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CB Skip...it's Back

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k8jd
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Re: CB Skip...it's Back

Post by k8jd » Mon Jul 12, 2021 3:47 pm

GMRS Intervehicle Comms
A few times we went on vacation trips up north with my older son in one car and my Bro/Sis in law in another Who I equiped with some old refurbished Uniden commercial mobiles programmed for my GMRS freq , and I had a GE Phoenix mobile on the seme freq. We used cigar lighter plugs and mag mount antennas .
With 25 W and 6" whips on the roof , we could get ten miles apart and still have full quieting copy !



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Calvert DeForest
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Re: CB Skip...it's Back

Post by Calvert DeForest » Fri Sep 24, 2021 12:16 pm

It will be interesting now that the FCC has given the green light to FM transmission on Citizens Band. Some new models will have a toggle for either AM or FM mode, with existing rigs using AM only. Having all 40 channels open to either mode should make for a fun traffic jam. I would have thought the logical option would be to designate the AM/FM feature on a block of channels (say channels 26-40), while reserving the remainder for AM operation only.


Shortwave is the ORIGINAL satellite radio.

Deleted User 14896

Re: CB Skip...it's Back

Post by Deleted User 14896 » Fri Sep 24, 2021 7:54 pm

Calvert DeForest wrote:
Fri Sep 24, 2021 12:16 pm
It will be interesting now that the FCC has given the green light to FM transmission on Citizens Band. Some new models will have a toggle for either AM or FM mode, with existing rigs using AM only. Having all 40 channels open to either mode should make for a fun traffic jam. I would have thought the logical option would be to designate the AM/FM feature on a block of channels (say channels 26-40), while reserving the remainder for AM operation only.
Personally, I like it.

The thought that crossed my mind is how this may work well for handheld wilderness communications. I'm thinking range will be greater than comms on VHF and UHF because rolling terrain isn't going to attenuate the signal as much. I'm sure aftermarket antennas will come out that have good gain.

As far as a traffic jam, I'm thinking FM will be the mode of choice. The FM side will be allowed to run a tx/rx pl and dpl. Folks on FM won't hear anyone on AM or SSB. Of course, those on the AM and SSB are going to be "tore up" by FM'ers that can't hear them. I'm sure AM'ers will do their best to crank up the linear amplifiers and create as much QRM as they can.



Kennelly Heaviside
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Re: CB Skip...it's Back

Post by Kennelly Heaviside » Sat Sep 25, 2021 9:26 am

FM should capture all but the strongest Kennelly Heaviside (E) Layer skip. Big improvement. I couldn't get a good signal a couple miles across a Lake with some 4 watt Radio Shack Walkie Talkies a couple decades ago, mostly due to linears and skip. FM would work well. Also, 27 MHz FM CB would be a good option for low power headset Walkie Talkies, which wouldn't cook your brain to the same extent like VHF and UHF. A good option for aging couples losing their hearing to communicate in the house. The FM would capture interference within the house and yard.


Kennelly Heaviside. The best Technical Consultant no money can buy.

km1125
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Re: CB Skip...it's Back

Post by km1125 » Sat Sep 25, 2021 10:23 am

Calvert DeForest wrote:
Fri Sep 24, 2021 12:16 pm
It will be interesting now that the FCC has given the green light to FM transmission on Citizens Band. Some new models will have a toggle for either AM or FM mode, with existing rigs using AM only. Having all 40 channels open to either mode should make for a fun traffic jam. I would have thought the logical option would be to designate the AM/FM feature on a block of channels (say channels 26-40), while reserving the remainder for AM operation only.
Yea, that surprises me too. A block of channels or maybe an odd/even delineation would have made some sense.

I have not been active on CB in quite a few years. Used to have a base (way back when) and had mobile units in both cars up until a few years ago. Still have a couple portables and the one mobile I removed from the truck.

Is there really much traffic out there on any of the channels?



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Calvert DeForest
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Re: CB Skip...it's Back

Post by Calvert DeForest » Sat Sep 25, 2021 1:11 pm

km1125 wrote:
Sat Sep 25, 2021 10:23 am
Yea, that surprises me too. A block of channels or maybe an odd/even delineation would have made some sense.

I have not been active on CB in quite a few years. Used to have a base (way back when) and had mobile units in both cars up until a few years ago. Still have a couple portables and the one mobile I removed from the truck.

Is there really much traffic out there on any of the channels?
I get no local traffic on my RS handheld. Same with my Degen multi-band radio when I scan the 26-27 MHz spectrum. It's all skip traffic when propagation permits. That being said, I have read that a lot of truckers still use CB to talk between vehicles. The FM transceivers are brand new to the market. There are a lot more AM-only CB's in use right now, and a lot of folks will probably opt not to drop the cash on a new radio as long as what they have works for them. It all depends on how quickly the FM radios catch on and how widely they penetrate the market. The price points of the radios are also likely to drop over time (in other words I wouldn't run out and buy one today). In the meantime we may see a lot of people pull their old AM CB's out of mothballs just because of the market buzz. Assuming there's an increase in AM traffic on Citizens Band (which may or may not happen), it could be an interesting clash with the steadily-increasing FM traffic. Another potential issue is bleed-over to adjacent channels, as FM transmissions require more bandwidth. The channel spacing was originally allocated for low-bandwidth AM transmission. Guess we'll see how it pans out.

