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Author Topic: Software vs Firmware  (Read 438 times)
GM4AHW
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Posts: 44




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« on: June 07, 2007, 12:20:27 PM »

It seems to me that a lot of the functionality in modern (high cost) rigs is software based. Or rather, firmware based. That is, the rigs have processors doing all kinds of things, including DSP filtering at IF, audio (mic) processing, RTTY demodulation, spot frequency memories, digital mode output text storage buffers, and a bunch of filtering applications for notch, noise, emphasis, passband width etc.

On the other hand, with a boat anchor and a decent computer, I believe that it ought to be possible to do most of the above using software, for a fraction of the cost. Of course I wouldn't be able to control the rig in the same way, so frequency recall would be out, but DSP at audio instead of IF, for example, would be entirely possible.

So are there any real useful bells-and-whistles in modern rigs that just can't be simulated reasonably effectively in external software?
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KV9U
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Posts: 166




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« Reply #1 on: June 12, 2007, 05:41:07 AM »

From my perspective, the main advantages to DSP rigs is that you have more control over filtering. It is very useful to be able to continuously adjust the passband width.

DSP will be used in most all new rigs due to the lower cost. It is not just the expensive rigs that have DSP. Even my Ten Tec Argonaut V has this.

Due to supply and demand, many older rigs are now becoming collector's items and are not as low cost as they once were. Retrofitting some kind of DSP would be very difficult and would require substantial hardware and software expertise.

For most contacts, especially for voice, whether you use a rig with DSP or crystal or mechanical filters is not that much different. I can still copy most signals on my Kenwood TS-440SAT that I can on my TT Argo V or my ICOM 756 Pro 2.

73,

Rick, KV9U
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AA4PB
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Posts: 12638




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« Reply #2 on: June 21, 2007, 08:20:30 AM »

It is certainly possible to do audio DSP outside of the radio, either in a computer or a dedicated box. It's been done for a number of years. The problem is that the DSP audio filtering is outside of the receiver's AGC. The audio filter can prevent you from hearing an interfering signal but it can't prevent that signal from affecting the AGC and the overall receiver gain. A strong signal in the IF passband, but outside the audio filter passband, can cause you to loose copy of a weak signal because it reduces the receiver sensitivity.

An audio DSP can certainly add value to a legacy receiver, but it will never perform as well as an IF DSP built into the receiver. In addition, the multiple processors in modern receivers bring a host of other features that are not possible unless the receiver is designed with them in mind.
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