[RFI] 2.4 GHz Phones

dgsvetan@collins.rockwell.com dgsvetan@collins.rockwell.com
Thu, 3 Aug 2000 08:25:44 -0500


The discussion earlier this week about RFI to Siemens 2.4 GHz cordless
phones prompted me to contact a colleague who is affiliated with Siemens
for more information.  This is his reply:

The usual complaints that I see are that our Gigaset 2420 system interferes
with video senders and other 2400 MHz devices.  I can tell you this, it has
been tested to show compliance with IEC/EN 61000-4-2, IEC/EN 61000-4-3,
IEC/EN 61000-4-4, IEC/EN 61000-4-5, and IEC/EN 61000-4-6.  The radiated
E-field immunity is at least 3 V/m from 27 MHz to 1000 MHz, and greater
6 V/m in the FM broadcast band.

The E-field ten meters away from an antenna driven by a 2 kW PEP
transmitter is about 31 V/m, peak.  Our phones were never intended to work
correctly when exposed to such high field strengths.  They should not be
damaged by such fields, but it is not astonishing that some users find
- - - - - - - - - -

Note that there would be no required E-field immunity if the unit complied
only with FCC specs.  If applying extensive common mode controls, including
chokes, does not clear the problem on a given unit, then either the unit
needs to be further away from the ham antennas, ham band transmit power
reduced, or the unit re-packaged by the owner into a "bullet-proof"
shielded housing.  If it has an external wall transformer for power, don't
forget to apply common mode control to the cord of that power unit.

It would be interesting to know what specs the Uniden system is designed to
meet.  I hope that anyone having the information will pass it along.

73, Dale, WA9ENA
----- ----- ----- ----- ----- ----- -----
Prior messages:

I own this phone same system, and I can tell you that it is NOT RF immune
my house during HF all-band contests. Quite the contrary.

I also have a Uniden cordless phone (900 Mhz?) and it is absolutely quiet
during the same periods.

Hope this helps.

Good luck!

73/Jeff K2KV

I saw this Siemens Cordless phone system that operates at 2.4 GHz Frequency
Hopping Spread Spectrum and wondered if it would have
enough noise immunity to operate around my KW station?  It uses several
cordless phones that operate with the base using a PCM
modulation at 2.4GHz.  Neat system if it would work in an rf environment.

Looked through the archives and didn't find much about really good success
with spread spectrum 900 or 2.3Ghz phones.  Has anyone
had any good luck with these.  I used a bunch of torroids on the phone line
and still had some interference on a 900 Mhz Uniden

Wendell W5FL

FAQ on WWW:               http://www.contesting.com/FAQ/rfi
Submissions:              rfi@contesting.com
Administrative requests:  rfi-REQUEST@contesting.com
Questions:                owner-rfi@contesting.com