[time-nuts] How hard is it to detect a GPS Jammer?

[J. Forster]

On spacecraft hardware, even though something is a bit old, it does make
sense to use it.

Space qualifying a piece of hardware is very, very expensive, because it
requires a lot of shake and bake plus thermal vaccuum and other things.

Furthermore, there are always unknowns.

Do YOU really want to see a Billion dollar mission go wrong, because you
used a new, unproven, design of Cammand Receiver or Sequencer?

In my view, if you are going into the unknown, you want to use the best
available, tested and proven, stuff you can get whereever you can.

Remember, many of the launch vehicles still used were made in the 1950s or
1960s, and sat in a missile silo somewhere, as ICBMs for 30+ years. Until
fairly recently, the Atlas used sub-mini vacuum tubes.

I'm not against inovation, but it's not necessarily about saving a few
bucks when older gear is used.

YMPV,

-John

=======================




> On 10/7/13 7:46 AM, Collins, Graham wrote:
>>
>> Indeed, the inexpensive DVB-T dongles are showing up in many places
>> including as David noted, decoding GPS.
>>
>>
>> The AMSAT Fun Cube Dongle is a very capable and interesting device.
>> Interestingly it uses the same Elonics E4000 front end chip that many
>> of the inexpensive DVB-T devices do. Apparently Elonics is no longer
>> in business and the inexpensive DVB-T devices using this chip are
>> becoming less common. The DVB-T devises using the R820T chip are
>> becoming the preferable versions when those with the E4000 cannot be
>> found. I wonder if the Fun Cube Dongle will be likewise changed
>> (perhaps it already has).
>>
>
> This illustrates is the fundamental problem with leveraging cheap
> consumer or government surplus gear.  The hacker community moves much
> slower than the commercial one, so you wind up with projects requiring
> things that are no longer sold.  It's particularly endemic in the
> amateur radio community where we are always repurposing something that
> hasn't been made for 30 years.  But it makes it hard for the new
> entrant, who doesn't have a box full of old MASTR-II VHF radios or Bell
> 202 modems or whatever sitting around.
>
> But the existence of that gear in some folks's garages tends to ossify
> the development.  How many Bell 202 modems are still in use? But VHF
> packet radio is 202 compatible, because every product made for the last
> 30 years was compatible with the 202.  Not because it's inherently good,
> but because you want to be compatible with the other people, and there's
> a sort of rolling compatibility.
>
> (Amateur radio is not the only instance of this. The Scientific
> Spaceflight community is the same.  We love to use spares from previous
> missions to reduce costs, but that brings along the need to be
> compatible with the interfaces of those spares.  As a result,
> MIL-STD-1553B Notice 2 or Notice 4 is still used on spacecraft, even if
> it's not the most appropriate, lowest power, etc.)
>
>
> For a particularly interesting example, look at the plethora of versions
> of the WRT-54G WiFi router popular with hackers; there's about 50
> versions listed on the DD-WRt website.  Some of he versions  are
> amenable to dropping in a new OS and/or software, others are not, and
> still others are "modifiable" (as in cutting traces, soldering, adding
> parts and/or connectors) to put in new software.
>
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