On 09/30/2010 06:14 AM, jimlux wrote:
Magnus Danielson wrote:
Doppler effects is much more important, and it's effects is being
treated regularly, such as when talking in the GSM phone while driving
the car...
Hmm.. I think crystal oscillator frequency variation in the phone is a
bigger
Magnus Danielson wrote:
On 09/30/2010 06:14 AM, jimlux wrote:
Magnus Danielson wrote:
Doppler effects is much more important, and it's effects is being
treated regularly, such as when talking in the GSM phone while driving
the car...
Hmm.. I think crystal oscillator frequency variation in
On 9/30/2010 8:43 AM, jimlux wrote:
how stable?
The parts are generally ~ 1 ppm over temp and another ppm or two aging.
I'm sort of curious, I wonder what sort of temperature range
cellphones are expected to really work over..
depends on the vendor to some extent. Not all standards spec
I need to build some small tracking transmitters (using a circuit similar to
http://www.jbgizmo.com/page4.html
This circuit uses a fifth overtone crystal to get an output in the 216 to 220
MHz range. The circuit is rather finicky about the crystal and transistor...
most don't work.
Mark to my inexpert eye that doesnt look like a very good overtone
oscillator but I appreciate that it is slimmed down to keep the weight and
size down, I can see why it is touchy. There is nothing to make the
oscillator degenerate at the crystal fundamental. In fact it looks like a
Pierce with a
LPRO needs to be calibrated. Once calibrated, should be pretty good for a
reasonable period of time, depending on what your performance criteria are,
probably a year or so for amateur radio type stuff.
Thunderbolt is linked to NIST, via the GPS satellites, and never needs
calibration.
LPRO more
To ease the requirements on your crystal, you might consider using a
diode frequency multiplier to bring your oscillator frequency into that
range. Wenzel has a good app note on one variety:
http://www.wenzel.com/documents/2diomult.html
--n
On Thu, 2010-09-30 at 18:57 +, Mark Sims wrote:
I
When I was in the television transmitter biz, we ran 5th, 7th and 9th up to
216MHz using JFET Pierce oscillators. We used the same oscillator for low VHF
to high VHF and only changed an LC circuit to make sure the oscillator would
take off on the correct overtone. Our supplier of choice was
I'm not sure if the thing actually operates on the 5th overtone. I have some
mystery TO5 44.7 MHz crystals that it puts out 223.5 MHz. The actual freq at
the collector seems to be 74.5 MHz (but it is a complex waveform).
The circuit generates a short burst every second or two. It is VERY
