<DocScrutinizer05>
you hardly can find much better for sat communications
<DocScrutinizer05>
well, their phones are allegedly 2 days standby
<DocScrutinizer05>
but then I wonder what "standby" means for a device that requires unfolding and extending the antenna before it can enter active mode
<DocScrutinizer05>
generally sat phones are not really meant to _receive_ calls
<DocScrutinizer05>
so you could guess like: battery capacity ~4Wh, 6-8h of standby without proper deep-sleep => 0.5W
<DocScrutinizer05>
no need for a crystal heating to burn power ;-)
<eintopf>
I remember my old smartphone, when I did to turn on the GPS it was extremely hot
<eintopf>
and my current smartphone, when it's hot _or_ cold then touchscreen doesn't work
<DocScrutinizer05>
wl1251 wlan chipset in AP scan mode (which forbids any powersaving (aka deepsleep) mode) also is known to be a terrible power hog
<eintopf>
I think, I need a neo900
<DocScrutinizer05>
hurry, we might have no more available for preorder at end of month ;-)
<eintopf>
:O
<DocScrutinizer05>
kidding aside, we might want to start N900 sourcing next month, and it's highly questionable if we could source further N900 for late customers
<DocScrutinizer05>
when you only want a NeoN board to upgrade your own N900, don't worry
<eintopf>
I don't have a N900
<DocScrutinizer05>
then your deadline is more relaxed
<eintopf>
I have a motorola milestone
<eintopf>
and now one without a keyboard and I want my keyboard back
<eintopf>
480 eur is a little bit too expensive for me :/
<DocScrutinizer05>
that's even only a down payment
<eintopf>
then wpwrak will kill me, I should buy a frequency spectrum analyzer for that money
<DocScrutinizer05>
o.O spectrum analyzer? what for?
<eintopf>
802.15.4 stuff
<DocScrutinizer05>
hmmmm
<DocScrutinizer05>
I doubt *I* could properly use a spectrum analyzer for such stuff
<DocScrutinizer05>
also isn't that 2.4GHz?
<wpwrak>
yup, 2.4 GHz
<DocScrutinizer05>
I wonder where you get which spectrum analyzer for 480 bucks that can do 2.4GHz
<eintopf>
mhh, if this device can do 2.4 Ghz spectrum of 802.15.4 then I could put a firmware on which implements 802.15.4 standard and using it as a transceiver?
<eintopf>
or is the modulation differs, or that doesn't matter?
<DocScrutinizer05>
it's RX only
<eintopf>
ah
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<DocScrutinizer05>
it provides I/Q digital data via USB
<eintopf>
I thought I could make atusb2
<eintopf>
with open firmware
<eintopf>
and atusb protocol ;-)
<DocScrutinizer05>
I *guess* you could use a cheap analog sat receiver for forntend as well
<eintopf>
you want to tell me now, that when I have some LNB and an analog receiver and I set the frequency to the right. Then I can see some patterns in the "analog snow screen" ?
<DocScrutinizer05>
eintopf: yep, analog sat receivers have a IF of 950−2150 MHz
<eintopf>
ok
<DocScrutinizer05>
anyway I wonder why you need a spectrum analyzer for those 802.15.4
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<eintopf>
determine xtal trims, I am not an expert. But the xtal pins of the transceiver has the feature to set the pin capacity
<eintopf>
they doing PLL and then I can set these capacity pins to the right value, when I see the result
<eintopf>
that's I think how it works, this is what wpwrak teach me :/
<DocScrutinizer05>
you need a frequency counter for this, or a very precise receiver, not a spectrum analyser
<eintopf>
but when I see the spectrum I can see the piek
<eintopf>
and the piek should be something like the frequency and around is some gauss curve
<DocScrutinizer05>
huh? no, it should not have any gauss curve
<eintopf>
a gauss curve and a piek in the frequeceny which is set
<eintopf>
mhh
<eintopf>
then only a piek in the middle where the frequency is set the rest is random
<DocScrutinizer05>
a gauss curve or the like would be seen by modulated signals
<eintopf>
it's modulated
<DocScrutinizer05>
which create sideband frequencies
<eintopf>
QPSK or something
<DocScrutinizer05>
the xtal frequency is NOT modulated
<eintopf>
yea, but I cannot touch the pins inside the transceiver
<eintopf>
then I need to listen to the frequency and the real result
<DocScrutinizer05>
even then you're simply not interested in that gauss curve, any arbitrary frequency counter will already pick up the "peek" for you
<DocScrutinizer05>
you say you need a spectrum analyzer to show the sidebands so you can ignore them, that's a tad awkward approach
<eintopf>
Then I could use maybe a atmega32 and use it as frequency counter
<DocScrutinizer05>
for 2.4GHz hardly
<eintopf>
it's PLL
<eintopf>
there is some 16 Mhz crystal
<eintopf>
can I not check this frequency?
