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.)

UHF Transmitter

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
Radiated Output Power Graph

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° 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
UHF Receiver Prototype

UHF Receiver prototype used for measurements and demonstrations

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