Subject: [NEXTEL-1] Advice on using spread spectrum link in critical communications

From: [email-masked]
Date: Tue, 18 Nov 2003 11:43:49 -0500

-------- Original Message --------
From: "Kevin Graybill" <[email-masked]>
Subject: Advice on using spread spectrum link in critical communications

Below is a couple of excerpts from an RFP to provide a complete upgrade of a
county wide, multi-agency communications infrastructure.  The RFP calls for
multiple spread spectrum links to be provided to 3 - 5  auxiliary sites for
voting and fire paging as well as the link from the dispatch center console
to the primary tower site.  What are your thoughts on using unlicensed
technology for a critical communications link based on the performance
requirements stated in 1.3 below?  Has anyone done this successfully?  Also,
one of the sites has a wireless internet provider using the same SS
technology with an omni antenna.

I should also mention that the county paid approximately $10K to have a
local vendor (which also will be bidding this project) write this complete
RFP, but yet any winning bidder is responsible to make the system work based
on this vendor's design.

Any advice will be greatly appreciated.

Kevin Graybill

1.3 Expected Results:<?xml:namespace prefix = o ns =
"urn:schemas-microsoft-com:office:office" />

1. Bidders are responsible to visit job site location(s) and verify existing
conditions and project

requirements. Bidders are solely responsible for all designs, equipment,
materials and services

proposed. It is the responsibility of the bidder to verify the completeness
of the materials list

and the suitability of devices proposed to meet this specification. Any
additional equipment or

service required after the execution of the contract, even if not
specifically mentioned herein,

shall be provided by the successful bidder without claim for additional
payment; it being

understood that a complete and operating system is required. The successful
bidder will be

obligated to provide a system, which meets all the requirements for the base
proposal. The

successful bidder will be responsible for verifying the accuracy of all
critical technical data

including, but not limited to, radio frequencies.

2.6 “Belle Plaine” Digital Microwave System.

The “Belle Plaine” microwave system, (between the Main tower site and the
Belle Plaine site)

shall consist of a 5.8GHz spread spectrum design, similar to Proxim
LYNX.sc6™ 31000 series,

capable of a minimum bandwidth of 1-DS1 (1.54MHz).

1. Full duplex spread-spectrum microwave radio system incorporating.

a. 120VAC, 48VDC or 24VDC operation.

b. MUX equipment for, at a minimum, the following circuits; (state in your
response if

MUX cards are interchangeable with “Primary MUX” system cards).

i. Base/repeater stations transmit & receive (2).

1. Belle Plaine County Fire Paging station, TX only. (to Dispatch).

2. Belle Plaine City transmit and receive. (to Dispatch)

i. Belle Plaine auxiliary receivers (3)

1. County Fire

2. Sheriff Repeater

3. Search and Rescue Repeater

ii. Belle Plaine FXO/FXS Telco circuit (to Dispatch)

1. The “Board” will provide the telephone circuit at the tower site.

iii. Site Alarms [see also Item 2.4 Alarm-Status System:]

1. Belle Plaine Tower Site

c. Antenna system to obtain sufficient signal strength for maximum
reliability.

d. Back-up power system (“make before break”) to operate equipment for
minimum of 4

hours.

i. Batteries, UPS or combination (this may be incorporated into “site”
back-up

power, specify in bid response).

e. Grounding and surge suppression.

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