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  #21   Report Post  
Old June 2nd 05, 09:44 PM
rkhalona
 
Posts: n/a
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I've been a SWLer for at least 20 years, have a Ph.D. in EE, have 20+
years of
experience in the telecomm industry (uwave, sats, cellular, UWB...) and
have taught
grad/undergrad comm courses at various U.S. universities.

I agree with another poster that the SW8/R8B sync. detectors are among
the best ever incorporated
into SWL gear. My previous comment about sync. doesn't mean that one
cannot achieve similar
signall quality without it (e.g., using PBT, but how many portables or
low-cost tabletops have PBT
these days?), but the convenience of being able to select sidebands in
sync mode is a big plus.

RK

  #22   Report Post  
Old June 2nd 05, 10:08 PM
dxAce
 
Posts: n/a
Default



rkhalona wrote:

I've been a SWLer for at least 20 years, have a Ph.D. in EE, have 20+
years of
experience in the telecomm industry (uwave, sats, cellular, UWB...) and
have taught
grad/undergrad comm courses at various U.S. universities.

I agree with another poster that the SW8/R8B sync. detectors are among
the best ever incorporated
into SWL gear. My previous comment about sync. doesn't mean that one
cannot achieve similar
signall quality without it (e.g., using PBT, but how many portables or
low-cost tabletops have PBT
these days?), but the convenience of being able to select sidebands in
sync mode is a big plus.


Yep... a newbie.

dxAce
Michigan
USA


  #23   Report Post  
Old June 2nd 05, 11:26 PM
Jim Douglas
 
Posts: n/a
Default

It's like a girl who is a Quasi Virgin, she's only allowed it in her mou$53!

"Lucky" wrote in message
...
Hi guys!

I saw this term mentioned in the specs of a radio. What does it mean
exactly? That if you hope and listen long enough you can convince yourself
it's synchronous?

Lucky




  #24   Report Post  
Old June 3rd 05, 03:44 AM
Michael Black
 
Posts: n/a
Default


"rkhalona" ) writes:
I've been a SWLer for at least 20 years, have a Ph.D. in EE, have 20+
years of
experience in the telecomm industry (uwave, sats, cellular, UWB...) and
have taught
grad/undergrad comm courses at various U.S. universities.

I agree with another poster that the SW8/R8B sync. detectors are among
the best ever incorporated
into SWL gear. My previous comment about sync. doesn't mean that one
cannot achieve similar
signall quality without it (e.g., using PBT, but how many portables or
low-cost tabletops have PBT
these days?), but the convenience of being able to select sidebands in
sync mode is a big plus.

RK

But it seems you are mixing apples and oranges.

Sync detection means a locally generated "carrier" is present, so
if the signal fades the lack of a strong carrier is not a factor.

It does nothing to prevent fading (which I bring up because someone
recently said something along those lines here) it merely helps when
the signal fades.

Selectable sideband really has nothing to do with synchronous
detection, other than that using the phasing method it's relatively
cheap to implement compared to an expensive IF filter. It's not
really like a few extra parts to a synchronous detector will
add selective sideband, the added parts may be cheap but it adds
complication to the circuit.

When Webb wrote about the synchronous detector in CQ Magazine
about it, it was the whole shebang. But, that was a time
when many receivers had fairly wide IF filters, and lacked
product detectors. At the same time, you'd see SSB adaptors
that used the phasing method, which added that product
detector and reduced the unwanted sideband. Adding
synchronous circuitry to those was relatively simple, so once
you added the sync circuitry you not only got DSBsc reception,
but better SSB reception.

What we often see is lower end receivers tossing it in (because
the phasing method is a cheap way of knocking out the unwanted
sideband, and plus there are ICs that do it all in one
package), but it doesn't make up for the lack of a narrow
IF filter with steep sides (at least not as implemented
in those cheap receivers). It's a means of adding something
without a major cost increase.

I'm not even sure where we've veered off to. I thought
the previous comment was something like synchronous detection
wasn't all that important. I'd say that's true, given that
people lived without it till it became a feature in relatively
recent years. Someone listening to broadcast radio (am or
shortwave) that are relatively strong may be the ones to
benefit the most, because you can get deep fades where
the sidebands are still nice and strong. Signals
that you have to strain to hear, it's far less likely to
be useful, because they are already below a minimum strength.
You'd want to pull in other techniques at that point, and that
includes the narrow IF filter that has good slopes.

Michael

  #25   Report Post  
Old June 3rd 05, 03:56 AM
Telamon
 
Posts: n/a
Default

In article .com,
"rkhalona" wrote:

I've been a SWLer for at least 20 years, have a Ph.D. in EE, have 20+
years of experience in the telecomm industry (uwave, sats, cellular,
UWB...) and have taught grad/undergrad comm courses at various U.S.
universities.

