[TechAssist] Re: Fw: Are onidirectional antennas any good(roof)
- From: "Hoyt's TV" <hoytstv@xxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Fri, 16 Sep 2005 15:53:07 -0400
So did you end up with the spectrum analyzer?
Russ Hoyt
Hoyt's TV
Exeter, NH
----- Original Message -----
From: "Wayne Vanaman" <Wayne@xxxxxxxxxxxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Friday, September 16, 2005 1:46 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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