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 How long before all new radios are SDR? 
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Post How long before all new radios are SDR?
Can't help but wonder how long it'll be before all new ham radios are SDR powered and legacy superhets are consigned to history.

No doubt 'amateurs' will continue to build superhets and professionals will use them where SDR is not cost effective (UHF and above perhaps), but the likes of ICOM, Yaesu, Kenwood will doubtless transition to the new technology for the majority of their products- but when ?

Given design cycle times my guess is within 2 - 3 years, time will tell.

Of course superhets will continue to be used for the very low end, but even then for how much longer ?

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Fri Sep 22, 2017 7:34 pm
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 How long before all new radios are SDR? 
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Post Re: How long before all new radios are SDR?
Well, you can't get something for nothing....
SDR technology is still in its infancy - allow me to explain;
A DSP is controlled by software, as we know, so in order to perform signal processing from 100,000 cycles per second up to 100,000,000,000 cycles per second you need an immense amount of processing power, unlike CPUs and MCUs a DSP must perform every task simultaneously, think of it as threads in a computer program, the quicker you wish to perform a parallel set of tasks the more threads you need.
So as an example, say you have to filter a 144MHz signal and extract an audio component from that you must be able to sample at 144 million cycles per second in real-time, that would require a clock speed in the high GHz region, not practical for a low power DSP, so in order to keep it cost effective and efficient then you need to lower the sample rate, in many cases into the KHz region so this requires an IF hence most SDR transceivers are hybrid - Heterodyne mixing and some form of signal conditioning in the form of bandpass filters at the front-end followed by a DSP IF.
So, with today's technology you are better off with a hybrid design, i am sure you could blow £100K on the latest R&D breakthrough but this is HAM radio, give me a single conversion Arduino controlled SSB transceiver any day of the week, it is an analogue hobby and you can't get any closer to real-time signal processing than a truly analogue transceiver (I make a clear exception to any local oscillators in this statement).

10 years from now we may have a direct "digital" replacement for filter mechanisms in radio systems which may come in the form of 25mm x 25mm black boxes, making the good analogue bandpass filter redundant.

the Icom 7300 is not direct sampling, it down mixes the incoming signal to 36KHz but it is a step in the right direction - now I await to be shot down in flames for my lack of knowledege in the technology, so apologies for any inaccuracies but this is based on my current knowledge of SDR and how a DSP works. :D


Fri Sep 22, 2017 8:00 pm
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 How long before all new radios are SDR? 
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Post Re: How long before all new radios are SDR?
Just a few points in no particular order :-)

The IC7300 is a true SDR, take a look at its block diagram - it decimates the digitized RF signal down to 36kHz, not to be confused with hetrodyne mixing.

Also consider how under sampling works which is how the 7300 works on 70MHz, so no need to sample at the nyquist rate ( 2 x Fo).

Thus it is entirely possible for a true SDR to have a sampling rate a fraction of the carrier freq and work perfectly ! Obviously care needs to be taken with aliasing issues.

Currently it is cost prohibitive for amatuer use sampling freqs above about 100Mhz so down converters would have to be used - be interesting to see how the IC9700 works.

That said an SDR radio is significantly lower cost (components, assembly and test / alignment) to produce than the equivalent multiband / multimode radio, hence my original question about timescales.

Anyway, time will tell......

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Fri Sep 22, 2017 8:25 pm
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 How long before all new radios are SDR? 
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Post Re: How long before all new radios are SDR?
Thanks for the information, I guess I did not read the block diagram correctly :) - I thought it was down-mixed and then sampled at 36KHz.


Fri Sep 22, 2017 9:46 pm
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 How long before all new radios are SDR? 
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Post Re: How long before all new radios are SDR?
The Flex 6700 already operates on 144-146MHz.

Some of the new cheap chinese handheld dualbanders are SDR.

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Mon Oct 09, 2017 9:26 am
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Post Re: How long before all new radios are SDR?
I was reading the other day that processor speed is coming up against physical barriers.

Strange though, the same was being said when the 486 got to 100 MHz :)

And a few years before that, a 286 was a fast machine

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Mon Oct 09, 2017 9:44 am
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 How long before all new radios are SDR? 
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Post Re: How long before all new radios are SDR?
A better question would be "does it matter that all radios will soon be sdr? What will we lose?"

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Mon Oct 09, 2017 10:06 am
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 How long before all new radios are SDR? 
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Post Re: How long before all new radios are SDR?
Being in the industry I should know more than I do, but I believe we are about as fast as we can
go it's all about more cores and lower power consumption these days,


Sangoma wrote:
I was reading the other day that processor speed is coming up against physical barriers.

Strange though, the same was being said when the 486 got to 100 MHz :)

And a few years before that, a 286 was a fast machine

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Mon Oct 09, 2017 1:58 pm
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 How long before all new radios are SDR? 
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Post Re: How long before all new radios are SDR?
ei2glb wrote:
Being in the industry I should know more than I do, but I believe we are about as fast as we can
go it's all about more cores and lower power consumption these days,


Sangoma wrote:
I was reading the other day that processor speed is coming up against physical barriers.

Strange though, the same was being said when the 486 got to 100 MHz :)

And a few years before that, a 286 was a fast machine

It sure is as the speed war has ceased and holds no more drive for the CPU manufactures. Now more and more integrated chips are becoming prevalent offering graphics and processor in one die.

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Mon Oct 09, 2017 2:01 pm
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 How long before all new radios are SDR? 
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Post Re: How long before all new radios are SDR?
I suspect there's a bit of misconception as to how much raw cpu power you need for an SDR.

The reality is that once you've digitized the spectrum of interest either by direct sampling, under sampling or even mixing down to within range of direct / under sampling then the amount of CPU power required is largely defined by the signal of interest bandwidth as you do not have to process all ADC samples representing DC to light which could be several gigabits / second.

There is a process called decimation usually performed in an FPGA which reduces the raw data rate down to a fraction for actual demodulation.

As an example most ICOM's use a final IF of 32kHz and this signal is digitally demodulated and allows varies IF filter shapes etc - all with a relatively low power CPU.

A lot of the CPU power in PC based SDR set up is used for driving displays, waterfalls, noise reduction etc..

The above is over simplified but hope it helps

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Wed Oct 11, 2017 8:44 am
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 How long before all new radios are SDR? 
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Post Re: How long before all new radios are SDR?
If they come in a black box like the 7300 then I may be able to accept it but they have to be of a better niggle free build in my opinion.
In the meantime I will buy a superhet spare and stick it in the loft but hey look the valve sets are still going strong so theirs no reason Hets shouldn't.
If their comes a time when radios have to be hooked up to a blasted PC to work then I won't be using them simple.

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Wed Oct 11, 2017 9:17 am
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