I have been testing my Tigertronics SignaLink USB on various modes. In fact, I have two stations set up here in the shack so that I can do tests with different software and modes. For example, ARQ modes can be tested between the two stations.
Station set up: - HP 4600+ AMD with Vista, Unified Microsystems SCI-6 interface, ICOM 756 Pro 2 - emachines 2.93 Intel with XP, Tigertronics SignaLink USB, ICOM IC-7000 I have been having trouble getting good results with the wider modes such as RFSM2400 (2.7 kHz audio bandwidth) and DRM, e.g., EasyPal (2.2 kHz) digital data transfer programs. In both cases you will note that I am using the narrowest mode. The rigs are set up for the widest possible modulation. The throughput is not as good in RFSM2400 as I would expect for a solid and clean connection with no QRN. The best I have been able to do is around 1000 bps and often less. The constellations displayed in RFSM2400 is a circular 8 point/2 point, and is not as well defined with the SL-USB side doing the transmitting compared with the SCI-6 interface. Another finding is that the throughput of EasyPal, when using the faster 64QAM mode is very poor when being sent via the SL-USB but works quite well when going the other way. At the 16 QAM speed, there was better throughput from the SL-USB but of course the overall speed is reduced. Upon looking at the 64QAM constellation display, it became rather clear that the pattern was not acceptable from the SL-USB side since the bits were all over the place instead of keeping within their required 8 by 8 grid pattern. The 16QAM was better since the tolerances are much lower for this speed with the 4 by 4 pattern. Have any of you that use the SL-USB and also use these wide bandwidth modes and noticed that you have what appears to be lower than expected throughput? Can you compare to any other interface/rig combination? Have you looked at the constellations of these two programs through several interfaces? 73, Rick, KV9U
