Our local phone company would like to place a few cell phone towers on our
roof. Their stated specs are shown below but only discuss the in-band
components and I am worried about the out-of-band components. We have 400
MHz and 500 MHz systems on the eighth floor lab and we are immediately
under the roof. We have a 600 MHz system in the basement and a 200 MHz
system on the fourth floor. One NMR equipment manufacturer is asking for
no external signals in-band above -65 dBm but they warn that any signals
above -80 dBm should be investigated. I do not know if the spread spectrum
they are using generates any spurs out-of-band. This may stop with my
request for no in-band signals above -65 dBm over all of our multiple
acquisition windows for multiple nuclei on four different systems. If it
progresses further I may request that they bring in their engineer and
have them meet with a site inspection engineer from one of our vendors.
Unfortunately, the next best option for the phone company may be the next
building over which might be tougher for us to control.
Receive Passband: 824 to 849 MHz
Transmit Passband: 869 to 894 MHz
Transmit Frequency Range 869.70 - 893.31 MHz
Transmitter Output Power per carrier-sector with equal sector power
sharing (simultaneous power) 44.3 dBm (27 W)
Max. Transmitter Total Power Out Per single carrier-sector:
Except channel 777 49.1 dBm (81 W)
Channel 777 only 44.8 dBm (30 W)
Per Trunked set (4 linear power amplifiers) 50.3 dBm (108 W)
Per Antenna using 4:1 combiners 56.4 dBm (432 W) (There will be 6
transmit antennas atop the roof)
The current configuration is for 5 CDMA (spread spectrum) carriers, with
expansion up to 8 carriers to be in operation inside the transmit
frequency range.
Does anyone have experience with having a cell phone tower this close to
their equipment? If you had problems have you managed to resolve them and
what did that require?
Thanks, I can post a summary if there are enough responses.
Joe Dumais, Ph. D.
Associate Research Professor
Director of Research Instrumentation Facility
Department of Chemistry / University of Nebraska Lincoln
834 Hamilton Hall / PO Box 880304
Lincoln, NE 68588-0304
Phone (402) 472 6255 / Fax (402) 472 9402
http://www.chem.unl.edu
Received on Fri Feb 18 2005 - 18:42:11 MST