Methodical
Heliman
Location: Fairbanks, Alaska
My Posts This: Topic Forum | As per the other thread about this
bigchopper=| Quote |
|
Synthesized transmitters are more vulnerable to this interference due to the way the RF section is designed. A synthesiser has high impedance parts in the closed loop tuning circuit which is less tolerance to external interference.. (nothing that better design shouldn't cure).. A crystal based system is slightly different here as they do not have this high impedance section in the oscillator circuit.
The level of interference caused to your transmitter is also a function of how far away your handset is from the nearest basestation. The handset will increase its power output as the signal loss increases to the basestation.. Thus causing more interference for your TX.
|
and my post after his
| Quote |
| I'd bet a broomstick that this will not happen with a CDMA phone.
What happens is like so, assuming some of you have TDMA, analog, or GSM phones.
once a while the cell system will "ping" for your handset, and your handset will ping back. This typically isn't at max-power, but it could cause a very short-term glitch if your on top of the game. If you receive a call, your jacked though.
Once a incoming phone comes in over the paging channel, a TDMA/GSM handset will output at max power (2 watts?) saying "im here! im here!"... then the cell tower comes back and says 'start ringing"... your phone sends back "im ringing!"... etc etc. One the call starts the handset will throttle down the amount of power being output.
high power narrow-band transmissions are bad news all around. If your phone has ever gone off near a set of speakers, you know what im talking about.
CDMA uses low-power spread spectrum. There are many advantages of this, but one of the biggest is that it causes a significantly lower amount of out of band interference, even at max power.
TDMA is being phased out, and the next versions of GSM will use spread spectrum. So thats good news for the future.
|
|
