AT48810 Features • • • • 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