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Cellular forums Home > Archive > Verizon wireless > May 2007 > Question about analog cell phones
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| Author |
Question about analog cell phones
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| Radium 2007-05-24, 10:33 pm |
| Hi:
Why do analog cell phones use FM? Why not AM?
Microwave-frequencies can be done in AM just as well as FM? Why not
use AM?
In order to avoid "clipping" and interference with nearby stations,
the modulator signal should be attenuated prior to D-A conversion and
transmission. At the receiving end, the carrier signal should be
amplified prior to demodulation and A-D conversion.
Thanks,
Radium
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| dpierce@cartchunk.org 2007-05-24, 10:33 pm |
| On May 24, 7:28 pm, Radium <gluceg...@gmail.com> wrote:
> Hi:
>
> Why do analog cell phones use FM? Why not AM?
>
Do you even know if they do?
> Microwave-frequencies can be done in AM just as well
> as FM? Why not use AM?
Why not use FM?
Do you know they use FM?
> In order to avoid "clipping" and interference with nearby stations,
> the modulator signal should be attenuated prior to D-A conversion and
> transmission.
Why?
Why would you use D-A conversion at the TRANSMITTER?
> At the receiving end, the carrier signal should be
> amplified prior to demodulation and A-D conversion.
Why would you use A-D conversion at the RECEIVER?
If it's an "analog phone," why is it using A-D and D-A?
Do you know what an "analog cell phone" is?
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| Geoff 2007-05-24, 10:33 pm |
| Radium wrote:
> Hi:
>
> Why do analog cell phones use FM? Why not AM?
>
> Microwave-frequencies can be done in AM just as well as FM? Why not
> use AM?
Why ? AM is more susceptable to noise and inrterference.
>
> In order to avoid "clipping" and interference with nearby stations,
> the modulator signal should be attenuated prior to D-A conversion and
> transmission. At the receiving end, the carrier signal should be
> amplified prior to demodulation and A-D conversion.
Yer what ?
geoff
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| John R. Copeland 2007-05-24, 10:33 pm |
| "Radium" <glucegen1@gmail.com> wrote in message =
news:1180049314.005680.205030@x18g2000prd.googlegroups.com...
> Hi:
>=20
> Why do analog cell phones use FM? Why not AM?
Because hard-limiting just prior to the discriminator in an FM receiver
provides a signal-capture effect, in which the strongest of several
competing signals will be received almost free of interference.
Unless the undesired signals are nearly the same strength as the
desired one, the undesired signals are greatly suppressed.
>=20
> Microwave-frequencies can be done in AM just as well as FM? Why not
> use AM?
Yes, the frequency is irrelevant. FM was chosen for other reasons.
>=20
> In order to avoid "clipping" and interference with nearby stations,
> the modulator signal should be attenuated prior to D-A conversion and
> transmission. At the receiving end, the carrier signal should be
> amplified prior to demodulation and A-D conversion.
A/D and D/A conversions are techniques used in digital systems, not =
analog.
However, I did not follow the logic of your statement.
It somewhat resembled the argument for audio-spectrum pre-emphasis
commonly used in recording and broadcasting, but not quite.
That part about amplifying the carrier signal prior to demodulation
made me blink, to say the least.
>=20
> Radium
>
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| Eeyore 2007-05-24, 10:33 pm |
|
Radium wrote:
> Hi:
Oh right. You're not blocked on this news server !
Bye.
Graham
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| Radium 2007-05-24, 10:33 pm |
| On May 24, 4:55 pm, dpie...@cartchunk.org wrote:
> On May 24, 7:28 pm, Radium <gluceg...@gmail.com> wrote:
>
>
>
> Do you even know if they do?
Yes. I read about it.
>
>
> Why not use FM?
FM is limited to line of sight.
>
> Why?
>
> Why would you use D-A conversion at the TRANSMITTER?
>
>
> Why would you use A-D conversion at the RECEIVER?
>
> If it's an "analog phone," why is it using A-D and D-A?
>
> Do you know what an "analog cell phone" is?
Sorry. I should've left out the D-A/A-D conversion.
Stupid me.
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| Radium 2007-05-24, 10:33 pm |
| On May 24, 4:53 pm, "Geoff" <g...@nospam-paf.co.nz> wrote:
> Radium wrote:
>
>
[color=darkred]
> Why ? AM is more susceptable to noise and inrterference.
