Tech Notes
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.
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 Noteshows 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.
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.
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.
Tech Note 15 - How to Update the SnIP kernel and Root Filesystem (PDF version available)