There are advantages I see to the use of FM on CB. The range is definitely higher than UHF bands such as GMRS, and HF is not nearly as susceptible to line-of-sight obstruction (buildings, trees, hills, etc). CB is license-free as where GMRS requires a license with a nominal fee (currently $70 for 10 years although the fee is expected to drop to $35 sometime next year). It's not a bad idea, but the implementation could have been better.


Shortwave is the ORIGINAL satellite radio.

paul8539
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Re: CB Skip...it's Back

Post by paul8539 » Sat Sep 25, 2021 5:56 pm

There is still some traffic on 19 on the highways. Truckers let other trucks know where the backups are.



Deleted User 14896

Re: CB Skip...it's Back

Post by Deleted User 14896 » Sat Sep 25, 2021 8:34 pm

Calvert DeForest wrote:
Sat Sep 25, 2021 1:11 pm
..... Another potential issue is bleed-over to adjacent channels, as FM transmissions require more bandwidth. The channel spacing was originally allocated for low-bandwidth AM transmission ....
I may need a refresher. I always thought that AM was a wide signal. I did a little googling. Couldn't ascertain just what the deviation is on AM CB. I was also unable to find what deviation FM on CB will be. Seems I read it will be 12.5 KHz but I can't prove it right now.



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SolarMax
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Re: CB Skip...it's Back

Post by SolarMax » Sun Sep 26, 2021 9:43 am

Mike Oxlong wrote:
Sat Sep 25, 2021 8:34 pm
Calvert DeForest wrote:
Sat Sep 25, 2021 1:11 pm
..... Another potential issue is bleed-over to adjacent channels, as FM transmissions require more bandwidth. The channel spacing was originally allocated for low-bandwidth AM transmission ....
I may need a refresher. I always thought that AM was a wide signal. I did a little googling. Couldn't ascertain just what the deviation is on AM CB. I was also unable to find what deviation FM on CB will be. Seems I read it will be 12.5 KHz but I can't prove it right now.
"Deviation" is not (or never should be) a characteristic of any AM signal. You probably mean bandwidth, which is typically 2.5-3 kHz, for voice grade communications. A few, on both Amateur bands and CB, feel their dulcet tones demand "high fidelity" transmission, and waste spectrum with a 10 kHz or wider AM or SSB signal.
Narrow band FM deviation spec is 5 kHz. I very rarely tune through the 27MHz band, but this new chaos could be fun to hear for a few minutes.



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HD74
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Re: CB Skip...it's Back

Post by HD74 » Wed Sep 29, 2021 1:27 pm

As to AM/FM operation, I ran an "import" radio for a number of years, a 2970, a friend had a 2950, same radio, the 2970 had more power.
You could still hear what people were saying on AM when in FM mode, and people without the FM could still make out what we were saying on their AM radios.
What I liked most about the 2970 radio was opening peoples garage doors when driving by, don't know why it happened, but it sure did. :lol


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k8jd
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Re: CB Skip...it's Back

Post by k8jd » Wed Sep 29, 2021 7:36 pm

Only time I hear any activity on 11 M CB is when there is a E-lyer skip opening, (Most of the late summer openings have died out) then I hear plenty of distant signals piling up on popular channels.
Recently my only decent antenna for listening to that is a 28 MHz , 3 element Yagi, temporarily stuck south.



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Calvert DeForest
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Re: CB Skip...it's Back

Post by Calvert DeForest » Thu Sep 30, 2021 9:44 am

Here's an interesting CB AM/FM demo:



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WOHO
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Re: CB Skip...it's Back

Post by WOHO » Thu Sep 30, 2021 11:24 am

Simple, leave the original 23 channels AM or SSB only, channels 24-40 FM primary, AM alternate.



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Calvert DeForest
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Re: CB Skip...it's Back

Post by Calvert DeForest » Thu Sep 30, 2021 12:18 pm

WOHO wrote:
Thu Sep 30, 2021 11:24 am
Simple, leave the original 23 channels AM or SSB only, channels 24-40 FM primary, AM alternate.
Now if we can just convince the FCC and the manufacturers to set the standard.

This is reminiscent of the AM stereo debacle in the 80's.


Shortwave is the ORIGINAL satellite radio.

km1125
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Re: CB Skip...it's Back

Post by km1125 » Thu Sep 30, 2021 4:29 pm

Calvert DeForest wrote:
Thu Sep 30, 2021 12:18 pm
WOHO wrote:
Thu Sep 30, 2021 11:24 am
Simple, leave the original 23 channels AM or SSB only, channels 24-40 FM primary, AM alternate.
Now if we can just convince the FCC and the manufacturers to set the standard.

This is reminiscent of the AM stereo debacle in the 80's.
That's the nice thing about standards....there are so many to pick from! :D



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