AM interferences are more interesting and entertaining than the boring
hiss you get with bad FM reception.
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| Radium 2007-05-24, 10:33 pm |
| On May 24, 5:15 pm, "John R. Copeland" <jcope...@columbus.rr.aol.com>
wrote:
> "Radium" <gluceg...@gmail.com> wrote in messagenews:11800493
14.005680.205030@x18g2000prd.googlegroups.com...
>
[color=darkred]
> Because hard-limiting just prior to the discriminator in an FM receiver
> provides a signal-capture effect, in which the strongest of several
> competing signals will be received almost free of interference.
> Unless the undesired signals are nearly the same strength as the
> desired one, the undesired signals are greatly suppressed.
Okay.
>
> Yes, the frequency is irrelevant. FM was chosen for other reasons.
All right.
>
[color=darkred]
> A/D and D/A conversions are techniques used in digital systems, not analog.
> However, I did not follow the logic of your statement.
Sorry. Please ignore the A/D-D/A part. I accidentaly included it.
> It somewhat resembled the argument for audio-spectrum pre-emphasis
> commonly used in recording and broadcasting, but not quite.
Meaning?
> That part about amplifying the carrier signal prior to demodulation
> made me blink, to say the least.
Why? The idea of amplifying the carrier signal prior to demodulation
is to increase the loudness of the psychedelic heterodynes.
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| John R. Copeland 2007-05-24, 10:33 pm |
| "Radium" <glucegen1@gmail.com> wrote in message =
news:1180052930.035517.86580@a26g2000pre.googlegroups.com...
> On May 24, 5:15 pm, "John R. Copeland" <jcope...@columbus.rr.aol.com>
> wrote:
>=20
>=20
> Why? The idea of amplifying the carrier signal prior to demodulation
> is to increase the loudness of the psychedelic heterodynes.
>
OK, now I realize I've been trolled. Sorry to waste the bandwidth. :-(
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| Eeyore 2007-05-24, 10:33 pm |
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"John R. Copeland" wrote:
> OK, now I realize I've been trolled. Sorry to waste the bandwidth. :-(
It's all Radium ever does.
Graham
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"Radium" <glucegen1@gmail.com> wrote in message
news:1180052659.659348.44940@x35g2000prf.googlegroups.com...
> Stupid me.
At last a Radium statement I can agree with :-)
MrT.
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| dpierce@cartchunk.org 2007-05-25, 7:33 am |
| On May 24, 8:24 pm, Radium <gluceg...@gmail.com> wrote:
> On May 24, 4:55 pm, dpie...@cartchunk.org wrote:
>
>
>
>
>
> Yes. I read about it.
Do you even KNOW if they do?
You seem to read about a lot of things and still consistently,
reliably get it wrong.
>
>
> FM is limited to line of sight.
Wrong. Utterly, totally, completely wrong.
I sit here listening to WCRB at about 100 MHz,
55 miles away, well beyond line of site distance.
Now, once again, why NOT use FM?
> Stupid me.
Okay, you're now on record for your FIRST correct
statement. How about going for a streak?
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| dpierce@cartchunk.org 2007-05-25, 7:33 am |
| On May 24, 8:28 pm, Radium <gluceg...@gmail.com> wrote:
> Why? The idea of amplifying the carrier signal prior to demodulation
> is to increase the loudness of the psychedelic heterodynes.
You're an idiot.
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| Bob's Backfire Burrito 2007-05-25, 10:33 am |
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"Radium" <glucegen1@gmail.com> wrote in message
news:1180052771.131522.253240@d30g2000prg.googlegroups.com...[color=darkred]
> On May 24, 4:53 pm, "Geoff" <g...@nospam-paf.co.nz> wrote:
>
Spoken like a true CB'er there Radium....
You are totally CLUELESS!
All you seem to know are buzzwords and have no idea how "radio" works.
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| Karl Uppiano 2007-05-25, 10:33 pm |
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"Bob's Backfire Burrito" < BLAMPOW!@pullmyfinge
r.org> wrote in message
news:qSB5i.3118$u56.1464@newssvr22.news.prodigy.net...
>
> "Radium" <glucegen1@gmail.com> wrote in message
> news:1180052771.131522.253240@d30g2000prg.googlegroups.com...
>
> Spoken like a true CB'er there Radium....
> You are totally CLUELESS!
> All you seem to know are buzzwords and have no idea how "radio" works.
The similarities between Usenet and CB are staggering.
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