Direction Finder

The µPC8211TK, µPC8215TU, and µPC8226TK are silicon germanium (SiGe) microwave monolithic integrated circuits (MMIC) designed as low noise, high-gain amplifiers for GPS and mobile communications. These ICs are manufactured using our 50 GHz fmax UHS2 (Ultra High Speed Process) SiGe bipolar process. The use of these three devices in evaluation boards implementing LNAs (Low Noise Amplifiers) at 1.575 GHz GPS is described in this document.

Frequency accuracy has been a topic of special interest to many amateurs and experimenters since the early days of radio. Until recently, the best frequency standard available to most hams was a crystal oscillator carefully adjusted to zero-beat with a station of known frequency, such as WWV.

This application note will focus on a simple, low-cost, hand-held digital compass design using a Microchip PIC18F2520 microcontroller.

APRS stands for Automatic Position Reporting System and now is taken to refer to a protocol that uses a subset of AX25 packet radio to provide a range of facilities not available to amateur radio before. The cornerstone of APRS is that the packets are sent using the BEACON text format - and do not require 'connects' to occur first.

Detects and counts inputs and outputs. Photoelectric detectors are usually unidirectional, i.e. they are able to detect when someone enters a particular area but not when leaves it. On the contrary, a system able to detect movement in both directions could be useful to control shops, rooms etc. If installed in a shop it could allow to know if all customers entering the premises have left them at the end of the day. Or, at home, it could be used to switch on the light (or any other electric device) when one enters the room and to switch off the electric device when he or she leaves it. Suited to control Lamps, Household Appliances etc.

When designing an EIA-485 control bus to link widely separated machinery and process controllers, devising a scheme to control the repeaters can be one of the more awkward tasks. In long buses, bus segments are joined with repeaters if the distance exceeds the maximum allowed by one cable segment.

The GPS interface can be fed in 2 ways: with a stabilized 5V supply or with a 10 to 25V unregulated DC supply. In both cases the power is fed into the RJ45 connector on point 8. Pin 7 is DC ground. The power supply current is first secured with a slow 315mA fuse (in socket). Then there is a Transzorb device to ground. This device is a short-circuit for reverse polarity voltages and for voltages above 27V. It causes the fuse to blow and in doing so, protecting the other electronics and GPS module.

The sensor used on the PC Board is the 1490 digital compass manufactured by Robson Company, see figure 2. This sensor is a solid-state Hall effect device. It is sensitive enough to detect the Earth's weak magnetic field. When rotated it can display the position of the four cardinal points on a compass, North (N), South (S), East (E) and West (W).

This application note will focus on a simple, low-cost, hand-held digital compass design using a Microchip PIC18F2520 microcontroller.

Similar to the system used in modern aviation where an antenna array modulates the phase of an incoming signal. The commercial system is known as Commutated Aerial Direction Finding (CADF) where a ring of 18 identical antennas are each switched on in sequence, just like winding a rotary switch round and round so that one antenna is always connected to the receiver. Consider: