[TechAssist] Re: Fw: Are onidirectional antennas any good(roof)
- From: "Damon" <damoneb@xxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Fri, 16 Sep 2005 19:45:33 -0500
Now that's amazing, I thought that NTSC signals have a 6Mhz bandwidth (which
it does) and I thought that Digital occupied the same 6 Mhz bandwidth
too....Sure doesn't look like it does tho'.
Damon B
Telrad Electronics
Fort Wayne IN
----- Original Message -----
From: "Wayne Vanaman" <Wayne@xxxxxxxxxxxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Friday, September 16, 2005 12:46 PM
Subject: [TechAssist] Re: Fw: Are onidirectional antennas any good(roof)
> Hey Damon:
> I have a customer that buys government surplus, warehouse liquidations
> and such. He brought in a spectrum analyzer and asked me to check it
> out. I was pleased to. Just couldn't get any decent pictures.
>
> The "spikes" are analog broadcasts and the wide ones are digital. The
> spectrum analyzer tells you what the frequencies are so it is easy to
> look at a channel assignment chart and see what you are looking at.
>
> Wayne Vanaman
> Omega Electronics
> 6904 W Fairfield Dr
> Pensacola, Fl. 32506-3310
>
> Wayne@xxxxxxxxxxxxxxxxxxxxx
> WWW.PensacolaTVRepair.Com
>
> 850-456-5995 voice
> 850-458-6369 fax
>
>
> Damon wrote:
> > Ok, so 19 21 and 23 are those SPIKES, correct?? And the big wide square
> > waves are the DIGITAL transmissions.
> > If not, then all I see are 3 square waves with 3 spikes......
> > Now what's this.....YOU HAD a Spectrum Analyser....whaddya do, run down
to
> > the Analyser Renta-Store??
> > Man, I wish I could rent one.....
> >
> > Damon B
> > Telrad Electronics
> > Fort Wayne IN
> > ----- Original Message -----
> > From: "Wayne Vanaman" <Wayne@xxxxxxxxxxxxxxxxxxxxx>
> > To: <techassist@xxxxxxxxxxxxx>
> > Sent: Thursday, September 15, 2005 4:24 PM
> > Subject: [TechAssist] Re: Fw: Are onidirectional antennas any good(roof)
> >
> >
> >
> >>Hey, I provide all the insight I can.
> >>
> >>Picture a square wave.
> >>With a digital transmission the entire 6MHz bandwidth transmission,
> >>viewed on a spectrum analyzer, would, ideally be similar in shape, were
> >>the analog transmission is a halversine waveform. If some portion of
> >>the transmission is greater or lesser amplitude you will have distortion
> >>to some degree.
> >>
> >>If the transmission amplitude is very low, almost "in the grass", the
> >>noise floor, but the shape is good, you would probably have a good
signal.
> >>
> >>If the transmission amplitude is high but the bandwidth is distorted,
> >>the data is confused and you will not have a usable signal.
> >>
> >>I had a spectrum analyzer in here for a while. Local channels in the
> >>thousands of microvolts, but with distorted wave forms could not be
> >>viewed on my TV, while there were channels 40dB down, with good even
> >>bandwidth that never showed signal breakup.
> >>
> >>Short of using a spectrum analyzer to aim the antenna it is pretty much
> >>a guess. Trees that cause ghosts in analog attenuate or distort
> >>portions of the signal so that the signal becomes unusable.
> >>
> >>Out in an open field a dipole should be good. In reality, my house is
> >>surrounded by trees.
> >>
> >>Look here:
> >>ftp://pensacolatvrepair.com/pub/IMAG0002.JPG
> >>I know, I know, pic stinks. What you see are analog and digital
> >>stations. Notice that none of the digital stations have a flat top.
> >>Not good. Guessing 'cause I don't remember for sure, you are looking
> >>at, left to right, channel 17, digital, 19, 21, 23, 27 digital, 31
> >>digital. Channel 17 I always get well. Chs 19 and 21 are snowy but
> >>watchable, channel 27 frequently breaks up. Notice the leading edge.
> >>Channel 31 is always good.
> >>
> >>
> >>Wayne Vanaman
> >>Omega Electronics
> >>6904 W Fairfield Dr
> >>Pensacola, Fl. 32506-3310
> >>
> >>Wayne@xxxxxxxxxxxxxxxxxxxxx
> >>WWW.PensacolaTVRepair.Com
> >>
> >>850-456-5995 voice
> >>850-458-6369 fax
> >>
> >>
> >>AL LEATHERMAN wrote:
> >>
> >>>Thanks Wayne, but does this mean we have to aim the antenna at the
> >
> > station,
> >
> >>>for digital.?
> >>>
> >>>Al's TV
> >>>Mine Hill, NJ. 07803
> >>>972-361-5796
> >>>WWW.ALS-TV.NET
> >>>----- Original Message -----
> >>>From: "Wayne Vanaman" <Wayne@xxxxxxxxxxxxxxxxxxxxx>
> >>>To: <techassist@xxxxxxxxxxxxx>
> >>>Sent: Thursday, September 15, 2005 3:27 PM
> >>>Subject: [TechAssist] Re: Fw: Are onidirectional antennas any
good(roof)
> >>>
> >>>
> >>>
> >>>
> >>>>RF emissions are not directional. The transmitting antenna on the
other
> >>>>hand...
