Say no to hi fi audio for communications

[W7XXX]

Original post is deleted due to most misunderstanding my point and this thread turning into accusations and misconceptions. I am now aware that most on this site are into high fidelity modulation and entertainment rather than communications and will try to tailor my post so not to offend those with different interest than myself. Long live AM, Best regards, Sam W7XXX all homebrew AM.

[ka3zlr]

Welcome to 2007,

 The Audio Emphasis has taken hold of hamdom and it is happening with all phone, it's a wonderful thing addressing audio characteristics opens up a whole new world. The Anti's feel they're reinforcing some type of "Farce" that doesn't exist. Todays MFG's are installing devices that you speak of internally, allow for expanded operations, everything at the operators command, What Today's Ham wants...

 If your gona come down on Hi Fi, you got alot of work to do across the spectrum.


jack KA3ZLR.
 

 

[w3jn]

These AMers, who hiss and WHISTLE into the microphone, so as to cause intentional splatter, up and down the band, are nothing less than Child Rapers

[W2INR]

Good morning.

Welcome to AMfone

Sam I was wondering if you could fill the group here in on your experiences and AM history.

Over the years the AM mode has been attacked and so when many see anything that might not be a main stream thought we will get defensive. Most of the time it is over reaction but we are like a beehive in a tree that is fine until someone kicks it.

New ideas and ideals will always kick the beehive.

If you would, give us some insight to the problems you guys have out on the west coast.



G

[WA3VJB]

the growing group of anti AMers that have ARRL support.

I make it a point to track such groups regardless of the reasons they feel animosity toward us.

Could you cite the basis and name any ringleaders, please ?


Paul

[W2INR]

In regard to your original post Sam,

I do not believe the problem is the audio bandwidth as much as it is the operator.
I have heard stations running AM that use stock equipment that splatter also.

Lets start with the definition of AM:

Definition: High fidelity or hi-fi reproduction is a term used by home stereo listeners and home audio enthusiasts (audiophiles) to refer to high-quality reproduction of sound or images that is very faithful to the original master recording. High fidelity equipment has minimal or unnoticeable amounts of noise and distortion and an accurate frequency response as set out in 1973 by the German Deutsches Institut für Normung (DIN) standard DIN 45500.

In my opinion the real problem is people running AM and not having a clue as to how to run their equipment.Unlike the modern gear (which you can splatter with that) I cannot tell you how many times I hear AM operators asking others how their signal is. What the hell is that? Many do not monitor their signal and that is the operators responsibility.

I can not tell you how many times I hear AMers asking how the signal "looks" and if they are "too" wide. They should know this before they get on the air. This also happens on SSB.

If a person is running AM and they do not have a way to listen to the transmitted signal and they do not have a scope , then they are going to have problems which as you have stated equate to the entire AM community being too wide or bandwidth hogs.

I say you can have splatter and the same problems with a rig that has a frequency response of 300 - 3000kc if the operator does not know how to operate the equipment.

G

[ka3zlr]

Good Day from me...nice to me ya,

 I like the ideas on the HomeBrew section and net.
 Operator conduct is something else.
 ARRL..I like the League miss sending in my Support..Have Problem with Present occupants...

[WA3VJB]

AM is all about good clean communications audio. If we observe reasonable bandwidth and run legal power, we can start defusing the anti AMers who have it now in the works to ban AM. A 3kc bandwith will stop AM as we know it.

You're taking a familiar, defensive posture here, and one that provides any remaining opponents with affirmation they may have a valid point. They do not.

I wrote to a guy in Montana nearly 15 years ago who took a position¹ similar to the one you've presented here, even if you don't agree with it personally.

The most relevant point I made to him also can provide guidance for you to consider:

By opening a claim of wasted spectrum, you put at risk all Amateur activities that fall outside the definition of emergency, essential communications Chit-chat so commonly found on SSB, packet, and FM might be considered just as wasteful, as well as DX’ing contesting, cross-band repeaters. . . the list goes on and on.

What I am responding with, if I have read your sentiments correctly, is that you have nothing to apologize for, nor to become defensive about, regarding the footprint an AM signal makes on available spectrum in allocations afforded radio hobbyists.

