[hpsdr] Janus frequency response ?

[David Woodhead]

I have my Janus/Ozy working with a homebrew SDR1000 clone and noted the
following in comparing with a Delta 44.

With the panoramic display on maximum span and sweeping a signal
generator across this span I see the signal drop about 10dB on the
display edges with Janus but only drops 2 or 3 dB with a Delta44. Both
tests with 48K sampling. I also see this in the noise floor which slopes
to about -10dB at the panoramic display edges vs. DC zero (noiuse floor
is much flatter with Delta 44). This suggests to me that my Janus board
has a frequency response problem and I wonder if others are seeing the
same thing? 

I also see a 2nd harmonic component in the panoramic display that is
about 10dB worse with Janus than my Delta 44. This is with a signal
input about 10dB below saturation (this is twice the input frequency on
IQ inputs to Janus). I have not checked to see if this is worse in I or
Q inputs yet.

I'd be interested in others observations?

Thanks!

David

KM5TZ