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Hard Limiters

Started by HardySpicer May 18, 2010
Used in FM before demodulation. Do they actually do any filtering
though apart from removing amplitude variations?
What I have seen is that for low SNRs (carrier to noise ratios) you
are better off without it! Many people have told me that too. For high
SNRs they are fine ie if you are connected to the ariel.


Hardy
HardySpicer wrote:
> Used in FM before demodulation. Do they actually do any filtering > though apart from removing amplitude variations? > What I have seen is that for low SNRs (carrier to noise ratios) you > are better off without it! Many people have told me that too. For high > SNRs they are fine ie if you are connected to the ariel.
Ideally a hard limiter does no filtering. Yes, they make things worse at low SNR -- at least in a NBFM system; I don't know if they'd make much difference in a WBFM system. -- Tim Wescott Control system and signal processing consulting www.wescottdesign.com

HardySpicer wrote:

> Used in FM before demodulation. Do they actually do any filtering > though apart from removing amplitude variations? > What I have seen is that for low SNRs (carrier to noise ratios) you > are better off without it! Many people have told me that too. For high > SNRs they are fine ie if you are connected to the ariel.
Cretin. This is what the recent tread of phase-amplitude detectors was about. You didn't bother to understand a thing, although you stick your stupid noze into it. VLV
On 5/18/2010 2:30 AM, Tim Wescott wrote:
> HardySpicer wrote: >> Used in FM before demodulation. Do they actually do any filtering >> though apart from removing amplitude variations? >> What I have seen is that for low SNRs (carrier to noise ratios) you >> are better off without it! Many people have told me that too. For high >> SNRs they are fine ie if you are connected to the ariel. > > Ideally a hard limiter does no filtering.
Well, they "filter out" AM. As implemented, they add to the selectivity of the IF, being coupled through selective interstage transformers. In the good old days, quality FM receivers had two limiters following one or two AGC'd IF amplifiers. The signal chain then had four or five tuned transformers providing twice that number of core slugs to twiddle. That made it easy to completely screw up the IF response or, if you understood the theory, to stagger tune for a broad, flat response. You could trade away bandwidth for gain if it was needed. Ratio detectors did away with the need to limit. In general, ratio-detector receivers performed more poorly than the limiter-discriminator combination. That turned out to be due more to transformer count than anything else.
> Yes, they make things worse at low SNR -- at least in a NBFM system; I > don't know if they'd make much difference in a WBFM system.
Most WBFM systems want at least 20 dB suppression of noise and 30 is better. That puts their operation far enough above threshold for such a difference to rarely matter. Jerry -- "I view the progress of science as ... the slow erosion of the tendency to dichotomize." --Barbara Smuts, U. Mich. �����������������������������������������������������������������������
Jerry Avins wrote:
> On 5/18/2010 2:30 AM, Tim Wescott wrote: >> HardySpicer wrote: >>> Used in FM before demodulation. Do they actually do any filtering >>> though apart from removing amplitude variations? >>> What I have seen is that for low SNRs (carrier to noise ratios) you >>> are better off without it! Many people have told me that too. For high >>> SNRs they are fine ie if you are connected to the ariel. >> >> Ideally a hard limiter does no filtering. > > Well, they "filter out" AM. As implemented, they add to the selectivity
I was going to say "is memoryless", but I didn't want to confuse things. Gee, thanks. -- Tim Wescott Control system and signal processing consulting www.wescottdesign.com
On May 19, 12:43&#2013266080;am, Vladimir Vassilevsky <nos...@nowhere.com> wrote:
> HardySpicer wrote: > > Used in FM before demodulation. Do they actually do any filtering > > though apart from removing amplitude variations? > > What I have seen is that for low SNRs (carrier to noise ratios) you > > are better off without it! Many people have told me that too. For high > > SNRs they are fine ie if you are connected to the ariel. > > Cretin. This is what the recent tread of phase-amplitude detectors was > about. You didn't bother to understand a thing, although you stick your > stupid noze into it. > > VLV
No need to be like that Vlad or we'll take you back to Transalvania...
On 5/18/2010 3:07 PM, HardySpicer wrote:
