Temperature compensated RF circuitry

Abstract

A temperature compensated RF sensing circuitry for use in a remotely mountable weatherproof bi-directional, half-duplex switching amplifier system designed to provide maximum range for low power half-duplex radios such as Spread Spectrum radio transceivers in utilizing a voltage reference that is connected between a power supply circuit and a reference potential with a thermistor for temperature compensation purposes.

Description

CLAIM OF PRIORITY AND CROSS REFERENCE TO RELATED APPLICATION [0001] This application is a divisional of and claims priority to and incorporates by reference, in its entirety, U.S. application Ser. No. 09 / 505,201, titled “Bi Directional Switched RF Amplifier, Waterproof Housing, Electrostatic Overvoltage Protection Device, and Mounting Bracket Therefor”, filed Feb. 16, 2000 and is a Conversion of Provisional Application Ser. No. 60 / 120,639, filed Feb. 18, 1999 BACKGROUND OF THE INVENTION [0002] The present invention is a result of the proliferation of low power, Spread Spectrum radio modem devices in the 902-928 MHz, 2.4 GHz and 5.7 GHz bands. Popularity of these radio devices is largely due to FCC regulations that allow appropriately certified radio transceivers to be operated license free. This certification requirement restricts the transmitter output power in order to enable many users to share the band. Further, since the radios are Spread Spectrum devices, they can generally to...

AI Technical Summary

Benefits of technology

"The invention provides a telecommunications system that can transmit signals over ranges up to 60 miles point-to-point while keeping the radiated power compliant with regulations. It also includes an improved arrangement for amplifying transmit and receive radio signals, with a half-duplex, switching bi-directional amplifier located close to the antenna. The RF amplifier has a waterproof housing enclosure for protection against water accumulation, and a universal mounting V bolt mounting bracket for the housing enclosure. The invention also provides temperature compensated RF level sensing circuitry for reliable operation over a wide temperature range, LED indicators on the DC injector circuitry to show the operational status of the remote bi-directional switching amplifier, a solid state switch for switching between the transmit and receive modes of the remote bi-directional switching amplifier, and an electrostatic overvoltage discharge protection device."

Problems solved by technology

Further, since the radios are Spread Spectrum devices, they can generally tolerate interference from other radios transmitting in the same geographical area.

The problem here is that the losses in the typical, inexpensive coaxial transmission line between the radio and the antenna at these frequencies can be excessive unless prohibitively expensive cable is used.

Putting an antenna on a tall radio tower or building would give clear line of sight to many locations, but this is largely defeated by the transmission cable loss.

However, this is in general unsatisfactory due to the fact that not only are both transmit and receive amplifiers are on at all times, thus leading to wasteful power usage, but also heavy filtering is also necessary to keep the transmit and receive signals from interfering with each other, leading to further expense and power wastage.

Still further, since each transmit and receive signal must be put to a separate frequency to avoid interference, this design is wasteful of spectrum bandwidth, a scarce commodity in many applications.

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