I agree with another poster that the SW8/R8B sync. detectors are
among the best ever incorporated into SWL gear. My previous comment
about sync. doesn't mean that one cannot achieve similar signall
quality without it (e.g., using PBT, but how many portables or
low-cost tabletops have PBT these days?), but the convenience of
being able to select sidebands in sync mode is a big plus.


This news group has more than it's share of Ph.D.'s and double E's it
seems.

Where do you think the future of telecom is going? Is it going to be
mostly fiber-optic or do you think RF for the last mile to the home or
business?

Do you think Ethernet is winning over ATM?

--
Telamon
Ventura, California


  #26   Report Post  
Old June 3rd 05, 04:47 AM
Telamon
 
Posts: n/a
Default

In article ,
(Michael Black) wrote:

"rkhalona" ) writes:
I've been a SWLer for at least 20 years, have a Ph.D. in EE, have 20+
years of
experience in the telecomm industry (uwave, sats, cellular, UWB...) and
have taught
grad/undergrad comm courses at various U.S. universities.

I agree with another poster that the SW8/R8B sync. detectors are among
the best ever incorporated
into SWL gear. My previous comment about sync. doesn't mean that one
cannot achieve similar
signall quality without it (e.g., using PBT, but how many portables or
low-cost tabletops have PBT
these days?), but the convenience of being able to select sidebands in
sync mode is a big plus.

RK

But it seems you are mixing apples and oranges.

Sync detection means a locally generated "carrier" is present, so
if the signal fades the lack of a strong carrier is not a factor.

It does nothing to prevent fading (which I bring up because someone
recently said something along those lines here) it merely helps when
the signal fades.

Selectable sideband really has nothing to do with synchronous
detection, other than that using the phasing method it's relatively
cheap to implement compared to an expensive IF filter. It's not
really like a few extra parts to a synchronous detector will
add selective sideband, the added parts may be cheap but it adds
complication to the circuit.

When Webb wrote about the synchronous detector in CQ Magazine
about it, it was the whole shebang. But, that was a time
when many receivers had fairly wide IF filters, and lacked
product detectors. At the same time, you'd see SSB adaptors
that used the phasing method, which added that product
detector and reduced the unwanted sideband. Adding
synchronous circuitry to those was relatively simple, so once
you added the sync circuitry you not only got DSBsc reception,
but better SSB reception.

What we often see is lower end receivers tossing it in (because
the phasing method is a cheap way of knocking out the unwanted
sideband, and plus there are ICs that do it all in one
package), but it doesn't make up for the lack of a narrow
IF filter with steep sides (at least not as implemented
in those cheap receivers). It's a means of adding something
without a major cost increase.

I'm not even sure where we've veered off to. I thought
the previous comment was something like synchronous detection
wasn't all that important. I'd say that's true, given that
people lived without it till it became a feature in relatively
recent years. Someone listening to broadcast radio (am or
shortwave) that are relatively strong may be the ones to
benefit the most, because you can get deep fades where
the sidebands are still nice and strong. Signals
that you have to strain to hear, it's far less likely to
be useful, because they are already below a minimum strength.
You'd want to pull in other techniques at that point, and that
includes the narrow IF filter that has good slopes.


I really do not understand this attitude toward synchronous detection.
It's the best thing to happen to AM reception in years. I have it in my
radios at home and wish I had it my car radio. Maybe it's that I live on
the coast that the selective fading is more problematic but SW anytime
or night time AM broadcast reception is greatly improved on weak and
strong signals alike.

The choice of double side band of single is an additional plus that I
would not minimize either. One side band of an AM signal can have have
interference on it and not the other. Often passband tuning takes care
of it but not always. Take the situation of a digital mode signal near
an AM broadcast and the passband tuning will get rid of most but not all
the digital mode interference. Using synchronous selective side band
detection is much more effective.

You can count me as one that would not want to live without it.

Do you own radios with synchronous detection? Try operating one with
sync on and another with sync off. Spend some hours listening to night
time AM or SW and then come back and tell us which you prefer.

--
Telamon
Ventura, California
  #27   Report Post  
Old June 3rd 05, 05:10 AM
Tebojockey
 
Posts: n/a
Default

On Fri, 03 Jun 2005 02:56:59 GMT, Telamon
wrote:

In article .com,
"rkhalona" wrote:

I've been a SWLer for at least 20 years, have a Ph.D. in EE, have 20+
years of experience in the telecomm industry (uwave, sats, cellular,
UWB...) and have taught grad/undergrad comm courses at various U.S.
universities.

I agree with another poster that the SW8/R8B sync. detectors are
among the best ever incorporated into SWL gear. My previous comment
about sync. doesn't mean that one cannot achieve similar signall
quality without it (e.g., using PBT, but how many portables or
low-cost tabletops have PBT these days?), but the convenience of
being able to select sidebands in sync mode is a big plus.


