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Datum Systems employees have been in the satellite communications business for
more than 25 years. We have attached several tech
and application notes here for reference
to visitors. These Tech Notes are no longer kept in numerical
order, so that newer (perhaps more relevant) notes appear closer to the top.
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Tech Note
12 -
Transitioning to the PSM-500 Modem (PDF
Only)
- The new PSM-500 series of modems is
being released on a world full of PSM-4900s. Here are some notes on making the
transition and linking this new modem to existing Datum Systems modems.
- Tech Note 1 - Bits, Symbols, Modulation and
Coding
- This tech note describes the relationship between the common terms used to describe the
performance of digital modems.
- Tech Note 2 - Synchronizing Link Data Rates
- This tech note describes some common methods of achieving data rate synchronization over
a link and pitfalls to avoid.
- Tech Note 3 - L-Band
Modem Station
Application Guide
- A new white paper on the design and construction of a simple station
based on the Datum Systems' PSM-4900L Modem.
This modem incorporates an L-Band IF interface, greatly reducing the cost of
building a small station. Download Tech Note 3 in Adobe
Acrobat Format here L-Band App
A second method
for medium size stations is shown in Tech Note 8 below using Hybrid modems.
- Tech Note 4 - Modem Carrier Tracking Rates
- This tech note describes some common methods of achieving data rate synchronization over
a link and pitfalls to avoid.
- Download/View Tech Note 4 in Adobe Acrobat Format
here CxrTrack
- Tech Note 5 - Modem Bit
Delays
- This tech note describes the delays encountered in our modem transmit and
receive paths.
- Tech Note 6 - BER vs. Eb/No
Performance
Revised 6/2007
- This tech note shows the performance for Datum Systems' modems both as raw
data and classic "Waterfall" curves.
Revised in June 2007 to show the new M500 series TPC-CT FEC
mode performance including 8PSK and 16QAM modulation.
- Tech Note 7 - Simulating
a Satellite Link with Delay on the Bench
- How to simulate a satellite link, complete with delay, on the bench using
two modems.
- Tech Note 8 -
Hybrid System Application
- This tech note describes how to use Datum Systems new PSM-4900H
"Hybrid" modem to build robust low cost VSAT earth stations.
- Download/View Tech Note 8 in Adobe Acrobat Format
here Hybrid App
- Tech Note 9 - About Turbo
Product Codes
- Introductory notes about what Turbo Product Codes are and what they can do
for a system. Mainly for users not familiar with this newly available FEC
technology.
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Tech Note
10 -
Connecting M5 Modems to Routers (PDF File
only) Revised 1/2008 with HSSI
info.
- How to connect to Cisco Routers (and
others) including modem settings, clocks and cables.
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Tech Note
12 -
Transitioning from the PSM-4900 to PSM-500
Modems (PDF File only)
- What's new and different and how to mix
units in a system.
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Tech Note
15 -
How to Update the SnIP kernel and Root
Filesystem (PDF version available)
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