SDR vs. Legacy Radio.. Which is better ?

VK2ACR/YMU

Member
Was having a discussion with a friend about what kind of radio system was better, my view is that SDR radios offer more scope in the discrimination of signal from noise, the discussion included the direct conversion SDR as used by the IC-7300 verses the new FTDR101 that uses SDR as an IF system.
The article deals with what it calls legacy that in fact is not, as it uses DSP (Digital Signal Processing) This technology opens many possibilities to do with noise reduction. A true legacy would be one that is all analog from the front end to the audio amp..

The article is copyright so all I can do is post the link if you wish to read or download. Its a good read.
https://www.ab4oj.com/sdr/apdxc16_sdr.pdf
 

VK3YNV

Moderator
The reality today is that computing power is cheap, and high speed dacs and adcs can outperform the older analog systems.

But there are high end older analog designs that are pretty impressive. Especially the ones where cost wasn't a design factor, Collins Mechanical filters, silver plated high Q filters, teflon and silver solid mechanical construction. Even if the digital stuff is cheaper and performs as well or better then old stuff has a certain magic that's hard to digitize. :)

But the bottom line is, you would struggle to build pure analog that matched the cost/performance of IC7300 era radios.
 

BillC

Member
The older receiver designs ,the good ones often used two rf amp stages with at least three tuned circuits as preselection for the desired signal .I think the design and engineering of those older radios is amazing . It is very instructive to read the handbook for the BC348 for example. You gain an insight into the design philosophy and electronic engineering .Of course with all the mechanical components they would cost a fortune to build in todays money , but they were expensive in their day too. If you own an old comms. receiver hang onto it , respect it , think of the effort and thought that went into its design and construction.
 

VK2ACR/YMU

Member
The reality today is that computing power is cheap, and high speed dacs and adcs can outperform the older analog systems.

But there are high end older analog designs that are pretty impressive. Especially the ones where cost wasn't a design factor, Collins Mechanical filters, silver plated high Q filters, teflon and silver solid mechanical construction. Even if the digital stuff is cheaper and performs as well or better then old stuff has a certain magic that's hard to digitize. :)

But the bottom line is, you would struggle to build pure analog that matched the cost/performance of IC7300 era radios.
The point is that in SDR technology, direct sampling and hybrid that uses SDR as a second IF are at play presently, I understand the new Yaesu uses this requiring analog style filters. (Roofing Filters), in my view direct conversion gives more scope on how to handle the noise or QRM with the adoption of DSP and bandwidth control, but the Yaesu adoption could provide better noise mitigation but I am not convinced, speaking to one that has both, he does not see a lot of difference in the two systems, I think Yaesu went that way to handle the sampling at a lower frequency, more to do with cost mitigation, having done so the first IF is open to all the problems to do with an etherodyne system
As DAC get faster and the number gets larger I think SDR will outperform many of the legacy technology of years gone, will be interesting to see what develops in future generation radios.
 
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VK2ACR/YMU

Member
This looks ok
Unfortunately due to our exchange rate this is no bargain

The freight will approx be at least $70 US
The total landed will include 10% GST

So 599.00 + 70.00 = 669
Add GST 66.90
Total 738.60

Convert to AU dollars at today rate 1 USD = 1.36826 AUD

Landed cost in AU dollars = $1006.90
For a 5Watt radio ?
 
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