This reliable UHF 2-FSK Radio Data Link was designed for use in
a high security and reliability application. It may be readily used in
Telemetry, Remote Control, RF Identification Tags and Security Systems
requiring ultra-low power consumption transmitters. The Link was designed to
comply with FCC CFR 47 part 15 regulations, so that no license is required for
operation. It consists of a miniature transmitter and a high performance
receiver. The design allows multiple transmitters to communicate with a single
receiver, using a single radio channel. Each transmitter sends out a unique 32
bit address and up to 16 bits of user data on a periodic basis (every 10
seconds or more.) It has no adjustable components and uses only surface mounted
components for miniaturization, still providing for a high volume production
yield.
Several real-life tests were performed using this Link, for
example:
it was tested outdoors with both transmitter and receiver
held about 5 feet above the ground. The Link operated reliably over a range of
more than 800 feet.
it was tested in a large 5 level concrete office building.
The transmitter was placed on the third floor, and the receiver reliably
detected the emitted signals anywhere in the building.
it was tested with the receiver held by a passenger in a
small airplane. The transmitter was placed outside, on the ground, at the
airport. Using the GPS receiver in the airplane to confirm distance from the
airport, a range of more than 5 miles was obtained for reliable reception.
The transmitters were originally fitted with a high efficiency
miniature antenna of MEI's design, making them operable as a slightly large
wrist watch sized device, with all parts included (Antenna, Transmitter,
Battery for 5 year continuous operation, plastic Housing and Strap.)
UHF Transmitter
Transmitter Measured Performance:
- Dimensions: The PCB has a 1.7" diameter and 0.3" height
- Operating Temperature: -20 C to +70 C
- Operating Voltage: 2.1 to 5V with Low Battery Detection
- Operating Current: 2uA and 4.5mA when transmitting
- Operational Life: 5 years using a standard 0.5Ah Lithium Coin
Cell (Transmitting every 10 Seconds)
- Transmission Period: 10s to 128s or Externally triggered
- Transmission Duration: 10 ms
- Transmission Bit Rate: 4 - 5 kb/s Crystal Controlled 4.8 kb/s
standard
- Transmission Frequency: 300 to 330 MHz Crystal
Controlled
- Frequency Stability: 10 ppm
- Radiated Power: 170 uW EIRP
- Modulation: 5 kHz peak deviation FSK, 10 kHz pk-pk
- Data Interface: Serial or Parallel
Above is a picture of the radiated output power, showing the
firing sequence (Power Up > low level Frequency Stabilization period >
Transmission (ID+Data) > Power Down)
Receiver Measured Performance:
- Dimensions: 5" x 5" x 1.5"
- Operating Temperature: -20 deg. C to +70 deg. C
- Operating Voltage: 5V
- Operating Current: 120mA, 200 mA maximum
- Standby Current: 20 mA
- Frequency: 300 to 330 MHz (Crystal Controlled)
- Frequency Stability: 10 ppm
- First IF Frequency: 90 MHz
- Second IF Frequency: 455 kHz
- Adjacent Channel: +/-50 kHz
- Alternate Channel: +/-100 kHz
- First IF Bandwidth: 30 kHz
- Second IF Bandwidth: 30 kHz standard, 15 kHz available
- Input Noise Figure: 0.8 dB
- Sensitivity: -120 dBm (30 kHz bandwidth)
- Third Order Intercept: 0 dBm
- First IF Image Rejection Ratio: 108 dB
- Second IF Image Rejection Ratio: 80 dB
- Adjacent Channel Rejection Ratio: 87 dB
- Alternate Channel Rejection Ratio: 97 dB
- Maximum allowed RF Input Power: +10 dBm
- Antenna Input: 50 ohm connector (BNC, N, TNC, SMA, etc.)
- Audio Bandwidth: 4 kHz
- Data Decoder: Crystal Controlled
- Data Interface: Serial or Parallel
UHF Receiver prototype used for measurements and demonstrations |
