[amsat-bb] What on earth (or in space...) is going on?

[Scott]

I would certainly be interested in learning how to utilize the higher frequencies without spending a fortune.

In that spirit, sure would appreciate it if the mentions of known-good hardware from Amazon & eBay could include links to the particular items.

Thanks!

-Scott, K4KDR
Montpelier, VA  USA


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  ----- Original Message ----- 
  From: Mike Seguin 
  To: amsat-bb at amsat.org 
  Sent: Monday, December 28, 2015 05:58
  Subject: Re: [amsat-bb] What on earth (or in space...) is going on?


  Hi Tom,

  I have a GPS locked 10 GHz beacon on Mt Mansfield here in Vermont and I 
  use the exact setup to monitor it.

  I use an old DSS dish and a $7 LNB plus a FunCube. IF frequency is about 
  617 MHz for the 10,368.320 beacon.

  I just looked on eBay and the LNB I use is there for $6.95 plus free 
  shipping.

  Mike

  On 12/28/2015 5:00 AM, Tom Clark wrote:
  > A related thread has been running on QRZ.com where I just posted this
  > comment:
  >
  >>     To all those who have been bewailing the fact that the microwave
  >>     technology needed to use the P4B digital GEO satellite let me
  >>     offer a couplke of comments. I preface this by saying I am a part
  >>     of both the AMSAT and VT "factions:".
  >>
  >>     All of you are making the mistake in believing that the 10 GHz
  >>     downlink will be complicated and expensive. Au contraire!
  >>
  >>     How many of you have a 20 to 40 inch dish you use to watch TV?
  >>     Well, the downlink that DirectTV uses is well up in the microwave
  >>     spectrum in Ka band, at about 12 GHz. Many of the other TV
  >>     satellites operate at ~11 GHz. Hams in several parts of the world
  >>     have found that the feed used in these dishes (called an LNB)
  >>     consists of a good feed (designed to work with the small offset
  >>     dishes) coupled to a HEMT Low-Noise Amplifier (don't believe the
  >>     advertising -- the Noise figure is closer to 1 Db and not the 0.1
  >>     dB the vendors claim). The LNA feeds a crystal-controlled down
  >>     converter which, off the shelf, makes the IF come out around 700
  >>     Mhz. I can go on Amazon, Ebay or Alibaba today and purchase a dish
  >>     plus a full LNB plus some dish mounting hardware plus 100 ft of
  >>     low-loss (foam) 75 ohm coax and have it delivered to my house for
  >>     less than $100.
  >>
  >>     The ~700 MHz IF can plug into a $200-300 RX SDR which converts the
  >>     ~10 MHz wide downlink into usable signal channels. Instead of
  >>     tuning an analog frequency dial, you will select an appropriate
  >>     channel to listen to your buddies. Or you can feed the SDR into
  >>     your local VHF/UHF LAN where you can user your existing HT. If you
  >>     are a skeptic about using the TVRO hardware in the amateur world,
  >>     I'll note that just such hardware has successfully copied the DL
  >>     10GHz EME beacon in San Diego using a DVB Dongle+a laptop as the
  >>     receiver.
  >>
  >>     What I described was the downlink side. The ~6 GHz uplink will
  >>     require the addition of a 1-5W PA, a small (probably array of
  >>     patches) with the TX side of an SDR and an upconverter from
  >>     whatever IF your SDR can generate to 6 GHz. The C-band TX should
  >>     cost under $500-$600 with the bulk of the cost in the SDR and TX PA.
  >>
  >>     If you add up the RX and TX hardware, the tariff is less than the
  >>     price of an FT-1200 or KX-3, i.e. under $1000. We are working hard
  >>     to meet this goal since it meets FEMA requirements for portable
  >>     first responder "Go Boxes" to cover the need during major
  >>     disasters (Katrina, tsunamis, earthquakes) for reliable
  >>     communications in the first 24-96 hours. The ARRL and FEMA have an
  >>     agreement to have a hundred such "Go Boxes" (which also includes
  >>     suitable portable radios to augment whatever local resources exist).
  >>
  >>     For those of you who want to use "conventional" modes our current
  >>     plans call for a ~100 kHz wide LINEAR C/X-band transponder. I note
  >>     (with pride) that I have figured out how we can have a LINEAR
  >>     transponder built on RX software running the "main" payload and
  >>     getting a LINEAR ANALOG output from a hard-limiting digital PA.
  >>     Using the linear transponder will require you to have a bit
  >>     antenna/TX power, but it will be there as a challenge!
  >>
  >>     For all the nay-sayers please realize that AMSAT is trying to make
  >>     a miracle happen. We need financial, moral and technical support.
  >>     The "Space Biz" of today is radically different from what it was
  >>     when NASA and ESA were launching their own rockets and when AMSAT
  >>     was able to get sympathy for a bunch of "Space Cadets".
  >>
  >>     73 de Tom, K3IO (ex W3IWI)
  >>
  >>
  >
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  -- 

  73,
  Mike, N1JEZ
  "A closed mouth gathers no feet"
  _______________________________________________
  Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
  to all interested persons worldwide without requiring membership. Opinions expressed
  are solely those of the author, and do not reflect the official views of AMSAT-NA.
  Not an AMSAT-NA member? Join now to support the amateur satellite program!
  Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb