"HarryHydro" wrote in message
...
Hi Folks:
We've been having intermittent problems with 'interference' on
6.8 gig Alcatel radios and 5.8 gig (freeband) Proxim radios. I just
came into the radio shack, turned on the 'widow maker', a big heavy
spectrum analyzer, and instead of finding 5.8GHz internerence, I
found VERY strong pulses of RF around 4.9GHz. With my Blackberry about
5 feet away, the analyzer is showing a -10dbW (yes, 100mW) on a 2.4
gig antenna. It must be saturating the front ends. This Blackberry
comes through speakers with the preamps, and even televisions a good
10 feet away! It makes the computer monitor's screen shake almost
like the degauss! (when placed close). And, I suspect it does this
with it next to my head also, straight out the front and back of the
phone.
I was just looking at 4.9gig info and it seems to be allocated to
public safety. Is it also WiFi? The WiFi on this phone is off, at
least in the 'Connections', but that doesn't suprise me as laptops
seem to transmit on WiFi while connected to LAN. (Laptops' WiFi
knocks off the Proxim's, also)
Anyone ever scoped out the RF power from a Blackberry? Can this be
safe power levels?
Harry

First off, you need to use a proper setup and evaluation of the spectrum
analyzer. A setup like you described can give wildly erroneous indications
and even damage sensitive circuits. Just having multipath in the room can
result in reinforcement of the signal. And you were standing where the
signal was best? You aren't the only one caught by that. I never brought
mine to work because "experts" had somehow convinced the powers that be that
burnt out test equipment was a normal thing, so invariably only one or none
might be working, being "in transit" to the depot.

A lot of devices are using modulation techniques that can be detected by
analog devices, and nothing seems to more prone than amplified computer
speakers. I can hear cell phone noise on mine even outside the building,
even though they don't respond to my HF station with the linear on.

It doesn't make sense that energy 1 gig away would cause interference. I
would be more suspicious of the audio circuits and switching transients.
Consider that since RF power is on-off keyed, there is much less than 100%
duty cycle of the On time, so heating effect are much lower than with FM.