Doug Lung /
07.18.2013 08:20 PM
‘Transpositional Modulation’ Could Greatly Boost Data Rates
Called ‘first truly new form of modulation in more than a decade’
TM Technologies, a division of Medusa Scientific, announced this week that it has successfully demonstrated a “breakthrough modulation technology” that has the potential to increase data rates between two and 33 times within a given amount of bandwidth.

The new modulation technique is called “Transpositional Modulation”(TM). Medusa Scientific's Chief Scientist Rick Gerdes said it is “the first truly new form of modulation in more than a decade, and the only form of RF modulation that has a real DC response and is completely transparent to other modulation forms.”

According to Gerdes: “TM allows transmission of much higher data rates than is possible with other forms of modulation alone; can be added to existing modulations or can operate stand-alone; is immune to Doppler effects; can combine multiple different data streams into and out of a single signal, and; generally provides the capability to meet the data rate demands of UHD and other data-intensive RF requirements.”

The news release said the company expects to complete a prototype satellite modem for testing in August that is expected to dramatically increase “bent-pipe” data rates. A demonstration of transmission of 4K UHD is planned for early September.

No details were provided on how transpositional modulation works, but the news release explanation triggered memories of an early DTV transmission technology. The news release said the patent on TM is still pending, but a search for patents with Richard Gerdes as the inventor turned up Patent #5200715 – Waveform modulation and demodulation methods and apparatus and Patent #5327237 – Transmitting data with video.

The abstract for Patent #5200715 reads: “The modulation circuit defines a non-linear voltage current transfer function wherein at low voltage levels the current voltage transfer function is substantially linear and at higher voltages, the transfer function is substantially exponential. The modulation circuit can be designed of three parallel branches…Demodulation circuitry is also disclosed that includes a circuit for determining the instantaneous phase and amplitude and then processing circuitry to decode the modulation information based upon the sampled phase and amplitude data.”

Drawings included in the Patent show the modulation results from changing the shape, but not the overall phase, frequency or amplitude, of the original RF sine wave by doing things such as adding indentations to it.

During the selection of the U.S. DTV standard, this was called the GENESYS system. It is listed in Development of HDTV Emission Systems in North America by Robert Hopkins at the Advanced Television Systems Committee and Kenneth P. Davies of Canada’s CBC. The paper describes the modulation “as a form of waveform modulation which carries the digital HDTV signal by modifying the shape--not the frequency or amplitude or phase--of the carrier making it 'invisible' to frequency or amplitude or phase demodulators.”

More information on transpositional modulation should be available after the announced demonstrations. The information provided so far mentioned an improved data rate in the same bandwidth, but I didn't see any mention of the critical third item in any modulation technology--the signal to noise (SNR) required to receive the higher data rate signal.

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Posted by: Anonymous
Sun, 08-04-2013 11:43 PM Report Comment
Without reviewing the patents in their entirety, I see they were filed in 1993 / 1994. Why has it taken until now. to realize? If this was such astounding technology, why no one has picked it up? And, did the actually demonstrate it? You can write all the patents you want to, but unless you can actually demonstrate it successfully, it isn't worth the paper it is written on. That's what is wrong with most Venture-capital endeavors. They promise astronomical profits and spectacular IP until they have to actually make it work. The best people to ask if this would really work is ARTM (Advanced Range Telemetry Modulation) group at Edwards AFB, Ca.
Posted by: Anonymous
Tue, 09-03-2013 03:51 PM Report Comment
I've reviewed the company and the technology and have witnessed that Transpositional Modulation function first-hand. Actually the patents filed by the company were only done in 2012 and 2013 and are materially different from those old, expired patents which their Chief Scientist participated in in 1993 & 1994.

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