.....and what does it sound like?
I used to think it was a type of radio but since reading this group
I see it is a sound.

Thanks,
C-

"coustanis" ) writes:
....and what does it sound like?
I used to think it was a type of radio but since reading this group
I see it is a sound.

Did you look in a dictionary for the basic definitions? Even if the
dictionary doesn't give a technical explanation, it should help you
when adding the context of radio around it.

A heterodyne is when two frequencies are beat together, causing a third
frequency to be generated.

So when two stations are too close together, their carriers will beat
together to cause a beat note in your receiver. If one is at 1MHz, and
the other at 1.001MHz, then you get a 1KHz beat note. This is one reason
AM broadcast stations are 10KHz apart. It's high enough that it will
be out of hearing range for most people, and high enough that if it's
a bother one can filter it out without really bothering the actual
contents of the modulation.

The less structured a service is, the more likely the heterodynes. Listen
to CB when the band is open, and it's full of beat notes, because the
stations aren't all on the same frequency. (Amateur radio bands could
also be the case, but when single sideband replaced AM, the carriers
which are what beat together disappeared.)

A beat note sounds like an audio note, because it's the difference of
two higher frequencies. You'd only hear the audio beats, because of
the frequency response of the receiver, and your hearing range. They
won't sound exotice because they aren't. They may vary in amplitude,
if the stations that are causing the heterodyne are varying in amplitude.

If you've got a receiver with a BFO, turn it on while listening to an AM
station. You will hear the heterodyne, or beat note, of the BFO and
the station's carrier. Vary the BFO tuning, and the frequency of
the beat will change.

Tune to a CW (ie a code station) and turn on the BFO, and what originally
sounded like thumping or the on and off of noise, is now a tone. The
BFO heterodyned the keyed carrier down to an audio frequency, where
you can hear it.

A superheterodyne receiver, which must be what you are thinking of,
just extends this idea. It heterodynes the incoming signal to an
intermediate frequency, where it can better be amplified and filtered,
before going on to further stages of heterodyning, or the ultimate
detection to audio.

Michael

On 10 Nov 2005 17:55:14 GMT, (Michael Black)
wrote:


"coustanis" ) writes:
....and what does it sound like?
I used to think it was a type of radio but since reading this group
I see it is a sound.

Did you look in a dictionary for the basic definitions? Even if the
dictionary doesn't give a technical explanation, it should help you
when adding the context of radio around it.

A heterodyne is when two frequencies are beat together, causing a third
frequency to be generated.

So when two stations are too close together, their carriers will beat
together to cause a beat note in your receiver. If one is at 1MHz, and
the other at 1.001MHz, then you get a 1KHz beat note. This is one reason
AM broadcast stations are 10KHz apart. It's high enough that it will
be out of hearing range for most people, and high enough that if it's
a bother one can filter it out without really bothering the actual
contents of the modulation.

The less structured a service is, the more likely the heterodynes. Listen
to CB when the band is open, and it's full of beat notes, because the
stations aren't all on the same frequency. (Amateur radio bands could
also be the case, but when single sideband replaced AM, the carriers
which are what beat together disappeared.)

A beat note sounds like an audio note, because it's the difference of
two higher frequencies. You'd only hear the audio beats, because of
the frequency response of the receiver, and your hearing range. They
won't sound exotice because they aren't. They may vary in amplitude,
if the stations that are causing the heterodyne are varying in amplitude.

If you've got a receiver with a BFO, turn it on while listening to an AM
station. You will hear the heterodyne, or beat note, of the BFO and
the station's carrier. Vary the BFO tuning, and the frequency of
the beat will change.

Tune to a CW (ie a code station) and turn on the BFO, and what originally
sounded like thumping or the on and off of noise, is now a tone. The
BFO heterodyned the keyed carrier down to an audio frequency, where
you can hear it.

A superheterodyne receiver, which must be what you are thinking of,
just extends this idea. It heterodynes the incoming signal to an
intermediate frequency, where it can better be amplified and filtered,
before going on to further stages of heterodyning, or the ultimate
detection to audio.

Michael

It's very important to point out that 2 different frequencies, when
mixed in a perfectly linear device, will not beat.

No, I didn't think to look in the dictionary. I just posted a radio
related topic to a radio related group.
Please accept my apology for my shortsightedness.
I apologize.
I appreciate your detailed explanation. That was nice of you to go to
the trouble.

Have a great day,

C-

Michael Black wrote:
"coustanis" ) writes:
....and what does it sound like?
I used to think it was a type of radio but since reading this group
I see it is a sound.

Did you look in a dictionary for the basic definitions? Even if the
dictionary doesn't give a technical explanation, it should help you
when adding the context of radio around it.

A heterodyne is when two frequencies are beat together, causing a third
frequency to be generated.

So when two stations are too close together, their carriers will beat
together to cause a beat note in your receiver. If one is at 1MHz, and
the other at 1.001MHz, then you get a 1KHz beat note. This is one reason
AM broadcast stations are 10KHz apart. It's high enough that it will
be out of hearing range for most people, and high enough that if it's
a bother one can filter it out without really bothering the actual
contents of the modulation.

The less structured a service is, the more likely the heterodynes. Listen
to CB when the band is open, and it's full of beat notes, because the
stations aren't all on the same frequency. (Amateur radio bands could
also be the case, but when single sideband replaced AM, the carriers
which are what beat together disappeared.)

