Datum Systems brings advanced Sharp Carrier Filter Roll-Off Technology

November 11, 2013 | By More

Datum Systems now offers improved Low Excess Bandwidth (Alpha) Filtering, in its new M7 line of Modems that allow carrier spacing at frequency offsets below 10% of the symbol rate.  Datum currently offers down to a 5% Alpha, which means that carriers can be spaced at 1.05 times the symbol rate instead of the historical factor of 1.35.  This allows an immediate spectral efficiency increase of 28.5%, resulting in 22% bandwidth savings.  Filter Roll-Off options in the new M7 modems Series include 5%, 8%, 10%, 15%, 20%, 25%, 30%, 35% and 40%.  These selections are standard options on the M7 via the front panel or remote interfaces.

 Sharp Carrier

Datum continues to save you money with more bandwidth efficient features in its new low cost M7 Series Satellite Modems.

The pioneers of Advanced Flexible LDPC coding have now added Sharper TX/RX Filter Roll-Off’s to its bandwidth reducing line-up.

Practical Example

Sharp Roll Off


The spectrum analyzer plot (Fig. 1) shows 3 16QAM carriers spaced at 1.08 times the symbol rate of 1 MHz.  The center carrier is disadvantaged by 10 dB, which is unlikely to occur on a satellite, but used to provide a worst case scenario.  The demodulator for the center carrier reports an Eb/N0 of 30 dB, which is the measurement limit for the Datum M7 demod.  This means that there is no measurable degradation in the Datum M7 modems for 16QAM at a carrier spacing of 1.08 x Symbol.

With higher transponder lease costs of up to $3500/MHz/Month, the new Sharp Carrier technique cuts the occupied bandwidth by 34% while maintaining power balance.  This in turn cuts the lease cost by up to 34%, or $1500/month, generally resulting in a payback time of less than 3 months.


This important advancement provides greater satellite bandwidth utilization and efficiency.  If you are leasing transponder space for multicarrier, and your spacing is more than 1.25 times the symbol rate, Datum advanced filtering techniques in the M7 can save you 30% or more of your transponder lease cost.

Learn more by downloading Datum´s Sharp Carrier White Paper:

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David Koblinski

About the Author ()

David Koblinski is currently the Vice President of Business Development and Partner at Datum Systems Inc., Headquartered in San Jose California. David has served in this role with Datum for the last 5 years, after a 14 year career as General Manager of Radyne Corporation. Mr. Koblinski has been working in the satellite industry for over 30 years, starting his career at Comtech Data in the 1980’s, and being part of the initial founding team of EFData. David’s entrepreneurship skills and vast experience in all facets of the satellite industry have been pivotal in bringing new products to market and meeting customers’ expectations. Being an Arizona native, David studied professionally at Arizona State University’s WP Carey School of Business Management.

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