International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / Today’s telemetry environment is becoming increasingly digital. Highly reliable and
relatively inexpensive digital recorders readily available, and most telemetry facilities are
migrating away from the older analog recorders which are difficult to calibrate and
expensive to maintain. Unfortunately, most site managers find they still have one or more
“legacy” signals (such as FM-FM, PAM, and pre-detect PCM) that still require analog
recording. To exclusively use digital recorders the TM site must integrate some device to
convert the analog signals to digital format before recording.
Until recently, the TM site managers had very few options short of building custom
equipment to convert and capture the legacy signals. One solution available from Racal
(for their Storeplex digital recorder) is to purchase their Analog Record/Play Signal
Module. Unfortunately, their module uses a 16-bit Sigma-Delta converter and has a
maximum bandwidth of 45.5 KHz, which is woefully inadequate for many analog signals.
Other manufacturers offer similar solutions with similar bandwidth restrictions. Another
solution is to purchase a multiplexor “front-end” which is capable of mixing multiple signal
types (both digital and analog) on to the recorder’s serial-digital data stream. This option
can provide higher analog bandwidths, but represents a significant investment (greater than
$100K and often more than the recorder itself).
This paper discusses the conceptualization, design, and performance of a unit to fill the
gap between the low-bandwidth analog channel module and the high-end signal
multiplexors. We will discuss how high-speed field-programmable gate arrays (FPGAs)
can be configured to provide a low-cost interface between the digital recorder and the
analog-to-digital converters (ADCs) and digital-to-analog converters (DACs) to capture
and playback the analog signals. Our design focuses on achieving the maximum possible
bandwidth for each analog signal while ensuring that IRIG-A or IRIG-B timecode are
recorded simultaneously (so the analog signals can be later synchronized with their digital
counterparts). We have found that such a solution permits multiple analog signals from 400
KHz up to 3 MHz to be easily and inexpensively recorded on the current generation of
digital recorders. Our conclusions show that such a device can permit most telemetry sites
to transition completely to more reliable, cheaper, and easier-to-maintain digital recorders.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/608382 |
| Date | 10 1900 |
| Creators | Bougan, Timothy B. |
| Contributors | Science Applications International Corporation |
| Publisher | International Foundation for Telemetering |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Proceedings |
| Rights | Copyright © International Foundation for Telemetering |
| Relation | http://www.telemetry.org/ |
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