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In: Amateur Radio, Audio, Computer
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Icom’s new IC-9700 can receive two bands at the same time. In DV mode, it can decode two digital signals at the same time, something even the IC-5100 cannot do. Since it has a stereo USB audio interface build in, it’s logical to expect the IC-9700 to output main and sub band audio at the same time over USB as well. Some sources on the Internet mention that only main band audio is output via USB. Given all the “at the same time” features of the IC-9700, I resisted to believe this to be true. So … let’s check the schematics first. Not only inRead More →

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Some time ago, I read the statement that the sample rate of a DAC is set by the audio file that you play. It then occurred to me, that this is – sort of – wrong. Let me explain why, using a turntable for comparison. The turntable speed is set by you, after you looked at the label on the record (or the size..). You can put on a single, and play that “file” at LP speed. With digital audio, it’s the same. Set the DAC to 44.1 sample rate, and feed it a 96 kHz file. The DAC will process 44.100 samples per second,Read More →

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In: Computer, Security
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I use SSH with port forwarding for secure remote access. For me it’s better than using a VPN. Here are my reasons why: Clear visibility on what’s happening on the network. You control what happens. Easy configuration of IP ports and addresses. Single config file for OpenSSH client. Asymmetric, i.e. client-server model. Better suited for remote access. Public/Private key based security setup. No PKI needed. User space client. No encapsulation, only encryption overhead on the payload. The biggest downside is that you cannot forward UDP ports. There’s no such thing as a free lunch. There are workarounds for this limitation, such as using netcat forRead More →

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The analog to digital converter in the IC-7300 is rumoured to be the LTC2208-14. This converter supports sample rates up to 130 MHz. This implies a max receive frequency in the first Nyquist zone of fs/2=65 MHz. So how can the IC-7300 receive on the 4m band then? Actually this was one of the first questions I had when reading about the IC-7300 and the ADC used. It looked like I was the only one wondering about it and so I moved on, until…. Until I hooked up the antenna on my new location and tuned across the bands, 29 Mhz, 30 , 31. Wow,Read More →