Dave Platt wrote:
In article ,
Thierry To answer me in private use http://www.astrosurf.com/lombry/post.htm wrote:

Hi,

For over 85 years now (Armstrong, 1918) the superheterodyne circuit is at
the base of all transceiver without exception I believe.

Your belief would be wrong, I think.

Superhets are certainly popular. However, there has been a very
significant increase in interest in direct-conversion transmitters and
receivers over the past few years, and a lot of such designs are now
being put into commercial use.

Most of the ones I've seen mentioned (in the commercial world at
least) are going into UHF and microwave systems - cellphones, 802.11
data radios of various sorts, and so forth.

But, among the "most" expert engineers of you, is there a way or does it
already exist somewhere some experiments to create a new model of
transceiver using another technology ?

Direct conversion (as noted above) is one variety. A lot of the
simpler QRP CW radios use direct conversion... hams have been building
tin-can-sized-or-smaller CW transceivers for years.

I've seen some interesting designs which handle sideband, by combining
direct-conversion RF front ends with phasing circuitry - an approach
used a fair bit back in the 1960s, recently revitalized by the
availability of affordable high-crunchpower DSP chips which can
implement the phasing method via digital techniques. Some HF radio
systems even work by sampling the RF directly, and doing pretty much
everything in the DSP... all of the fine tuning, and the various
modulations and demodulations are done digitally.

And the US Dept. of Defense is sponsoring research into _direct_ DC-
to-daylight receivers that sample the RF directly and do everything
digitally. This should prove _very_ interesting indeed, as the number
of signals handled by the receiver -- and what is done with them --
is pretty much limited only by the speed of the computers processing
the signals.

Now _there_'s some equipment I want to be able to buy -- preferably at
surplus prices, of course.

--
Mike Andrews

Tired old sysadmin

Receivers of the future will be digital signal processors from the antenna
onwards.

Hi Dave,

I am agree with your ideas about cellphones (PTT feature) and other Wi-Fi.
I speak about these technologies on my site as well as all developments in
DivX and other DVD technologies associated to Internet and cable TV, and
more. They are a lot of new technologies in these areas that will concern
the ham community too.
All the story at http://www.astrosurf.com/lombry/qsl-ham-history.htm (page
16 for the future)

But I wanted first some info about new HF transceivers, not the direct
conversion that ARRL discusses from time to time. I do not really see my
FT1000 MarkV be converted in a can... Hi !

I speak also about DSP in various pages of my site, and seeing in which
(excellent) way it is used in the latest HF RTX, I think that you have
highlighted the sensitive point where the future high-end RTX can still be
improved and surprise us.
I should be interested in seeing the new Yaesu high end HF RTX (but nothing
heard about it). The Mark V is an old system now (10 years or even more
including the blueprints), even if it is still one of the best in its
category. Consequently the new one should be soon released... Maybe an
hybrid between the new Tec-Tec Orion and a true DSP system... Rest to insert
some optical circuits and it will be updated... To follow.

Any info is always welcome about the trends of future HF RTX.

Thierry, ON4KSY


"Dave Platt" wrote in message
...
In article ,
Thierry To answer me in private use
http://www.astrosurf.com/lombry/post.htm wrote:

Most of the ones I've seen mentioned (in the commercial world at
least) are going into UHF and microwave systems - cellphones, 802.11
data radios of various sorts, and so forth.

But, among the "most" expert engineers of you, is there a way or does it
already exist somewhere some experiments to create a new model of
transceiver using another technology ?

Direct conversion (as noted above) is one variety. A lot of the
simpler QRP CW radios use direct conversion... hams have been building
tin-can-sized-or-smaller CW transceivers for years.

I've seen some interesting designs which handle sideband, by combining
direct-conversion RF front ends with phasing circuitry - an approach
used a fair bit back in the 1960s, recently revitalized by the
availability of affordable high-crunchpower DSP chips which can
implement the phasing method via digital techniques. Some HF radio
systems even work by sampling the RF directly, and doing pretty much
everything in the DSP... all of the fine tuning, and the various
modulations and demodulations are done digitally.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Dave Platt wrote:
In article ,
Thierry To answer me in private use http://www.astrosurf.com/lombry/post.htm wrote:

Hi,

For over 85 years now (Armstrong, 1918) the superheterodyne circuit is at
the base of all transceiver without exception I believe.

Your belief would be wrong, I think.

Superhets are certainly popular. However, there has been a very
significant increase in interest in direct-conversion transmitters and
receivers over the past few years, and a lot of such designs are now
being put into commercial use.

Most of the ones I've seen mentioned (in the commercial world at
least) are going into UHF and microwave systems - cellphones, 802.11
data radios of various sorts, and so forth.

But, among the "most" expert engineers of you, is there a way or does it
already exist somewhere some experiments to create a new model of
transceiver using another technology ?

Direct conversion (as noted above) is one variety. A lot of the
simpler QRP CW radios use direct conversion... hams have been building
tin-can-sized-or-smaller CW transceivers for years.

I've seen some interesting designs which handle sideband, by combining
direct-conversion RF front ends with phasing circuitry - an approach
used a fair bit back in the 1960s, recently revitalized by the
availability of affordable high-crunchpower DSP chips which can
implement the phasing method via digital techniques. Some HF radio
systems even work by sampling the RF directly, and doing pretty much
everything in the DSP... all of the fine tuning, and the various
modulations and demodulations are done digitally.

And the US Dept. of Defense is sponsoring research into _direct_ DC-
to-daylight receivers that sample the RF directly and do everything
digitally. This should prove _very_ interesting indeed, as the number
of signals handled by the receiver -- and what is done with them --
is pretty much limited only by the speed of the computers processing
the signals.

Now _there_'s some equipment I want to be able to buy -- preferably at
surplus prices, of course.

--
Mike Andrews

Tired old sysadmin

In article ,
Thierry To answer me in private use http://www.astrosurf.com/lombry/post.htm wrote:

Hi,

For over 85 years now (Armstrong, 1918) the superheterodyne circuit is at
the base of all transceiver without exception I believe.

Your belief would be wrong, I think.

Superhets are certainly popular. However, there has been a very
significant increase in interest in direct-conversion transmitters and
receivers over the past few years, and a lot of such designs are now
being put into commercial use.

Most of the ones I've seen mentioned (in the commercial world at
least) are going into UHF and microwave systems - cellphones, 802.11
data radios of various sorts, and so forth.

But, among the "most" expert engineers of you, is there a way or does it
already exist somewhere some experiments to create a new model of
transceiver using another technology ?

Direct conversion (as noted above) is one variety. A lot of the
simpler QRP CW radios use direct conversion... hams have been building
tin-can-sized-or-smaller CW transceivers for years.

I've seen some interesting designs which handle sideband, by combining
direct-conversion RF front ends with phasing circuitry - an approach
used a fair bit back in the 1960s, recently revitalized by the
availability of affordable high-crunchpower DSP chips which can
implement the phasing method via digital techniques. Some HF radio
systems even work by sampling the RF directly, and doing pretty much
everything in the DSP... all of the fine tuning, and the various
modulations and demodulations are done digitally.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!