
A homemade receiver for GPS and GLONASS satellites - brian-armstrong
http://lea.hamradio.si/~s53mv/navsats/theory.html
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aw3c2
This is the internet I know and love. Pure content created by someone loving
what they are doing. No bullshit blingbling, no ads, no tracking, just sharing
experiences and knowledge. Wonderful and inspiring!

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brian-armstrong
Well, to be fair, this article is from the 90s. It's probably just a
reflection of the times it was made in.

~~~
sasas
Also a possible reflection on this fact; the site may not have been designed
to handle the influx of traffic we just sent it from HN as it's now
unreachable. Here is the archive.org mirror:

[https://web-beta.archive.org/web/20161109161053/http://lea.h...](https://web-
beta.archive.org/web/20161109161053/http://lea.hamradio.si/~s53mv/navsats/theory.html)

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ohazi
That helical antenna is gorgeous.

There's a similar project that used an FPGA here:
[http://www.aholme.co.uk/GPS/Main.htm](http://www.aholme.co.uk/GPS/Main.htm)

~~~
nateguchi
That must be one of the most professional looking electronics DIY project I've
seen for a while.

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NelsonMinar
Archive link: [http://archive.is/AMNvJ](http://archive.is/AMNvJ)

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iaw
FYI, The technology detailed on that page is governed by ITAR for US citizens.
You can end up facing some serious penalties if you are a US citizen and build
a GPS receiver (capable of operating > 10,000 feet) for someone in another
country.

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mikeyouse
They relaxed the ITAR restrictions on GPS quite a bit a few years ago. The new
rules only involve decryption of the precise positioning signals, steerable
antennas designed to avoid jamming, and GPS designed as missile guidance
technology (ability to deliver 500kg payload at least 300km).

[http://www.insidegnss.com/node/4051](http://www.insidegnss.com/node/4051)

~~~
LeifCarrotson
Additionally, the previous restrictions specified they were to be inoperable
when BOTH above 18,000m altitude (not 10,000 ft) AND 515 m/s velocity.

Many manufacturers accomplished this by restricting operation when either
condition was sensed, but you could find some that could be used in
applications that only violated one condition, like high-altitude balloons.

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ams6110
So does that mean my phone's GPS won't work in flight on a commercial
jetliner? (never tried it).

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fnj
Commercial jetliners never fly at 18,000 m (nor at 515 m/s). Max is about
11,000 m or so, and about 250 m/s. It would be interesting to know if consumer
GPS ever worked aboard the Concorde.

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knz
If you're going to use the Concorde for a speed test then you might as well
also test the SR-71. For..er... science!

~~~
DiabloD3
The story: [http://oppositelock.kinja.com/favorite-
sr-71-story-107912704...](http://oppositelock.kinja.com/favorite-
sr-71-story-1079127041)

Merry Christmas to everyone who hasn't read it yet.

~~~
sitic
This one is my favorite story from the same Blackbird pilot (Brian Shul):
[https://www.reddit.com/r/todayilearned/comments/2q2ctc/til_t...](https://www.reddit.com/r/todayilearned/comments/2q2ctc/til_that_the_sr71_blackbird_was_so_fast_that_a/cn26i0z/)

Bonus story, also from Brian Shul:
[https://www.reddit.com/r/MilitaryPorn/comments/1mimvu/80000_...](https://www.reddit.com/r/MilitaryPorn/comments/1mimvu/80000_ft_where_the_wild_blue_yonder_meets_the/cc9ze0p/)

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drmpeg
Modern day technique with SDR.
[https://www.youtube.com/watch?v=uf2vatqek_o](https://www.youtube.com/watch?v=uf2vatqek_o)

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Sephr
Does anyone have a mirror including
[http://lea.hamradio.si/~s53mv/navsats/software.zip](http://lea.hamradio.si/~s53mv/navsats/software.zip)
?

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jakeogh
[https://web-beta.archive.org/web/20160322050334/http://lea.h...](https://web-
beta.archive.org/web/20160322050334/http://lea.hamradio.si/~s53mv/navsats/software.zip)

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dharma1
For affordable and small high precision (centimeter level) GNSS, I really like
this [https://emlid.com/reach/](https://emlid.com/reach/)

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prashnts
Can anyone suggest a good textbook for Radio, Antenna theory, Ham radio in
general?

I'm quite interested in learning these but most books I've come across either
seem too basic, or too advanced. I am a math major so mathematics isn't a
problem for me if it is supported with enough text. Thanks!

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b_emery
The Radar Handbook by Merrill Skolnik often comes up as a basic reference
covering some of these topics, radar and radio being intimately related. Plus
the pdf is usually around:
[http://airspot.ru/book/file/961/radar_handbook.pdf](http://airspot.ru/book/file/961/radar_handbook.pdf)

~~~
dfc
> Plus the pdf is usually around

It's a bonus that you don't have to compensate the creator of a useful
product?

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wolfgke
Freedom does not imply free beer and vice versa.

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dfc
What are you talking about? I think you might have replied to the wrong
comment. The suggested book is not under a libre license.

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the_duke
Pft, no Galileo support? Just pathethic...

(Kidding of course. Awesome write-up.)