<DocScrutinizer05>
but you should be able to touch one of the two XTAL pins of the chip with a high impedance probe
<DocScrutinizer05>
or even couple inductively to the RF emission of the xtal
<DocScrutinizer05>
the XTAL1/2 pins are output and input basically
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<DocScrutinizer05>
you probably can touch the output without detuning the xtal oscillator too much, when you use e.g. a 10MOhm scope probe
<DocScrutinizer05>
but honestly why do you worry that much about exact tuning? just tune your one receiver so it works fine with the peer transmitter, so both use same (possibly not totally correct) frequency
<DocScrutinizer05>
you only worry about absolute correct frequency when building a 1000 or a million devices and all should be inter-operable with each other
<DocScrutinizer05>
and possibly even to 2nd source devices not built by you
<DocScrutinizer05>
or you worry when you need to pass approvals my FCC and the likes
<DocScrutinizer05>
s/my/by/
<qi-bot>
DocScrutinizer05 meant: "or you worry when you need to pass approvals by FCC and the likes"
<DocScrutinizer05>
sorry when I'm assuming (e.g. existence of external xtal and XTAL1(2 pins on chip) and your situation looks different. I have no info what you actually do and what's your circuit
<DocScrutinizer05>
but generally for adjusting frequency you don't use a spectrum analyzer
<DocScrutinizer05>
you may, when you already have one
<DocScrutinizer05>
and when the one you have is calibrated and pretty exact
<DocScrutinizer05>
for your average dirt cheap spectrum analyzer (500 bucks) odds are your own DIY circuit is more precisely tuned to the target frequency than the SA's internal reference clock
<DocScrutinizer05>
take a shortwafe radio, tune it to 16MHz and see if you can pick up the XTAL signal
<DocScrutinizer05>
if you're lucky you may create interference with a nearby (in freq) broadcast station, and form the pitch/freq of resulting beat product tone you can know the difference in freq between your xtal signal and the broadcast station. Then you just need to find out which broadcast station this is you hear, and you easily can find their exact frequency they transmit on, which is pretty precise
<DocScrutinizer05>
whatever the chip you use, when it has a xtal oscillator then it also provides a means to tune that, by either providing the 16MHz to a test pin so you could run whatever freq counter you like on it (use a 1/16E6 divider and compare the number of seconds counted in one hour against an arbitrary watch), or the chip has built in freq offset evaluation and all it needs is a correct freq external 2.4MHz signal and the chip tells you in
<DocScrutinizer05>
some diagnostic register how much the internal xtal is offset from the applied external reference signal
<DocScrutinizer05>
and for a last resort you can attach to the crystal mechanically/acoustically, using e.g. a piezo. This shouldn't detune your xtal oscillator frequency and will even work for (never seen yet) chips with integrated crystal
<DocScrutinizer05>
while on this topic: a generally unknown/neglected issue is mechanical-acoustical coupling and interference between different crystals SMT-mounted to same PCB
<DocScrutinizer05>
crystals would make for nice hidden/stealth microphones in an exploited circuit :-)
* DocScrutinizer05
should find out if the crystal's frequency (or at least phase) also gets detuned/modulated from the acceleration by audible frequency mechano-acoustic waves introduced to the PCB
<whitequark>
oh, cool idea
<whitequark>
you know tantalum caps are piezoelectric, right?
<whitequark>
that also works
<DocScrutinizer05>
err, not known of tantalum, no
<DocScrutinizer05>
X5R yes
<whitequark>
er, yes, ceramic of course
<whitequark>
brain fart
<DocScrutinizer05>
wouldn't feel surprised to see similar effects in generic electrolytic caps though
<DocScrutinizer05>
particularly when they are already a tad aged and dried, so some gas is inside between the electrodes
<DocScrutinizer05>
for gas-free electrolyte I dunno if we could expect much sensitivity to pressure / mechanical interference
<DocScrutinizer05>
(phase modulation of reference clock) wouldn't be any threat in a PLL design, since the PLL has LPFs that filter this out completely
<DocScrutinizer05>
(never seen yet) sorry, incorrect. The legendary DALLAS chip must have had an integrated crystal iirc