SSB bandwidth question

[secret squirrel]

Do some SSB radios have a tighter or broader bandwidth when tuned properly. Listening to SSB net tonight. I am using a Texas Ranger 696 FD1 mobile version on a base. I always let the radio warm up for about 30 min before I talk SSB. My clarifer stayed dead on tonight no floating. Everyone on the net sounded dead on tonight expect on gentleman pretty close within 20 miles. He came in high pitched like he was off frequency a little. I could not tune him in clear. He must have sounded OK to all other no one mentioned him sounding off. I could hear his speech clear. Most of the time on local nets I am the only one with a CB and barefoot, everyone else on a HAM rig or a 2950 type. I am sure he had every thing tuned correctly. My question is could my radio just be hearing a wider sample of the channel than hes transmitting. I may be using incorrect terminology. All opinions welcome. Thx ahead of time

 

[Handy Andy]

Yes, for several reasons - you can hear the "tone" of the main PEAKNIG frequency of their radio versus the "peaking frequency" you have to obtain the tonal response.

In both terms used, and this is really harder to explain than it is to simply show you.

IT's how your conversion works.

In a typical CB, the bandpass for typical SSB signals (again depending on conversion method) is about 1.5kHz AT THE MOST. This means you can hear from say 300Hz to as high up as 1.8kHz - which is more tonal range than you need - and most CB Radios' have hi-cut filters that roll off about 1kHz.

Best to show you what you can utilize in the MANUAL you get with the radio...


Depending on the conversion and the number of "Stages" it goes thru to get processed, you get different results.

The best way to explain this is that with more stages of conversion used, you get better ISOLATION of signal from the noise.

In a typical PC-122 or even the 146GTL (above large font) - it "converts" at the completion of the 1st stage IF - it goes to a mixer and the Audio in De-coupled/Derived from the IF signal beat against the IF RECEIVED signal - you're audio and noise is there...

But in a dual conversion - more than one stage of IF - that places the audio and Noise quality in a different light. You get less noise, more rejection and a better audio signal - but at the cost of it's fidelity due to the "carrier" you use is inside the radio - to carry it thru the extra stages of processing - you lose some bandwidth or fidelity but the intelligibility is improved.

I'll stop here and let this sink in for it takes a lot to explain the rest of what I could add...

 

[secret squirrel]

Thank you so much very easy to understand your explanation.

 

[Handy Andy]

To put it in simpler terms,

The fewer stages of "mixing" you have to get the radio to produce the audio - yes, you get noise, but the faithfulness to the original captured signal - is there - more so than the extra stages of conversion most Ham radios have to obtain the signals intelligence.

In some peoples' view, it's called Emphasis and De-Emphasis - the processing required for re -equalization of a signal because of the processing needed to obtain it - requires equalization of audio signal due to the very processing used to attain that signal.

To help, in light of the number of stages to convert a signal - remember that IF (Intermediate Frequency) is simply a carrier signal - no audio - just signal - at a precise frequency.

The RF signal received, is added to (mixed in with) - and you get three sets of signals by Original - and the Summation ones - Added into and Subtracted from.

Each "conversion" stage requires your radio to re-inject the signal from the previous stage - into another carrier to obtain (again) three sets of signals The Original, and their Added, Subtracted ones.

Once the signal gets into the radio from the antenna - it's already having to beat against carrier signals the radio uses to "lower" the captured signal - into lower ones that can allow for tighter bandpass, filtering and amplification - and in some cases COMPRESSION of signal called an IMAGE of the original - only in a new frequency..

So even though you may have more noise because of the less processing, you also have a more faithful reproduction of audio signal as originally captured by the radio - only it has the noise because it can't "narrow it down" in more stages - which in a way - is a self defeating principle - you can't get blood from turnip, so you lose fidelity because the signal you got and processed from the previous IF stage, now has to be reconverted over to another carrier-based signal.

I'll let this sink in...

 

[Robalo]

ok on cb band on AM from mobil to mobil we get 3 to 5 milles on ssb we get about 7-to 12 milles. can you explain that please

 

[Handy Andy]

ok on cb band on AM from mobil to mobil we get 3 to 5 milles on ssb we get about 7-to 12 milles. can you explain that please

Again this may be beyond the scope of the OP's intent - but AM requires a Carrier to decode, that signal is from the ORIGINAL and is amplitude based (AM) but in the last stages of IF - in a typical CB (Cobra 29) that is a 455kHz carrier signal - IMAGED from the original. So you have a "carrier" but it's 455kHz IMAGE from the original - so to decode the audio - the carrier is rectified and the audio plus carrier as a BIAS is obtained - the Audio being an AC signal can then be transferred to and thru filters (ANL - DSP)- ANF) to be amplified and then heard thru the speaker.

