I have not even tried the Softrock on my Dual Core Laptop machine. I was aware of the need for not just a decent sound card for serious SDR use. This was the 'need' for a new shack computer that I had been overlooking for several years.
I have just come across the following from Duncan M0KGK, I will let him do the talking.
As usual Right Click on the image and select View Image for a full size view.
06-Nov-2005: The Delta card has arrived, and the difference in performance is absolutely astounding. Click the pic on the right (below) to see the substantial difference in noise performance between the AC97 onboard chipset and the Delta-44.
I was going to repeat the test above with the spurs and overlay them on the graph, but this exercise proved pointless. At the same 48kHz sampling rate all unwanted images were down in the noise and could not be measured.
Quality of received audio using Softrock 40 / Delta-44 / PowerSDR is excellent. I did some back to back listening tests on CW and SSB during busy contests between the Softrock and the Yaesu FT-857D which happened to be plugged in at the time. In all cases, the readability of weak DX signals from the SDR was better. The signal to noise seemed to be noticeably better too.
The 857 is not graced with the best receiver in the world, so it's my intention to do back-to-back tests when time permits with the FT-990 and FT-101E, both of which are (IMHO) better performers. Next steps are to get the Softrock into an enclosure and feed with an external supply.
If you are not too sure of your dB's and analysing graphs at a quick glance there is well over 100 times more noise there.
Another very useful graph from Duncan is the noise comparisons of different sound cards. The Delta44 is the same performance as the Delta66,in fact I understand it has been optimised recently.
I am sure Duncan will not mind me repeating this. Incidentally he is the author of the KGKSDR Software. Yes I have SSB transmit working fine now, it has benn tested across town but no distant contacts have been made yet. Whereas the narrow band mode BPSK31 has produced more contacts, a nice long one with PA0MJK in the Netherlands today revealed that he too has built a RX/TX v6.1 but has not had it on TX yet.
Delta44 cards have been in short supply, I purchased mine from Dolphin Music. I was astounded by their price,service, delivery speed and after sales follow up. I told them I would not hesitate to recommend them to the radio world as a supplier.
Dolphin Music
Venture Point West
70-72 Evans Rd
Liverpool
L24 9PB
For information contact :- info@dolphinmusic.co.uk
