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PC-based telemetry receiver.

The 500 series of receivers-on-a-PC card provide telemetry users with a low cost, easily-reconfigured telemetry receiver. These receivers have a small footprint package without sacrificing functional capabilities. They plug into one full length PC bus slot and are controlled by the host personal computer. To receive and process telemetry data then becomes a simple matter of attaching the RF input to an antenna and its base-band output to a bit-synchronizer. Personal computer-based bit-synchronizers and decommutators are available from several sources. The introduction of this technology, used with these receivers, enables the systems designer to assemble powerful, compact, fully functional portable telemetry reception and processing systems whose costs are a fraction of their larger counterparts. The block diagram of the series 500 telemetry receiver is shown in Figure 1. The second IF, FM discriminator and post detection amplifier/filter plug-in modules are indicated on the diagram with the solid black outline.

General Receiver Description

The receiver provides reception and FM demodulation for telemetry signals transmitted in the L and S frequency bands. Four models are available. The model PCTR-500L receiver provides reception in the 1435 to 1540 MHz frequency band; the model PCTR-500S1, in the 2200 to 2300 MHz band; the model PCTR-500S2, in the 2300 to 2400 MHz band; and the model PCTR-500S3, in the 2400 to 2500 MHz band. All S-band receiver models provide up to 200 user programmable channels with 500 kHz frequency resolution. The L-band receiver model provides up to 105 channels with 1 MHz frequency resolution.

The series 500 receiver offers user replaceable plug-in modules for the second IF stage, FM discriminator and post detection amplifier/filter sections. The receiver can be controlled via a simple menu-driven DOS program that is supplied with the receiver or can easily be integrated into a custom developed DOS or Windows application program. The control program equipped with the receiver allows selection of the desired receiver frequency. After the frequency is selected, the program indicates the signal strength for that frequency. The control program can accommodate multiple receivers, each operating at different frequencies.

Plug-In Modules

The receivers can support a wide variety of telemetry applications in the L or S frequency bands. To provide a low cost and flexible alternative to more costly receivers, the series 500 employs a modular architecture that enables the user to configure the receiver for a variety of different PCM data rates, IF bandwidths, FM deviation responses and signal output voltage levels.

The receiver offers six different plug-in modules with bandwidths from 250 kHz to 20 MHz. Four different FM discriminator plug-in modules are available with deviation responses from 200 kHz to 5 MHz. Seven different post detection amplifier/filter plug-in modules are available for maximum data rates from 70 Kb/s to 10 Mb/s.

ISA Bus Interface Card

The radio portion of the telemetry receiver is mounted on, and electrically interfaces with, a standard full length, eight-bit, IBM-AT expansion bus card. This card, commonly referred to as an industry standard architecture or ISA bus card, provides the radio with power, controls the frequency at which the receiver operates and gives digital signal strength to the processor bus. The ISA bus section of the receiver plugs into the 62-pin connector portion of any standard 16-bit AT expansion slot.

Mechanical/Electrical Packaging

The radio portion of the series 500 telemetry receiver is packaged in a sealed, machined aluminum housing. Each of the sub-sections depicted in Figure 1 are contained within separate cavities of the housing and are connected together via semi-rigid coaxial cable. Connection of the RF signal between the plug-in modules of the receiver and the main housing are made via blind-mate connectors. This type of mechanical packaging minimizes the radiated emissions of the receiver and prevents interference from affecting the receiver or the surrounding computer circuitry.

The receiver module is mounted onto a full length ISA bus card and is interconnected to the card via a small D-connector cable. The antenna input and baseband output of the receiver are connected via semi-rigid cable to the mounting bracket of the ISA bus card.


The series 500 telemetry receiver has been integrated with several personal computer-based telemetry acquisition and processing systems. These systems typically consist of a single card slot bit-synchronizer and decommutator. The bit-synchronizer recovers the clock and data from the baseband signal provided by the receiver. The bit-synchronizer must perform this function even under poor signal conditions, including noise corruption, amplitude fluctuations due to multipath, and bit-rate variations due to a Doppler phase shift. The decommutator card then acquires frame and subframe synchronization and disassembles the recovered PCM stream. The decommutated data are then moved into the memory area of the personal computer. During decommutation, each telemetry parameter can be time-tagged with information derived from GPS or IRIG sources. Single slot ISA bus cards provide IRIG time code for time-tagging of processed data. If an external IRIG range time signal is unavailable, it can still be provided using a GPS receiver. Several single slot ISA bus GPS receiver cards are available for this purpose.

Most telemetry applications require real time observation and monitoring of only a small number of flight parameters, followed by a more in-depth analysis of all flight parameters after the mission. To support this requirement, all flight data are archived in some form during the flight. In PC-based systems, this recording function can be performed by the hard disk subsystem, or by external recording devices, such as nine-track tape, optical disk or digital audio tape (DAT). Data rates achievable with this recording technology range from 30 to 250 Kb/s of continuous recording with storage capacity of up to 50 Gb (8 mm DATs).

A typical application for this receiver is the test and evaluation of airborne telemetry data packs for surface-to-air and surface-to-surface missile flight testing. To support both depot and flight line testing requirements, a PC-based telemetry acquisition and processing receiver has been developed. The maximum PCM data rate that the bit-synchronizers in larger systems can support is 10 Mb/s. The series 500 can also support this data rate. However, the processing bandwidth of the host microprocessor does not allow for the complete decommutation, processing and storage of PCM streams at these rates, as it is limited by the data transfer rate of the ISA bus architecture. The series 500 airborne telemetry packs employ much slower data rates of 256 Kb/s and are well suited for a PC-based system.


The series 500 PC-based receivers provide telemetry users with a low cost, easily reconfigured product. The receiver modules cost $8550 and the plug-in modules cost from $800 to $2400.

SEMCO RF PRODUCTS, Carlsbad, CA (619) 438-8280.
COPYRIGHT 1993 Horizon House Publications, Inc.
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Copyright 1993 Gale, Cengage Learning. All rights reserved.

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Title Annotation:Product Feature
Publication:Microwave Journal
Article Type:Product Announcement
Date:Mar 1, 1993
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