(meteorobs) ICOM PR1000 + FM Antenna on Channel 6 = No resultsyet
siddhartha at siddharthajain.net
Tue Jun 12 04:21:13 EDT 2007
Ok, I have installed a new TV antenna (Channel Master 3018) and its
now set an angle of ~45 degrees due south-east towards Santa Barbara
(I am in Santa Clara, CA).
The splitter is gone and the scanner is set at 87.750Mhz (Channel 6
audio) on the WFM mode (230khz filter). I am listening to crickets at
the moment and leaving the setup to record the activity thru dawn. I
checked others channels 2, 4 and 5 with this setup and was able to
hear the audio.
Not too hopeful about this setup because if it worked I should've
atleast heard something in a few minutes of listening but I am willing
to give it a shot for tonight.
On 6/11/07, stange34 at sbcglobal.net <stange34 at sbcglobal.net> wrote:
> My take on this URL is that their site is central to a circular array of
> channel 6 transmitters almost all equally distant. Under that condition it
> is possible there is no PREFERRED direction to aim the antenna to receive
> all of the stations reflected signals equally....
> (But I do have a problem with that personally). I would not aim vertical,
> especially with 1 or 2 stations in a specific direction, because it covers
> only an area overhead whereas an aiming point lower toward those 1 or 2
> stations would cover a longer distance & a larger section of the sky area
> tho' the signal strength would be diminished from the greater distances. But
> that is open to experimentation.
> Apparently the receiver has selectable upper and lower offset. They appear
> to be using the negative(?) side and about 700 Hz offset. I am not clear as
> to why they think the doppler effect is occuring in only one direction when
> it could occur with the meteor going away or approaching. Approaching would
> give a stronger signal might be their thinking.
> Anyway maybe someone else has better info. I am doing a lot of second
> guessing here.
> ----- Original Message -----
> From: "Siddhartha Jain" <siddhartha at siddharthajain.net>
> To: "Global Meteor Observing Forum" <meteorobs at meteorobs.org>
> Sent: 2007/06/11 15:07
> Subject: Re: (meteorobs) ICOM PR1000 + FM Antenna on Channel 6 = No
> > On 6/11/07, stange34 at sbcglobal.net <stange34 at sbcglobal.net> wrote:
> >> Not sure what you are doing now.
> >> I thought you were interested in the FM band.
> > Yes, I started with that but after discovering that the FM range is
> > completely cluttered in my area, I was forced to give up on it.
> >> Channel 6 if it is in the frequency of 83 mhz is far below the maximum
> >> gain
> >> frequency of the FM-6.
> >> The URL data I sent you earlier shows an increasing LOSS of antenna gain
> >> at
> >> the low end of the FM band(88 mhz) with a FM-6.
> >> You are operating apparently well below the antenna's FM design.
> > That is what I understood as well but being a newbie with radio-stuff,
> > I just wanted to confirm that it is the antenna that seems to be the
> > biggest culprit here.
> >> Not sure why you have a "splitter" in the system. Splitters decrease
> >> signal
> >> strength
> > Yes, will remove that. The split was feeding the FM radio. But that's
> > no longer required and can go away.
> >> The CW filter should probably be set toward 15Khz. The 2.8Khz (3.0) may
> >> be
> >> too narrow for the audio spectrum of meteors. Not sure myself of where
> >> the
> >> meteor sound spectrum is most prevelant. Others may know.
> > I tried to find the URL earlier before posting this message but
> > couldn't find it. Here it is now the reason I chose the CW mode with
> > the 3khz default filter.
> >>From http://www.spaceweather.com/glossary/nasameteorradar.html
> > "The antenna we use [pictured left] is a 6-element Yagi; it is a
> > commercially available cut-to-frequency channel 4 TV antenna sitting
> > on the ground and pointed straight up," says Dr. Rob Suggs of the MSFC
> > Engineering Directorate. "We use the CW demodulator on our Icom
> > PCR-1000 so that 67.250 MHz (channel 4 zero offset) appears at about
> > 700 Hz. This also inverts the passband so that the doppler shift of
> > meteor echoes is reversed (frequency increases rather than decreases
> > to the 'zero' frequency of the trail echo). The filter is set to 3 kHz
> > bandwidth and the AGC is turned off."
> >> I assume from your language the antenna is not truly straight up, but is
> >> aimed at a distant zenith(60 miles up), MID-WAY between you and the
> >> transmitting station.
> >> I do not engage in RF meteor detection so this is ONLY my opinion of the
> >> whole thing you are doing.....
> > Thanks for your comments, Larry.
> > - Siddhartha
> >> ----- Original Message -----
> >> From: "Siddhartha Jain" <siddhartha at siddharthajain.net>
> >> To: "Global Meteor Observing Forum" <meteorobs at meteorobs.org>
> >> Sent: 2007/06/11 12:59
> >> Subject: (meteorobs) ICOM PR1000 + FM Antenna on Channel 6 = No results
> >> yet
> >> > Hi,
> >> >
> >> > My setup:
> >> > A Radioshack FM-6, connected to a RG6 cable via a 300-to-75ohm
> >> > transformer, into a splitter, then connected to a ICOM PR1000 with a
> >> > RG59 cable and F-to-BNC connector. The antenna points almost straight
> >> > upward towards the zenith/south (There are a couple of Channel 6
> >> > stations located southwards in Santa Barbara and San Diego)
> >> >
> >> > The PR1000 is tuned to 83.25Mhz (Channel 6) and set on CW mode (filter
> >> > 3khz). The audio output goes into the soundcard of a pc and recorded
> >> > thru audacity.
> >> >
> >> > So far all I have is a straight line when I look at the waveform of
> >> > the recorded audio.
> >> >
> >> > Any suggestions to improve my chances of observing meteors? Or am I
> >> > missing something here? Do you think its absolutely necessary to
> >> > upgrade to a TV antenna for this purpose?
> >> >
> >> >
> >> > Thanks,
> >> >
> >> > - Siddhartha
> >> > ---
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> >> >
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