hi Magnus, how about the effect of that cheap 2,7K on the active device
if it is bipolar?
Greetings
Alex
On 2/6/2017 4:35 PM, Magnus Danielson wrote:
Hi,
On 02/07/2017 12:36 AM, jimlux wrote:
On 2/6/17 2:37 PM, Bob Camp wrote:
Hi
One of the most basic reasons for putting out > +20 dbm is that you
had a spec of -195 dbc / Hz for the noise floor :)
Some of these specs *are* a bit mutually exclusive.
Sure.. And to be honest, I'm not sure that some of the folks coming up
with paper requirements for these speculative low power transmitters are
aware of that. They take dBc values from 1 Watt transmitters and assume
you can meet that with your 1 mW transmitter.
Then again couldn't you cool your oscillator.. that gets the T part of
the kT down lower <grin>
Cool that puppy down to <1K and get 25dB noise improvement, eh?
Your 50 ohm termination resistor will be a great source of that noise.
For a narrow-band fixed signal you can terminate with whatever
reactive network you feel confident with instead. If you match
impedance well enough it will work fairly well. Some oscillators have
far-out impedances far from 50 Ohm anyway so impedance matching is
so-so and most of the noise comes from the termination resistor.
Besides, for the deep space stuff you have cheap access to 2.7 K or so
anyway, right? :)
Cheers,
Magnus
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