A beat note sounds like an audio note, because it's the difference of
two higher frequencies. You'd only hear the audio beats, because of
the frequency response of the receiver, and your hearing range. They
won't sound exotice because they aren't. They may vary in amplitude,
if the stations that are causing the heterodyne are varying in amplitude.

If you've got a receiver with a BFO, turn it on while listening to an AM
station. You will hear the heterodyne, or beat note, of the BFO and
the station's carrier. Vary the BFO tuning, and the frequency of
the beat will change.

Tune to a CW (ie a code station) and turn on the BFO, and what originally
sounded like thumping or the on and off of noise, is now a tone. The
BFO heterodyned the keyed carrier down to an audio frequency, where
you can hear it.

A superheterodyne receiver, which must be what you are thinking of,
just extends this idea. It heterodynes the incoming signal to an
intermediate frequency, where it can better be amplified and filtered,
before going on to further stages of heterodyning, or the ultimate
detection to audio.

Michael

Michael Black wrote:
"coustanis" ) writes:
....and what does it sound like?
I used to think it was a type of radio but since reading this group
I see it is a sound.

Did you look in a dictionary for the basic definitions? Even if the
dictionary doesn't give a technical explanation, it should help you
when adding the context of radio around it.

A heterodyne is when two frequencies are beat together, causing a third
frequency to be generated.

So when two stations are too close together, their carriers will beat
together to cause a beat note in your receiver. If one is at 1MHz, and
the other at 1.001MHz, then you get a 1KHz beat note. This is one reason
AM broadcast stations are 10KHz apart. It's high enough that it will
be out of hearing range for most people, and high enough that if it's
a bother one can filter it out without really bothering the actual
contents of the modulation.

The less structured a service is, the more likely the heterodynes. Listen
to CB when the band is open, and it's full of beat notes, because the
stations aren't all on the same frequency. (Amateur radio bands could
also be the case, but when single sideband replaced AM, the carriers
which are what beat together disappeared.)

A beat note sounds like an audio note, because it's the difference of
two higher frequencies. You'd only hear the audio beats, because of
the frequency response of the receiver, and your hearing range. They
won't sound exotice because they aren't. They may vary in amplitude,
if the stations that are causing the heterodyne are varying in amplitude.

If you've got a receiver with a BFO, turn it on while listening to an AM
station. You will hear the heterodyne, or beat note, of the BFO and
the station's carrier. Vary the BFO tuning, and the frequency of
the beat will change.

Tune to a CW (ie a code station) and turn on the BFO, and what originally
sounded like thumping or the on and off of noise, is now a tone. The
BFO heterodyned the keyed carrier down to an audio frequency, where
you can hear it.

A superheterodyne receiver, which must be what you are thinking of,
just extends this idea. It heterodynes the incoming signal to an
intermediate frequency, where it can better be amplified and filtered,
before going on to further stages of heterodyning, or the ultimate
detection to audio.

Michael

Michael Black wrote:
A heterodyne is when two frequencies are beat together, causing a third
frequency to be generated.

Hams often describe their offspring as "harmonics". Some say that it
would be more appropirate to call them "heterodynes". If the children
were especailly wonderful, they would be "superheterodynes".

wrote in message
oups.com...
Michael Black wrote:
A heterodyne is when two frequencies are beat together, causing a third
frequency to be generated.

Hams often describe their offspring as "harmonics". Some say that it
would be more appropirate to call them "heterodynes". If the children
were especailly wonderful, they would be "superheterodynes".


Or spurious emissions huh
Just kiddin

--
CL -- I doubt, therefore I might be !

Many years ago,Superheterodyne Shortwave Radios were all the
rage,Shortwave Radios wise,that is.There were ads in magazines
gloryfying the advantages of Superheterodyne.Factory made and kits were
available,Superheterodyne Shortwave Radios.
Superheterodyne cuhulin

) writes:
Many years ago,Superheterodyne Shortwave Radios were all the
rage,Shortwave Radios wise,that is.There were ads in magazines
gloryfying the advantages of Superheterodyne.Factory made and kits were
available,Superheterodyne Shortwave Radios.
Superheterodyne cuhulin

Maybe the newsgroup would be better if you didn't spew nonsense.
If you know nothing of a topic, don't bother posting.

Virtually every shortwave receiver in production today, and for many a
decade, is superheterodyne. They all convert the incoming signal
down to a fixed frequency for selectivity and amplification.

The exceptions would be fairly obscure kits, using regeneration,
or maybe some commercial amateur radio receivers or transceivers,
using direct conversion (which heterodynes, the incoming signal
directly down to audio).

You'd have to go back many decades before you hit a point where
a large percentage of shortwave receivers were regenerative. Go
back forty, and some would be regenerative, albeit they'd be at
the low cost end of the spectrum. Go back to the thirties, and
regeneration likely was still common, because superheterodyne designs
used more components and hence were too costly for many in the depression
era. Go back to the twenties, and besides cost there were still bugs
(the issue of images for instance), and maybe even a reluctance to move
to something new.

Once again, Howard Armstrong received the patent for the regenerative
receiver in 1914, US patent number 1,113,149,

He received the patent for the superheterodyne receiver in 1920, US
patent number 1,342,885.

And he received the patent for the superregenerative receiver in 1922,
US patent number 1,424,065.

Howard Armstrong took care of all basic receiver design beyond the
simple "crystal radio" and the TRF (Tuned Radio Frequency) receivers.
And took care of that by 1922.

Everything that came later were variants of those three (or more
like two, regen and superhet) basic concepts, incremental improvements
but no fourth type of receiver.

Michael