UHF Transmitter and Receiver

Sample of prior work showing our RF design capabilities: High Performance UHF Radio Data Link.

Overview

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.)

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

Mini-UHF Transmitter RF Power Output Profile

Receiver Measured Performance:

Dimensions: 5″ x 5″ x 1.5″
Operating Temperature: -20° C to +70° 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