I also am saying your point of view is doomed as soon as you attempt to place a value judgment on any activity, including the quality of AM audio that you may or may not agree with.

Where does such a judgment draw the line?
¹See editorial correspondence from Jack Greenwood, WB7QDN, April 1993 QST magazine.

[N2udf]

This seems to me like the "If you don't think or do like I do you must be wrong" theory of operation.Let's just all get along....Lee,N2UDF.

[WB2CAU]

Low frequency response on AM is difficult to copy if conditions are not perfect. It is unnecessary and uses excessive bandwidth giving fuel to the growing group of anti AMers that have ARRL support.

I'm somewhat at a loss here. Could you please explain how low frequency response uses excessive bandwidth?

[WBear2GCR]

Modifying a rig like a Ranger to so called broadcast audio is a crime in my opinion.
<snip>

Low frequency response on AM is difficult to copy if conditions are not perfect. It is unnecessary and uses excessive bandwidth giving fuel to the growing group of anti AMers that have ARRL support.

All that is required in ham voice communications is simple audio circuits using coupling capacitors never to exceed .02 mfd and proper biasing.<snip>

"...a mind is a terrible thing to waste..." Dan Quayle

Friend,

Unfortunately, even if your heart is in the right place, it is fairly clear that you've perhaps misunderstood some things.

First of all, please explain to us how "bass" uses up excessive "bandwidth" on AM telephony??

Secondly, a "0.02ufd" cap value is meaningless without the context of the impedance it is driven by and it is loaded by.

               _-_-WBear2GCR

[Blaine N1GTU]

this is voice only and tailoring audio for music frequencies is unnecessary and can lead to distortion. In broadcast audio the extra fullness we hear under ideal conditions is called presence. To much presence can lead to low frequency rumble and mask necessary midrange voice frequencies leading to no copy if any qr nancy or mary is present.

all i can say to this is ...HUH??
since when does presence and hf response lead to rumble?
as for masking midrange freq, that is incorrect, if you are using a multi band audio processor as I am your averages will stay fairly constant without the pumping and attenuation of hf energy you are describing.
I am also not reproducing music, my voice is the only energy that comes out of my transmitter.

Futher more how many of you have tailored your receivers audio to reproduce this hi fi audio? What kind of speaker are you using? Communication receivers were designed for communications audio, not hi fi.

my receiver will reproduce 20hz-9khz easily, but i can narrow as much as needed during bad conditions qrm
i am feeding the output  of the receiver into a 150 watt per channel audio amp driving  a pair of 15" 4" and 2" speakers.
sounds nice.

[WBear2GCR]

Furthermore, let me paraphrase a post I made on QRZ.com on a similar issue:

Some, including the ARRL seem to hold the viewpoint that Amateur Radio = communication.

Amateur Radio != communication. (not equal to)

Amateur Radio uses communication as a basis or medium, beyond that we have art[/i].

At the point in time that the art is curtailed, limited, denied, removed or otherwise inhibited in a significant way, you will have effectively killed Amateur Radio.

The "art" has many forms and aspects. (A reasonably self-evident statement)

Once you include the concept that Amateur Radio is actually an art form into your thought process, you can only then begin to fully comprehend its scope. Then perhaps what is best and "right" will become more apparent.

Ymmv.

              _-_-WBear2GCR

[WBear2GCR]

Low frequency response allows for lower than voice frequencies to be transmitted. While this may add a depth or presence to audio, it blends in with bandnoises unless conditions are good and makes a signal uncopyable that would have otherwise been easy to copy. The low frequencies should not dominate the midrange and highs. I speak of and promote well rounded audio which is not always easy to obtain. Most people have certain voice frequencies that are of more amplitude than others. If one knows how to use a compressor, then they can even the amplitude of certain voice freqs out and have a better signal. Most I hear using compressors aren't even close to correct and this is varified by my scope. Many tend to try and bring up the amplitude of their voices low freqs, forgetting this may mask the most important midrange freqs. <snip>

Depends quite a bit on who is talking, now doesn't that?? 

Dunno what people out west are doing.

