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Modem Consulting

Floyd Kling 



I am a modem professional.  I have been in data communications for over 20 years with major focus on dial-up and Telco interfacing.  I was with Racal-Vadic for over 14 years and Ven-Tel Inc. over 5 years.  Both were pioneers in dial-up and leased-line modems.  I have worked in all levels of modems from product definition, development planning to sales and management.  


If you are trying to decide to make or buy a modem, select the chipset, questions in layout, have questions regarding certifications, or simply need general direction suggestions, I am available to help you. 


It's very confusing trying to decide the best modem for the application, and then the most cost efficient direction.  There are many technical issues to resolve before a design commences… Here are a few:


§          Do I really need 56Kbps or will 33.6Kbps work in my application?

o         What is the difference between V.92, V.90, V.34, V.32, V.32bis and even lower speeds?

o         What are the benefits or liabilities of these speeds? 

o         Which has the fastest negotiation?


§          Should I hunt down a 2400?.. a 9600? or maybe a 14.4 is better for my needs?

o         What are the benefits/liabilities of these speeds


§          Whose chipset to consider?

o         Should I consider ZiLog, Clare, AMD, TI, Agere(Lucent), SiLabs or maybe Conexant (Rockwell) – Are there others? - Can/should I make my own?

o         Which modem company/chipset will last for my product cycle?

o         What should I do if the modem/chipset I'm using is EOL'd - (yikes! -and- HELP!!!)

o         Are there alternates for the final decision?

o         Are there backup options to protect my final design?


§          Do I need to monitor or control all the I/O on a serial interface?

o         What are the minimum I/O signals I 'really' need to monitor or control?

o         How do I manage flow controls?  -

§          What are the advantages of "inband" vs. "out of band" flow control?

§    What the heck is flow control anyway and why is it important?


§          What is auto baud and auto parity?

o          Are they important? Do I need them?... Why would I need them?


§          Do I need data compression or error correction?

o         Does it make a difference? 


§          What is the appropriate setup string for my application?

o         What the heck is a ‘setup string’?


§          Should I consider parallel or serial interface?

o         TTL, RS232, USB? ...or is there another?

o         What about I/O voltage/load compatibility?


§          Do I have a power problem?

o         What are the considerations for power efficiency of the chipset/or module available?

o         Should I look at 3.3V or 5V? - Are there others?

o         Are there performance issues with the different voltages?

o         Is there an efficient way to get to "0" power??? (Yes, there is!...)

o         Hmmm, can I run a modem on telephone line power?


§          Should a "Soft Modem" fit into my plans?


§          Are there patent issues with any modem decision?

o         How do I protect myself


§          What are the FCC/DOC certification issues with connecting to a phone line?

o         How about International Homologation?

o  Which countries are the easiest? – Which are difficult?

o  What is CTR-21? Does it affect my design?


§          How does the modem effect Pt. 15A/B in my final product?

o         Is there a way to keep the EMI/RFI emissions to a minimum?


§          What can/should I add on the DAA without violating the agency requirements?


§       Should the modem withstand an inadvertent connection to digital PBX?


§       Can I operate my modem over VoIP?


§       Do I really want to become a modem company?

o   Does one modem design warrant the agency and support effort?


Together we can save research time and development effort.  I can help you make the right decision early in the definition stage and ease the development and production release times.  We can save literally tens of thousands of dollars – Even more depending on your anticipated production volumes.


As marketing and design professionals, we all have formulated a design direction only to find late in the project there were better decisions that could have been made.  We have all said, “If I had only known...”.


Drop me an email and we will quickly decide if I can help.


Floyd Kling


Copyright © 1997-2011 Floyd Kling 
- All Rights Reserved -