Last night I visited Matt, VK5ZM, with a SM1000 Beta. He configured the SM1000 to interface to his IC706 using the CN12 connector patch socket. This allowed an RJ45 cable from the SM1000 to connect to the RJ45 mic/audio connector on the IC706. A few level adjustments and he was using FreeDV to talk to Andy, VK5AKH on 40m! It all went very smoothly.
Here is Matt in action, using the SM1000 in the hand-held mic configuration. He also tried a Heilsound headset, which also worked well.
Here is the audio received by Andy:
I was monitoring Matt’s FreeDV signal using FT817 and FreeDV on a laptop. I did notice a slope to the spectrum, and a cross shape to the scatter diagram (screenshot below). This suggests some of the carriers are at a lower level than others. This is bad news as these carriers will hit the noise floor sooner, causing bit errors and poor speech quality. I really need to look into this carefully, testing a selection of radios with a carefully crafted test signal to measure the tx transmit spectrum slope and flatness. This may explain why people running Flex Radios and SDRs get consistently good performance with FreeDV.
SM1000 Progress Update
Since the last post Rick has been doing some fine work on the enclosure. My beta PCB works well so we are happy with the electronics and firmware. Once we have checked the next revision of the enclosure we plan to start manufacturing the Beta units after the Chinese New Year holiday. I’ll start taking pre-orders shortly.