> On May 19, 12:43 am, Vladimir Vassilevsky<nos...@nowhere.com> wrote: >> HardySpicer wrote: >>> Used in FM before demodulation. Do they actually do any filtering >>> though apart from removing amplitude variations? >>> What I have seen is that for low SNRs (carrier to noise ratios) you >>> are better off without it! Many people have told me that too. For high >>> SNRs they are fine ie if you are connected to the ariel. >> >> Cretin. This is what the recent tread of phase-amplitude detectors was >> about. You didn't bother to understand a thing, although you stick your >> stupid noze into it. >> >> VLV > > No need to be like that Vlad or we'll take you back to Transalvania...
You might learn how to spell on the other side of the woods. Jerry -- "I view the progress of science as ... the slow erosion of the tendency to dichotomize." --Barbara Smuts, U. Mich. &#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;
On May 18, 3:35&#2013266080;pm, Jerry Avins <j...@ieee.org> wrote:
> On 5/18/2010 3:07 PM, HardySpicer wrote: > > > On May 19, 12:43 am, Vladimir Vassilevsky<nos...@nowhere.com> &#2013266080;wrote: > >> HardySpicer wrote: > >>> Used in FM before demodulation. Do they actually do any filtering > >>> though apart from removing amplitude variations? > >>> What I have seen is that for low SNRs (carrier to noise ratios) you > >>> are better off without it! Many people have told me that too. For high > >>> SNRs they are fine ie if you are connected to the ariel. > > >> Cretin. This is what the recent tread of phase-amplitude detectors was > >> about. You didn't bother to understand a thing, although you stick your > >> stupid noze into it. > > >> VLV > > > No need to be like that Vlad or we'll take you back to Transalvania... > > You might learn how to spell on the other side of the woods. > > Jerry > -- > "I view the progress of science as ... the slow erosion of the tendency > &#2013266080; to dichotomize." --Barbara Smuts, U. Mich. > &#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;
Vlad or Tim?
Dirk Bell wrote:
> On May 18, 3:35 pm, Jerry Avins <j...@ieee.org> wrote: >> On 5/18/2010 3:07 PM, HardySpicer wrote: >> >>> On May 19, 12:43 am, Vladimir Vassilevsky<nos...@nowhere.com> wrote: >>>> HardySpicer wrote: >>>>> Used in FM before demodulation. Do they actually do any filtering >>>>> though apart from removing amplitude variations? >>>>> What I have seen is that for low SNRs (carrier to noise ratios) you >>>>> are better off without it! Many people have told me that too. For high >>>>> SNRs they are fine ie if you are connected to the ariel. >>>> Cretin. This is what the recent tread of phase-amplitude detectors was >>>> about. You didn't bother to understand a thing, although you stick your >>>> stupid noze into it. >>>> VLV >>> No need to be like that Vlad or we'll take you back to Transalvania... >> You might learn how to spell on the other side of the woods. >> >> Jerry >> -- >> "I view the progress of science as ... the slow erosion of the tendency >> to dichotomize." --Barbara Smuts, U. Mich. >> &#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095; > > Vlad or Tim?
Wait! How did I get pulled into this? And I don't think "Transalvania" is "the other side of the woods". With that "salvation" in there it's got to have some deep, possibly perverse, religious meaning. -- Tim Wescott Control system and signal processing consulting www.wescottdesign.com
On May 19, 8:59&#2013266080;am, Tim Wescott <t...@seemywebsite.now> wrote:
> Dirk Bell wrote: > > On May 18, 3:35 pm, Jerry Avins <j...@ieee.org> wrote: > >> On 5/18/2010 3:07 PM, HardySpicer wrote: > > >>> On May 19, 12:43 am, Vladimir Vassilevsky<nos...@nowhere.com> &#2013266080;wrote: > >>>> HardySpicer wrote: > >>>>> Used in FM before demodulation. Do they actually do any filtering > >>>>> though apart from removing amplitude variations? > >>>>> What I have seen is that for low SNRs (carrier to noise ratios) you > >>>>> are better off without it! Many people have told me that too. For high > >>>>> SNRs they are fine ie if you are connected to the ariel. > >>>> Cretin. This is what the recent tread of phase-amplitude detectors was > >>>> about. You didn't bother to understand a thing, although you stick your > >>>> stupid noze into it. > >>>> VLV > >>> No need to be like that Vlad or we'll take you back to Transalvania... > >> You might learn how to spell on the other side of the woods. > > >> Jerry > >> -- > >> "I view the progress of science as ... the slow erosion of the tendency > >> &#2013266080; to dichotomize." --Barbara Smuts, U. Mich. > >> &#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095; > > > Vlad or Tim? > > Wait! &#2013266080;How did I get pulled into this? > > And I don't think "Transalvania" is "the other side of the woods". &#2013266080;With > that "salvation" in there it's got to have some deep, possibly perverse, > religious meaning. > > -- > Tim Wescott > Control system and signal processing consultingwww.wescottdesign.com
Vampires