> >>>>
> >>>>Wayne Vanaman
> >>>>Omega Electronics
> >>>>6904 W Fairfield Dr
> >>>>Pensacola, Fl. 32506-3310
> >>>>
> >>>>Wayne@xxxxxxxxxxxxxxxxxxxxx
> >>>>WWW.PensacolaTVRepair.Com
> >>>>
> >>>>850-456-5995 voice
> >>>>850-458-6369 fax
> >>>>
> >>>>
> >>>>AL LEATHERMAN wrote:
> >>>>
> >>>>
> >>>>>Thajnks Damon!
> >>>>> NOW: Does anybody know if digital is highly directional? I would
> >
> > say
> >
> >>>>>no,but what do I know?
> >>>>>
> >>>>>Al's TV
> >>>>>Mine Hill, NJ. 07803
> >>>>>972-361-5796
> >>>>>WWW.ALS-TV.NET
> >>>>>----- Original Message -----
> >>>>>From: "Damon" <damoneb@xxxxxxxxxxx>
> >>>>>To: <techassist@xxxxxxxxxxxxx>
> >>>>>Sent: Thursday, September 15, 2005 6:03 AM
> >>>>>Subject: [TechAssist] Re: Fw: Are onidirectional antennas any
> >
> > good(roof)
> >
> >>>>>
> >>>>>
> >>>>>
> >>>>>>For those "Philly" stations consider a Yagi or
Parabolic.....generally
> >>>>>>the
> >>>>>>gain on those are 7 to 10 db....look up "Yagi Parabolic antenna
gain"
> >
> > on
> >
> >>>>>>Google. The Yagi is highly directional....normally has a 15 degree
> >
> > lobe
> >
> >>>>>>for
> >>>>>>reception, great if you have all your TV stations located on the
same
> >>>>>>side
> >>>>>>of town like Fort Wayne does......
> >>>>>>Helps to limit reflections in closer areas...but with Digital
> >>>>>>transmission
> >>>>>>does that really matter?
> >>>>>>
> >>>>>>Damon B
> >>>>>>Telrad Electronics
> >>>>>>Fort Wayne IN
> >>>>>>----- Original Message -----
> >>>>>>From: "AL LEATHERMAN" <alleathe@xxxxxxxxxxx>
> >>>>>>To: <techassist@xxxxxxxxxxxxx>
> >>>>>>Sent: Wednesday, September 14, 2005 2:13 AM
> >>>>>>Subject: [TechAssist] Re: Fw: Are onidirectional antennas any
> >
> > good(roof)
> >
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>>Thanks Al.
> >>>>>>>
> >>>>>>>Al's TV
> >>>>>>>Mine Hill, NJ. 07803
> >>>>>>>972-361-5796
> >>>>>>>WWW.ALS-TV.NET
> >>>>>>>----- Original Message -----
> >>>>>>>From: "Al Gutz" <alg@xxxxxxxxxxx>
> >>>>>>>To: <techassist@xxxxxxxxxxxxx>
> >>>>>>>Sent: Tuesday, September 13, 2005 9:31 PM
> >>>>>>>Subject: [TechAssist] Re: Fw: Are onidirectional antennas any
> >
> > good(roof)
> >
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>>Al
> >>>>>>>>When talking antenna gain omni is still a joke. If it has good
> >>>>>>>>compression of vert lobe you may get a 1 or 2 db gain, about the
> >
> > same
> >
> >>>>>>>>as
> >>>>>>>>a rabbit ears mounted on the roof.
> >>>>>>>>If you are going basicly 2 directions use a low gain for closer
> >
> > stuff
> >
> >>>>>>>>and higher gain for longer haul, join with a coupler. If looking
for
> >>>>>>>>stations in several directions look at a rotor.
> >>>>>>>>
> >>>>>>>>Al G
> >>>>>>>>
> >>>>>>>>AL LEATHERMAN wrote:
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>>Sent: Tuesday, September 13, 2005 10:45 AM
> >>>>>>>>>Subject: Are onidirectional antennas any good(roof)
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>>>Omnidirectional used to be a joke, a bad one.Has technology
> >>>>>>>>>>improved,as
> >>>>>>
> >>>>>>I
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>>>>>am 35 miles from NYC,about 90 miles from Philly. Sounds too good
> >
> > to
> >
> >>>>>>>>>>be
> >>>>>>>>>>true. al L
> >>>>>>>>>>
> >>>>>>>>>>Al's TV
> >>>>>>>>>>Mine Hill, NJ. 07803
> >>>>>>>>>>972-361-5796
> >>>>>>>>>>WWW.ALS-TV.NET
> >>>>>>>>>
> >>>>>>>>>
>
>>>>>>>---------------------------------------------------------------------
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