DirecPC is a high-speed satellite network card for home computers and was one of the first retail products for Hughes Network Systems (HNS).  It has been a very successful product spawning several versions and international derivatives.  Until DirecPC, HNS built mostly commercial and industrial satellite network equipment.  A DirecPC system can be purchased at almost any retail computer store and consists of a DirecPC receiver for your PC and a small 18 inch satellite dish.  DirecPC can also be combined with DirecTV using a system known as DirecDuo which allows one satellite dish to be used for both DirecPC data and DSS DirecTV television

Shown here are the PCI and USB versions of DirecPC receivers.  They are not shown to scale here.  The original version was ISA based and there is a fourth version which is also PCI based for use with satellite systems using DVB signaling such as in Europe.

It looks complicated but it isn't really.    With a DirecPC receiver in your PC (shown here installed in a network server) internet access reaches speeds far greater than even ISDN.  There are two types of data on most networks like this, outbound data in the form of requests and inbound in the form of  data or graphics or both.  It is the huge volumes of inbound traffic that choke and slow down a network.  DirecPC opens the bottle neck by sending inbound data through your high-speed satellite receiver instead of back through your modem.    Your outbound requests for data go through your modem as usual but the returning traffic comes back almost instantly through your DirecPC receiver.

The test system consists of three major components:

• There are any number of attached testers which host the UUT (Unit Under Test) with either a PCI, ISA, or USB bus connection.  The tester can then apply stimulus to and communicate with each UUT during the test process.   Each UUT is tested for bus transactions and digital characteristics as well as AC and DC characteristics of the tuner's output section.  The tuner on each unit supplies power to the dish-mounted electronics and signaling for polarization adjustments.   As built the system can supply RF signaling to 16 separate testers all running asynchronously.  The system could be easily adapted to accommodate many more testers.

• The RF section (bottom half) supplies L-Band signals at various frequencies, modulations, coding, symbol rates as well as Eb/No and power level settings.  These signals are connected to each tester and used to characterize the receiver and A/D section of each UUT (Unit Under Test).

• The testers are also connected to a 'Master' computer which controls registration and routing of test result data and UUT encryption information.  The 'Master' and the RF section are housed in the same cabinet in the illustration above.  The 'Master' acts as a router to connect each tester to the company database and encryption servers.

Separate pseudo-random data streams are used, one set packetized as a DirecPC data stream and the other as if it were carried on a DVB stream.   Each of these streams uses different combinations of BPSK and QPSK modulation, different Viterbi and Reed Solomon coding rates and different symbol rates.   In addition, one channel from each set carries either a DirecPC or DVB formatted true data signal. 

Each signal path is mixed with Gaussian white noise and upconverted by a separate L.O. to L-Band.  The separate frequencies are combined onto one cable and then split again for distribution to each of the functional testers.   This design allows the signal-to-noise ratio and power level of each path to be separately configured.

Each tester is networked to a 'Master' system which routes the test result data from each tester to a company database and also securely connects each tester to an encryption system for final product configuration.   A 10Base2 topology was chosen because of the proximate distance between the testers and the 'Master' and a single coaxial cable connection was more robust and serviceable for some factory conditions.  A m odified IPX protocol is used for simplicity and A triple DES encryption scheme is used to secure real-time communications between remote servers which supply adapter key information for product configuration in the factory.

The tester itself has the following features:

• Removable hard drive to allow rapid reconfiguration between test types

• Small individual strip printer for printing test results and factory travel tags

• Barcode scanner for quick and accurate data entry and serial number input

• Quick-change disposable bus interface connectors to reduce down-time

• Easy and full access to internal tester components for ease-of-service

• Other features of design, build and software too numerous to mention here