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Re: [Discuss-gnuradio] Mode-S/ADS-B and UAT
From: |
DOHA |
Subject: |
Re: [Discuss-gnuradio] Mode-S/ADS-B and UAT |
Date: |
Sun, 17 Apr 2011 23:57:58 -0700 (PDT) |
hello eric
i was searching for your mode s ads b code in gnu radio so pleas can you
send it to me .
cheers
doha
Eric Cottrell wrote:
>
> Hello,
>
> I was emailed by a few people off list that are interested in the
> Mode-S/ADS-B code. I am still working on it.
>
> I got the DPD Productions antenna just before Thanksgiving, but it was too
> windy to put up right away. Sitting on the first floor in the middle of a
> wood frame house, the antenna was picking up aircraft from 40 to 140 miles
> away depending on direction. I could not see low altitude aircraft to the
> south of the nearest busy airport, which is eight miles south. 44 feet
> above the ground on my roof is a different story and I can see aircraft
> from 150 to 210 miles depending on direction. Although the DPD antenna is
> higher gain, I do not get the same level of interference as the colinear.
> The DPD antenna is suppose to be a narrow bandwidth antenna. I tried the
> wideband preamp with the DPD antenna and had the same problem with the
> noise floor rising and decreasing range.
>
> I bought a SBS-1 last week. It is a commercial Mode-S/ADS-B receiver that
> is smaller than the USRP. The sensitivity seems slightly better. It
> could handle the wideband preamp better with just a slight decrease in
> range. I am currently working on providing a port 30003 compatible output
> for my receiver. Then I can use Planeplotter and can compare my code to
> the SBS-1.
>
> My nearby major airport has a ASDE-X system for monitoring aircraft and
> vehicles on the airport surface. It appears they are installing an ADS-B
> Multilateration system as I get a couple of the sensors. They use DF18
> (Non-Transponder Extended Squitter) and just send an ID and
> Multilateration status. Two of them ID as STEST123 with the category of
> Fixed Ground/Tethered Obstacle. The third recently appeared with an ID of
> PTEST123. The SBS-1 also picked up the IDs so it can decode at least some
> DF18 formats.
>
> I want to do a UAT receiver and was planning a trip to Philly to look at
> the TIS-B/FIS-B ground segment transmissions. I got a surprise when I
> found out the New England area has TIS-B/FIS-B services. Someone did a
> demo of a receive only system. The TIS-B service only transmits if there
> is a ADS-B aircraft using UAT in the area. Being able to receive TIS-B
> would be good because it includes non-ADS-B aircraft. There is also
> cross-linking of UAT and Mode-S so ADS-B aircraft on Mode S ADS-B should
> show up on UAT.
> http://www.youtube.com/watch?v=NmYrUGxRC88
>
> It is an iPhone application using a separate UAT receiver costing $1100.
> http://www.skyscope.net/
>
> I looked at the 978 MHz UAT frequency and think I see the signal but it
> does not completely match up with the specifications. The system uses
> slightly over 1 megabit per second FSK with a over 600K shift. I see what
> looks like the mark frequency, but instead of the space frequency I get
> another signal at the center frequency (978.0 MHz). If I use a simple PLL
> FM detector flow graph with a scope sink I do see what looks like a
> bitstream. The current plan is to get my laptop updated and setup, then
> go mobile. I suspect there is a transmitter at a nearby airport.
>
> 73 Eric
>
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>
>
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