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Equipment and software requirements


Personal computer

**SC** PolarPlot runs on a standard PC that has sound recording capability with a line-in or microphone socket.  It has been tested on Windows 2000, Windows XP, Windows Vista and Windows 7, running on desktop machines and laptops. To use the external triggered readings facility you must use pin 8 (CTS) of a 9-pin serial port. The trigger is a 1 to 5ms +6V pulse. Satisfactory results will be achieved with a desktop PC that has a quality sound card fitted - many of the on-the-motherboard sound systems tried generated some residual noise at very low levels that affected the depth of nulls being recorded.

**WM** PolarPlot runs on a standard PC.  It has been tested on Windows 2000, Windows XP, Windows Vista and Windows 7, running on desktop machines and laptops. To use the external triggered readings facility you must use pin 8 (CTS) of a 9-pin serial port. The trigger is a 1 to 5ms +6V pulse.

Receiver

**SC** At a minimum, your receiver must be capable of controlling the RF gain to such an extent as to be able to negate the operation of AGC.  If you can turn AGC off as well as control the RF gain then this is ideal.

**WM** You do not need a receiver. Instead you need a digital wattmeter either connected to a serial port on your PC or providing readings by running another program such as LP-100-VCP or FTBMeter. A DIY wattmeter design by OZ2CPU is documented on his website here. A kit-form or ready-built wattmeter by Fox Delta (their model PM3) is available here

Signal source

**SC** As a source of signal to receive there are basically two options.  The first is another amateur who is willing to devote some time to transmit a suitable signal for you to receive.  This method has the added interest in that you can not only measure your own beam, but can also measure that of the other amateur.  The second, and preferred, option is to provide your own signal source, either by way of a signal generator or another rig.  This method has the added requirement of another antenna to transmit from, but a simple dipole is very easy to set up and you have the ability to control the polarity of the signal source.  The principal problem of using another transmitter is that of getting the signal level low enough to be usable without overloading the receiver.  A signal generator is probably the most flexible signal source, particularly as it probably has a calibrated attenuator and can be operated with very low power levels.

**WM** Use a transceiver or signal generator connected to another beam antenna as a signal source. It will be useful if you can control the transmit power level, but if not then you will need a switched RF attenuator between the antenna receiving the signal and the wattmeter to avoid overloading. The Analog Devices AD8307 can comfortably handle a signal level of +10dBm.

Other

For both methods another very useful piece of equipment is a switched attenuator that you can insert between the antenna lead and the receiver or wattmeter.  Such an attenuator can be employed to adjust the received signal level if you cannot control the transmit power level.