Labeling and Letters and Schematics and Processing Gain

FCC ID: NL54100

ID Label/Location Info

Download: PDF

FCCID_21755

Computational Systems, Inc.

Antenna Description for Model 4100 RF Smart Sensor

Manufacturer: Cushcraft Corporation
48 Perimeter Road
P.O. Box 4680
Manchester, NH 03108

Type: Offset Patch

Model Number: Custom Made

Gain: 0 dBd

Connector: Hirose H.FL-R

Determination of Processing Gain for CSI Model 4100
November 17, 1998

The CSI Model 4100 incorporates a radio section that is identical to that used in the CSI Models 4200 and
4210. The only difference in the radio circuitry between the Model 4100 and the Model 4200 / 4210 is
that the physical printed circuit board dimensions and characteristics were changed to accommodate the
product application. The CSI model 4200 and 4210 have been granted an Equipment Authorization
Certification with FCC Identifier of NL54200.

Since the Spread Spectrum Transceiver circuits of the products are identical, the processing gain of the
Model 4100 will be identical with that of the Model 4200 / 4210. The report on the measurement of
processing gain for the Model 4200 / 4210 is included in this application as being completely applicable to
the Model 4100.

Determination of Processing Gain for CSI Models 4200 and 4210
July 27, 1998

Measurements were made to show the compliance of CSI Models 4200 and 4210 with 47 CFR 15.247(e)
which requires a direct sequence spread spectrum transmitter to have a processing gain of at least 10dB.

The model 4200/4210 uses a baseband processor integrated circuit manufactured by Harris Semiconductor
Corp., model HFA3824A. In the 4200/4210 the baseband processor is programmed to use a spreading
code (PN code) with a length of 15 chips. The code used is a modified Barker code, 1F35. A
spectrogram of the transmitter output signal using this PN code is shown in Figure 1. Note: The CSI
Models 4200 and 4210 are identical except that the Model 4200 is line powered and the 4210 is battery
powered.

Figure 1 - Spectrum with Spreading Enabled

The processing gain was measured by comparing two bit-error rate (BER) versus signal strength curves;
one with signal spreading enabled and the other with spreading disabled. The HFA3824A allows non-
spread spectrum communication by setting the register that contains the spreading code to an all-ones
value (7FFF for a 15-chip code).. A spectrogram of the transmitter output signal using this PN code is
shown in Figure 2.

Figure 2 - Spectrum with Spreading Disabled

The results of this are plotted in Figure 3. It is seen that at lower BER values the two curves have
approximately the same slope but are separated by more than 10 dB of signal strength.

In order to arrive at a more precise determination of the processing gain a least squares fit of the data
represented by the 5 lowest BER points was determined. Using the linear equation thus derived, the
signal power necessary for the reference BER (1 x 10-6) was determined. The results of this yield the
following:

Power for reference BER with spreading = -95.394 dBm
Power for reference BER w/o spreading = -83.587 dBm

The processing gain is the difference in these two power levels:

Processing Gain = 11.807 dB

The theoretical processing gain for a 15 chip direct sequence spread spectrum system is given by:

Processing Gain = 10 x Log(15) = 11.761 dB

The agreement between the theoretical and measured processing gain is excellent and clearly shows that
the Model 4200 complies with 47 CFR 15.247(e).

BER vs. Signal Level: PN 1F35 &
1

0.1

0.01

3
1 10

BER1
n

BER2
m
4
L1 1 10
n

L2
m

5
1 10

6
1 10

7
1 10

8
1 10
105 100 95 90 85 80
P1 , P2 , P1 , P2
n m n m

Figure 4 - Plot of Experimental Data

8 7 6 5 4 3 2 1

UPC2762 MGA81563 HMC175 MGA81563 PM2117
0dB PAD

2.4GHz TX

GAIN GAIN PAD 9.6dB GAIN GAIN
MIXER
ANT
D D

TXI
HMC174 LFSN

T/R

TR BP 2450 MHz
240MHz IF
SP?
UPC2762 6dB
RF2903 BP? MIXER?
IF CLK 2.2GHz LO
UPC2745 SM515101

SPLITTER
2.4GHz TX
GAIN GAIN
GAIN LVCO
IF BP MIXER SPLITTER
C RX I C

LP
ES6315 TC7W74 PLL?

10MHz LOOP FILTER
RX Q
2
240MHz LO
LP 20MHz FF PLL
RSSI AT-31033

2.2GHz LO

LOOP FILTER

B HFA3824A PIC16LC65A TMP93CS41 HM62W8128 AT29BV020 B
RSSI

RX I

RX Q 12.288MHz
TX I
Bassband Radio u
T/R Processor Controller Processor

BB PIC UP 32.768KHz RAM FLASH

20MHz

A A
Computational Systems, Inc.
ADC
835 Innovation Drive
Knoxville TN 37932
ACCELEROMETER ANALOG PROCESSING TEL: (615) 675-2110
Analog Processing & FAX: (615) 675-3100
Micro Core Size Document Number Rev
B BLOCK DIAGRAM

Date: Wednesday, December 02, 1998 Sheet 1 of 1
8 7 6 5 4 3 2 1

Document Created: 1998-12-08 11:16:16
Document Modified: 1998-12-08 11:16:16

© 2024 FCC.report
This site is not affiliated with or endorsed by the FCC