Here on the East Coast, the midwest, and to the south there are a great number of ops with rigs that range from DX-60s (or less) up through full blown modified broadcast rigs, with and without side chains - and let's not forget the Class E rigs.

Many here have wonderful sounding audio - including some that have let us say "extended" LF response in the rig. They sound clear and excellent, period. Few if any have excessive HF bandwidth, nor do any I am aware of splatter. We frequently have QSOs with powerful stations spaced 5kHz. (although that about as tight as you want).

I have heard almost no AM sigs on the air within my listening range (on 75m & 160m), including night conditions that are difficult to understand, or are somehow having a problem making anyone else hard to copy due to LF information in the signal. Sure, there are some folks just coming on with misadjusted gear, or those putting a new device in the line and struggling to make it "fly right" - but that's an exception. Few of those do not get their rigs set up well after a while, and with help from the community.

Perhaps you'd do well to listen to "The East Coast Sound"??
There are internet remote receivers, perhaps not the best thing, but maybe better than nothing?

As far as receiving, I deliberately do not have my receivers set up to pass much LF information to the ear, because my speakers acoustically start to roll off about 100Hz. This is a conscious decision that I have made. I can easilly switch to speakers that have significant bass response. So, IF you do not want to hear BASS, all you have to do is to set your rig up so that it is not reproduced in your shack, and you'll never know it is even there!

Otoh, if ur listening using a junk speaker, or the little tiny speaker in an transciever, perhaps they can be overloaded at normal or loud volumes by LF energy in a signal? Imho, that counts as operator error. I have no such problems whatsoever.

Dunno where your perspective has come from, or if there are some sort of special issues going on in your part of the country or not. Out this way, where there is significant AM activity and easily hundreds of active AM stations (don't think I'm overstating that) the problems you suggest simply do not exist.

           _-_-WBear2GCR

[WBear2GCR]

Yes, art form.

From your comments, and lack of forthcoming responses to the specific points raised, you've given the impression of a person with an agenda, and axe to grind, or else someone who is quite isolated and has a fixed perspective.

You're posting on a site where a great many participants have built "homebrew" equipment of significant sophistication and quality. Odd that you've somehow missed this??

While you make a point, building gear is just one aspect of the ART of Amateur Radio.

What the ARRL thinks, believes, or preaches is reasonably irrelevant.
Are you or were you ever an ARRL officer? Just curious.

In the event of an emergency, as you well know, Amateur Radio stations may be volunteers and/or pressed into service for communciation. Thus it remains as a "service." But that is irrelevant to this discussion, now isn't it?

We are NOT left with a hobby that merely "offeres all kind various modes of COMMUNCIATONS" at all. The various modes are what are known as media. What you do within and with said media can range from the pedestrian and uninspired to the sublime. Within that range is a personal expression that remains artistic. You can chose to deny it, or pretend that it doesn't exist, but ham radio as long as it involves people interacting and being unique is and will always be an art form.

And as I said, why do you think that AMers are not taking a high road and are not good operators?? Is there a problem out where you are??

Try answering the specifics this time??

          _-_-WBear2GCR

[Bill, KD0HG]

Let me ask something. Is there a place in ham radio for those that DO wish to experiment with and use high fidelity, professional audio gear on the air?
On AM, SSB, digitized voice or whatever?

I also want to point out that in itself and within reason, using high fidelity audio on the air is NOT unlawful. Granted, while doing so doesn't lend itself to to maximum communications efficiency under adverse conditions, that's the business of the parties involved as long as they comply with the laws on the books.

There is a big difference between using 'pro' grade audio gear on AM and operating unlawfully by splattering, either by misusing a linear amplifier on SSB or by exceeding -100% modulation peaks on AM. One is lawful and the other is not.

My own opinion is that there are FAR more SSB operators operating their equipment in an unprofessional, splattering mode, with highly distorted, clipped audio (listen to ANY contest for the best of it) than there are bad apples in the AM community.

I happen to enjoy listening to broadcast quality AM. Aside from the usual 3880-3885 KHz zoo, there's plenty of open space on 75 and 160 to enjoy using same, particularly in the new expanded parts of the phone bands.

