ATMEL AT48810-CH 900 mhz spread- spectrum rf module Datasheet

AT48810
Features
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Designed for use with Atmel’s AT48802 Spread-Spectrum Signal Processor
FCC Part 15, Unlicensed Operation
RF Despreading and Narrowband IF for Highest Jamming Margin
1 mW Narrowband Operation, or 1 and 50 mW Spread-Spectrum Operation
Description
The AT48810 RF module is intended for time domain duplex spread-spectrum communications under FCC Part 15, 902-928 MHz unlicensed operations. This module
features RF despreading and narrowband IF for powerful interference rejection.
Spreading is via direct sequence. The unit can also be operated in a narrow-band
configuration (FCC limits power to 1 mW in narrow band) by restricting the DC voltage
to the power amplifier so that the transmit power is less than 0 dBm per FCC regulations. The unit can also be run in slow half duplex or simplex mode.
900 MHz
SpreadSpectrum RF
Module
Preliminary
Pin Diagram
15.36 MHz Clock Out
Ground
VCC
Synthesizer Data Clock Input
Synthesizer Data Input
Synthesizer Data Latch Input
Modulation Input
No Connection
PN Spreading Enable Input
PN Input
Note:
1
3
5
7
9
11
13
15
17
19
2
4
6
8
10
12
14
16
18
20
Audio Out
Ground
RSSI Out
T/R Switch
LNA Gain Hi/Low
VCC
No Connection
Transmit Power On/Off Input
Power Amp VCC Input
Power Amp VCC Input
1. Connector on module is Dupont/Berg part number 87814-610.
Mating connector is 87409-110.
0625A
3-1
Block Diagram
ON/OFF
TX PWR
fC = 83.16 MHz
Bw = 30 kHz
fC = 1.23 MHz
GAIN
LNA
IF AMP
ANTENNA
PORT
DISCRIMINATOR
3
DOWN
CONVERTER
XTAL OSC
83.16 ± 1.23 MHz
HANDSET OR BASE
T/R
SWITCH
902928 MHz
TR SW
RSSI
UPCONVERTER
SYNTHESIZER
DATA
TCXO
15.36 MHz
SPREAD
AMP
CLOCK
fC = 915 MHz
TX PWR
AUDIO
ON/OFF
ON/OFF
OTHER CIRCUITS
PA VCC
PN
PN ENABLE
VCC
Note:
1. The module cannot legally be certified without an antenna; this is an FCC requirement.
TDD Rate
7.5 kHz max
Operating Frequencies
Table 1. Version “B” (1, 2, 3, 4, 5, 6, 7, 8)
Note:
3-2
Channel
N
End B
First LO, MHz
TX, MHz
RX, MHz
1
1334
825.7536
910.1424
908.9136
2
1350
829.4400
913.8288
912.6000
3
1356
833.1264
917.5152
916.2864
4
1363
837.4272
921.8160
920.5872
1.
2.
3.
4.
5.
Second LO = 84.3888 MHz
Reference Divider = 25
Phase Detector = 614.4 kHz
First IF = 83.160 MHz
Second IF = 1.229 MHz
AT48810
6. Synthesizer PLL Bandwidth = 80 kHz nominal
7. Frequency Accuracy = ±3.5 ppm
(including temperature 0° to 50°C)
8. Switching Time = 2.2 ms nominal, Ch 1 to Ch 4
AT48810
Table 2. Version “H” (1, 2, 3, 4, 5, 6, 7, 8)
Note:
Channel
N
First LO, MHz
TX, MHz
RX, MHz
1
1346
826.9842
908.9136
910.1424
2
1352
830.6688
912.6000
913.8288
3
1358
834.3552
916.2864
917.5152
4
1365
838.6560
920.5872
921.8160
1.
2.
3.
4.
5.