In SSB, the ORIGINAL is not carrier based, but FM - a FREQUENCY MODULATED (Deviation) ENVELOPE of RF that contains the audio power (the Amplitude) - so when that is decocded, the SSB signal the carrier is removed, the IF IMAGE is processed, but to obtain that image, a carrier needs to be injected to obtain the IMAGE for that Stages IF to process the "envelope" - you still need a means to remix the IF to get a newer image. But when you process the SSB signal - you remove that IF carrier thru the Crystal lattice filter - the envelope that remains is the IMAGE MINUS the carrier and opposite sideband.

The purpose of AN612 - in the Transmit side, is for this purpose of "mixing" the IF to the Audio signal - which then is the FREQUENCY MODULATED envelope of Audio and it's power (Amplitude) - mixed to the IF frequency and then is passed thru a multi-pole crystal lattice filter removing the carrier (Carrier BAL control) and opposite sideband envelope - what remains is the single Sideband of the frequency range of the mode you selected.

To put this back on the rails if only for this post, the newer methods of signal capture are thru the digital realm of sampling and processing - which many Ham pieces of Equipment are using today - DSP is a generic term for it but the premise is the same - obtain the signal - captured and streamed thru a series of filters using digital algorithms to remove noise and the output result - although heavily filtered in reproduction - is the audio.

How well this process is done - I call Aliasing - it's an alignment of fidelity emphasis used to reproduce the audio embedded within noises - it's the result of errors in the processing - trying to bring back fidelity of missing data the radio (or processing system) mistook as noise and removed. Again, you can't get blood from a turnip so they use the processing of Emphasis and De-Emphasis to give you a best value result of audio reproduction within the noisy signal..

​

In the above example, although crude, we need to remember the digital realm is trying to make it a series of 1 and 0's - in a means to obtain a word in both Bit and in Audio conversion DAC/ADC - so the error occurs in the "decision making process" of the "Should it be a 1 or a 0 here"

 

[nomadradio]

ok on cb band on AM from mobil to mobil we get 3 to 5 milles on ssb we get about 7-to 12 milles. can you explain that please

You have discovered the original reason SSB was invented. More miles per Watt.

SSB has two advantages, one in the receiver, one in the transmitter.

To receive AM, the receiver's bandwidth must be wide enough to admit both the upper and lower sidband. Once we get rid of the carrier, and one sideband, the receiver bandwidth only needs to be half as "wide". Making the receiver's passband half as wide brings in half as much noise. This makes a distant signal behave as if it had twice the power, compared to the now-reduced noise level. At the transmitter, all the power is now devoted to the audio part of the AM signal, that sideband. The same transmitter power devoted to just one sideband, used to be spread across the other sideband and the carrier, both. This has the effect of making that one sideband signal as strong as an AM signal roughly four times the power. The receiver-side advantage and the transmit-side add up, giving you double or more the range of AM.

Serious development of the technology was financed to improve the radio range of SAC bombers carrying nukes. Saving weight at the transmitter is a big deal when you're airborne. And it's a double whammy. A radio that draws less power on transmit also saves weight on the generating equipment that powers it. When hams heard about this new technology they said "More miles per Watt? Where do we sign?"

73

 

[Robalo]

Handy Andy ,Nomadradio

 

[Handy Andy]

@secret squirrel - there are tricks that a Tech can use - or notice in differences in the radio parts and values used.

You said...

I am using a Texas Ranger 696 FD1 mobile version on a base - ... - Everyone on the net sounded dead on tonight expect on gentleman pretty close within 20 miles. He came in high pitched like he was off frequency a little. I could not tune him in clear. He must have sounded OK to all other no one mentioned him sounding off. I could hear his speech clear. Most of the time on local nets I am the only one with a CB and barefoot, everyone else on a HAM rig or a 2950 type. I am sure he had every thing tuned correctly.

Ok, the key words here are RCI 2950 type...

Other rigs - due to their proprietary nature are not as easily "revealed" - nor is it needed...

Since RCI and Galaxy - Uniden and Dynascan are all similar - they use a Balanced Modulator to generate an SSB signal - which starts off as the radios IF - as least 1/2 of the IF - a set frequency and they shift 2.5kHz above and Below the main frequency - the "carrier" - your Clarifier can adjust this if you have a radio "unlocked".

Audio is directly applied to the carrier - but in doing so, you get the amplitude and the frequency component of the inception or instantaneous frequency of audio shifting both above and below the set frequency, as a mirror image of each other non-inverted and inverted.