Ham radio is about challenges. If it wasn't so, many of us would leave it. If I wanted to merely communicate with the east coast on 75 meters, I could do so easily, at any time, using the legal limit on SSB or less. Piece of cake.

And what a bore.

On AM, it's a challenge and a thrill to work cross country, especially with 'less-than-optimum' non-communications grade audio. That's the AMers version of the personal satisfaction that others get from making DXCC.

Excuse me, I'm going out with the XYL to ride the horses this afternoon. By today's standards, not a very efficient form of transportation. I should be ashamed.

[KA1ZGC]

Study the writings of Bill Orr on audio, you might learn something.

Stop talking down to everyone, you might be taken seriously.

--Thom
Kilimanjaro Africa One Zulu Goat Cheese

[Steve - WB3HUZ]

My goal is not to either make friends or enemies, but to educate those that love AM before we lose it. Good quality communications audio is one thing and audio tailored for music is another.

AM has been growing in numbers since the early/mid 1970's. The rate of growth has only increased over that time. Why do you think we are going to lose it?

Who is tailoring their audio for music? Come on, give us some calls.

I have been a ham and a musician since 1964 and building radios since 1956. My now antique trade school degree is in Broadcast and Audio Engineering. I have designed and built numerous tube audio circuits over the years for everything from guitar amps to high power modulators.

Many others that are into hi-fi AM have similar backgrounds.

Yes, I know it is a trend to play with audio on AM, but remember this is voice only and tailoring audio for music frequencies is unnecessary and can lead to distortion.

Sure, it's a trend - a trend that has been in existence since the 1960's! You are a little late to the party.

In broadcast audio the extra fullness we hear under ideal conditions is called presence. To much presence can lead to low frequency rumble and mask necessary midrange voice frequencies leading to no copy if any qr nancy or mary is present.

This statement is completely inaccurate. It tends to put your curriculum vitae above in a very negative light.

Futher more how many of you have tailored your receivers audio to reproduce this hi fi audio?

I have and I know of dozens of others who have too. Like I said, some of the guys out here on the east coast have been doing this since the 1960's. Years of experimentation, testing, on-air listening tests and extensive measurements have perfected both ends of this hi-fi AM communications channel for many. It would appear you have a few decades of catching up to do.

What kind of speaker are you using?

LOL. Even your question shows the lack of depth you have on this subject. I use at least three speakers with just about every receiving set up I have. Two for the mid-range and highs and a subwoofer for the lows. Crosley made receivers with speaker systems like this back in the 1930's. It's well past the time to start using such.

 Communication receivers were designed for communications audio, not hi fi.

Some are, some aren't. All receivers are not the same. Simplistic statements like this are largely devoid of meaning.

 What kind of mic are you using? I laugh when one tells me of all the processors, equalizers, etc., they are using on their D104 mic or how they replaced the .01 coupling caps with .1 like the broadcast preamps have.

Why? One of the best sounding stations on the air, K4KYV uses a D-104.

This is all my opinion and preference and I still believe in using good clean communications audio over hi fi that gets muddied up under less than ideal conditions and requires running illegal power so it can be copied resulting in excessive bandwidth and splatter.

Then run such audio and leave room for those who choose to do something different. The beauty of amateur radio and of AM is its diversity. Within AM there are those who like to homebrew, those who like vintage gear, those who like military gear, those who like modern gear, those who like hi-fi audio, those who like comms audio, those who are receiver gurus, those who are antenna gurus and so on. If everyone was the same, I would find it extremely boring.

Now you are accusing people of running illegal power. Got any calls? Come on, if you are really as concerned about this subject as you claim, you will put up or shut up.

I am all homebrew AM. I have no commercial equipment anymore, no FM, no SSB, nothing but AM. I am an AM advocate and do not want to see AM die as it will if we all do not take personal responsibility for transmitting clean voice frequency audio. Use a broadcast mic and a high quality speaker for starters. Your audio is no better than your mic and can't be appreciated if ones receiver has an inferior speaker. I say keep it simple, keep it clean, and keep AM alive.

So, you're telling us you built you own broadcast mic? Cool. Please share the design, so others can do the same.

