Just found out that the 2MB card we've all been using to update our GX
55, 60's etc will *not* work for the next data update. Jepp (to its
credit) will *give* you a new 4mb card in return for your old one, but
*act fast* since they are overwhelmed with requests and the deadline is
fast approaching.

Considering that the update begins on the 21st (aka tomorrow), and
given the Christmas rush, I suspect I will not be able to get a new
card from them by Thursday. {:<(

Considering that those cards have been obsolete for at least 10 years,
it's not surprising that they are having trouble finding a supply.

wrote:
> Just found out that the 2MB card we've all been using to update our GX
> 55, 60's etc will *not* work for the next data update. Jepp (to its
> credit) will *give* you a new 4mb card in return for your old one, but
> *act fast* since they are overwhelmed with requests and the deadline is
> fast approaching.

Hmmm... I don't think this is as much an "emergency" as you make it
sound. I called them as soon as I read this post, and they basically
said "sure, we'll send it right out". I specifically asked the guy about
the 2MB to 4MB change, and he said it wasn't a big deal. He didn't sound
overwhelmed.

--- Jay


--
__!__
Jay and Teresa Masino ___(_)___
http://www.JayMasino.com ! ! !
http://www.OceanCityAirport.com
http://www.oc-Adolfos.com

wrote:
> Just found out that the 2MB card we've all been using to update our GX
> 55, 60's etc will *not* work for the next data update. Jepp (to its
> credit) will *give* you a new 4mb card in return for your old one, but
> *act fast* since they are overwhelmed with requests and the deadline is
> fast approaching.
>
Both of my cards are already 4 MB. I didn't even know that they ever
used 2 MB cards.

wrote:
> Just found out that the 2MB card we've all been using to update our GX
> 55, 60's etc will *not* work for the next data update. Jepp (to its
> credit) will *give* you a new 4mb card in return for your old one, but
> *act fast* since they are overwhelmed with requests and the deadline is
> fast approaching.

I have 4MB cards so I am fine but I find it amazing that they can get
what they need on the 4MB cards let alone the 2MB cards. That must be
some amazing algorythm.

Steven Nichols
N501AC
GAI

In article . com>,
wrote:

> wrote:
> > Just found out that the 2MB card we've all been using to update our GX
> > 55, 60's etc will *not* work for the next data update. Jepp (to its
> > credit) will *give* you a new 4mb card in return for your old one, but
> > *act fast* since they are overwhelmed with requests and the deadline is
> > fast approaching.
>
> I have 4MB cards so I am fine but I find it amazing that they can get
> what they need on the 4MB cards let alone the 2MB cards. That must be
> some amazing algorythm.

Here's some back-of-the-envelope numbers for the database size.

The biggest part of the database is the waypoints. I've got a two year old
copy of the ATA-100 database which lists about 36,000 fixes. The raw data
file the FAA distributes is in an exceptionally verbose text format. It's
about 51 meg, but gzips down to about 1.5 meg.

If you throw away extraneous data, you can do a lot better than that. Each
fix has a 5-character name, from a alphabet of 26 letters and 10 digits, or
under 6 bits per character, so the name fits in 4 bytes.

The fix positions are recorded in the database to 0.001 arc seconds lat &
long, but at first glance, it appears all the last digits are 0, so there's
really 8 decimal digits of resolution on each axis. At a little over 3
bits per digit (plus a sign bit for E/W, N/S), that's maybe 50-couple bits
for the location. With a little clever work (break it up into zones and
store each coordinate as an offset from the zone origin), you can probably
get it down to 6 bytes per fix.

Add in another couple of bytes for random status information about the fix,
and you're up to 12 bytes per fix. Times 36,000 fixes is a little under
1/2 meg of data for the fixes.

Of course, you need airport info, VOR/ILS info, need to tie the fixes
together into approaches (but not, in the GX series, airways), etc, but
it's not hard to imagine packing it all into 2 meg with careful data
packing.

Of course, those boxes were designed back when 2 meg on a card was a lot.
These days, you can get a 128 meg memory stick at Staples for $29 (make
that $1500 with the TSO paperwork).

I just spoke to a very nice lady at Jeppesen and she promised to call
me back as soon as their computers were up and running again. The
implication was that she would exchange my card for a 4 MB one. I did
ask her (nicely) why, given what we pay for the subscription, and given
that they have our shipping, billing, and e:mail addresses, why
Jeppesen couldn't be bothered to at least send out an e:mail to let us
know about the problem - rather than find out at the last minute (the
new database is effective today). Especially would this have been nice
since otherwise most of us are going to be traveling this Christmas
with an expired database in our IFR GPS.

Her answer was that this was a very good question.

jmk