APT System

APT satellites give about 12 good images a day, wherever you are in the world. The resolution is 4km per pixel and there are visible and infrared sensors. This is a simple system where the satellite is in low earth orbit and very easily received at 137MHz.  These simple omni-directional antennas do not need moving or tracking to receive the satellite. The satellite is so strong that when is about 10 degrees above the horizon perfect results will be obtained.

There are two problems with using receivers not specifically designed for weather satellites. The first and most important is bandwidth, an APT signal needs about 40kHz of bandwidth, between 30 and 50 is OK. Most scanners have 15kHz which is far too narrow and 180kHz or more which is far too wide. Only a few scanners have the correct bandwidth and these are currently the AOR5000 and Icom IC-PCR1000. The second problem with all scanners, including the ones mentioned, is that a weather satellite system needs a very good performance receiver, one that provides high sensitivity, good signal to noise and high immunity to other adjacent transmissions. So, you may get your scanner to work, but it will not provide the results you see in our colour images. Our PROscan receiver has been specially designed to provide optimum performance.

APT Polar Antenna

The Quadrifilar helix antenna is designed especially for marine use. It is made entirely from 316 stainless steel and derelin plastic and is extremely strong.

 

PROscan APT receiver

This receiver has become a legend in the weather satellite field with over 3,500 in service all over the world. In tests this receiver has outperformed every other similar receiver. It provides greater signal to noise and hence better image quality. It is more resistant to pagers and other nearby radio transmissions. It is easy to use and has direct frequency read out. It can be computer controlled so that completely automatic operation is possible.

All 6 known APT satellite frequencies are fitted and just in case there are two spare unallocated channels. There is selectable channel lockout if some satellites are not required. The PROscan receiver uses a lot of filtering, 3 coils in the optional preamplifier, 4 coils in the RF amp (total 7 coils at RF), 3 coils in the oscillator, 1 matching coil at first IF, 5 ceramic filters at first IF, 5 coils at second IF (total 11 IF filters) and a quadrature discriminator for linearity and high ultimate signal to noise. As with any weather satellite receiver, you need an interface and software to get images into your computer.

APT 137 Preamplifier

The Enhanced Polar Preamplifier is designed to go with our Quadrafilar Helix antenna, although it can equally be used with our crossed dipole or any other antenna where the best possible performance is required. It has the lowest noise figure on typically just 0.5dB and bandpass filtering giving over 50dB rejection to pagers on 153MHz.

Prices

An APT Polar system
Antenna
 Quadrifilar helix 975
Preamplifier
 Enhanced 425
Cable
 40m 40
Receiver
 PROscan 975
Interface /software
 PROsat for Windows i :The definitive versatile unit with full i software 475
Power supply
 Timestep 90-260V PSU 65
Total cost
 2,955  (plus shipping and taxes if applicable) UK pounds sterling (UKL)

 

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