This news group has more than it's share of Ph.D.'s and double E's it
seems.

Where do you think the future of telecom is going? Is it going to be
mostly fiber-optic or do you think RF for the last mile to the home or
business?

Do you think Ethernet is winning over ATM?


Ermmmm...ATM (asynchronous transfer mode) is a 53-byte packet
protocol that travels OVER ethernet (a method of transferring data
over coax cable - and wire pairs.). See IEEE standard 802.3.
Ethernet is the most widely installed local area network technology.
The most commonly installed Ethernet systems are called 10BASE-T,
providing transmission speeds up to 10 Mbps. Fast Ethernet LANs,
100BASE-T, provide transmission speeds up to 100 Mbps.

ATM is a dedicated-connection switching technology that organizes
digital data into 53-byte cell units and transmits them over a
physical medium using digital signal technology. Individually, a cell
is processed asynchronously relative to other related cells and is
queued before being multiplexed over the transmission path. Because
ATM is designed to be easily implemented by hardware (rather than
software), faster processing and switching speeds are possible. The
prespecified bit rates are either 155.520 Mbps or 622.080 Mbps. Speeds
on ATM networks can reach 10 Gbps.

Regards,

Al in CNMI


----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----
  #28   Report Post  
Old June 3rd 05, 05:17 AM
Tebojockey
 
Posts: n/a
Default

On Fri, 03 Jun 2005 03:47:00 GMT, Telamon
wrote:

In article ,
(Michael Black) wrote:

"rkhalona" ) writes:
I've been a SWLer for at least 20 years, have a Ph.D. in EE, have 20+
years of
experience in the telecomm industry (uwave, sats, cellular, UWB...) and
have taught
grad/undergrad comm courses at various U.S. universities.

I agree with another poster that the SW8/R8B sync. detectors are among
the best ever incorporated
into SWL gear. My previous comment about sync. doesn't mean that one
cannot achieve similar
signall quality without it (e.g., using PBT, but how many portables or
low-cost tabletops have PBT
these days?), but the convenience of being able to select sidebands in
sync mode is a big plus.

RK

But it seems you are mixing apples and oranges.

Sync detection means a locally generated "carrier" is present, so
if the signal fades the lack of a strong carrier is not a factor.

It does nothing to prevent fading (which I bring up because someone
recently said something along those lines here) it merely helps when
the signal fades.

Selectable sideband really has nothing to do with synchronous
detection, other than that using the phasing method it's relatively
cheap to implement compared to an expensive IF filter. It's not
really like a few extra parts to a synchronous detector will
add selective sideband, the added parts may be cheap but it adds
complication to the circuit.

When Webb wrote about the synchronous detector in CQ Magazine
about it, it was the whole shebang. But, that was a time
when many receivers had fairly wide IF filters, and lacked
product detectors. At the same time, you'd see SSB adaptors
that used the phasing method, which added that product
detector and reduced the unwanted sideband. Adding
synchronous circuitry to those was relatively simple, so once
you added the sync circuitry you not only got DSBsc reception,
but better SSB reception.

What we often see is lower end receivers tossing it in (because
the phasing method is a cheap way of knocking out the unwanted
sideband, and plus there are ICs that do it all in one
package), but it doesn't make up for the lack of a narrow
IF filter with steep sides (at least not as implemented
in those cheap receivers). It's a means of adding something
without a major cost increase.

I'm not even sure where we've veered off to. I thought
the previous comment was something like synchronous detection
wasn't all that important. I'd say that's true, given that
people lived without it till it became a feature in relatively
recent years. Someone listening to broadcast radio (am or
shortwave) that are relatively strong may be the ones to
benefit the most, because you can get deep fades where
the sidebands are still nice and strong. Signals
that you have to strain to hear, it's far less likely to
be useful, because they are already below a minimum strength.
You'd want to pull in other techniques at that point, and that
includes the narrow IF filter that has good slopes.


I really do not understand this attitude toward synchronous detection.
It's the best thing to happen to AM reception in years. I have it in my
radios at home and wish I had it my car radio. Maybe it's that I live on
the coast that the selective fading is more problematic but SW anytime
or night time AM broadcast reception is greatly improved on weak and
strong signals alike.

The choice of double side band of single is an additional plus that I
would not minimize either. One side band of an AM signal can have have
interference on it and not the other. Often passband tuning takes care
of it but not always. Take the situation of a digital mode signal near
an AM broadcast and the passband tuning will get rid of most but not all
the digital mode interference. Using synchronous selective side band
detection is much more effective.

You can count me as one that would not want to live without it.

