[TechAssist] Re: Fw: Are onidirectional antennas any good(roof)
- From: "J Silverman" <greentron@xxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Sat, 17 Sep 2005 15:21:42 -0400
Years ago we used to get brochures from a place in Texas called Tucker
Electronics that rented all sorts of electronic instruments. They also
refurbish, calibrate, and sell them. Lots of government contracts for the
manufacture of even small numbers of instruments or circuit boards spell out
exactly what instruments must be used for testing and calibration so it was
common for the contractors and subcontractors to just rent the equipment
needed for the job. There are probably quite a few places that rent the same
sort of equipment.
Jerry Silverman
Greentron Inc
4 Newland Ave
Greenville SC 29609
Fax/Phone 864 232 3889
mail to: greentron@xxxxxxx
----- Original Message -----
From: "Damon" <damoneb@xxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Friday, September 16, 2005 6:46 AM
Subject: [TechAssist] Re: Fw: Are onidirectional antennas any good(roof)
> 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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