开云体育

Hi Chris,

I made several videos:

Initial testing:

Compare original and modified to a Perseus.
The modified is about 9 dB better than the original
and not far from the Perseus:

By use of a better soundcard than my modified Delta44
one could most probably improve by another 10 dB, maybe
even more and make the Softrock better than the Perseus.

The UADC that HB9DRI is working on would allow this and
most probably also the Pi-SDR IQ. One would probably
need some more mods to the Softrock to achieve this.
Maybe even replacing the Si570 by a X-tal oscillator.

One would end up with a single band Softrock having a
fairly narrow front-end and a set of selectable crystals.
Could be good for users with special interests....

Most users would be perfectly happy with the original
Softrock and a standard soundcard.

Here is a list ranking soundcards by reciprocal mixing
dynamic range on my modified Soiftrock. Best so far
is the Terratec DMX 6fire USB

- but it is not good at all for Tx:

Look 14:00 into the video. The noise floor is at -68
dBm in a bandwidth of 2.4 kHz with a carrier at
+30 dBm. That is at a separation of 20 kHz and might
be acceptable - but far from the performance on the
receive side. At a separation of 100 kHz the noise
is at -27 dBm in 2.4 kHz bandwidth. That is horrible,
the noise is -57 dB below the carrier in SSB bandwidth.
An SSB signal that peaks at S9+20 dB would lift the
noise floor to S3. Assuming that the unlucky amateur
neighbour has an optimized system with the noise floor
without an antenna at S0 and the noise with the antenna
connected at S1, the loss would be 2 S units.

20 dB above S9 for a 1W signal from a neighbour is not
unlikely...

I do have personal problems and my list of un-answered
E-mails goes back to July 25. I put prio on this one
because I am curious to know if [email protected]
works for me....

73

leif