200D two weeks ago and am quite happy with it.
Having two high performance phase coherent receivers was the main reason 
to buy it.

Please let me share with you one single wish for the "improvement wish 
list".

I have a number of applications for it e.g. measuring NVIS polarization 
and playing with noise/qrm reduction techniques.
They all have in common that they need two identical receivers.
Identical in pass band characteristics (amplitude and phase) and phase 
coherent (phase difference 0 degrees).
SDR is the only practical way to implement that.

Up until now I used two Elecraft K2 receivers made phase coherent by 
sharing the same oscillators.
The IF Xtal filters e.g. are not identical, so I had to connect a noise 
source to both receivers and to equalize the pass bands in the DSP.
Every time I switched bands and/or mode I had to perform the equalization.

I am using two laptops in my setup.
The first one runs PowerSDR and controls the ANAN200D.
The second one is dedicated to my DSP using Matlab/Simulink.
In that way I have all the performance of the second laptop available 
for the DSP.
The audio of the line outs on the DB25 connector on the ANAN200D is fed 
into a USB sound card which is connected to the second laptop.

By using VFOSync, CTUN and Stereo Diversity the phase relation between 
RX1 and RX2 is fixed.
Any phase jumps in the phase difference between RX1 and RX2 are directly 
visible in my setup.
However the actual phase difference can be anything.
So I still have to perform the equalizing.

I noticed that changing bands is not possible with CTUN enabled.
This makes changing bands complicated and each time the phase difference 
between RX1 and RX2 changes.
May be there is a better way of doing it?

I am happy with the ANAN200D. It fits very well my applications.
However it would be great if the Stereo Diversity switch would always 
force the RX1 and RX2 phase difference locked to zero degrees.

73 Jan PA0SIM

My PowerSDR settings
enabled: RX2, VFOSync, CTUN, SD
AGC: Fixed GAIN e.g. at 80
Master AF: e.g. at 15
ATT: -20dB
Pan main receiver: left
Pan RX2: right
ANAN200D firmware: Orion 4.3