SDR receiver noise performance vs analog

[bob prohaska]

How do software defined radios perform compared to traditional
analog superhets for casual listening? I realize SDRs do things
superhets can't do at all, but if one simply wants a sensitive,
selective and quiet receiver for listening to audio broadcasts
does an SDR offer benefits compared to a traditional superhet?

I'm thinking mostly in terms of self-noise, is that misguided?

Thanks for reading, and any insights!

bob prohaska

[joe]

Post by bob prohaska
How do software defined radios perform compared to traditional
analog superhets for casual listening? I realize SDRs do things
superhets can't do at all, but if one simply wants a sensitive,
selective and quiet receiver for listening to audio broadcasts
does an SDR offer benefits compared to a traditional superhet?
I'm thinking mostly in terms of self-noise, is that misguided?
Thanks for reading, and any insights!
bob prohaska

Your question is too vague. Quality of the radio's implementation is an
important factor.

High sensitivity is good, but if it comes at the expense of being easily
overloaded, is it worthwhile?

Selectivity can be too narrow resulting in muffled audio, or it can be
too wide allowing for interference from nearby stations. Shape factor of
a filter can be significant to you.

SDRs and/or DSP based radios also frequently include a spectrum display.
That can make finding stations easier.

Listening to AM broadcast is different than shortwave broadcast
stations, AM can broadcast with much better fidelity during the day
allowing you to recover (perhaps) 10 kHz wide audio. SW stations would
generally be limited to 5 kHz audio.

How much you are willing to spend is also important.

New vs. used should be considered.

Don't forget the antenna you use will also be a factor. An outdoor
antenna can avoid much of the electrical noise generated within a house.

There is no simple answer for your question.

For me, the radio that I have that has the best audio is a conventional
superhet with well chosen IF filters.

For me, the radio that makes it easy to find new stations is a hybrid SDR.

Both can be listened to for multiple hours, but they are different to
use and sound different.

[bob prohaska]

Post by joe

Post by bob prohaska
How do software defined radios perform compared to traditional
analog superhets for casual listening? I realize SDRs do things
superhets can't do at all, but if one simply wants a sensitive,
selective and quiet receiver for listening to audio broadcasts
does an SDR offer benefits compared to a traditional superhet?
I'm thinking mostly in terms of self-noise, is that misguided?
Thanks for reading, and any insights!
bob prohaska

Your question is too vague. Quality of the radio's implementation is an
important factor.

Many years ago I used a Sony SW100S to listen to BBC World Service with
the included long-wire powered antenna. Recently I became aware of SDR
and wondered if a modern SDR in a similar configuration would work
significantly better. I realize the shortwave world has changed a lot,
so maybe the application doesn't make sense any more, but the question
of old vs new radio performance is still interesting to me. The idea
of digitizing everything from (IIRC) 100 kHz to 30 MHz and sorting it
out in software is little short of amazing, if it's really better.

Post by joe
High sensitivity is good, but if it comes at the expense of being easily
overloaded, is it worthwhile?
Selectivity can be too narrow resulting in muffled audio, or it can be
too wide allowing for interference from nearby stations. Shape factor of
a filter can be significant to you.
SDRs and/or DSP based radios also frequently include a spectrum display.
That can make finding stations easier.
Listening to AM broadcast is different than shortwave broadcast
stations, AM can broadcast with much better fidelity during the day
allowing you to recover (perhaps) 10 kHz wide audio. SW stations would
generally be limited to 5 kHz audio.
How much you are willing to spend is also important.
New vs. used should be considered.
Don't forget the antenna you use will also be a factor. An outdoor
antenna can avoid much of the electrical noise generated within a house.
There is no simple answer for your question.
For me, the radio that I have that has the best audio is a conventional
superhet with well chosen IF filters.
For me, the radio that makes it easy to find new stations is a hybrid SDR.
Both can be listened to for multiple hours, but they are different to
use and sound different.

I appreciate the convenience advantages of an SDR. I'm more curious
about how SDR compares in absolute terms to analog under what might
be considered poor conditions.

Thanks for writing!

bob prohaska

[joe]

Post by bob prohaska

Post by joe

Post by bob prohaska
How do software defined radios perform compared to traditional
analog superhets for casual listening? I realize SDRs do things
superhets can't do at all, but if one simply wants a sensitive,
selective and quiet receiver for listening to audio broadcasts
does an SDR offer benefits compared to a traditional superhet?
I'm thinking mostly in terms of self-noise, is that misguided?
Thanks for reading, and any insights!
bob prohaska

Your question is too vague. Quality of the radio's implementation is an
important factor.

Many years ago I used a Sony SW100S to listen to BBC World Service with
the included long-wire powered antenna. Recently I became aware of SDR
and wondered if a modern SDR in a similar configuration would work
significantly better. I realize the shortwave world has changed a lot,
so maybe the application doesn't make sense any more, but the question
of old vs new radio performance is still interesting to me. The idea
of digitizing everything from (IIRC) 100 kHz to 30 MHz and sorting it
out in software is little short of amazing, if it's really better.

