VMA Simple Spectrum Analyser: Important bug fix
Hi,
Shame on me!
When I first started playing with my first SMA Simple Spectrum Analyser device, I noticed that all individual measurements are sent from the device as 4 Bytes.
On the original NWT series, the first two Bytes form a 10 Bit value, which is repeated on the second two Bytes. With all my tests using my ADF4350/ADF4351 based device, the second and fourth Byte was always zero.
This led me to believe that the ADF4350/ADF4351 based device could only produce an 8 Bit measurement.
And so I programmed the software accordingly...
Only yesterday a new user (thanks!) complained about a strange clipping on Signals with more than -40dBm. And he told me that with WinNWT4 those Signals are displayed correctly.
My first reaction: impossible.
Today, after some discussion with said user I realized a huge mistake I made: the ADF4350/ADF4351 can of course do 10 Bit resolution. I just never fed a signal with more than -50 dBm!
Arghhh! How stupid of me. Always playing with TV, CATV and SAT signals, I never tried to feed a signal from a signal generator with -30 dBm, -20 dBm. heck 0 dBm (it is safe to go up to +5 dBm).
This is how it looks like:
Please download the latest version!
Regards,
Vitor
Shame on me!
When I first started playing with my first SMA Simple Spectrum Analyser device, I noticed that all individual measurements are sent from the device as 4 Bytes.
On the original NWT series, the first two Bytes form a 10 Bit value, which is repeated on the second two Bytes. With all my tests using my ADF4350/ADF4351 based device, the second and fourth Byte was always zero.
This led me to believe that the ADF4350/ADF4351 based device could only produce an 8 Bit measurement.
And so I programmed the software accordingly...
Only yesterday a new user (thanks!) complained about a strange clipping on Signals with more than -40dBm. And he told me that with WinNWT4 those Signals are displayed correctly.
My first reaction: impossible.
Today, after some discussion with said user I realized a huge mistake I made: the ADF4350/ADF4351 can of course do 10 Bit resolution. I just never fed a signal with more than -50 dBm!
Arghhh! How stupid of me. Always playing with TV, CATV and SAT signals, I never tried to feed a signal from a signal generator with -30 dBm, -20 dBm. heck 0 dBm (it is safe to go up to +5 dBm).
This is how it looks like:
Picture 1: Clipping due to my software only evaluating the first 8 Bit instead of the whole 10 Bit
Picture 2: WinNWT4 showing the signal correctly
As a result, I sat down and corrected all routines, adding the missing two bits.
It does work now:
Picture 3: Same signal shown correctly using 10 Bit resolution of the ADF4350/ADF4351
Regards,
Vitor
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