Do you own radios with synchronous detection? Try operating one with
sync on and another with sync off. Spend some hours listening to night
time AM or SW and then come back and tell us which you prefer.



I have to say, from a personal instead of an engineering standpoint
(yes, I'm a EE too - but only a Bachelor's), I love the sync mode I
have available to me.

I use a Sony ICF-2001D (yeah, I know, museum piece...) and the sync
detection allows me to dig stuff out of the dirt as well as clear off
some splatter and clutter. It makes for easy ID of stations that
always seemed to elude me. My ears are old and I am a little deaf
(military time), so it's a godsend to me. Audio filtering and
headphones just cannot do what sync detection does as far as locking
onto a sideband.

Now, I can't switch select the sideband, but what I *can* do it tune
off +/- 100 Hz until the detector locks onto the sideband that I
desire.

Al in CNMI

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http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----
  #29   Report Post  
Old June 3rd 05, 05:27 AM
Telamon
 
Posts: n/a
Default

In article ,
Tebojockey wrote:

On Fri, 03 Jun 2005 02:56:59 GMT, Telamon
wrote:

In article .com,
"rkhalona" wrote:

I've been a SWLer for at least 20 years, have a Ph.D. in EE, have
20+ years of experience in the telecomm industry (uwave, sats,
cellular, UWB...) and have taught grad/undergrad comm courses at
various U.S. universities.

I agree with another poster that the SW8/R8B sync. detectors are
among the best ever incorporated into SWL gear. My previous
comment about sync. doesn't mean that one cannot achieve similar
signall quality without it (e.g., using PBT, but how many
portables or low-cost tabletops have PBT these days?), but the
convenience of being able to select sidebands in sync mode is a
big plus.


This news group has more than it's share of Ph.D.'s and double E's
it seems.

Where do you think the future of telecom is going? Is it going to be
mostly fiber-optic or do you think RF for the last mile to the home
or business?

Do you think Ethernet is winning over ATM?


Ermmmm...ATM (asynchronous transfer mode) is a 53-byte packet
protocol that travels OVER ethernet (a method of transferring data
over coax cable - and wire pairs.). See IEEE standard 802.3.
Ethernet is the most widely installed local area network technology.
The most commonly installed Ethernet systems are called 10BASE-T,
providing transmission speeds up to 10 Mbps. Fast Ethernet LANs,
100BASE-T, provide transmission speeds up to 100 Mbps.


I suppose ATM could be stuffed into a ethernet frame but I have not
heard of it. In the telecom world it's ATM over SONET that terminates
at my DSL modem. The DSL modem is used as a bridge. Between my DSL
modem to the computer it's ethernet so I can use the usual routers and
or hubs.

ATM is a dedicated-connection switching technology that organizes
digital data into 53-byte cell units and transmits them over a
physical medium using digital signal technology. Individually, a cell
is processed asynchronously relative to other related cells and is
queued before being multiplexed over the transmission path. Because
ATM is designed to be easily implemented by hardware (rather than
software), faster processing and switching speeds are possible. The
prespecified bit rates are either 155.520 Mbps or 622.080 Mbps.
Speeds on ATM networks can reach 10 Gbps.


It can go over any of the SONET rates.

Maybe I should have been more specific. The question is whether
ethernet will take over the local metro area from ATM over SONET. I
expect that ATM over SONET will be maintained at higher levels in the
network.

--
Telamon
Ventura, California
  #30   Report Post  
Old June 3rd 05, 08:51 PM
Lucky
 
Posts: n/a
Default


"Pete KE9OA" wrote in message
...
I had one of those. It did have quite a bit of RF gain, but the I.F. strip
did not have the gain that the Plessey SL6700 that is used in the HF-150
does. They are not the same receiver, performance wise. If you can find one
in the 125 dollar range, it isn't a bad deal.

Pete

"Lucky" wrote in message
...

"John S." wrote in message
ups.com...
Which radio...haven't heard that term.


OK

I'm interested in the old Lowe SRX-100 also known as the AKD Target HF3
and now the Nasa Target HF3/p or Nav-fax 200. Check on the very bottom
specs under "demodulator: I'm going to buy one. They look cool and seem
to have the same Lowe slower rate, faster rate knob. Simple receiver but
I seem to like it from what I've read about them. Now this company makes
a Nasa Target HF5E that I can only find in Germany. It's supposed to be
comparable with the Lowe 150.

http://www.pyacht.net/cgi-local/Soft....htm?E+scstore

Lucky




Pete,

I ordered one yesterday and found a dealer in this country who has them.
Wasn't easy for sure but I did it. They are much cheaper here then in the UK
for sure. Like 1/2 the price. I should be getting it hopefully today or
tomorrow!
I asked around and one supplier tracked the radio down for me. It's renamed
again in the U.S. Can't wait to fool around with it.
Have a good day.

Lucky


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