Post by joe
High sensitivity is good, but if it comes at the expense of being easily
overloaded, is it worthwhile?
Selectivity can be too narrow resulting in muffled audio, or it can be
too wide allowing for interference from nearby stations. Shape factor of
a filter can be significant to you.
SDRs and/or DSP based radios also frequently include a spectrum display.
That can make finding stations easier.
Listening to AM broadcast is different than shortwave broadcast
stations, AM can broadcast with much better fidelity during the day
allowing you to recover (perhaps) 10 kHz wide audio. SW stations would
generally be limited to 5 kHz audio.
How much you are willing to spend is also important.
New vs. used should be considered.
Don't forget the antenna you use will also be a factor. An outdoor
antenna can avoid much of the electrical noise generated within a house.
There is no simple answer for your question.
For me, the radio that I have that has the best audio is a conventional
superhet with well chosen IF filters.
For me, the radio that makes it easy to find new stations is a hybrid SDR.
Both can be listened to for multiple hours, but they are different to
use and sound different.

I appreciate the convenience advantages of an SDR. I'm more curious
about how SDR compares in absolute terms to analog under what might
be considered poor conditions.
Thanks for writing!
bob prohaska

Again, you question is too vague.

For me, given the factors that define quality audio, to me, I prefer an
analog radio.

However, SDR implementations have improved over the past several years
and I expect that trend to continue. I'm not sure the continued
improvements will lead to a radio that I consider better compared to
what I currently have.

In part, this is due to the goals for the larger market which does not
match the niche that represents my needs.

Until you can articulate your needs it will not be possible to determine
how which radio architecture best meets your needs.

[Brian Gregory]

Post by bob prohaska
The idea
of digitizing everything from (IIRC) 100 kHz to 30 MHz and sorting it
out in software is little short of amazing, if it's really better.

That would be an expensive top of the range SDR.
Most only digitize a small section of the HF bands at a time.

The Airspy HF+ Discovery I use with my PC for LF, MF and HF can only
digitize up to about a 700kHz wide section.

Does it work better than my analog receivers? - Yes I think so but my
analog receivers are all quite simple and cheap.

I don't think the digital processing gives any inherent advantage
compared to analog. But advanced features like noise reduction and
impulse noise blanking are more likely to be available with SDR since
they are then just a bit of extra software rather than some extra
hardware. Neither seems to give me a huge advantage though.

Actually good noise reduction is probably digital anyway, even when the
rest of the receiver is analog.

[bob prohaska]

Post by Brian Gregory

Post by bob prohaska
The idea
of digitizing everything from (IIRC) 100 kHz to 30 MHz and sorting it
out in software is little short of amazing, if it's really better.

That would be an expensive top of the range SDR.
Most only digitize a small section of the HF bands at a time.
The Airspy HF+ Discovery I use with my PC for LF, MF and HF can only
digitize up to about a 700kHz wide section.

That was a most helpful reference. The AirSpy webpage makes it clear
there's an analog front end on the ADC, possibly more than one. It
clears up a considerable misconception on my part.

Post by Brian Gregory
Does it work better than my analog receivers? - Yes I think so but my
analog receivers are all quite simple and cheap.
I don't think the digital processing gives any inherent advantage
compared to analog. But advanced features like noise reduction and
impulse noise blanking are more likely to be available with SDR since
they are then just a bit of extra software rather than some extra
hardware. Neither seems to give me a huge advantage though.
Actually good noise reduction is probably digital anyway, even when the
rest of the receiver is analog.

As I think further about it, receiver noise is probably dominated by
atmospheric noise for MF and HF signals. The radio isn't the problem.

The AirSpy Discovery looks very impressive for $135.

Thanks for writing!

bob prohaska

[Marco Moock]

Post by Brian Gregory
I don't think the digital processing gives any inherent advantage
compared to analog. But advanced features like noise reduction and
impulse noise blanking are more likely to be available with SDR since
they are then just a bit of extra software rather than some extra
hardware. Neither seems to give me a huge advantage though.

Another feature I really like is that some can notch out carriers from
other AM stations and even CW can be notched out.

Another helpful feature is the adjustable bandwidth for each sideband.
If there is noise, I can just reduce the bandwidth.

The only feature I miss is to notch out a certain frequency area inside
the bandwidth, so if there is a 0.5 kHz wide noise/jammer on 6062 kHz,
I could only notch out that instead of reducing the entire bandwidth of
the sideband to 1.75 kHz when listening to 6060.

[Marco Moock]

The idea of digitizing everything from (IIRC) 100 kHz to 30 MHz and
sorting it out in software is little short of amazing, if it's really
better.

I really like that idea. I can now listen to stuff at other places in
the world via the Internet. I can also check certain things.

[Marco Moock]

Post by bob prohaska
How do software defined radios perform compared to traditional
analog superhets for casual listening? I realize SDRs do things
superhets can't do at all, but if one simply wants a sensitive,
selective and quiet receiver for listening to audio broadcasts
does an SDR offer benefits compared to a traditional superhet?

I don't know, I have too less experience with it. I often use
WebSDR/KiwiSDR and the signal quality extremely depends on the
environment. There are public KiwiSDRs that have a good SNR, but I
think this is because of the local noise around the antenna from the
neighborhood/other devices.

Another feature of some SDRs is that they can do noise reduction. I
don't know how they implement it.