The clarifier moves the bias level of a Varactor used in a tuning circuit controlled by a crystal - the IF frequency shifts - so does the audio applied to it in the Balanced modulator as bands above and below it - you're really generating an IMAGE that will then have the center Carrier and Opposing Sideband Audio filtered off sharply when you're in SSB mode else all the radio will then produced is the Carrier IF that mixes in with the PLL's side to make TX IF at the TX Mixer - which then gives you your main frequency start, origin, for your TX Strip SSB envelope or Carrier et - al.

The Carrier Balance control is part of this method. It is a feedback principle of the main IF and the Audio that DEVIATES from the center - the Carrier is pretty narrow, but how much you apply in signal feedback - against the audio level - determines how much envelope and it's amplitude - is generated.

For you to hear the "clarity" of the signal - requires the effort on the TX side to pass the right level of Tonal Audio passband - to make it to the TX mixer.

If the IF signal tuning is too far off - you can lose the ability to tune the user in because it's their main signal is not mixing properly and in proportion to - their own IF signal being mixed together - you can get a "gravely" Gruff sounding audio from the incomplete mixing that their radio produces...you can also over mix the audio from the wrong portion of the passband and you'll hear Bass to nearly Tenor audio "fidelity and quality" - that is due to the types of mixing that has to occur inside their radio to obtain their SSB IF signal the passband that trims and peaks the respective sides of the signal USB or LSB - is set for a range of tone too high or low for many radios to be able to process it properly.

When you hear them "clearly" yet with higher treble, their passband may be set properly - but the input range of frequency as well as the pre-emphasis filter used, may skew in favor to the higher treble range. That is normal - but for some radios - like ANF and DSP types - they tend to "mush out" the higher tones because of filters used in the audio processing to remove an effect called "White noise" that seems to be prevalent - it's due to the nature of the beast (circuit design used now) and how it is interpreted in definition. To me this effect is the internal noise or birdies and amplifier generated noise floor that is amplified and adds to the overall distinctiveness of reception and a ping against the ability to the transceiver to faithfully reproduce what it hears in RF to convert to Audio.

 

[BJ radionut]

You have discovered the original reason SSB was invented. More miles per Watt.

SSB has two advantages, one in the receiver, one in the transmitter.

To receive AM, the receiver's bandwidth must be wide enough to admit both the upper and lower sideband. Once we get rid of the carrier and one sideband, the receiver bandwidth only needs to be half as "wide". Making the receiver's passband half as wide brings in half as much noise. This makes a distant signal behave as if it had twice the power, compared to the now-reduced noise level. At the transmitter, all the power is now devoted to the audio part of the AM signal, that sideband. The same transmitter power devoted to just one sideband used to be spread across the other sideband and the carrier, both. This has the effect of making that one sideband signal as strong as an AM signal roughly four times the power. The receiver-side advantage and the transmit-side add up, giving you double or more the range of AM.

Serious development of the technology was financed to improve the radio range of SAC bombers carrying nukes. Saving weight at the transmitter is a big deal when you're airborne. And it's a double whammy. A radio that draws less power on transmit also saves weight on the generating equipment that powers it. When the hams did hear about this new technology they said "More miles per Watt? Where do we sign?"

Well Done NOMAD! Worth repeating!
All the Best
Gary

 

[Slowmover]

“If that pilot’s good . .if he’s really, really good . . . . “

.

 

[Slowmover]

Received Wing Attack Plan R”

 

[Tallman]

Main reason SSB works so well is that 100% of the radiated power is information.
No wasted carrier, No wasted side band. Fm is not nearly as good. The higher the modulation the more side bands you create.

One reason he might sound off to you is because many ham radios have the ability to split the receive and the transmit frequencies.

 

[M0GVZ]

Everyone on the net sounded dead on tonight expect on gentleman pretty close within 20 miles. He came in high pitched like he was off frequency a little. I could not tune him in clear. He must have sounded OK to all other no one mentioned him sounding off. I could hear his speech clear. Most of the time on local nets I am the only one with a CB and barefoot, everyone else on a HAM rig or a 2950 type.

They'll have just used their clarifiers or RIT controls until he sounded right. Chances are he's a little off frequency. Unless you're running a TXCO oscillator in your transceiver usually a radio is slightly off, even amateur gear. Whilst it doesn't really make much difference on AM and FM it can be very noticeable on SSB which is why clarifiers and RIT controls exist.

 

[Road Squawker]

They'll have just used their clarifiers or RIT controls until he sounded right....which is why clarifiers and RIT controls exist.

Exactly
Don't be "that guy" that tells the net control station that he is off freq,................... Jus Sayin