Transcript RX array
A REMOTE STEERABLE RECEIVING ARRAY FOR 1.8 MHz GREG SMITH ZL3IX
REASON FOR THE PROJECT
• TO STUDY SKEWING ON LONG PATHS.
• TO AID THE RECEPTION OF WEAK DX SIGNALS.
REMOTE STATION BLOCK DIAGRAM Signal Combiner 160m Rx 438 MHz Tx 433 MHz Rx Controller Telemetry Solar Power Supply Duplexer
ANTENNA DESIGN REQUIREMENTS.
• BEAM WIDTH NOT EXCEEDING 60 DEGREES.
• MUST BE STEERABLE TO COVER ALL COMPASS POINTS • MUST FIT INTO A REASONABLE SIZE, eg 1 HECTARE
THE BEVERAGE ANTENNA
• Long low wire about 2-3m off ground • Needs to be about 2 wavelengths long.
F
ARRAY OF BEVERAGES NEEDS 330m X 330m OR ABOUT 10 Ha
BROADSIDE ENDFIRE ARRAY
BroadSide EndFire ARRAY (ref W8JI www.w8ji.com) 100 m 21 m
100X21m BSEF ARRAY
REQUIRES ABOUT 1 Ha
E/W NW/SE N/S NE/SW
92X38m BSEF ARRAY
ELEMENT CHOICE
• SHORT LOADED VERTICAL • SHORT VERTICAL WITH Hi Z BUFFER.
• SMALL LOOP
FET BUFFER
Ant Element C4 47p C1 270p C2 270p C3 56p R1 100R Q1 J310 L1 90u R2 10k R3 500R R4 Q2 J310 C7 100n C6 100n L2 220u Output 75 ohm T1 C5 100n L3 220u
ANT 1 ANT 2 ANT 3 ANT 4 ANT 5 ANT 6 ANT 7 ANT 8 RL1 N/S RL2 NE/SW RL3 +13.6 V REVERSE 150 150 T1 T2 T3 100n 220u 100n T4 100n 100n 220u RL5 COAX PHASE DELAY 820 15 820 150 T5 T6 ARRAY OUTPUT E/W RL4
SIGNAL COMBINER
SE/NW
From Antenna Bandpass Filter 14.4 MHz TCXO Direct Digital Synth 5.38-5.48 MHz IF Xtal Filter 3.579 MHz IF Amp AGC Xtal Osc Product Detector Audio Amp
CONTROLLER
• 16F876 PIC • WIZ C • DECODES SERIAL CONTROL DATA • PROGRAMS DDS IN Rx • SELECTS CORRECT ELEMENTS FOR REQUIRED DIRECTION
UHF Rx/Tx
• Rx - MODIFIED DEVELOPMENT MODEL TB8100 • 500 mW WHEN “ASLEEP” • Tx - TM8100 PA • CTCSS TONE TO SWITCH ON • LACK OF CARRIER FOR 4 s, OR A DIFFERENT CTCSS TONE, SWITCHES SYSTEM OFF.
• DATA LINK 4800 Bd RAW RS232
POWER SYSTEM
Solar Panel Constant Voltage Controller 45 Ah Lead Acid Battery Load
LOCAL STATION BLOCK DIAGRAM Controller Telemtry Rx Headphone Amp 433 MHz Tx 438 MHz Rx Duplexer
TUNER BLOCK DIAGRAM Shaft Encoder 4x4 Keypad 16F876 Processor LCD Display 4800 Bd Serial Data
THE UHF LINK
TELEMETRY • PARAMETERS - 160m RSSI, UHF RSSI, Batt Volts, Solar Volts.
• SUPERIMPOSED ON AUDIO • 300 Bd FSK, Tones at 1850 and 2150 Hz • Telemetry has HP filter at Tx • Audio has LP filter at Rx
THE TELEMETRY RECEIVER 1850 Hz 2150 Hz Switched Capacitor Filters + 300 BAUD 16F876 PIC 4800 BAUD
PROBLEMS • UNEQUAL ELEMENT PICKUP PREAMP GAIN VARIATIONS
PROBLEMS • UNEQUAL ELEMENT PICKUP PREAMP GAIN VARIATIONS PICKUP FROM COAX BRAID
PROBLEMS •
NOISE FROM COMMON Tx/Rx ANTENNA
HOSE CLAMPS SERIOUS OFFENDERS METAL MOUNTING PLATE PVC TAPE UNDER U BOLTS COAX BRAID • •
FADING ON UHF LINK
AIRCRAFT FLUTTER CAUSES DEEP SIGNAL FADES ON BOTH UP AND DOWN LINKS.
SLOW FADING DUE TO GENERAL TROPOSPHERIC PROPAGATION VARIATIONS
TESTING
W NW SW N REMOTE NE HOME E SE S