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Author Topic: Enhancements to LiveATC receive site in Harvard, MA  (Read 13840 times)
dave
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« on: April 19, 2009, 11:05:16 AM »

I have access to a location (and tower) in Harvard, MA that I use to run some of the Boston, MA area LiveATC feeds.   Yesterday I removed the discone antenna that I had up at 30' (above ground) and installed a DPD Productions dual-band (VHF/UHF) antenna up at the 100' (above ground) level on the tower.  The owner of the tower has spare runs of Heliax (low-loss hardline cable) and the ATC antenna is hooked to one of those runs of cable.  I didn't bring a camera up there but the view from the 100' level of the tower is phenomenal.  The site is located on top of a decent hill.

So we now have enhanced coverage for the following feeds:
KBED - Bedford/Hanscom Field
Boston Approach - North Satellites (124.4)
KLWM (new feed) - Lawrence, MA  (Fitchburg, MA UNICOM is now on this feed as well)
ZBW GDM/CON Sectors (Gardner, MA)
KORH - Worcester, MA (+Bradley Approach 119.0)
ZBW High (aircraft only, misc ZBW high alt freqs)

The difference in reception between the 30' and 100' level is striking (no surprise).  We can now hear most of the aircraft on the ground at Bedford, Lawrence, and Worcester.

There is an interference issue on the ZBW GDM/CON feed which is caused by one of the other scanners in the stack.  That will hopefully be cured some time next weekend.  When you have more than four scanners, sometimes it is possible to get local oscillator or clock leakage/radiation - should be easily fixed by swapping in a different (model) receiver.  The interference is primarily affecting reception on 134.700 (not 123.750).

Attached is a camera phone picture of the ATC antenna - you can make it out right below the top set of guy wires.

Enjoy.

-Dave

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smeuse
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« Reply #1 on: April 20, 2009, 12:48:12 PM »


That's a whole lotta aluminum Smiley

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Biff
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« Reply #2 on: April 20, 2009, 01:38:57 PM »

You climbed 100' up that thing??

Wow  Smiley
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Eleventeen
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« Reply #3 on: April 24, 2009, 12:34:54 AM »

Heh antennae porn.
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Joseph Alexander
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« Reply #4 on: May 11, 2009, 04:48:31 PM »

Could you tell us what the other antennae are for?  I'm an ex-ham and an EE, so all that stuff in the photo caught my eye.  Looks very fixed freq, point to point, I would guess.
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Squawk 7700
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« Reply #5 on: May 14, 2009, 03:57:24 PM »

Wow, this is nice Dave!  grin
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Feeder:
KHWD Ground/Tower
KOAK Del/Gnd/Twr
KSFO NORCAL App Rwy 28L/R
KSFO Tower/Ground
NORCAL Approach (KOAK)
NORCAL Departure (KSFO/KOAK)
KSJC NORCAL Approach #2
ZOA Oakland Center (35/40/41)


RJTT App/Dep
RJTT Tokyo Control
RJTT Twr/TCA
dave
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« Reply #6 on: May 17, 2009, 09:28:05 PM »

Could you tell us what the other antennae are for?  I'm an ex-ham and an EE, so all that stuff in the photo caught my eye.  Looks very fixed freq, point to point, I would guess.

The rest of the antenna are rotary and fixed monoband HF Yagis, spread across two towers.  They are used for HF contesting.

Dave
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Joseph Alexander
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« Reply #7 on: May 18, 2009, 07:17:11 PM »

Thank you, Dave, for the antennae descriptions.  The lack of taper in the elements of the yagi antennas told me they were narrow band.  And I even know what contesting is!  But I failed to note that some were on rotors.  I'll go back and have another look.

On another matter, could you please tell us why is it that you cannot copy the ground xmissions from ZBW?  I would imagine that they use quite directional radiators, pointed upward, but at your QTH I would have expected enough to leak from a side lobe of what I suspect is a rather near xmitter to open your squelch.  Are these in the HF range, or VHF freqs?

I much enjoy what I am learning here.  Thanks to you and to all who contribute feeds.
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dave
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« Reply #8 on: May 26, 2009, 05:11:57 PM »

Thank you, Dave, for the antennae descriptions.  The lack of taper in the elements of the yagi antennas told me they were narrow band.  And I even know what contesting is!  But I failed to note that some were on rotors.  I'll go back and have another look.

On another matter, could you please tell us why is it that you cannot copy the ground xmissions from ZBW?  I would imagine that they use quite directional radiators, pointed upward, but at your QTH I would have expected enough to leak from a side lobe of what I suspect is a rather near xmitter to open your squelch.  Are these in the HF range, or VHF freqs?

I much enjoy what I am learning here.  Thanks to you and to all who contribute feeds.

If you think those are cool, go check out the KC1XX Web Site.  I helped put a lot of that together.

On ZBW...the transmitters are spread far and wide.  So unless a receiver is near one of those transmitters, you only hear one side.  Right now this is only true of a couple of the ZBW feeds.  The GDM/CON feed gets the ground transmitters fine as does the CAM receiver.  ZBW is all VHF.  They use UHF for military.

Hope this helps.

Dave

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Joseph Alexander
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« Reply #9 on: May 27, 2009, 08:21:34 PM »

Thanks for the reply.  I do know about military use of UHF freqs, in a band that is just about double the VHF  freqs, if memory serves me.  Such as 121.5 and 243.0, again if memory serves.  But I though a good deal of oceanic traffic was HF, and I thought still was.  VHF does not go that far, even if one side is at 40,000 feet.  And I thought that some of ZBW comms dealt with Atlantic traffic. 

I know I have listened to aircraft directly, many years ago, reporting from mid-ocean at several bands in the HF region.  I also remember listening to wx voice from a series of xmitters in round robin fashion, for something like 10 minutes each, covering an hour.  I seem to remember one was at 3001 kHz.  I even remember that the NY guy had a very gravelly voice, and that his chair would squeak every once in a while.  I could imagine him sitting in a little room, reading the reports, probably every six hours or so. 

Then you would hear a Canadian station, and sometimes somebody on the other side of the pond, reporting wx from a standard group of airports.  It is my memory that there were about 4 to six stations in the group, and that there were simultaneous broadcasts on several freqs.  I sometimes did this listening on a research vessel somewhere in the North Atlantic, to pass the night watch hours.  I did not know where some of the reporting stations were, and would then get to the charts, trying to match the names I would hear with wx stations all around the North Atlantic.  Part of my misspent youth.

I made a quick stop at KC!XX and will spend more time there, after I get this off.  Good to talk, and thanks for the whole idea behind liveatc.net.  I have learned a lot.  73
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