In-building bi-directional amplifier ~483MHz - RF Cafe Forums

 Post subject: In-building bi-directional amplifier ~483MHz

Posted: Wed Dec 21, 2005 12:05 pm 

There is a move towards this technology for fire department communications in high rise buildings instead of traditional hardwired telephones in stairs and lobbies. These are low power, [1 watt, -95dBm] devices with radial antenna below grade and a riser antenna that penetrates each floor and the roof. I believe this system, at least theoretically, can enhance occupant and fire department safety in an emergency but question it's efficacy when installed in an existing building.

Do any of you RF engineers have opinions on potential signal interference to this type device? Many of these existing buildings have large DC elevator motors w/ high voltage rely controllers, large capacitance sprinkler pump motors, metal studding / steel reinforcing, etc.

I would seem to me that retrofitting such a device and making it work properly might effect existing systems and other building components and could also effect how an onwer is able to use his building in the future.

All comments are welcome.

 Post subject:

Posted: Fri Dec 23, 2005 10:35 am 

Greetings Kmwood:

A fellow named Shekar Kulashekaran (shekar.pk@gmail.com) recently submitted a very nice presentation that addresses what you are looking for. He does consulting, so you can contact him to help out.

In-Building RF Coverage Solutions

This presentation offers a methodical approach to planning and implementing in-building solutions for GSM 900 & 1800 MHz, and CDMA phone systems that helps solve the problem of coverage in offices, garages, shopping centers, etc. Shekar has 6 years of experience planning and installing these systems.

http://www.rfcafe.com/references/articl ... g_Coverage

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 Post subject:

Posted: Thu Dec 29, 2005 11:34 pm 

The Atlanta International Airport has just installed a state-of-the-art In-Building System using a Distributed Antenna System. And all of the scenarios that you have described were actually present here with hundreds of elevators, DC machinery, scanning devices, baggage handlers. With all of that the noise floor of the just the electronics was pretty decent and the in-building system works absolutely fine. We have even the City Police and Public Safety on our system for the in-building part. Careful measures were taken here so as to prevent any sort of interference. Most significantly, the system here is one of its kind - "Neutral Host". which means that we have multiple providers that operate over different spectrum peices and use different wireless protocols over the same system and provide service at the world's busiest airport. It is truly a great feat.
Thanks,
Daver