[k4kyv]

It is important that the sound be balanced.  "Bassy" audio is often as not, a problem with not enough highs to balance the lows.  Likewise, "tinny" audio is usually not too much high frequency response, but a lack of lows to balance those highs.

My three transmitters (two homebrew and one converted broadcast box) are all flat down to at least 40 Hz and up to at least 11K.  I use a pre-emphasis or an equalising curve, or whatever you wish to call it, which is accomplished in the first stage of the audio chain in my homebrew tube-type mike pre-amp/two-channel audio mixer unit.  The response remains flat from 40~ up to about 800~; at that point the response curve begins to rise in near-linear fashion from 800~ up to about 9 dB @ 2000 Hz, and then levels off and remains flat out to the limits of the frequency response of what follows.

A low-pass audio filter follows the mic preamp/mixer, using (probably military surplus) potted, passive L-C type low-pass filters.  I have three choices to select from: a very sharp brick-wall cutoff at 3400 Hz, or a more gradual cutoff that begins at 5,000 Hz and rolled off to be undetectable on the scope at 7500 Hz, or as a 3rd choice the filter can be switched out of the circuit entirely.

Most of the time, under less congested conditions, I use the 5 kHz low-pass, but when the band gets too congested to copy comfortably using the 8 kHz mechanical filter in the receiver, I change to the 3400~ filter, and switch the receiver to 6 kHz with a different mechanical filter.

I have found that with the 3400~ filter in line, the 800-2000 Hz presence rise compensates for the lack of highs above 3400~, and most signal reports say the signal is "broadcast quality".  If I cut out the pre-emphasis and run the mic at flat response, it has a dull, bassy sound and carries less well through the background noise.  When the listener is monitoring with wide selectivity, I nearly always get reports of a noticeable difference between the filters, with the 5 khz low-pass sounding better.

Two microphones are used, mixed together in phase, each with its own varible attenuater.  One is a D-104 and the other an Electrovoice model 670 dynamic that for some reason has impaired high frequency response.  That mic reinforces the anaemic low-frequency response of the D-104, while its impaired high frequency response avoids the comb-filter effect that might otherwise occur throughout the high frequency range with random phase differences between the two mics.

Following the low-pass audio filter unit, I use a Urei BL-40 Modulimiter that was taken out of AM broadcast service.  This unit combines "rms limiting" which is essentially a form of compression, and peak limiting, which can be adjusted asymmetrically. It does an excellent job of maintaining the audio peaks at near 100% with varying distance between the talker and the microphone, or with varying voice levels, without having to constantly watch the scope and ride the master level control to the transmitter.  The thing I like about this unit is its transparency; it doesn't audibly affect the sound quality of the transmitted voice.  It works much better than the older tube-type Collins peak limiter I used to deploy.

Regarding the frequency response of the audio chain, for years I have accepted the recommendation made by the United Transformer Company (UTC) back in the 30's, that the flat response of an audio amplifier should go at least one octave above and one octave below the actual intended frequency range to be transmitted through the system, and that any shaping of the response curve should be done as early as possible in the audio chain.  This avoids undesirable phase shifts that can distort the waveform of the audio signal and cause audible distortion, or change the natural asymmetry of the voice signal that emerges from the microphone.

[W7IXZ]

I think the main point of bandwidth has been overlooked in this thread.  The new band plan allowing an OCCUPIED bandwidth of 2.7 KHz is being overshadowed by the AUDIO bandwith.  Even Sam's transmitter when properly modulated (no overmodulation) with his communications audio of 300 to 3000 hertz would generate an AM signal with an OCCPIED BANDWIDTH of 6 KHz, an illegal signal when referenced to the proposed OCCUPIED BANDWIDTH of 2.7 KHz.  The same SSB signal of 300 to 3000 Hertz (properly operated transmitter) would generate a SSB signal with an OCCUPIED BANDWIDTH of 3 KHz.  To fit into the proposed 2.7 KHz, the audio on a properly operated AM station would have to be limited to 300 (or whatever the low end was desired) to 1.35 KHz, and THAT would be a nasty sounding signal and hard to copy.  Amatuer Radio is a hobby where all concerned can follow their interests, from SSB, AM, RTTY, Digital modes, Rag Chewing and emergency service and message handling.  Amatuer Radio is like any other hobby from fast cars, antique airplane, to model railroading.  The interests of one group should not be imposed on any other member of that group.  I hope this makes sense.