Second LO = 81.9312 MHz
Reference Divider = 25
Phase Detector = 614.4 kHz
First IF = 83.160 MHz
Second IF = 1.229 MHz
6. Synthesizer PLL Bandwidth = 80 kHz nominal
7. Frequency Accuracy = ±3.5 ppm
(including temperature 0° to 50°C)
8. Switching Time = 2.2 ms nominal, Ch 1 to Ch 4
Transmit Modulation Input
Type
PM, inside the phase lock loop
Bandwidth
200 Hz to 70 kHz, -3 dB
Sensitivity
20 cycles/V nominal
Distortion
-30 dBC max. for 10 cycle peak deviation at 1 kHz rate
Spreading Input
Type
BPSK
Bandwidth
30 MHz
Sensitivity
2.5 VPP for BPSK
PN Enable Input
+5V = spread, high Z = CW
Carrier Suppression
-15 dBc max.
Code Leakage
-30 dB max. (for baseband modulation signal of better quality)
PN Input Load Resistance
1K nominal
Antenna Port
Zo
50 ohms nominal
VSWR
2.5:1 max., 902-928 MHz
T/R Switch
Low = transmit, CMOS compatible. Isolation 35 dB nominal
3-3
Transmit Power
Power Output
+17 dBm at VCC = 5.0 VDC,
VPA = 4.0 VDC
On/Off Control
TX PWR input pin 16, CMOS
compatible, low = power on
RF power amp VCC is on a separate pin
from the other circuits VCC.
Receive
Sensitivity
-105 dBm max. at 12 dB SINAD (C-weighted)
IF Bandwidth
30 kHz at -3 dB nominal
Signal-to-Noise
30 dB min. C-weighted at -80 dBm
Post Detection Net Bandwidth
15 kHz, limited by IF filter
RSSI Output
Log compressed. Slope 0.24 uA/dB nominal into a zero ohm load. Rout =
58K nominal. Bandwidth 15 kHz, limited by IF filter. Noise floor - 110 dBm
equivalent input.
Attenuators
T/R switch → T gives 35 dB nominal, low = transmit. GAIN control gives
17 dB nominal in LNA low = high gain. (binary controls: on/off only, CMOS
compatible.)
Audio Output
Sensitivity 0.4 uA/kHz nominal into a zero ohm load. Rout = 58K nominal.
This output must be lowpass filtered (-3 dB at 200 Hz, 6 dB/octave) to give
net link frequency response which is flat.
Interface Rejection
Out of Band
Antenna filter is -6 dB at fo ±32.5 MHz and approx. -30 dB at fo ±100 MHz.
A cellular phone with 1 watt power at a distance of 5 feet produces no
noticeable SNR degradation in the receiver for the mating transmitter at a
distance of 10 feet, running spread spectrum R13 code.
In Band
Processing gain depends on code length. The use of RF despreading
assures that the high processing gain can be maximally effective by
allowing narrow IF bandwidth thus significantly reducing IF jamming
induced desensitization.
Clock Output
Data Port
15.360 MHz buffered from TCXO, CMOS compatible, one
standard load.
SPI/3-wire, 3 lines. Synthesizer device is National Semiconductor LMX1501 or equal.
3-4
AT48810
AT48810
Power Supply
Voltage
+4.5 VDC min., +5.5 VDC max.
Current
Transmit only 185 mA nominal
TDD 50/50 130 mA nominal
Receive only 85 mA nominal
Turn-On Time
for 1 ppm error from final frequency
1. TCXO, from VCC edge = 3 ms max.
2. Synthesizer, VCC stabilized, from data latch edge = 3 ms max. (1)
Power Amp
+4.0 VDC full power, +0.6 VDC for Pout < 0 dBm
Note:
1. It is allowable to program the synthesizer before the TCXO is fully stabilized
Adjustments
There are no user adjustments. The three adjustments
are discriminator frequency adjust, TCXO nominal frequency, and transmit upconverter filter tuning.
Environment
Temperature
0° to 55°C
Humidity
10% to 90% non-condensing
Vibration
Shock
Physical
(Dimensional Drawings)
Antenna Port Options
Center, Left, Right
Weight
Ordering Information
Ordering Code
Antenna
Frequency Plan
Second LO
AT48810-RB
AT48810-RH
Right
Right
B
H
84.3888 MHz
81.9312 MHz
AT48810-CB
AT48810-CH
Center
Center
B
H
84.3888 MHz
81.9312 MHz
AT48810-LB
AT48810-LH
Left
Left
B
H
84.3888 MHz
81.9312 MHz
3-5
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