Discussion in 'General Announcements' started by K5YGC, Jul 21, 2012.
What's the benefit of DSB vs SSB, under ideal circumstances?
The DSB synchronous detector knows exactly where to reinsert the carrier. You don't have to guess what the operators voice actually sounds like when you manually tune SSB (useful for female voices). Also, it can help if there is selective fading.
But given the power disadvantage and the fact that you're using twice the bandwidth, the advantages of DSB aren't enough (and SSB is the way to go).
I don't have a response for when you're listening under ideal circumstances.
But under similar circumstances, with or without a synch detector, the signal with two sidebands lets you select the portion that has the least amount of interference.
In addition, having a full carrier and two sidebands enhances the ability to withstand poor reception because of static. The carrier helps many receivers maintain a good audio gain balance (AVC or AGC, with attack times fast or slow) during a static crash, since it helps mute that crash.
The carrier also provides important information much like teletype's mark and space protocol, where nothing is something. The carrier is a form of punctuation. When someone is presenting a thought, the carrier lets the listener know that the person has not yet concluded that thought, minimizing the chance for talking over their transmission still underway.
For these reasons, AM is the way to go.
Hope to hear you on the radio soon. Most modern transceivers can be adjusted to sound very good on AM, unlike the 1980s when manufacturers shortchanged the mode. The Flex 3000 that you have can sound especially fine on both transmit and receive. Here are two examples. One, I am recorded on a Flex as received in the Chicago area (with sync detector ON), and the other, I have recorded that station as received on a vintage tube receiver, using the "diode load" tap.
The quality is remarkable.
I cannot understand the "AM" effort. I hear guys on AM trying new mikes and things to "sound better". If the truth be known (believed), it is only the different filtering/ or lack of audio processsing in the transmitters and receivers that makes AM sound better. ABsent that, there is absolutely no difference between either AM sideband and SSB. k2lck
First you have to factor-in the allure of vintage gear that features AM, although there's a substantial presence of multi-mode Flex radios with AM synchronous detection, and other contemporary transceivers that sound very good transmitting on AM and can also receive it with adequate quality besides. This set of people forms the "AM Community" drawn to the mode on its own merit.
You've pointed to some distinguishing features. But when you say "absent that," you've actually put your finger on the practical difference and answered your own question. Here's a great sounding station on SSB:
But look at his rundown.
Most transceivers come without an emphasis on making the human voice sound human. They come with a combination of crappy sounding microphones, computer-quality speakers, inadequate receive bandwidth and severe compression that destroys natural dynamic range. None of those conditions is a "problem" for users who aren't interested in something better, possibly including yourself.
Those who prefer to get beyond what's been called "space shuttle audio" have gravitated to AM, as well as taking steps to improve what's possible on SSB.
Here's an example of what you're missing:
With ALL this talk about AM 'phone, what ever happened to S.P.A.M. - The Society for the Preservation of Amplified Modulation? No, it's not mistery meat or a message you never
asked for. 8-P
SPAM, founded by the late Hoisy Hoisington, W4CJL, was a popular group that raised the visibility of our part of the hobby, took an activist role with regulatory proposals, and represented the AM community to Amateurs at large.
I got my "card" from Hoisy in 1976, back when SPAM was being called the Society for the Preservation of Advanced Modulation. There have been some variations on the acronym, but that's what my card says.
As Hoisy got up in years, he reluctantly handed administration and leadership of the group over to others. Many of the records have been lost. Meantime, groups like AMInternational, and publications like Electric Radio (which also has a website, www.ermag.com) , and websites such as http://amfone.net and www.amwindow.org, have proven worthy successors with more immediacy, greater participation, and a wider audience than his old group could ever have imagined.
The announcement that started this thread is another example of the growth of interest in AM in recent years. Best of luck to the new website.
SPAM, and a publication of the era, AM Press/Exchange, filled a void not covered by national hobbyist publications and general radio clubs like the ARRL. I don't remember much in the way of regularly issued newsletters from SPAM, but news may have been concurrent and included with the AM Press/Exchange.
To get a flavor of the era, pick around among these issues, scanned from the original hardcopy in those pre-Internet days.
Try mentally picturing this in your mind.
Its an autumn or spring late afternoon or evening. You're in QSO with a station that is 20-30/9 with just a trace of QSB. That station has excellent audio, and your eyes are glued to the S-meter while your ears are enjoying the fidelity. Then in the distance mixed with the minor QSB is just a hint of QRN from maybe a distant storm. The intermitte background "crackling sound" just adds to the flavor of the recieved signal.
You have to perhaps experience what I am trying to explain to comprehend it. Once you do, you'll never ask the above asked question again. Trust me!!