I have several BC rigs as well as converted ham rigs and I want to be able to operate them and experiment.  Most of the communications systems and modes in use today were perfected by experimenters on the ham bands.

Larry

[Tom WA3KLR]

My understanding is that the bandwidth listed in the IARU band plan is NECESSARY bandwidth.  This is not stated as yet however and leaves us open for future stunts by our trusted ARRL and IARU committee people. 

OCCUPIED bandwidth is the measurement result of an actual transmitter's r.f. emissions.

I believe that NECESSARY bandwidth is a specification of the input modulation range needed to achieve the desired communications mode.

Obviously when implemented, the necessary bandwidth of the signal will grow by the time it leaves the transmitter due to phase noise, intermodulation distortion, ALC action, other circuit noises inadvertently added, etc.

I am not aware of an accurate way to measure the OCCUPIED bandwidth over the air, other than to be in very close proximity of the target transmitter.  Also I am not aware of any rule of thumb correlations existing to back-correlate to NECESSARY bandwidth from an OCCUPIED bandwidth measurement. 

[KA1ZGC]

I think the main point of bandwidth has been overlooked in this thread.

This isn't a thread about bandwidth, so that's not "the main point".

The new band plan allowing an OCCUPIED bandwidth of 2.7 KHz is being overshadowed by the AUDIO bandwith.  Even Sam's transmitter when properly modulated (no overmodulation) with his communications audio of 300 to 3000 hertz would generate an AM signal with an OCCPIED BANDWIDTH of 6 KHz, an illegal signal when referenced to the proposed OCCUPIED BANDWIDTH of 2.7 KHz.

(emphasis mine)

 

(Pulling hair out) AAAAAAAARRRRRRRGGGGHHHHHH!!!!!

People, please stop this! These bandplans are not codified in law! There is absolutely nothing "illegal" about failing to conform to the terms of an IARU bandplan! There never was, there never will be!

The only bandplan we are required to follow is the one that says where our licenses allow us to operate. It's always been that way, and always will.

I am not the only one sick to death of the "chicken little" misconceptions about yet another IARU bandplan that isn't going to become the word of law any more than every single IARU bandplan that came before it.

There is already a thread dedicated to discussing the proposed IARU bandplan. Please keep that well-beaten dead horse confined to that thread for the sake of the rest of us. We really don't need it spilling out into every single discussion that takes place here.

Please, and thank you!

--Thom
Killer Agony One Zipper Got Caught

[Tom WA3KLR]

I would say that most SSB transceiver have a 2.4 to 2.7 kHz NECESSARY bandwidth.  I would venture to say that the OCCUPIED bandwidth of most SSB transceivers is in the range of 3.0 to 3.5 kHz BAREFOOT.  Operation with an additional outboard linear amplifier will further increase the OCCUPIED bandwidth.

[KB2WIG]

                       "  These AMers, who hiss and WHISTLE into the microphone, so as to cause intentional splatter, up and down the band, are nothing less than Child Rapers.   "

Thats quite the message. 

klc 

[W9GT]

For a site that is dedicated to the enjoyment and furtherment of AM, our common interest in amateur radio, there is an incredible amount of condescension, impolite name calling, nasty discourse, and down right pontification appearing herein.  Much of it coming from a so-called "AMer".  I think you started this thread in a bad light and it is going deeper into the darkness of in-fighting amongst people who should be enjoying each other's comments and contributions to the "art", not casting aspersions and accusing fellow amateurs of crimes against mankind and the brotherhood!!  You are certainly entitled to your opinion, but quit lumping everyone into the same category and generalizing about a large number of people that you obviously have not known or even heard on the air.  You would do well to be able to assemble even half of the technical knowledge and operating prowess of many members of this list.
Please listen and read before preaching and inserting foot-in-mouth or on keyboard!!

73,  Jack, W9GT